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{{Adams
#REDIRECT [[L-2008-030, Supplemental Response to NRC Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors]]
| number = ML080650560
| issue date = 02/27/2008
| title = St. Lucie, Units 1 & 2, Supplemental Response to NRC Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors
| author name = Johnston G L
| author affiliation = Florida Power & Light Co
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000335, 05000389
| license number =
| contact person =
| case reference number = GL-04-002, L-2008-030
| document type = Letter, Report, Miscellaneous
| page count = 86
}}
 
=Text=
{{#Wiki_filter:Florida Power & Light Company, 6501 S. Ocean Drive, Jensen Beach, FL 34957 February 27, 2008 F=PL L-2008-030 10 CFR 50.54(f)U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Florida Power & Light Company St. Lucie Units 1 and 2 Docket Nos. 50-355 and 50-389
 
==Subject:==
Supplemental Response to NRC Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors"
 
==References:==
 
(1) Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors," dated September 13, 2004 (2) Letter from J. A. Stall (FPL) to U. S. Nuclear Regulatory Commission"Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized Water Reactors," dated March 4, 2005 (3) Letter from B. T. Moroney (U. S. Nuclear Regulatory Commission) to J. A.Stall (FPL), "St. Lucie Plant, Units 1 and 2 -Request for Additional Information (RAI) Related to Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Sump Recirculation During Design Basis Accidents at Pressurized Water Reactors," dated June 2, 2005 (4) Letter from J. A. Stall (FPL) to U. S. Nuclear Regulatory Commission"Request for Additional Information
-Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized Water Reactors," dated July 20, 2005 (5) Letter from J. A. Stall (FPL) to U. S. Nuclear Regulatory Commission"Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized Water Reactors -Second Response," dated September 1, 2005 (6) Letter from B. T. Moroney (U. S. Nuclear Regulatory Commission) to J. A.Stall (FPL) "St. Lucie, Units 1 and 2, Request for Additional Information Re: Response to Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design-Basis Accidents at Pressurized-Water Reactors," dated February 8, 2006 (7) Letter from C. T. Haney (U. S. Nuclear Regulatory Commission) to Holders of Operating Licensees for Pressurized Water Reactors, "Alternate Approach for Responding to the Nuclear Regulatory Commission Request an FPL Group company St. Lucie Units 1 and 2, Docket Nos. 50-335 and 50-389 L-2008-030, Page 2 of 4 Approach for Responding to the Nuclear Regulatory Commission Request for Additional Information RE: Generic Letter 2004-02," dated March 28, 2006 (8) Letter from C. T. Haney (U. S. Nuclear Regulatory Commission) to Holders of Operating Licenses for Pressurized Water Reactors, "Alternate Approach for Responding to the Nuclear Regulatory Commission Request for Additional Information Letter Regarding Generic Letter 2004-02," dated January 4, 2007 (9) Letter from W. H. Ruland (U. S. Nuclear Regulatory Commission) to A.Pietrangelo (Nuclear Energy Institute), "Content Guide for Generic Letter 2004-02 Supplemental Responses," dated August 15, 2007.(10) Letter from W. H. Ruland (U. S. Nuclear Regulatory Commission) to A.Pietrangelo (Nuclear Energy Institute), "Revised Content Guide for Generic Letter 2004-02 Supplemental Responses," dated November 21, 2007 (11) Letter from W. H. Ruland (U. S. Nuclear Regulatory Commission) to A.Pietrangelo (Nuclear Energy Institute), "Supplemental Licensee Responses to Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors," dated November 30, 2007 (12) Letter from J. A. Stall (FPL) to U. S. Nuclear Regulatory Commission"Request for Extension of Completion Date of the St. Lucie Unit 1, St. Lucie Unit 2 and Turkey Point Unit 3 Generic Letter 2004-02 Actions," dated December 7, 2007 (13) Letter from J. A. Stall (FPL) to U. S. Nuclear Regulatory Commission"Response to Questions Regarding Request for Extension of Completion Date of the St. Lucie Unit 1, St. Lucie Unit 2 and Turkey Point Unit 3 Generic Letter 2004-02 Actions," dated December 20, 2007 (14) Letter from T. H. Boyce (U. S. Nuclear Regulatory Commission) to J. A.Stall (FPL) "St. Lucie Nuclear Plant, Units 1 and 2, and Turkey Point Nuclear Plant, Unit 3 -Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design-Basis Accidents at Pressurized Water Reactors, Extension Request Evaluation," dated December 28, 2007 The purpose of this submittal is to provide the Florida Power & Light Company (FPL)supplemental response to Generic Letter (GL) 2004-02 (Reference
: 1) for St. Lucie Units 1 and 2. The U. S. Nuclear Regulatory Commission (NRC) issued Reference 1 to request that addressees perform an evaluation of the emergency core cooling system (ECCS) and containment spray system (CSS) recirculation functions in light of the information provided in the GLand, if appropriate, take additional actions to ensure system functions.
St. Lucie Units 1 and 2, Docket Nos. 50-335 and 50-389 L-2008-030, Page 3 of 4 Additionally, the GL requested addressees to provide the NRC with a written response in accordance with 10 CFR 50.54(f).
The request was' based on identified potential susceptibility of the pressurized water reactor (PWR) recirculation sump screens to debris blockage during design basis accidents requiring recirculation operation of ECCS or CSS and on the potential for additional adverse effects due to debris blockage of flowpaths necessary for ECCS and CSS recirculation and containment drainage.Reference 2 provides the initial FPL response to the GL. Reference 3 requested additional information regarding the Reference 2 response to the GL for St. Lucie Plant, Units 1 and 2.Reference 4 provided the FPL response to Reference
: 3. Reference 5 provides the second of two responses requested by the GL. Reference 6 requested FPL to provide additional information to support the NRC staff's review of References 2, 4, and 5. Reference 7 provided an alternative approach and timetable that licensees may use to address outstanding requests for additional information (i.e., Reference 6).Reference 8 supplemented Reference 7 with the NRC expectation that all GL 2004-02 responses will be provided no later than December 31, 2007. For those licensees granted extensions to allow installation of certain equipment in spring 2008, the NRC staff expects that the facility response will be appropriately updated with any substantive GL corrective action, analytical results, or technical detail changes within 90 days of the change or outage completion.
As further described in Reference 8, the NRC expects that all licensees will inform the NRC, either in supplemental GL 2004-02 responses or by separate correspondence as appropriate, when all GSI-191 actions are complete.Reference 9 describes the content to be provided in a licensee's final GL 2004-02 response that the NRC staff believes would be sufficient to support closure of the GL. Reference 10 revised the guidance provided in Reference 9 by incorporating minor changes which were viewed by the NRC as clarifications.
However, Reference 10 was issued after major development of this response, using the guidance of Reference
: 9. Therefore, this response was prepared using the guidelines of Reference 9.Reference 11 authorized all PWR, licensees up to two months beyond December 31, 2007 (i.e., to February 29, 2008), to provide the supplemental responses to the NRC.In Reference 12, FPL requested an extension for completing St. Lucie Unit 1 and Unit 2 chemical effects testing and analysis activities until June 30, 2008, and in-vessel and ex-vessel downstream effects evaluations until March 31, 2008. Reference 13 provided FPL's response to NRC questions regarding Reference
: 12. The request for an extension was approved in the Reference 14 evaluation.
In accordance with References 1, 7, 8, 9, and 11, FPL is providing the necessary supplemental response, addressing GL actions at St. Lucie Units 1 and 2, in Attachments 2 and 3 to this letter.Regulatory commitments made in this submittal are summarized in Attachment 1.This information is being provided in accordance with 10 CFR 50.54(f).
St. Lucie Units 1 and 2, Docket Nos. 50-335 and 50-389 L-2008-030, Page 4 of 4 Please contact Ken Frehafer at (772) 467-7748 if you have any questions regarding this response.I declare under penalty of perjury that the foregoing is true and correct.Attachments:
(3)cc: NRC Regional Administrator, Region II USNRC Project Manager, St. Lucie Nuclear Plant Senior Resident Inspector, USNRC, St. Lucie Nuclear Plant St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 1 Page 1 of 2 ATTACHMENT 1 Summary of Commitments St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 1 Page 2 of 2 Commitments Contained in this Letter Commitment Description NRC Commitment Date Final demonstration that ECCS/CSS recirculation pumps can operate 31-Mar-08 under long-term post-LOCA conditions.
Final in-vessel/in-core demonstration that core fuel temperatures are acceptably low based on chemical evaluations and considerations 31-Mar-08 regarding the potential for chemicals plating-out on nuclear fuel.St. Lucie Unit 2: Completion of integrated chemical effects testing in a large flume on the St. Lucie strainer designs that provides results and 30-Jun-08 analysis that supports generic letter compliance.
St. Lucie Unit 1: Completion of integrated chemical effects testing and 30-Jun-08 analysis that supports generic letter compliance.
Final submittal to NRC with responses to RAIs, affirmation of compliance to the regulatory requirements of the generic letter including revised calculations/results as required, summary of the updated licensing and design basis.Submit Technical Specification Amendment Requests to increase RWT 30-Jun-08 levels for St. Lucie Units 1 and 2.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 2 Page 1 of 33 ATTACHMENT 2 St. Lucie Unit 1 GL 2004-02 Supplemental Response St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 2 of 33 Topic 1: Overall Compliance FPL Response The response to GL 2004-02 that was submitted to the NRC on September 1, 2005 (September 1 response) was based on the information that was available at that time.Subsequent to the September 1 response, the identified corrective actions have been completed, (e.g., new sump strainers, pump seal replacement and insulation improvements).
In addition, improvements in programmatic controls have been implemented to ensure that the potential quantity of debris is maintained within the new sump strainer design values.These corrective actions have created NPSH margin, reduced the size of debris that can pass through the sump strainers, reduced the maximum quantity of insulation that could be generated and transported to the sump strainers and enhanced the capability of the HPSI pump for long-term operation in the recirculation mode. Walkdowns have confirmed that there are no choke points that could prevent the design basis volume of water from being available for recirculation.
However, as discussed in the request for extension submitted on December 7, 2007 (FPL Letter L-2007-155), completion of selected confirmatory tests and analyses has been delayed until June of 2008. The delayed tests and analyses are those that depend on the resolution of chemical effects issues and those that are impacted by the recent revision to WCAP-16406-P, "Evaluation of Downstream Sump Debris Effects in Support of GSI-191," Revision 1, August, 2007.As noted in Topic 3.g, Net Positive Suction Head Available (NPSH), sump level calculations were revised to accommodate potential areas for water holdup based on lessons learned from the NRC audit of the Waterford sump program. This resulted in calculated values of the post-LOCA containment sump level below those that were tested and analyzed for the St. Lucie Unit 1 strainer system. As further discussed in Topic 3.0, Licensing Basis, FPL recently determined that an amendment to the Technical Specifications, raising the minimum Refueling Water Tank (RWT) level, is required to correctly bound St. Lucie Unit 1 strainer test results and calculations.
Hence, an amendment to the St. Lucie Unit 1 Technical Specifications requesting the necessary increase in RWT level will be submitted by June 30, 2008. Until this amendment is approved and implemented on-site, existing administrative controls for maintaining a higher water level in the RWT will remain in effect. Some calculations and results provided in Topic 3.f, Head Loss and Vortexing, and in Topic 3.g, Net Positive Suction Head Available (NPSH), credit this current/higher RWT level.Additional information to support the staff's evaluation of St. Lucie Unit 1 compliance with the regulatory requirements of GL 2004-02 was requested by the NRC in a Request for Additional Information (RAI) dated February 8, 2006 (NRC Letter to FPL (J. A. Stall), St. Lucie Plant, Units 1 and 2, Request for Additional Information RE: Response to Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized-Water Reactors" (TAC Nos. MC4710 and MC471 1), dated February 8, 2006). Each RAI question is addressed in this response.
The RAI question (and specific RAI response) is identified by the RAI question number in the following format: [RAI ##], where ## is the RAI question number.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 3 of 33 Based on the completed corrective actions, enhanced procedural controls, and planned Technical Specification amendment, it is expected that upon completion of the confirmatory tests and analyses, St. Lucie Unit 1 will be demonstrated to be in compliance with the regulatory requirements listed in GL 2004-02.However, although not expected, the final testing and analyses may result in further reexamination of original assumptions and bases of other calculations or, potentially, additional corrective actions. In the case that additional corrective actions are required, FPL will contact the Commission.
Topic 2: General Description of and Schedule for Corrective Actions FPL Response The corrective actions identified for St. Lucie Unit 1 have been completed.
However, Florida Power & Light requested, and received, a short extension to complete selected confirmatory tests and analyses.
The delayed tests and analyses are those that depend on the resolution of chemical effects issues and those that are impacted by the recent revision to WCAP-16406-P, Evaluation of Downstream Sump Debris Effects in Support of GSI-191, Revision 1, August, 2007.A general description of the actions already taken or planned to be taken is presented below. Additional details are contained in subsequent sections of this response.The original sump screens have been completely replaced with a strainer system that has a strainer surface area of 8,275 ft 2.The new system consists of 21 strainer modules with interconnecting piping, and is passive (i.e., it does not have any active components or rely on backflushing).
The strainer system is described in the response to NRC Topic 3.j, Screen Modification Package.The High Pressure Safety Injection (HPSI) pump seals and cyclone separators have been replaced with a seal system that does not use cyclone separators or rely on the HPSI pumped water for flushing and cooling the mechanical seals. The new seal system recirculates the seal cavity water through an external heat exchanger to flush and cool the seal faces. The new seal system will prevent the potential failure of shaft seals that could be caused by the carryover of debris in the pumped water when the HPSI pumps take suction of potentially debris-laden fluid from the new containment strainer system in the recirculation mode.The calcium-silicate insulation (cal-sil) on selected piping in the containment has been reinforced with a banding system to reduce the cal-sil zone of influence (ZOI) from 5.45D to 3.OD. The banding system consists of 11/2-inch wide stainless steel bands spaced approximately 3 inches on center. The banding system and the test that confirms the efficacy of the system are described in the response to NRC Topic 3.b, Debris Generation/Zone of Influence (ZOI) (excluding coatings).
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 4 of 33 A walkdown to confirm the absence of potential choke points was completed.
The results of this walkdown are described in the response to NRC Topic 3.1, Upstream Effects.The downstream effects assessments of the fuel and vessel are ongoing. FPL is participating in the PWR Owners Group (PWROG) program to evaluate downstream effects related to in-vessel long-term cooling using the methodology of WCAP-16793-NP, "Evaluation of Long-Term Cooling Considering Particulate, Fibrous and Chemical Debris in the Recirculating Fluid," Rev. 0 (WCAP-16793-NP).
Still ongoing is a St Lucie Unit 1 calculation using plant-specific parameters and WCAP-16793-NP methodology to confirm that chemical plate-out on the fuel is acceptable.
It is planned to have this assessment completed in accordance with the schedule provided to the NRC Staff in letter L-2007-155.
The downstream effects assessment of pumps is being revised to incorporate the methodology of WCAP-16406-P, Revision 1, "Evaluation of Downstream Sump Debris Effects in Support of GSI-191" (WCAP-16406-P).
It is planned to have this assessment completed in accordance with the schedule provided to the NRC Staff in letter L-2007-155.Enhancements to programmatic controls have been put in place at St. Lucie Unit 1.Engineering procedures have been revised to provide guidance to the design engineer working on plant modifications to take into account the impact of the design on the"containment sump debris generation
& transport analysis and/or recirculation functions." As an enhancement to the existing process for controlling the quantities of piping insulation within the containment, the engineering specification that controls thermal insulation was revised to provide additional guidance for maintaining containment insulation configuration.
New controls have been instituted limiting the permissible quantity of unqualified coatings in the containment building to ensure that the ECOS strainer design requirements, as documented in the St. Lucie Unit 1 debris generation calculation, remain within permissible limits.Based on the results of the latent debris and foreign material walkdowns that were performed, it was determined that changes in the St. Lucie Unit 1 housekeeping procedures are not required because of the limited amount of material observed.The September 1 response stated that updates to the licensing basis would be performed in accordance with the requirements of 10 CFR 50.59. However, it has recently been determined, based on a review of the Waterford audit results, that the current administratively controlled Refueling Water Tank (RWT) water level should be incorporated into the Technical Specifications.
Chemical effects testing will be performed by Alion Science and Technology.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 5 of 33 A final submittal will be made to the NRC on or before June 30, 2008 that will provide the final conclusions regarding St. Lucie Unit 1 compliance with GL 2004-02. This submittal will also include responses to the remaining RAls.As discussed further in Topic 3.0, Licensing basis, FPL will also submit an amendment request to raise the Technical Specification minimum level for the Refueling Water Tank (RWT) by June 30, 2008.Topic 3.a: Break Selection FPL Response In agreement with the staff's SE of NEI 04-07, the objective of the break selection process was to identify the break size and location which results in debris generation that will maximize the head loss across the containment sump strainers.
Breaks were evaluated based on the methodology in Nuclear Energy Institute (NEI) guidance document NEI 04-07 as modified by the staff's SE of NEI 04-07.The following specific break location criteria were considered:
* Breaks in the reactor coolant system with the largest amount of potential debris within the postulated ZOI," Large breaks with two or more different types of debris, including breaks with the most variety of debris," Breaks in areas with the most direct path to the sump,* Medium and large breaks with the largest potential particulate debris to insulation ratio by weight, and* Breaks that generate an amount of fibrous debris that, after transport to the sump strainers, could form a uniform "thin bed." The spatial distribution of the strainer modules around the containment perimeter minimizes any beneficial effects that debris transport mechanisms would have on reducing the quantity and mix of debris that could be transported to a strainer module (or modules).
Therefore, for St. Lucie Unit 1, the break location is of secondary importance, and the primary consideration is the debris generated by the break.[RAI 34] Reactor Coolant System (RCS) piping and attached energized piping was evaluated for potential break locations.
Inside the bioshield, breaks in the hot legs (42-inch ID), cold legs (30-inch ID), crossover legs (30-inch ID) and the pressurizer surge line (12-inch nominal) were considered.
Feedwater and main steam piping were not considered for potential break locations because ECCS in recirculation mode is not required for Main Steam or Feedwater line breaks. The other piping lines located in the same general area as the RCS piping were not considered for potential break locations because they have a smaller diameter (10 inches maximum), which will produce a much smaller quantity of debris.[RAI 33] Inside the bioshield, the break selection process used the systematic approach in the staff's SE of NEI 04-07. Break locations were selected in 5-foot increments along the applicable RCS piping to determine the maximum worst case debris mix.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 6 of 33 A hot leg or cold leg line break at the reactor pressure vessel (RPV) was also considered.
The RPV is covered with Transco reflective metallic insulation (RMI) on the vessel, and Nukon insulation on the top head. This break would affect the reactor insulation and the insulation on the RCS lines adjacent to the break up to the penetrations.
However, this debris would fall to the bottom of the reactor vessel cavity.In addition, the amount of debris would be bounded by a hot or cold line break elsewhere on the line. Therefore, a hot leg or cold leg break at the RPV was not analyzed.Outside the bioshield, breaks were considered in the safety injection lines. The safety injection lines are of smaller diameter than the RCS piping, and are located in the same general area inside the bioshield.
Therefore, inside the bioshield, a break in these lines would be bounded by the reactor coolant loops, and thus need not be analyzed.However, each safety injection line travels outside the bioshield before the second isolation valve. (These lines each have a check valve located inside the bioshield that will isolate the RCS from the upstream portion of the line outside the bioshield.)
The safety injection lines are the only RCS-connected larger lines that travel outside the bioshield before the second isolation valve, and, therefore, were selected in order to include a break outside the bioshield.
The two steam generator (SG) loops are nearly identical, except that Loop B also includes the pressurizer and associated piping. Both SG loops were investigated, and it was found that Loop B contained the limiting breaks.The postulated break locations were as follows: S1 Loop B hot leg at the base of the steam generator (42-inch ID)S2 Loop B crossover leg at the base of the steam generator (30-inch ID)S3 Safety Injection line outside the missile barrier (12-inch nominal line)Break S1 generated the greatest quantity of debris. Therefore, it was selected for the strainer design basis.Topic 3.b: Debris Generation/Zone of Influence iZOI) (excluding coatings)FPL Response The debris generation calculation used the methodologies of Regulatory Guide 1.82, Rev. 3, NEI 04-07 and the staff's SE of NEI 04-07. However, there have been changes in the input to the analyses since the September 1 response.Debris specific ZOIs were used in the debris generation calculation for low density fiber glass (LDFG), reflective metal insulation (RMI) and calcium-silicate (cal-sil).
The ZOIs for insulation materials, with the exception of reinforced cal-sil, were obtained from Table 3-2 and § 3.4.2.2 of the staff's SE of NEI 04-07. The ZOIlfor reinforced cal-sil is based on testing. The ZOI for each debris type is discussed below.The ZOI used for LDFG (Nukon and Transco Thermal-Wrap) is 17.OD, which was obtained from Table 3-2 of the NRC staff's SE of NEI 04-07. The staff's SE of NEI 04-07 does not have specific ZOI information for Transco Thermal-Wrap, which is installed on the steam generators.
This insulation is fiber blanket insulation with stainless steel St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 7 of 33 jacketing, which is similar to Nukon. For this reason, the Nukon ZOI is applied to Transco Thermal-Wrap.
The ZOI used for RMI is 2.0D, which was obtained from Table 3-2 of the NRC staff's SE of NEI 04-07.Two ZOIs were used for cal-sil; 5.45D for unmodified cal-sil and 3.0D for reinforced cal-sil.The ZOI for unmodified cal-sil was obtained from Table 3-2 of the staff's SE of NEI 04-07.The ZOI for reinforced cal-sil is based on testing as discussed below.In order to reduce the quantity of cal-sil debris that could be generated by a LOCA, reinforcing stainless steel bands were installed on selected sections of cal-sil insulated piping during the recently completed outage, SL1-21 (spring 2007). The banding system consists of 11/2-inch wide stainless steel bands that are installed around the outside of the insulation jacket. The bands are spaced approximately 3 inches on center. Tests to determine the efficacy of the banding system were conducted by Westinghouse utilizing the facilities of Wyle Laboratories.
A description of the tests and the test results are contained in WCAP-1 6851-P ("Florida Power and Light (FPL) Jet Impingement Testing of Cal-Sil Insulation," Rev. 0, October 2007). The tests confirmed that when this stainless steel banding system is in place "... the material outside a ZOI of > 3D may be excluded as a debris source for the purposes of GSI-1 91 post-LOCA sump screen, downstream and chemical evaluations," (i.e., the ZOI for the reinforced cal-sil is 3.0D). The test thermal-hydraulic conditions (pressure and temperature) were selected so that conditions associated with a postulated large-break LOCA (LBLOCA) blowdown were accurately simulated, and the data from the test is directly applicable to PWRs without any scaling or other type of compensation.
This included simulating an instantaneous break to create an initial shock wave followed by a 30-second blowdown (which bounds a PWR LBLOCA).The cal-sil on small attachments to the piping, such as Tees and valves was not reinforced.
This was taken into account in the debris generation calculation by adding the calculated volume of cal-sil on these attachments, 10.21 ft 3 , to the calculated volume of cal-sil debris.The updated debris generation calculations make use of two assumptions related to non-coating debris generation.
Assumption 1 Supporting members fabricated from steel shapes (angles, plates) are installed to provide additional support for the mirror insulation on equipment such as reactor coolant pumps, Steam Generators and Pressurizer.
It is assumed that, as a result of the postulated pipe break, these supporting members will be dislodged from the equipment, and may be bent and deformed, but will not become part of the debris that may be transported to the sump.Assumption 2 In the September 1 response, it was noted that an analytical process was used that conservatively overstated the quantity of debris from insulation by 5-15%. This analytical process has been completely replaced.
However, a 10% margin has been added to the insulation volume results. In addition, a uniform factor of 1.1 is applied to St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 2 Page 8 of 33 the ZOI used for calculating piping insulation volumes to account for minor variances such as insulation around valves, irregularities in the as-installed configuration, etc.The quantities of debris and the ZOI for each debris type are provided below.Table 3.b-1: Destruction ZOI and Break Comparison in Table 3.b-1 Debris Type Destruction Break S1 Break S2 Break S3 ZOI (Note 1) (Note 1) (Note 1)RMI 2.OD 857.2 ftý 419.4 ftC 0.0 ft Cal-Sil (total) 91.1 ft" 56.6 24.4 ftJ Reinforced 3.OD Unreinforced 5.45D Nukon 17.OD 169.0 ftW 111.0 ftW 9.1 ft Transco Thermal-Wrap 17.OD 1197.6 ft" 866.5 ft 4.7 ft" Insulation Jacketing (total) 4988 ft" 3396 ft 2  241 -ft Cal-Sil (total)Reinforced 3.OD Unreinforced
.5.45D Nukon 17.OD Transco Thermal -Wrap 17.OD Coatings (Note 2)Qualified
-Concrete 4.0D 3.66 ft 3  1.80 ft 3  0.50 ft 3 Qualified
-Steel 4.0D 1.59 ft 3  1.25 ft 3  0.25 ft 3 Unqualified N/A 9.96 ft 3  9.96 ft 3  9.96 ft 3 Latent Debris N/A 134.7 Ibm 134.7 Ibm 134.7 Ibm (15% fiber, 85% particulates)
I_ I_ I Foreign Materials (Note 3) N/A 88.1 ft' 88.1 ft' 88.1 ft 2 Notes: 1. Break locations are discussed in the response to NRC Topic 3.a, Break Selection.
: 2. The destruction ZOI for qualified coatings is discussed in the response to NRC Topic 3.h, Coatings Evaluation.
: 3. Strainer "Sacrificial" Area It is also noted that FPL has determined that there is approximately 128.5 ft 2 of PVC jacketing on conduits inside of containment.
This conduit does not have a post-LOCA qualification record that would substantiate whether or not the PVC jacketing would remain intact. FPL will be conducting post-LOCA qualification testing on this material, to affirm that the jacketing remains attached and does not become a coating-like debris that can transport to the sump. It is further noted that FPL maintains an unqualified coatings log for St. Lucie Unit 1, and that the amount of PVC jacket is calculated to be within the margin of the unqualified coatings contained in this log. Hence, analyzed debris loading assumptions are maintained.
This issue will be revisited when the conduit testing is completed, and will be managed within existing margins.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 9 of 33 Topic 3.c: Debris Characteristics FPL Response[RAI 35] As discussed in the staffs SE of NEI 04-07, the categories in any size distribution are related to the transport model. A conservative, straightforward, transport model was used for St. Lucie Unit 1 because the distribution of the strainer modules around the containment perimeter minimizes the effects that debris transport mechanisms would have on the quantity and mix of debris that reaches the module(s).
As a result, instead of a CFD based transport analysis, the St. Lucie Unit 1 transport model consisted of assuming that transportable debris reaches the modules. Therefore, detailed debris size distributions or other transportability characteristics are not required or developed for transport analyses.
A discussion of the debris that was assumed to be transportable is provided in the response to NRC Topic 3.e, Debris Transport.
Because a detailed transport model was not developed, the debris characteristics related to downstream effects analyses are addressed in the response to NRC Topic 3.m, Downstream Effects-Components and Systems.For the purpose of determining the strainer debris load and head loss, the only size distribution that was used was for low density fiber glass (LDFG) insulation, which consisted of a large size, 6"x3"xl", and a small size 1"xl"xl".
These sizes were used in performing the generic LDFG erosion testing. The technical basis for the applicability of LDFG erosion testing is provided in the response to NRC Topic 3.e, Debris Transport.
The bulk densities that were used to ensure that the proper quantities of the surrogate materials were used in the sector head loss tests (excluding chemical effects) are provided in Table 3.c-1 below.Table 3.c-1: Bulk Densities Used For Sector Tests Debris Type Bulk density Cal-sil 14.5 Ibs/ft 3 Fiber 2.4 Ibs/ ft 3 Zinc Filler (surrogate for zinc coatings) 457 Ibs/ ft 3 Silicon Carbide (surrogate for coatings) 94 Ibs/ ft 3 The technical basis for the surface areas of signs, placards, tags, tape, etc is provided in the response to NRC Topic 3.d, Latent Debris.The specific surface area, Sv, is a parameter that is used in the NUREG/CR-6224 head loss correlation.
The head loss across the strainers was determined by testing, not the NUREG/CR-6224 correlation.
Therefore, the specific surface area was not calculated or used. The head loss determination is described in the response to NRC Topic 3.f, Head Loss and Vortexing.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 10 of 33 Topic 3.d: Latent Debris FPL Response The bases and assumptions related to latent and miscellaneous debris, and the resulting quantities used for analyses and testing, have been updated since the September 1 response.
In that response it was noted that the quantity of latent debris was an assumed value in lieu of applied survey results, and that the sacrificial area for miscellaneous debris was an estimated value. Subsequently, walkdowns have been completed in the St. Lucie Unit 2 containment specifically for the purpose of characterizing latent and miscellaneous debris. The results of the walkdowns are discussed below and summarized in Table 3.b-1 in the response to NRC Topic 3.b, Debris Generation/Zone of Influence (ZOI) (excluding coatings).
The walkdowns utilized the guidance in NEI 02-01 and the staff's SE of NEI 04-07. The methodology, the results, and the justification for basing Unit 1 latent and miscellaneous debris on Unit 2 data are discussed below.The methodology used to estimate the quantity and composition of latent debris in the Unit 2 containment is that of the staff's SE of NEI 04-07, Section 3.5.2. Samples were collected from eight surface types; floors, containment liner, ventilation ducts, cable trays, walls, equipment, piping and grating. For each surface type, a minimum of four (4)samples were collected, bagged, and weighed to determine the quantity of debris that was collected.
A statistical approach was used to estimate an upper limit of the mean debris loading on each surface. The horizontal and vertical surface areas were conservatively estimated.
The total latent debris mass for a surface type is the upper limit of the mean debris loading multiplied by the conservatively estimated area for that surface type, and the total latent debris is the sum of the latent debris for each surface type.St. Lucie Unit 1 and Unit 2 are of a similar design. The internal containment horizontal and vertical surface areas are similar. The procedures for containment closeout are the same and the organizations who perform these procedures are the same. Therefore, the Unit 2 latent debris is representative of the Unit 1 latent debris.Based on the walkdown data, the quantity of latent debris in the Unit 2 containment is estimated to be 67.36 pounds. However, in order to ensure that differences are bounded, the Unit 2 quantity of latent debris is doubled to 134.72 pounds (100% margin)for use in the Unit 1 analyses.
The latent debris composition is assumed to be 15% fiber and 85% particulate in agreement with the staff's SE of NEI 04-07.Two Unit 2 containment walkdowns were performed for the purpose of identifying and measuring plant labels, stickers, tape, tags, and other debris. This information was used to determine the strainer area that is assumed to be covered by miscellaneous
("foreign")
debris in the strainer head loss analyses.
Based on the walkdown data, the quantity of miscellaneous debris in the Unit 2 containment is estimated to be 70.482 ft 2.Unit 1 and Unit 2 are of a similar design, and the procedures for labeling and lights are similar between Unit 1 and Unit 2. Therefore, the miscellaneous debris will be similar.However, in order to allow for differences, the quantity of miscellaneous debris that was determined in the Unit 2 walkdown was increased to 88.10 ft 2 (-25% margin) for use in Unit 1 analyses and testing.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 11 of 33 Topic 3.e: Debris Transport FPL Response[RAI 41] In the September 1 response it was noted that debris transport would be analyzed using the computational fluid dynamics (CFD) based methodology outlined in NEI 04-07. However, the spatial distribution of the strainer modules around the containment perimeter minimizes the effects that debris transport mechanisms would have on the quantity and mix of debris that could be transported to the strainer modules.As a result, for the purposes of determining the strainer debris load and head loss, it was conservatively assumed that debris was uniformly distributed throughout the containment prior to the start of recirculation, and that transportable debris reached the strainer modules. For example, no credit was taken for an inactive volume or for the settling of fine debris. Because transport effects were not credited, a CFD transport analysis was not performed for the installed St. Lucie Unit 1 strainers.
However, the determination of the transportable fraction is discussed below because it was used in the determination of the debris that ultimately reached the strainer surfaces.The fraction of fibrous material (Low density fiber glass, LDFG) that is transportable during recirculation is approximately 34.2%. However, the sector head loss test conservatively assumed a transportable fraction of 36% for fibrous material.
Reflective metal insulation (RMI) and insulation jacketing are not transportable during recirculation (i.e., the transportable fraction is 0.0%). As discussed below, these values are based on the fraction of the sump pool that is turbulent and conservative estimates of the flow velocities in the fraction that is non-turbulent.
The fraction of the sump pool that is turbulent was calculated to be 20.6% for large pieces, and 30.6% for small pieces. The difference is due to a conservative assumption that fibrous material was assumed to erode and be transported to the strainers from two areas; (a) the turbulent zone and (b) the non-turbulent zone where the flow velocity is greater than the incipient tumbling velocity.
Areas where the flow velocity exceeded the incipient tumbling velocity were included with the turbulent zone. Since small pieces have a lower incipient tumbling velocity, there is a larger area of containment where this velocity is exceeded, and this larger area increased the fraction that was defined as turbulent for small pieces. This model is conservative compared to a CFD analysis because a CFD analysis would be expected to reveal low-flow areas and dead spots in places that are sheltered from the break's turbulence, and these low flow areas and dead spots would not experience complete erosion.The flow velocities in the non-turbulent areas inside the bioshield were based on the assumption that the entire flow moves in one direction from the break. This is conservative because the distribution of the strainers (which are the recirculation intake points) ensures that water will flow to several sectors, not in one direction.
Inside the bioshield, the flow velocity was calculated to be 0.113 ft/sec. The flow velocities in the non-turbulent areas outside the bioshield were based on the assumption that; (a) flow is from containment spray and is evenly distributed throughout the containment, and (b)the flow moves towards the nearest module. Outside the bioshield, two flow velocities were calculated; 0.14 ft/sec for 26.4% of the area and 0.07 ft/sec for 73.6% of the area.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 12 of 33 In the non-turbulent zone where the flow velocity is less than the incipient tumbling velocity a fraction of the fibrous material was assumed to erode and be transported.
The erosion fraction was determined by tests conducted by Alion Science and Technology.
Testing was performed in both a vertical test loop and a horizontal transport flume.Large sample pieces (6 inch x 3 inch x 1 inch) were tested at an average flow velocity of 0.37 ft/s, and small sample pieces (1 inch x 1 inch x 1 inch) were tested at an average flow velocity of 0.12 ft/s. Three methods were used to analyze the test results, and the most conservative method yielded an upper bound value of 10.3%. That is, the non-transportable fiber that is submerged in the containment pool of St. Lucie Unit 1 is expected to release 10.3% of its mass, which then travels to the sump strainer modules.The size distribution was assumed to be 60% small pieces and 40% large pieces in agreement with the staff's SE of NEI 04-07. With the assumptions and test data described above, the transportable fraction of fibrous debris was calculated to be 34.17%.RMI and insulation jacketing are considered to be non-transportable because the maximum calculated flow velocity is 0.14 ft/sec. As discussed in NUREG/CR-6808 (NUREG/CR-6808, LA-UR-03-880, "Knowledge Base for the Effect of Debris on Pressurized Water Reactor emergency Core Cooling Sump Performance," Los Alamos National Laboratory, 2003) the velocity required to transport intact RMI is >1 ft/sec, and from 0.2 to 0.8 ft/sec for single sheets. The velocity required to transport "crumpled" sheets is not provided, but is qualitatively stated as "lower" than the provided velocities.
Given that the maximum calculated velocity, 0.14 ft/sec, is below the minimum required velocity, 0.2 ft/sec, it is judged reasonable to consider RMI and insulation jacketing non-transportable.
The qualitative statement that "crumpled" sheets transport at lower velocities is countered by the margin (approximately 100%) in the velocity calculations.
The Quantity of debris that ultimately arrives at the strainer modules is provided in Table 3.e-1 below.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 2 Page 13 of 33 Table 3.e-1: Debris at Sump Strainer Modules for Limiting Case Constituent Quantity Transportable Quantity at Generated Fraction Strainer INSULATION RMI 857.2 ft 2  0.0 0.0 ft 2 Calcium Silicate (Note 1) 91.1 ft 3  1.0 91.1 ft Nukon (Note 2) 169.0 ft 3  0.3417 57.75 ft 3 Transco Thermal Wrap (Note 2) 1197.6 ft 3  0.3417 409.22 ft 3 Insulation Jacketing 4988 ft 2  0.0 0.0 ft 2 QUALIFIED COATINGS Concrete)
.3.66 ft 3  1.0 3.66 ft 3 Steel 1.59 ft 3  1.0 1.59 ft 3 UNQUALIFIED COATINGS Unqualified Coatings Log with 4.17 ft1 1.0 4.17 ft'Margin Added (50%)RCP Motor 1.85 ft 3  1.0 1.85 ft 3 HVAC Duct Joints 2.34 ft 3  1.0 2.34 ft 3 Steel Piping (Uninsulated) 0.87 ft 3  1.0 0.87 ft 3 Steel Piping (Zones 1,2) 0.73 ft 3  1.0 0.73 ft 3 LATENT DEBRIS 15% Fiber 20.2 Ibm 1.0 20.2 Ibm 85% Particulate 114.5 Ibm 1.0 114.5 Ibm FOREIGN MATERIALS (Note 3) 88.1 ft" N/A 88.1 (Signs, placards, tags, tape, etc.)Notes: 1. The sector test head loss test results were conservatively based on assuming 109.4 ft 3 of cal-sil. See the response to Topic 3.f, Head Loss and Vortexing.
: 2. The transportable fraction for insulation fiber is 34.17%. The sector head loss test results were conservatively based on assuming a transportable fraction of 36%, that is, 36% of the available fiber is transported to the strainers.
However the limiting head loss occurred at 25% of this calculated fiber load. See the response to Topic 3.f, Head Loss and Vortexing, for additional discussion.
: 3. Foreign material is actually a "sacrificial area" and a transport fraction is not applicable.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 14 of 33 Topic 3.f: Head Loss and Vortexing FPL Response A piping schematic of the ECCS and containment/reactor building spray systems is provided in Figure 3.f-1 below. A description of the strainer system, including the capability to accommodate thin bed effects, is provided in the response to NRC Topic 3.j, Screen Modification Package.[RAI 37] [RAI 40] The entire distributed strainer system is fully submerged from the initiation of recirculation through the duration of the event. At the minimum Large Break LOCA (LBLOCA) water level, the submergence of the highest opening in the strainer system is 14 inches. At the minimum Small Break LOCA (SBLOCA) water level, the submergence of the highest opening in the strainer system is 8 inches.The potential for vortexing was evaluated for the strainer modules and the highest opening in the strainer system and the inlet to the pump suction line. The results confirm that vortexing will not occur in the strainer system or pump suction inlet.Of the 21 strainer modules, there are two that are most susceptible to vortex formation due to their submergence, physical proximity to the pump suction line, and placement out on the open containment floor. The possibility of vortex formation at these two modules was evaluated and found to be negative, with a large margin. The evaluation included the assumption of a flow rate 3 times higher than the average module flow value to account for the proximity of these modules to the pump suction lines. This evaluation is, therefore, considered bounding for the rest of the module locations.
The highest opening in the strainer system is the vent on top of the intake manifold that acts as a collector for the strainer module piping runs. The possibility of vortex formation was evaluated at this location and found to be negative with a large margin. This evaluation conservatively assumed a flow rate based on a pressure differential across the vent hole greater than the maximum "crush pressure" used for strainer structural analysis.[RAI 40] Vortexing will not occur at the sump ECCS/CSS suction inlets because water from the strainers is piped directly to the suction inlets. That is, there is no location between the strainers and pump suction inlets where vortexing could occur.[RAI 40]The possibility of buoyant debris accumulation is bounded by the case of the two modules located out on the containment floor. As noted above, the minimum submergence for the strainer system is 14 inches for the LBLOCA, and 8 inches for the SBLOCA. This is judged to provide adequate separation between floating debris and the strainer system perforated surfaces.[RAI 39] The new strainer system has a surface area of approximately 8,275 ft 2 , which can accommodate the maximum debris load from the bounding break discussed in the response to NRC Topic 3.a, Break Selection.
The strainer capability to accommodate a thin bed is discussed in the response to NRC Topic 3.j, Screen Modification Package.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 15 of 33 The head loss from this system is made up of two components; the strainer disk head loss and the module/piping head loss.The strainer disk head loss, excluding chemical effects, is based on the sector head loss tests that were run specifically for St. Lucie Unit 1 by Continuum Dynamics, Inc (CDI).The sector test used two discs of a modular strainer immersed in a test tank. The sector discs were aligned vertically in the same manner as the plant strainer discs are installed above their plenums. The sector tests were performed with a submergence of 11.88+1/-0 inch. The sector tests simulated the strainer approach velocities and plant debris loads with one exception.
That exception is that the quantity of cal-sil used in the test corresponded to 109.4 ft 3 , which is 20% greater than the 91.1 ft 3 that was calculated for the bounding case. The sector test head loss was scaled to the full sized strainer system based on velocity, kinematic viscosity, and bed thickness differences.
The scaling process assumed that flow through the strainer internals is turbulent due to the abrupt direction changes and abrupt expansions from the strainer discs to plenum.At the conclusion of the tests it was determined that the maximum head loss was found to be a case with 25% plant fiber. One possible mechanism for this effect is that as fiber content increases, the particulate to fiber ratio decreases such that the fiber bed is cleaner, and water passes more easily through the debris bed.[RAI 36] The near-field effect was not credited in the design or tests. The steps taken to minimize near-field effects in the tests included placing the flow return near the bottom of the test tank to help suspend debris, and using five (5) motor driven agitators to ensure that debris remained suspended.
The agitators were started prior to debris addition to facilitate mixing and prevent settling of debris prior to strainer test pump startup. The materials used to represent the St. Lucie Unit 1 debris in the test are listed in Table 3.f-1 below.The module/piping head losses are the hydraulic losses associated with flow from the strainer plenums to the manifold and then through the manifold discharge piping to the ECCS suction. Assumptions, margins and conservatisms used in establishing the head losses are:* A maximum temperature of 210°F* A minimum temperature of 65°F" A flow rate of 8530 gpm that is conservatively assumed to apply for the duration of the event. It is based on simultaneous hot and cold leg recirculation, which is not initiated until 4 to 6 hours into the event.* A transportable fraction of 36% was assumed for low density fiberglass (LDFG)in the sector tests (i.e., 36% of the LDFG was assumed to erode and reach the strainers).
The actual transport fraction was calculated to be 34.17%.* The quantity of cal-sil in the sector test was based on 109.4 ft 3 at the strainer modules. The calculated quantity is 91.9 ft 3.* Debris accumulation was assumed to be proportional to flow rate.* Debris head loss is assumed to be directly proportional to the debris bed thickness and flow rate through the debris bed. Debris bed compression is not taken into account.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 2 Page 16 of 33* Pipe connections between the 10-foot sections of pipe are modeled as orifices that restrict the flow, which is conservative.
[RAI 39] The head loss for the strainer system, not considering chemical effects, is provided in Table 3.f-2 below. The piping head loss with clean strainers is smaller than the piping head loss with debris laden strainers.
This is because unbalanced flow (with the majority of the flow entering the strainers nearest the sump) can be modeled with clean strainers, and the unbalanced flow leads to lower piping head loss.Table 3.f-1: Sector Test Debris Materials Debris Type Material Density Manufacturer Fiber Transco Thermal Wrap (shredded) 2.4 lb/ft Transco Cal-Sil Thermo 12 Gold (pulverized) 14.5 Ib/ft Industrial Insulation Group Inorganic Zinc Carboline Carbo-Zinc 11 filler 457 Ib/ft3 Carboline Particulates Silicon Carbide (- 10 micron dia) 94 I1b/f Electro Abrasives Table 3.f-2: Strainer System Head Loss Summary (Excludinq Chemical Effects)Condition Flow Strainer Piping Total Rate Head Loss Head Loss Head Loss__ft_ igpm) f (ft) ft Debris Laden (210 OF) 8,530 1.92 5.87 7.79 Debris Laden (65 'F) 8,530 5.77 5.87 11.64 Clean 8,530 0.11 1.85 1.96 St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 2 Page 17 of 33 Figure 3.f-1: ECCS/CSS Piping Schematic St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 18 of 33 Topic 3.g: Net Positive Suction Head Available (NPSH)FPL Response Following a large break LOCA (LBLOCA) both trains of the Low Pressure Safety Injection (LPSI) Pumps, Containment Spray (CS) pumps and High Pressure Safety Injection (HPSI) pumps are automatically started. At a minimum, recirculation is not initiated until at least 20 minutes after the LBLOCA. At the present time, the RWT level is administratively controlled to be above the Technical Specification level, which increases the water volume available for recirculation and extends the time to the Recirculation Actuation Signal (RAS) beyond 20 minutes.Just prior to RAS, operators are procedurally directed to align the containment spray to the HPSI pump suction ("piggy-back" mode). On receipt of the RAS, the LPSI pumps are stopped automatically and the CS and HPSI pumps continue to operate taking suction from the containment sump. At 4 to 6 hours post-LOCA, one LPSI pump is started when the hot leg injection mode is manually initiated by operator action. For the purposes of establishing the demands on the sump strainers, simultaneous hot and cold leg recirculation flow, which is the highest post-RAS recirculation flow, is assumed for the entire event.Following a small break LOCA (SBLOCA), both trains of the HPSI and LPSI pumps are started automatically on a Safety Injection Actuation Signal (SIAS). Both trains of the CS pumps may start if the containment pressure setpoint is reached. For a SBLOCA, where the RCS pressure is above the LPSI pumps shut-off head, the LPSI pumps do not deliver flow into the RCS during the injection phase of the small break LOCA. Under these conditions the time to the Recirculation Actuation Signal (RAS), which is based on refueling water tank (RWT) level, is increased beyond the LBLOCA value of 20 minutes.On receipt of RAS, recirculation flow will begin. The range of SBLOCA breaks includes those that require recirculation from the containment sump as well as those that permit the operators to depressurize the RCS and initiate the shutdown cooling mode of decay heat removal, which does not require suction from the containment sump. Because the SBLOCA produces less debris, the debris load on the sump strainers is less than the design basis debris load. However, for the purpose of evaluating the sump strainer under SBLOCA conditions, it is conservatively assumed that the recirculation flow from the containment sump and the debris load are the same as the LBLOCA, and that the water level is that of the SBLOCA.The minimum sump water level is 23.86 feet for the LBLOCA and 23.36 feet for the SBLOCA. These water levels account for following volumes:° Volume Additions o Use of administratively controlled RWT water level o Volume occupied by the new strainer system (strainer modules, piping, etc.)* Volume Subtractions o Empty containment spray piping o Spray droplets o Bottom of the refueling cavity o Volume of water held up on horizontal and vertical surfaces St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 19 of 33 o Steam in the containment atmosphere o Reactor vessel (reflood volume)The LBLOCA flow rate used to calculate the NPSH margin is 8,530 gpm, which is the same as that used to determine the strainer system head loss discussed in the response to NRC Topic 3.f, Head Loss and Vortexing.
This flow is conservatively assumed to apply for the duration of the event. It is based on simultaneous hot and cold leg recirculation, which is not initiated until 4 to 6 hours into the event. The maximum flow rate is made up of the following components:
* Two Containment Spray System (CSS) pumps 8,130 gpm* One Low Pressure Safety Injection (LPSI) pump 400 .qpm* Total 8,530 gpm The HPSI pump flow is 640 gpm per pump. However, because the HPSI pump operates in "piggy back" mode on the CSS pump during recirculation, the HPSI flow is included in the CSS pump flow above.The temperature range used to calculate the NPSH margin is 65 0 F to 260 OF. The minimum NPSH margin occurs at a temperature of approximately 200 OF.With these conditions, the NPSH margin, excluding chemical effects, is approximately 9 ft for the LBLOCA and 8.5 ft for the SBLOCA. The key assumptions are listed below.* Containment accident pressure is consistent with Regulatory Guide 1.1 guidance (i.e., for lower temperatures where the vapor pressure of water is less than the partial pressure of air, the total containment pressure is set equal to the minimum partial pressure of air and is not increased:
for higher temperatures where the vapor pressure of water is greater than the minimum partial pressure of air, the total containment pressure is set equal to the vapor pressure of water)* NPSH required (NPSHR) is based on pump test curves* Strainer head loss, excluding chemical effects, was determined by testing* 1% is added to flow rates to account for uncertainties The single failure relevant to sump strainer performance is the failure of an operating LPSI pump to trip on receipt of the RAS. It is expected that the operator would take action to trip this pump manually during verification of RAS actions, one of which is to"ENSURE LPSI Pumps STOPPED." Thus, this condition is expected to be temporary or short term. Nevertheless, the consequences of a LPSI pump failing to trip at RAS have been analyzed.
The analysis showed that the maximum crush pressure from this condition is 5.2 psi, which is well below the design value of 20 psi. The analysis also showed there is sufficient NPSH margin for the CSS pumps to continue operating (3.6 ft for an LBLOCA and 3.1 ft for an SBLOCA). However, there is insufficient NPSH to support continued LPSI pump operation after RAS. Should this condition lead to the loss of one LPSI pump, this is an existing design basis case that is analyzed in the UFSAR and does not lead to unacceptable consequences.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 2 Page 20 of 33 Topic 3.h: Coatings Evaluation FPL Response Coatings are classified as qualified or unqualified.
The qualified coating systems used in the St. Lucie Unit 1 containment are listed in Table 3.h-1 below.Table 3.h-1 Qualified Coatinqs in the St. Lucie Unit 1Containment Substrate Application Coating Application Product Thickness (mils)Steel 1st Coat Carboguard 890 6 2na Coat Carboguard 890 6 1st Coat Carbozinc 11 5 2n- Coat Phenoline 305 6 Concrete Floor Ist Coat Carboguard 2011S 50 2nd Coat Carboguard 890 7 3ra Coat Carboguard 890 7 1St Coat Carboline 195 20 2nd Coat Phenoline 305 6 Concrete Wall 1st Coat Carboguard 2011S 35 2nd Coat Carboguard 890 7 3jra Coat Carboguard 890 7 1st Coat Carboline 195 20 2nd Coat Phenoline 305 6 Concrete Sump 1st Coat Phenoline 300 15 2nd Coat Phenoline 300 10 3 -d Coat Phenoline 302 10[RAI 30] For St. Lucie Unit 1, the analyzed LOCA cases generated sufficient fiber to form a thin fiber bed. Consistent with the staff's SE of NEI 04-07 for thin fiber bed cases, all coating debris is treated as particulate with 100% transportation of generated coatings to the sump screen. ElectroCarb black silicon carbide with 10-micron particle diameter was used as a surrogate for coatings other than inorganic zinc because 10 microns is the limiting size for head loss, and the density (94 lb/ft 3 approximates the density of coating systems. Carboline Carbo-zinc filler was used as the surrogate for inorganic zinc because it is the principal constituent.
Selected features of the treatment of qualified and unqualified coatings in the determination of coating debris that reaches the sump strainers have been updated since the September 1 response.
These changes are discussed individually below.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 21 of 33[RAI 29] The qualified coating ZOI in the September 1 response for St. Lucie Unit 1 was 1 OD. The ZOI for qualified coatings has subsequently been reduced to 4D. The 4D ZOI is based on testing that was completed at the St. Lucie Plant during February of 2006.A description of the test, the test data, and the evaluation of the test data, were previously provided to the NRC staff for information on July 13, 2006 in FPL Letter L-2006-169 (R. S. Kundalkar (FPL) to M.G. Yoder (NRC), "Reports on FPL Sponsored Coatings Performance Tests Conducted at St. Lucie Nuclear Plant," July 13, 2006). The evaluation of the test results confirms that a 4D ZOI is applicable to the in-containment qualified coating systems at St. Lucie Unit 1. As stated in the test plan, heat and radiation increase coating cross linking, which tends to enhance the coating physical properties.
Therefore, since artificial aging, heat, or irradiation to the current plant conditions could enhance the physical properties and reduce the conservatism of the test, the test specimens were not aged, heated, or irradiated.
The coating thicknesses in the September 1 response were assumed to be 3 mils of inorganic zinc primer plus 6 mils of epoxy (or epoxy-phenolic) top coat for qualified coatings and 3 mils of inorganic zinc (IOZ) for unqualified coatings.
Subsequently the analyses have been updated. The current debris generation model conservatively assumes the maximum thicknesses for each applicable coating system.The coating area in the ZOI in the September 1 response was assumed to be equal to the surface area of the ZOI. Subsequently, the updated debris generation calculations calculate the quantity of qualified coatings for each break by using the concrete and steel drawings to determine the amount of coating that will be within the ZOI for each break. Coatings that are shielded from the jet by a robust barrier are not included in the total. The calculated volume of qualified steel coating is then increased by 10% to account for small areas of additional items such as piping, pipe/conduit/HVAC/cable tray supports, stiffener plates, ladders, cages, handrails, and kick plates.The estimated quantity of unqualified/failed coatings in the September 1 response was 11 ft 3.With the changes discussed above, the estimated quantity of unqualified/failed coatings is now 9.96 ft 3.Subsequent to the September 1 response, the process for controlling the quantity of degraded qualified coatings in containment has been enhanced to ensure that it does not exceed the sump strainer design basis.The previous program for controlling in-containment coatings was described in the FPL response to NRC Generic Letter 98-04, "Potential for Degradation of the Emergency Core Cooling System and the Containment Spray System After a Loss-of-Coolant Accident Because of Construction and Protective Coating Deficiencies and Foreign Material in Containment" in letter L-98-277 on November 9, 1998. The letter summarized the program in place at that time for assessing and documenting the condition of qualified/acceptable coatings in primary containment at St. Lucie Unit 1.[RAI 25] The current program for controlling the quantity of unqualified/degraded coatings includes two separate inspections by qualified personnel during each refueling St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 22 of 33 outage, and notification of plant management prior to restart if the volume of unqualified/degraded coatings approaches pre-established limits.The first inspection takes place at the beginning of every refueling outage, when areas and components from which peeling coatings have the potential for falling into the reactor cavity are inspected by the FPL Coating Supervisor.
The second inspection takes place at the end of every refueling outage when the condition of containment coatings is assessed by a team (including the Nuclear Coating Specialist) using guidance from EPRI Technical Report 1003102 ("Guidelines On Nuclear Safety-Related Coatings," Revision 1, (Formerly TR-109937)).
Accessible coated areas of the containment and equipment are included in the second inspection.
Plant management is notified prior to restart if the volume of unqualified/degraded coatings approaches pre-established limits.The initial coating inspection process is a visual inspection.
The acceptability of visual inspection as the first step in monitoring of Containment Building coatings is validated by EPRI Report No. 1014883, "Plant Support Engineering:
Adhesion Testing of Nuclear Coating Service Level 1 Coatings," August 2007. Following identification of degraded coatings, the degraded coatings are repaired per procedure if possible.
For degraded coatings that are not repaired, areas of coatings determined to have inadequate adhesion are removed, and the Nuclear Coatings Specialist assesses the remaining coating to determine if it is acceptable for use. The assessment is by means of additional nondestructive and destructive examinations as appropriate.
Topic 3.i: Debris Source Term Refinements FPL Response The third debris source term refinement discussed in Section 5.1 of NEI 04-07, "Modify Existing Insulation" was utilized.
The existing calcium-silicate insulation on selected piping runs was modified by installing stainless steel bands. The application and justification for the calcium-silicate banding is included in the information provided in the response to NRC Topic 3.b, Debris Generation/Zone of Influence (excluding coatings).
Topic 3.0: Screen Modification Package FPL Response The original sump screens have been completely replaced with a single, non-redundant, distributed sump strainer system that consists of 21 strainer modules and interconnecting piping. The strainer system uses the General Electric discreet modular stacked disc strainers.
The strainer surface area is approximately 8,275 ft 2.[RAI 32] The new strainer system is completely passive (i.e., it does not have any active components or rely on backflushing).
As in the original sump screen design, the new distributed strainer system serves both ECCS suction intakes. Because the original St. Lucie Unit 1 strainer did not utilize redundant sump strainers, this is not a departure from the existing design basis. It is consistent with the current design basis, Technical Specifications, and regulatory commitments for St. Lucie Unit 1. Because a single non-redundant strainer system is St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 23 of 33 used, the system has been designed such that there is no credible passive failure mechanism that could render both ECCS trains inoperable.
Active strainer failure mechanisms are not considered because the strainer system is completely passive. The strainer system structural design is discussed in the response to NRC Topic 3.k, Sump Structural Analysis.The strainer modules use an arrangement of parallel, rectangular strainer disks that have exterior debris capturing surfaces of perforated plate covered with woven wire mesh. The wire mesh decreases the head loss across the strainer plates by breaking up debris beds. Each strainer disk, constructed of two plates, has an open interior to channel disk flow downward to the strainer plenum. The disks are mounted on the discharge plenum, which channels disk flow to the interconnecting suction piping. Type 304 or other austenitic stainless steel is used as the primary material of construction.
For St. Lucie Unit 1, the analyzed LOCA cases generated sufficient fiber to form a thin fiber bed or greater. However, the debris plate and the small pitch between disks allow the GE Modular Strainer to mitigate thin bed effects.The strainer perforations are nominal 1/16th-inch diameter holes. This is an enhancement from FPL's statement in the September 1, 2005 submittal, where the stated expectation was only that the perforation size would be smaller than a 1/8-inch by 1/8-inch square.The strainer modules are grouped together into 4 groups. Each group is piped separately to the strainer manifold where the total strainer flow is combined.
The manifold is connected to the recirculation suction inlets by two outlet pipes, one for each ECCS inlet.The outlet pipes from the strainer manifold terminate at the ECCS recirculation suction inlets. Debris intrusion is prevented by an interface collar and backing plate installed at the suction inlets.The entire strainer system is designed and situated to be fully submerged at the minimum containment water level during recirculation.
Perforated passive vents are provided to preclude air entrapment during containment flood-up prior to recirculation.
During flood-up, water would fill the strainer system from the bottom up, forcing air out of the perforated vents, thereby venting the system. Because the vents are below the containment water level prior to the start of recirculation, air will not be sucked in through the perforated panels. Venting is passive and uses perforations at least as small as the strainer perforated plate. Fabrication and installation tolerances of equipment are such that debris larger than allowable cannot bypass the strainer system. Therefore, debris retention capacity of the entire system is at least as good as the strainer modules.The strainer modules and suction manifold are designed in accordance with ASME Section III subsection NC (Class 2 components) or NF (supports).
The capability of the strainer perforated plate disks as structural members is based on the equivalent plate approach as specified by ASME Section III Article A-8000. Modification of existing supports or design of new supports is in accordance with AISC, 9th Edition or ASME Section III, Subsection NF.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 24 of 33 The capability of the strainer system to accommodate the maximum mechanistically determined debris volume has been confirmed by a combination of testing and analysis.The volume of debris at the screen is discussed in the response to NRC Topic 3.c, Debris Characteristics.
The capability to provide the required NPSH with this debris volume is discussed in the response to NRC Topic 3.g, Net Positive Suction Head (NPSH). The capability to structurally withstand the effects of the maximum debris volume is discussed in the response to NRC Topic 3.k, Sump Structural Analysis.One additional modification was completed that supports the new strainer installation.
This modification created two 22-inch diameter core bores for thel 8-inch piping that connects the suction manifold to the ECCS inlets. The core bores are a nominal 22-inch diameter to allow for a circumferential gap between the 18-inch nominal piping and the bioshield concrete.
The configuration has been analyzed to be acceptable with regard to bioshield structural integrity.
Topic 3.k: Sump Structural Analysis FPL Response The previous sump strainer system has been completely replaced by a new distributed strainer system. The new system is passive, and does not utilize backflushing.
It is described in the response to NRC Topic 3.j, Screen Modification Package. Assurance that the strainer system is inspected for adverse gaps or breaches prior to concluding an outage is discussed in the response to NRC Topic 3.p, Foreign Material Control Programs.The new strainer system is comprised of several components.
Twenty one (21) strainer modules are connected by four (4) pipe runs that terminate at a common suction manifold.
The common manifold is connected to the ECCS/CSS suction inlets by piping that runs through two (2) horizontal 22-inch nominal diameter core bores in the 4 foot thick secondary shield wall. The pipe runs that connect the strainer modules and common suction manifold are 12-inch stainless steel, schedule 10S. The pipe runs that connect the common manifold to the ECCS/CSS suction inlets are 18-inch stainless steel, schedule 10S.The strainer system is no longer protected by the secondary biological shield wall as was the original sump screen. Analyses and walkdowns have been performed which confirm that the strainer modules, interconnecting piping, manifold and appurtenances are not subject to high energy line break (HELB) jet impingement, pipe whip or missiles.The analyses assumed a HELB ZOI of 10D. The approved "leak-before-break" methodology was used to eliminate the reactor coolant system (RCS) loops from consideration.
Therefore, dynamic effects due to breaks in the RCS loops were not considered in the structural analysis/design of the strainer system. Main steam and feedwater piping were eliminated from review because breaks in these lines do not require the plant to enter into recirculation mode.The system only operates once the containment is filled with water, and the entire system is fully submerged.
The system is designed to vent during containment flood up, so there is no requirement to be leak tight. However, the strainer components and St. Lucie Units 1 and 2 L-2008"-030 Docket .Nos. 50-335 and 50-389 Attachment 2 Page 25 of 33 piping systems are designed using ASME Section III as a guide where applicable.
The component anchorages and piping supports are designed following the AISC Manual of Steel Construction.
For purposes of describing the structural analysis, it is useful to divide the strainer system into the following components.
* Strainer modules (disks and plenums)* Common manifold* Piping and pipe supports* The anchorages for the strainer plenums and manifold box* The horizontal 22" diameter core bores through the 4'-0" thick secondary shield wall The strainer module and manifold element stresses were determined using the ANSYS computer program, and the allowable stresses were obtained from ASME Section III Appendices.
Weld stresses for the strainer modules were evaluated by ANSYS, the Blodgett method, or hand calculation, and allowable stresses were obtained from ASME Section III Appendices.
The manifold is a box shaped structure and meets the structural design requirements.
The strainer module is a more complex structure, and the structural loads and load combinations are summarized in Tables 3.k-1 and 3.k-2 below.The strainer module structural qualification results are summarized in Table 3.k-3.The 12-inch pipe runs that connect the strainer modules and common suction manifold have specially designed pipe clamps that allow for thermal expansion.
The interface and pipe support configuration for the 18-inch pipe runs are designed such that negligible loads are imposed on the ECCS/CSS guard pipes and containment penetrations.
Piping was analyzed using hand calculations and an S&L proprietary finite element modeling computer program PIPSYSW. Pipe supports were analyzed using hand calculations.
Expansion anchor base plates for pipe supports, strainer and manifold anchorages were analyzed using hand calculations and an S&L proprietary finite element modeling computer program APLAN. The core bores are qualified using hand calculations.
The piping, pipe supports, anchorages and core bores were qualified using the allowable stress method. Portions of the core bore were qualified using ultimate strength design. The resulting design margins (ratio of stress allowable
/ calculated stress) were greater than 1.0 for all components.
With regard to trash racks, the GE design is robust and the trash rack function is incorporated into the strainer module design. Separate trash racks are not required.This is consistent with the original St. Lucie Unit 1 strainer/sump design, which did not have separate trash racks.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 2 Page 26 of 33 Table 3.k-1: Strainer Module Loads and Load Combinations Load Strainer Load Combination 1 D+L +Ej 2 D+L'+E 2 3 D+L+T + E, 4 D+L'+T + E2 5 D+L +T + E', 6 D+L + L' +TA + Ft 7 D+L'+TA + E'2+ PCR Table 3.k-2: Structural Load Symbols Symbol Load Definition D Dead Load, in air L' Debris Weight Submerged plus Hydrodynamic Mass L Live Load, Outage Maintenance Personnel Ft Flow Initiation Transient Momentum Load T Normal Operating Thermal Load TA Accident Thermal Load E 1  Earthquake Load, OBE in air E 2  Earthquake Load, OBE in water E', Earthquake Load, SSE in air E'2  Earthquake Load, SSE in water P, Differential (Crush) Pressure Table 3.k-3: Strainer Module Stress Ratio Results Load Combination 1 2 3 4 5 6 7 Allowable Stress Sh 1.2 Sh 1.2 Sh Sy Sy j Sy Sy Value (ksi) 16.6 19.9 19.9 22.5 22.5 22.5 22.5 Stress Ratio (Note 1)Plenum Cover 24.3 12.47 28.11 16.92 27.08 20.55 4.08 Plenum Rib 12.73 8.13 15.26 9.19 14.53 11.40 1.88 Plenum Box 14.16 8.46 15.88 9.56 15.13 11.85 2.32 Plenum Joint 9.17 5.39 10.11 6.09 9.69 7.46 1.16 Wedge 5.60 8.05 1.90 3.22 4.69 4.52 1.99 Tie Rod 73.45 40.61 76.25 45.92 69.23 62.67 5.95 Ribs 11.97 7.09 13.31 8.02 12.64 10.00 2.99 Main Frame 16.42 10.30 19.34 11.65 18.31 14.61 2.84 Composite Plate 16.10 9.57 17.94 10.81 15.91 15.75 15.75 Composite Plate (Note 2) N/A N/A N/A N/A N/A N/A 1.0 Notes: 1 Stress Ratio = ASME Code Stress Limit at 300 OF / Calculated Stress 2 Deflection Ratio = Deflection Limit at 240 OF / Calculated Deflection St. Lucie Units 1 and 2 Docket Nos. .50-335 and 50-389 L-2008-030 Attachment 2 Page 27 of 33 Topic 3.1: Upstream Effects FPL Response[RAI 42] In the September 1 St. Lucie submittal it was noted that it was planned to obtain additional confirmation that there are no choke points. This confirmation was obtained from a walkdown that was conducted in the St. Lucie Unit 1 containment specifically to evaluate ECCS recirculation flow paths. The walkdown utilized the guidance in Nuclear energy Institute (NEI) Report 02-01, NEI Report 04-07, and the staff's SE of NEI 04-07.[RAI 38] The information obtained during the walkdown confirms that water will not be held up by choke points or otherwise prevented from reaching the ECCS intakes via the distributed strainer system. Special attention was paid to the fuel transfer canal, which is drained by two 6-inch nominal diameter pipes. These pipes are oriented horizontally with the bottom of the pipe approximately 3 inches above the transfer canal floor. They are not screened or capped. Because of the size and orientation of these drain pipes they will not create a choke point that would retain water in the fuel transfer canal.However, because the pipes are 3 inches above the floor, it is assumed that the water below 3 inches is held up and does not reach the sump.Other specific NEI and NRC concerns that were addressed in the walkdown are itemized below.* There were no gates or screens in the recirculation flow paths.* All passages have sufficient flow clearances such that choke points are not expected.* Curbs and ledges within the flow paths were found to be unable to retain water from returning to the sump area. Curbs at upper elevations had at least one open side to allow the free flow of water to the ground floor.* No potential choke points were observed at upper elevations, including floor grates, which would be expected to retain fluid from reaching the containment floor.* The containment floor was surveyed for choke points formed by equipment, components and other obstructions.
Where equipment congestion did occur, other flow paths were available so as to not restrict water transport.
Topic 3.m: Downstream Effects -Components and Systems FPL Response In the September 1 response it was noted that, at that time, the downstream evaluations identified instrumentation and eight (8) components that required further evaluation.
Subsequently, the strainer opening size has been reduced from an assumed square opening of 1/8-inch by 1/8-inch (diagonal dimension of 0.177 inch) to an actual round opening of 1/16-inch diameter (0.062 inch), the high pressure safety injection (HPSI)pump seal cyclone separators have been removed and the seals replaced, and stainless steel bands have been installed on selected cal-sil insulation.
The new strainer system is described in the response to NRC Topic 3.j, Screen Modification Package. The HPSI pump seal replacement is described in the response to NRC Topic 2, General Description of and Schedule for Corrective Actions. Cal-sil banding St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 28 of 33 is discussed in the response to NRC Topic 3.b, Debris Generation Zone of Influence (ZOI)(excluding coatings).
[RAI 31] With the exception of pumps and related analytical work, component downstream analyses have been completed using the methodologies of WCAP-16406-P Revision 1 (WCAP-16406-P, "Evaluation of Downstream Sump Debris Effects in Support of GSI-1 91," Revision 1, August 2007). FPL plans on completing the remaining downstream pump analysis in accordance with the schedule provided to the NRC staff in letter L-2007-155.
As discussed in the response to NRC Topic 3.e, Debris Transport, detailed debris size distributions were not required or developed for the purposes of determining the debris load at the strainer and the strainer head loss. However, debris size distributions are required for the downstream analyses.
As a result, a conservative set of debris characteristics was developed independently of transport considerations.
The debris characteristics that were used in the downstream analyses are provided in Table 3.m-1 below.Consistent with the staff's SE of NEI 04-07, the inactive volume is less than 15% of the total volume. Consistent with the guidance in WCAP-16406-P Revision 1, the evaluation considered debris larger than the largest dimension of the sump strainer opening, 1/16 inch (62 mils). However, four (4) clarifications of the methodology of WCAP-1 6406-P were also utilized in the downstream analyses.
These clarifications are discussed below.Clarification 1 In lieu of the guidance provided in WCAP-16406-P Revision 1 regarding particle sizes, the analyses conservatively defined the "smaller" flow clearance as the circular dimension able to pass a 0.100-inch spherical particle.
The definition of "smaller" as 0.100-inch diameter sphere exceeds all dimensional attributes except for the length dimensions.
However the overall dimension (cross-sectional area) for a 0.100-inch diameter sphere is approximately 250% greater than the guidance provided in WCAP-16406-P Revision 1. Therefore, this is acceptable.
Clarification 2 Size distributions were calculated in lieu of the particulate size distributions (large, medium and small) specified in WCAP-16406-P, Revision 1, for RMI, cal-sil and latent debris. For unqualified coatings, the size/mass distributions of WCAP-16406-P, Revision 1 were used.Clarification 3 All particulate debris is assumed to be spherical when calculating settling sizes and associated velocities.
Clarification 4 The time dependent debris decay and depletion model uses the debris decay coefficients of a cold leg break and the reactor lower plenum settling sizes and velocities of a hot leg break. Cold leg recirculation cooling is assumed for both cases. This model St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 29 of 33 minimizes the debris settling and depletion, which maximizes the debris concentration over the mission time, thus establishing conservative values for the wear analysis.Evaluation Results The results of the downstream component evaluations that were completed with the WCAP-1 6406-P Revision 1 methodology are provided below.ECCS Valves ECCS valves in the recirculation path were evaluated with respect to erosion, plugging, and the capability to change position.
It is assumed that a manually throttled valve as defined in WCAP-16406-P is one that requires an operator to locally adjust the valve (at the valve location) as opposed to a remote manual valve that can be adjusted from the control room. It is further assumed that a remote manual valve can be adjusted from the control room to compensate for an increase in flow area due to erosion wear. Therefore, erosion wear analyses were not performed for remote manual valves. With this assumption, no further actions are required to accommodate downstream effects on ECCS valves in the recirculation path.ECCS relief valves were evaluated with respect to erosion, plugging, and debris interference with valve reseating.
Each ECCS relief valve on an ECCS recirculation flow path was evaluated by first comparing its set pressure to its recirculation mode pressure.Where the set pressure is higher than the expected recirculation mode pressure, the valve does not have the potential to open during recirculation.
Based on a comparison
*of the valve set pressures to conservative expected recirculation mode line pressures, no ECCS relief valve is expected to operate during recirculation.
Therefore, failure is precluded, and no further actions are required to accommodate downstream effects on ECCS relief valves.ECCS Flow Restrictions The ECCS flow restrictions (orifices, flow elements, and spray nozzles) were evaluated with respect to plugging and erosion. Based on the results of the analyses, there are no downstream effects concerns due to wear or plugging for flow restrictions, and no further actions are required to accommodate downstream effects on ECCSflow restrictions.
ECCS Instrumentation The ECCS instrumentation was evaluated based on tap orientation and the velocity of the fluid passing the tap. The results of the evaluations confirm that no further actions are required to accommodate downstream effects on ECCS instrumentation.
ECCS Heat Exchanqers The ECCS heat exchangers were evaluated with regard to plugging and erosion. The results of the evaluations confirm that no further actions are required to accommodate downstream effects on heat exchangers.
As discussed above, with the exception of downstream effects on pumps, the results of the downstream component evaluations provide assurance that, with the changes implemented at St. Lucie Unit 1, the evaluated components can perform their function in terms of long term cooling. FPL plans to complete the downstream pump analysis in accordance with the schedule provided to the NRC staff in letter L-2007-155.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 2 Page 30 of 33 Table 3.m-1: Debris Characteristics Debris Category Percentage Fiber Insulation Fines 8%Small 25%Large 32%Intact 35%Latent Fiber Fines 100%Particulates Cal-sil Fines 100%Qualified Coating Fines 100%Unqualified Coating Fines 100%Latent Particulate Fines 100%RMI Fines 75%Intact 25%Topic 3.m: Downstream Effects -Fuel and Vessel FPL Response FPL is participating in the PWR Owners Group (PWROG) program to evaluate downstream effects related to in-vessel long-term cooling. The results of the PWROG program are documented in WCAP-16793-NP (WCAP-16793-NP, "Evaluation of Long-Term Cooling Considering Particulate, Fibrous and Chemical Debris in Recirculating Fluid," Rev. 0, May, 2007), which was provided to the NRC staff for review in June 2007.The program was performed such that the results apply to the entire fleet of PWRs, regardless of the design (e.g., Westinghouse, CE, or B&W).The PWROG program demonstrated that the effects of fibrous debris, particulate debris, and chemical precipitation would not prevent adequate long-term core cooling flow from being established.
In the cases that were evaluated, the fuel clad temperature remained below 800 OF in the recirculation mode. This is well below the acceptance criterion of 2200 °F in 10 CFR 50.46, Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors.
The specific conclusions reached by the PWROG are noted below.Adequate flow to remove decay heat will continue to reach the core even with debris from the sump reaching the RCS and core. Test data has demonstrated that any debris that bypasses the screen is not likely to build up an impenetrable blockage at the core inlet. While any debris that collects at the core inlet will provide some resistance to flow, in the extreme case that a large blockage does occur, numerical analyses have demonstrated that core decay heat removal will continue.
Per WCAP 16793-NP, Revision 0, no plant specific evaluation is recommended.
This conclusion thus applies to St. Lucie Unit 1.* Decay heat will continue to be removed even with debris collection at the fuel assembly spacer grids. Test data has demonstrated that any debris that St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 31 of 33 bypasses the screen is small and consequently is not likely to collect at the grid locations.
Further, any blockage that may form will be limited in length and not be impenetrable to flow. In the extreme case that a large blockage does occur, numerical and first principle analyses have demonstrated that core decay heat removal will continue.
Per WCAP 16793-NP, Revision 0, no plant specific evaluation is recommended.
This conclusion thus applies to St. Lucie Unit 1.Fibrous debris, should it enter the core region, will not tightly adhere to the surface of fuel cladding.
Thus, fibrous debris will not form a "blanket" on clad surfaces to restrict heat transfer and cause an increase in clad temperature.
Therefore, adherence of fibrous debris to the cladding is not plausible and will not adversely affect core cooling. Per WCAP 16793-NP, Revision 0, no plant specific evaluation is recommended.
This conclusion thus applies to St. Lucie Unit 1.Using an extension of the chemical effects method developed in WCAP-16530-NP to predict chemical deposition of fuel cladding, two sample calculations using large debris loadings of fiberglass and calcium silicate, respectively, were performed.
The cases demonstrated that decay heat would be removed and acceptable fuel clad temperatures would be maintained.
WCAP-1 6530-NP, Revision 0 evaluated the potential for chemical precipitation to form on the cladding surface as summarized in the preceding bullet, which is demonstrated in WCAP-1 6793, Revision 0, to produce acceptable fuel clad temperature results for two sample cases. As recommended in the WCAP-16793-NP, Revision 0, FPL has decided to perform a plant-specific calculation using plant-specific parameters and the recommended WCAP methodology to confirm that chemical plate-out on the fuel does not result in the prediction of fuel cladding temperatures approaching the 800 OF value.We plan to have this assessment completed in accordance with the schedule provided to the NRC staff in letter L-2007-155.
Topic 3.n: Chemical Effects FPL Response As described in Attachment 2 of our December 7, 2007, extension request, a purchase order has been issued for performing a 30-day integrated chemical effects test. As described in Attachment 1 of our December 7, 2007, extension request, the purchase order is with Alion Science and Technology.
It is anticipated that the chemical testing and analyses will be completed by June 30, 2008. In the meantime, the new strainer system that was installed during outage PSL1-21 increased the strainer surface area to approximately 8,275 ft 2.After accounting for head losses due to debris and temperature dependent effects, the new strainer system provides an NPSH margin of approximately 9 ft for the LBLOCA and 8.5 ft for the SBLOCA. Pending resolution of chemical effects issues, this margin is available to accommodate strainer head loss due to chemical effects at the sump strainers.
Upon completion of the chemical effects tests, the available NPSH margin will be updated to incorporate the results of the chemical effects tests and analyses.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 32 of 33 As discussed in our December 7, 2007 extension request, although the identified corrective actions have been completed, the impact of chemical effects on full implementation of GSI-191 corrective actions will not be fully assessed until June 30, 2008. Therefore, responses to the staff's RAI items related to chemical effects in the NRC RAI dated February 8, 2006 (TAC Nos. MC4710 and MC4711) will be provided at that time, as necessary.
Topic 3.o: Licensing Basis FPL Response As discussed in other sections of this response, physical plant changes and procedural changes have been made to St. Lucie Unit 1 to resolve GL 2004-02 and GSI-191 concerns.
These are summarized in Topic 2 along with additional work that is planned to be completed.
A submittal will be made to the NRC providing responses to remaining RAIs and describing final compliance with the regulatory requirements of GL 2004-02 by June 30, 2008.As noted in Topic 3.g, Net Positive Suction Head Available (NPSH), sump level calculations were revised to accommodate potential areas for water holdup based on lessons learned from the NRC audit of the Waterford sump program. This resulted in calculated values of the post-LOCA containment sump level below those that were tested and analyzed for the St. Lucie Unit 1 strainer system.It is noted, that following the issuance of Bulletin 2003-01, St. Lucie Unit 1 put in-place administrative controls to maintain a higher water level in the RWT than the required Technical Specification minimum, with the intent that this higher level would remain until such time as sump issues were completely resolved.
Some calculations and results provided in Topic 3.f, Head Loss and Vortexing, and in Topic 3.g, Net Positive Suction Head Available (NPSH), credit this current/higher RWT level. FPL has determined that an amendment to the Technical Specifications to raise the minimum allowable RWT level to the current/higher administrative level is required in order to assure that sufficient post-LOCA containment level bounds the submerged testing and calculations for the strainer system. The amendment request for this increase in minimum Technical Specification RWT level will be submitted by June 30, 2008. The current/higher RWT level will remain in effect until the amendment request is reviewed by NRC, approved, and implemented on-site.Topic 3.p: Foreign Material Control Programs FPL Response Information related to programmatic controls for foreign materials was provided to the NRC in previous submittals.
Such information was provided in letter L-2003-201 which responded to NRC Bulletin 2003-01, and most recently in letter L-2005-181 which responded to GL 2004-02. In general, the information related to programmatic controls that was supplied in these responses remains applicable.
However, subsequent to the September 1 response, modifications, tests and walkdowns have been completed, and these have been used to inform and update the programmatic controls that support the new sump strainer system design basis.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 2 Page 33 of 33 The results of the recently completed walkdowns to assess the quantities of latent and miscellaneous debris are discussed in the response to NRC Topic 3.d, Latent Debris.These walkdowns were conducted without any preconditioning or pre-inspections.
Consequently, the debris found during the walkdowns is characteristic of approximately 23 years of operation under the existing housekeeping programs.
In addition, as discussed in the response to NRC Topic 3.d, Latent Debris, the St. Lucie Unit 2 quantity of latent debris is doubled (100% margin) for use in the St. Lucie Unit 1 analyses and testing, and the St. Lucie Unit 2 quantity of miscellaneous debris is increased by approximately 25% for use in St. Lucie Unit 1 analyses.
Based on these walkdowns, it was determined that current housekeeping procedures were appropriate, hence no changes have been made to these procedures.
Currently insulation and materials inside containment are controlled by procedures that require; (a) a review of changes to insulation or any other material inside containment that could affect the containment sump debris generation and transport analysis and/or recirculation functions and (b) a review of the effect of any change package for its impact on containment sump debris generation and transport.
This guidance has been enhanced by a new engineering specification that brings together, in one document, the insulation design documents that determine the design basis for the insulation debris component of the containment recirculation strainer design. This specification provides guidance for evaluating and maintaining piping and component insulation configuration within the containment building at St. Lucie Unit 1. In addition, the St. Lucie Plant procedure for controlling work orders was revised to assure that insulation work inside containment required signoff to the requirements of this specification.
One new procedure has been written for inspection of the new strainer system, and the containment close-out procedure has been updated. The new procedure requires that there are no holes, gaps or tears greater than 1/16 inch (0.0625 inch) in any component of the strainer system (e.g., including connections).
The containment closeout procedure was updated to include all of the strainer system components in the final containment closeout inspection.
The effect of these changes is to ensure that all components (strainer modules, piping, and pipe connections) are inspected, and that there are no holes, gaps or tears greater than 1/16 inch in any strainer system component.
Note that programmatic controls related to coatings are provided in the response to NRC Topic 3.h, Coatings Evaluation.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 1 of 47 ATTACHMENT 3 St. Lucie Unit 2.GL 2004-02 Supplemental Response St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 2 of 47 Topic 1: Overall Compliance FPL Response The Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 2004-02,"Potential Impact of Debris Blockage On Emergency Recirculation During Design Basis Accidents At Pressurized-Water Reactors," on September 13, 2004 that requested a series of responses to address actions, status, and provide assurance of final closure of the GL issues. Florida Power & Light (FPL) provided the 90-day response to the GL in FPL Letter to NRC, L-2005-034, "NRC Generic Letter 2004-02 Potential Impact on Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized Water Reactors," on March 4, 2005. The second response to the GL was provided in FPL Letter to NRC, L-2005-181, "NRC Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized Water Reactors -Second Response," September 1, 2005. This September 1 response to the GL provided the details and plans for achieving GL compliance at St. Lucie Unit 2.The plant change commitments in the September 1 letter were implemented during the St. Lucie Unit 2 fall 2007 outage. These included the installation of a new Emergency Core Cooling System (ECCS) sump strainer system and the removal of cyclone separators and installation of new pump seals on the High Head Safety Injection (HPSI)pumps and the Containment Spray System (CSS) pumps. In addition, as discussed in subsequent sections of this response, improvements in programmatic controls have been implemented to ensure that the potential quantity of post-Loss Of Coolant Accident (LOCA) debris does not exceed the evaluation assumptions for Net Positive Suction Head (NPSH) margins on recirculation ECCS/CSS pumps, or the evaluation assumptions in down stream analysis for components and systems, or for fuel and in-vessel effects.As discussed in subsequent sections, walkdowns have been completed to assure that chokepoints would not hold back water from the recirculation paths to the containment recirculation sump, and calculations have been revised to account for other potential hold-ups of ECCS/CSS recirculation water.However, as discussed in FPL Letter to NRC, L-2007-155, Request for Extension of Completion Date of the St. Lucie Unit 1, St. Lucie Unit 2 and Turkey Point Unit 3 Generic Letter 2004-02 Actions, December 07, 2007, confirmatory tests and analyses have been delayed until June 30, 2008. Per NRC Letter (T. H. Boyce to J. A. Stall), St. Lucie Nuclear Plant, Units 1 and 2, and Turkey Point Nuclear Plant Unit 3 -Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents At Pressurized-Water Reactors," Extension Request Evaluation (TAC Nos. MC4710, MC471 1, and MC4725) December 28, 2007 the extension for the additional testing and analysis was approved by the NRC.Following the St. Lucie Unit 2 integrated chemical effects testing in a large flume, and strainer system and additional downstream effects analyses, FPL will evaluate existing post-LOCA calculations and evaluations.
A follow-up submittal to this response will be made in order to more fully address and finalize compliance with GL 2004-02 on or before June 30, 2008.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 3 of 47 As noted in Topic 3.g, Net Positive Suction Head Available (NPSH), sump level calculations were revised to accommodate potential areas for water hold-up based on lessons learned from the NRC audit of the Waterford sump program. Based on these results, FPL recently determined that an amendment to the Technical Specifications, raising the minimum Refueling Water Tank (RWT) level, is warranted to provide additional post accident sump level margin for St. Lucie Unit 2. Hence, an amendment to the St. Lucie Unit 2 Technical Specifications requesting the necessary increase in RWT level will be submitted by June 30, 2008. Until this amendment is approved and implemented on-site, existing administrative controls for maintaining a higher water level in the RWT will remain in effect. This is.further discussed in Topic 3.o, Licensing Basis.Additional information to support the Staff's evaluation of St. Lucie Unit 2 compliance with the regulatory requirements of GL 2004-02 was requested by the NRC in a"Request for Additional Information" (RAI) dated February 8, 2006 (NRC Letter to FPL (J. A. Stall), St. Lucie Plant, Units 1 and 2; Request for Additional Information RE: Response to Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized-Water Reactors" (TAC Nos. MC4710 and MC471 1). Each RAI question is addressed in this response if the information is available, and is noted as [RAI ##], where the ## is the RAI question number. RAIs that are related to testing or analysis that is scheduled for future completion will be provided in a June 30, 2008 submittal.
It is possible that the final testing and analysis may result in further reexamination of original assumptions and bases of other calculations or, potentially require additional outage related modifications.
The subsequent outage for St. Lucie Unit 2 would.be spring 2009. In the case that additional corrective actions are required, FPL will contact the Commission.
Topic 2: General Description of and Schedule for Corrective Actions FPL Response Physical plant changes have been implemented to resolve GL 2004-02 and GSI-191 concerns at St. Lucie Unit 2. These are summarized below, along with other work related to evaluations and the establishment of programmatic controls.[RAI 39] As discussed in Topic 3.j, Screen Modification Package, the original containment recirculation strainer system has been removed, and the new strainer system, with approximately 5,607 ft 2 of strainer area, was installed in the containment recirculation sump at St. Lucie Unit 2 during the recent fall 2007 outage. As discussed in Topic 3.f, Head Loss and Vortexing, the strainer system design is based on testing that was conducted for the Point Beach Nuclear plant. Head loss calculations are based on hydraulic calculation of the clean St. Lucie Unit 2 design, with the addition of the temperature compensated total debris laden head loss from the Point Beach tests. This conservative methodology results in a debris laden head loss of approximately 1.82 ft at 210 'F for the St. Lucie Unit 2 design. As discussed in Topic 3.g, Net Positive Suction Head Available (NPSH), this results in a conservatively calculated NPSH margin of approximately 0.17 ft, for the worst case HPSI pump, and 6 ft for the operating CSS St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 4 of 47 pump. As noted in Topic 1 and further discussed in Topic 3.o, Licensing Basis, St.Lucie Unit 2 will be filing an amendment request for a higher minimum level in the Refueling Water Tank (RWT) which will provide an additional 0.83 ft of head margin for the ECCS/CSS pumps. Topic 3.j, Screen Modification Package, provides greater detail on the sump screen modification, and Topic 3.k, Sump Structural Analysis, provides the structural evaluation.
As discussed in Topic 3.m, Downstream Effects -Components and Systems, the HPSI pumps have been modified by removing the cyclone separator and associated piping, and replacing the mechanical seals with a new seal design that uses recirculated seal cavity fluid for flushing and cooling of the seal faces. Hence, HPSI pump seal injection no longer relies on process fluid via a cyclone separator, thus the potential for debris clogging of the cyclone separator and related equipment has been eliminated as a GSI-191 downstream effects concern for the HPSI pumps. Further, the original mechanical seals on the CSS pumps also relied on cyclone separators for removal of fluid particulate in seal injection water. The CSS pumps have been modified by removing the cyclone separator and associated piping, and replacing the mechanical seals with a new seal design that uses recirculated seal cavity fluid. Hence, CSS pump seal injection no longer relies on process fluid via a cyclone separator, and the potential for debris clogging of the cyclone separator and related equipment has been eliminated as a GSI-191 downstream effects concern for the CSS pumps.As further discussed in Topic 3.m, Downstream Effects -Components and Systems, downstream analysis has been completed on all components except for the ECCS/CSS pumps, and downstream analysis for in-vessel fuel issues have been completed except for the evaluation of potential plate-out of chemicals on the fuel. It is planned to have this assessment completed in accordance with the schedule provided to the NRC Staff in letter L-2007-155.
As described in Topic 3.1, Upstream Effects, plant walkdowns have been completed to evaluate the potential for chokepoints in the flow path from potential break locations to the containment recirculation sump, and it was concluded that there were no chokepoints that would inhibit flow.Topic 3.d, Latent Debris, describes plant walkdowns that have been completed to determine the amount of latent debris and miscellaneous debris present in containment under the current house keeping procedures.
These walkdowns determined the amount of latent and miscellaneous debris that was present under current house keeping procedures.
Also,, as discussed in Topic 3.c, Foreign Materials Control Program, additional controls are in-place to further assure proper containment walkdown prior to restart, and revised programmatic controls have been put in place including specifications for insulation and coatings inside of containment.
Calculations that have been revised for post-LOCA sump levels based on observations from the Waterford audit and revised NPSH calculations were also performed with the new sump levels and sump screen strainer pressure loss calculations.
These calculations included the addition of a LPSI pump failing to trip at Recirculation Actuation Signal (RAS).
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 5 of 47 However, as discussed in the request for extension submitted on December 7, 2007, (FPL Letter L-2007-155) completion of testing and selected analyses have been delayed. The integrated chemical effects testing in a large flume of the St. Lucie Unit 2 strainer design is scheduled to be completed during the 2 nd quarter of 2008. Completion of other analysis and evaluations of the downstream effects on ECCS/CSS recirculation pumps, and in-vessel fuel chemical effects are planned to be completed by March 31, 2008.A final submittal will be made to the NRC on or before June 30, 2008 that will provide the final conclusions regarding St. Lucie Unit 2 compliance with GL 2004-02. This submittal will also include responses to the remaining RAIs.As discussed further in Topic 3.o, Licensing Basis, FPL will also submit an amendment request to raise the Technical Specification minimum level for the Refueling Water Tank (RWT) by June 30, 2008.Topic 3.a: Break Selection FPL Response In agreement with the staff's SE of NEI 04-07, the objective of the break selection process was to identify the break size and location which results in debris generation that will maximize the debris transport to the containment sump during recirculation.
Breaks were evaluated based on the methodology in Nuclear Energy Institute (NEI)guidance document NEI 04-07 as modified by the staff's SE of NEI 04-07.[RAI 33] The following specific break location criteria were considered:
* Breaks in the reactor coolant system with the largest amount of potential debris within the postulated ZOI,* Large breaks with two or more different types of debris," Breaks in areas with the most direct path to the sump," Medium and large breaks with the largest potential particulate debris to insulation ratio by weight and," Breaks that generate an amount of fibrous debris that could form a uniform "thin bed."[RAI 33] Reactor Coolant System (RCS) piping and attached energized piping was evaluated.
Smaller piping has a much smaller ZOI than the RCS piping and will affect a much smaller quantity of insulation.
The discrete approach described in Section 3.3.5.2 of the SER (Reference 7.1.3) was applied for these smaller lines, and the smaller lines were clearly bounded by the RCS line breaks inside the bioshield.
The staff's SE of NEI 04-07 notes that the concept of equal increments is only a reminder to be systematic and thorough.
As stated in the staff's SE of NEI 04-07, the key difference between many breaks (especially large breaks) will not be the exact location along the pipe, but rather the envelope of containment material targets that is affected.
Insulated piping spreadsheets, piping isometric drawings, and general arrangement drawings were used to systematically determine worse case pipe break locations using node points on the piping. Break locations were selected in 5-foot St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 6 of 47 increments along the applicable RCS piping to determine the maximum worst case debris mix. This systematic technique was the basis for determining the worst case debris loads for postulated break locations based on pipe size and target debris zones of influence in the selected piping locations.
[RAI 34] Feedwater and main steam piping were not considered for potential break locations because ECCS in recirculation mode is not required for Main Steam or Feedwater line breaks. Small-bore piping breaks (less than 2-inch diameter) were not evaluated because they are not bounding.The largest energized lines in containment that require evaluation are; the hot leg (42-inch ID), crossover leg (30-inch ID), cold leg (30-inch ID), pressurizer surge line (12-inch nominal), shutdown cooling line (12-inch nominal) and safety injection line (12-inch nominal).
The other piping lines have a smaller diameter (10-inch maximum), which will produce a much smaller quantity of debris and are therefore not considered.
Inside the bioshield, breaks in the hot legs, the cold legs, crossover legs and pressurizer surge line were considered.
Outside the bioshield, breaks were considered in the safety injection lines. The safety injection lines are of smaller diameter than the RCS piping, and are located in the same general area inside the bioshield.
Therefore, inside the bioshield, a break in these lines would be bounded by the reactor coolant loops, and thus need not be analyzed.However, each safety injection line travels outside the bioshield before the second isolation valve. (These lines each have a check valve located inside the bioshield that will isolate the RCS from the upstream portion of the line outside the bioshield.)
The safety injection lines are the only RCS-connected larger lines that travel outside the bioshield before the second isolation valve, and, therefore, were selected in order to include a break outside the bioshield.
The two steam generator (SG) loops are nearly identical, except that loop "B" also includes the pressurizer and associated piping. For this reason, only loop "B" was modeled for insulation debris purposes.
Any break in loop "B" will have an equal or greater quantity of insulation due to the addition of the pressurizer and associated piping.A hot leg or cold leg line break at the reactor pressure vessel (RPV) was also considered.
The RPV is covered with Transco reflective metal insulation (RMI) on the vessel, and Nukon insulation on the top head. This break would affect the reactor insulation and the insulation on the RCS lines adjacent to the break up to the penetrations.
However, this debris would fall to the bottom of the reactor vessel cavity, and would have an indirect path to the strainer modules. In addition, the amount of debris would be bounded by a hot or cold line break elsewhere on the line. Therefore, a hot leg or cold leg break at the RPV was not analyzed.The postulated break locations were as follows:$1 Loop "B" hot leg at the base of the steam generator (42-inch ID)S2 Loop "B" crossover leg 2B1 at the connection to the RCP (30-inch ID)S3 Safety Injection line SI-150 outside the missile barrier (12-inch nominal line)
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 7 of 47 After performing several iterations, the S1 break was found to generate the greatest quantity of debris and, therefore, was selected for the strainer design basis.Topic 3.b: Debris Generation/Zone of Influence (ZOI) (excluding coatings)FPL Response The debris generation calculations used the methodologies of Regulatory Guide 1.82, Rev. 3, NEI 04-07 and the staff's SE of NEI 04-07. ZOls for insulation systems used at St. Lucie Unit 2 were obtained from Table 3-2 of the staff's SE of NEI 04-07.The debris generation calculations have been updated and make use of three assumptions related to non-coating debris generation.
Assumption 1 Supporting members fabricated from steel shapes (angles, plates) are installed to provide additional support for the mirror insulation on equipment such as reactor coolant pumps, Steam Generators and Pressurizer.
It is assumed that, as a result of the postulated pipe break, these supporting members will be dislodged from the equipment, and may be bent and deformed, but will not become part of the debris that may be transported to the sump.Assumption 2 In the September 1 response, it was noted that an analytical process was used that conservatively overstated the quantity of debris from insulation by 5-15%. This process is no longer used. Instead, a uniform ZOI factor of 1.1 for insulation debris has been used to account for minor variances in the insulation analysis coordinates used for the systematic break selection process, small insulated drain lines, etc. This revision to the methodology is appropriate for accommodating minor deviations and is considered to be conservative.
Assumption 3 Small drain and tap lines located throughout containment are not modeled in the debris calculation.
These small lines are typically no more than two or three feet in length. In order to account for this small volume of fiber insulation, 5 ft 3 has been added to the fiber totals for the S1 and S2 breaks. No adjustment was made for the S3 break debris generation for small lines.The insulation ZOls and the quantities of debris are provided in Table 3.b-1 below.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 8 of 47 Table 3.b-1: Destruction ZOI and Limiting Break Comparison Debris Type Destruction Break S1 I" Break S2(1) Break S3V 1)zo' _ _ __ _ _ _ __ _ _ _Transco RMI 2.0 D 2475.72 ftW 0.0 ft 2  0.0 ft Mirror RMI 28.6 D 3591 ftW 3591 ftW 0.0 W SS Insulation Jacketing 17.0 D 8487 W 6691 ft' 1008 ft 2 Cal-sill"'
5.45 D .13.76 ftW 13.76 ftW 13.76 ft Fiberglass (Nukon/Knaupf) 17.0 D 1435.31 ft 3  1180.78 ftW 74.61 t Foamglass 17.0 D 18.05 ft' 11.31 ft 17.10 t Coatings Qualified
-Concrete 4.0 D 6.06 ft 3  3.14 ft 3  0.32 ft 3 Qualified
-Steel 4.0 D 1.65 ft 3  1.20 ft 3  0.47 ft 3 Unqualified N/A 10.32 ft 3  10.32 ft 3  10.32 ft 3 Latent Debris (15% Fiber, N/A 67.36 Ibm 67.36 Ibm 67.36 Ibm 85% Particulate)
Foreign Materials Labels, Stickers, Tags, etc. N/A 24.4 ft 2  24.4 ft 2  24.4 ft 2 Glass (Containment N/A 46.082 ft2 46.082 ft 46.082 ft2 Lighting)Adhesive N/A 0.018ft 3 0.018ft 3 0.018ft Notes: (1) Break locations are discussed Selection.
(2) 25.0 ft 3 assumed for S1 break in the response to NIRC I opic 3.a, Break ToDic 3.c: Debris Characteristics FPL Response As discussed in Topic 3.f, Head Loss and Vortexing, the newly installed St. Lucie Unit 2 strainer system is based on previous successful strainer testing for the Point Beach Nuclear Plant. St. Lucie Unit 2's higher strainer area is based on the higher ratio of the ECCS/CSS recirculation flow as compared to the Point Beach ECCS/CSS flow and strainer surface area. Flume testing of the Point Beach strainer design used higher debris loadings than those at St. Lucie Unit 2 for the S1 break. The Point Beach test did not use FOAMGLAS or other potentially miscellaneous broken glass as a debris source in their testing. Since the FOAMGLAS is a closed cellular glass product it would float on the top of the water surface and not interfere with the sump screens. Miscellaneous glass on the containment floor and in the trench leading to the sump would not be transported to the strainer system. Hence, FPL is confident that this design will meet St.Lucie Unit 2 calculated post-LOCA debris loads.Detailed discussion of the debris characteristics used in the Point Beach test program is not provided in this submittal.
FPL will be conducting integrated chemical effects testing in a large flume on the St. Lucie Unit 2 design, using the calculated debris loading and post-LOCA chemistry conditions, and detailed debris characteristics will be available at that time. Following completion of this test program, a revision of this section will be provided to the NRC.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 9 of 47 The future St. Lucie Unit 2 integrated chemical effects testing in a large flume will use a debris transport calculation and Computational Fluid Dynamics (CFD) model to establish the velocity gradients, strainer approach velocity, and test flume configuration.
The technical requirements of the program will properly characterize and prepare debris, coatings, and other chemistry conditions to acceptable industry standards.
Standard industry materials will be used and, as required, surrogates will be selected to assure that they meet specific characteristics of St. Lucie Unit 2 materials.
Results of this testing and other RAIs applicable to debris characteristics will be addressed in the June 30, 2008 submittal to the NRC.Topic 3.d: Latent Debris FPL Response The bases and assumptions related to latent and miscellaneous debris, and the resulting quantities used for analyses and testing, have been updated since the September 1 response.
In that response it was noted that the quantity of latent debris was an assumed value in lieu of applied survey results, and that the sacrificial area for miscellaneous debris was an estimated value. Subsequently, walkdowns have been completed for St. Lucie Unit 2 specifically for the purpose of characterizing latent and miscellaneous debris. These walkdowns utilized the guidance in NEI 02-01 and the staff's SE of NEI 04-07.The NRC's SE for NEI 04-07 recommended that a walkdown guideline be developed to assess debris sources inside containment.
A walkdown plan and procedure were developed and implemented to determine the amount of foreign debris in the Unit 2 containment.
Samples were collected from eight surface types; floors, containment liner, ventilation, cable trays, walls, equipment, piping and grating. For each surface type, a minimum of (4) samples were collected, bagged, and weighed to determine the quantity of debris that was collected.
A statistical approach was used to estimate an upper limit of the mean debris loading on each surface. The horizontal and vertical surface areas were conservatively estimated.
The total latent debris mass for a surface type is the upper limit of the mean debris loading multiplied by the conservatively estimated area for that surface type, and the total latent debris is the sum of the latent debris for each surface type.Based on the walkdown data, the quantity of latent debris in the Unit 2 containment is estimated to be 67.36 pounds, and is included in Table 3.b-1. The latent debris composition is assumed to be 15% fiber and 85% particulate in agreement with the staff's SE of NEI 04-07.Two Unit 2 containment walkdowns were also performed for the purpose of identifying and measuring plant labels, stickers, tape, tags, and other debris. Based on the walkdown data, the quantity of miscellaneous debris in the Unit 2 containment is estimated to be 70.482 ft 2 , and is included in Table 3.b-1.Sacrificial area was not used for latent or miscellaneous debris in the design of the St.Lucie Unit 2 strainers.
For further discussion, see in Topic 3.f, Head Loss and Vortexing.
These debris types will be included in future testing for St. Lucie Unit 2.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 10 of 47 Topic 3.p, Foreign Material Control Programs, provides information on programmatic controls regarding coatings and insulation programs.
Regarding latent and miscellaneous debris, current procedures adequately address keeping loose debris and loose fibrous material at a minimum. It is further noted that detailed containment sump inspections are performed at the end of each outage and the Plant General Manager and the Site Vice President perform a detailed walkdown of the containment prior to entry into Mode 4 to assess restart readiness at the end of each outage.Topic 3.e: Debris Transport FPL Response In the September 1 response it was noted that debris transport would be analyzed using the computational fluid dynamics (CFD) based methodology outlined in NEI 04-07. A preliminary debris transport calculation was completed for St. Lucie Unit 2, but because of vendor and strainer supplier changes, the calculation was not used for the design of the currently installed St. Lucie Unit 2 strainer system. See Topic 3.f, Head Loss and Vortexing, for the bounding evaluation used to support the design of the strainer system.A transport model will be used with the S1 break debris loading provided in Table 3.b-1 to properly establish test configurations, debris velocity gradients, and strainer approach velocities.
This worse case debris load and flow will be used along with the necessary surrogates in the integrated chemical effects testing in a large flume for the St. Lucie Unit 2 strainer design verification.
The results from this testing along with applicable RAI responses will be provided in the June 30, 2008 submittal, along with the transport model results used to support the testing. The results of this testing are expected to affirm the margins available on the new St. Lucie Unit 2 strainer system.Topic 3.f: Head Loss and Vortexing FPL Response A basic schematic of the ECCS and CSS for St. Lucie Unit 2 is provided in Figure 3.f-1 below. A description of the strainer system is provided in the response to NRC Topic 3.j, Screen Modification Package.[RAI 37] [RAI 40] For Large Breaks and Small Breaks, where the break flow rate provides adequate means of heat removal from the RCS in the long term, recirculation flow and subsequent simultaneous hot and cold leg injection from the HPSI pump makes up the inventory loss through the break. For these scenarios, the newly installed strainer system would be fully submerged from the initiation of recirculation through the duration of the event. As'shown in the figures in Topic 3.j, Screen Modification Package, the top of each plate in seven of the eight stacks of strainers is at the same elevation.
At the minimum post LOCA containment water level (using the current Technical Specification minimum RWT level), the submergence of the highest strainer disks is approximately 12 inches. As noted in Topic 3.0, Licensing Basis, the current administrative level of the Refueling Water Tank (RWT) will be made permanent with an amendment to the Technical Specifications to this higher level, and under these conditions, the highest strainer plate would be covered by approximately 22 inches.For Small Breaks, with the RCS reflooded, the minimum water level would be approximately
 
===0.2 inches===
above the highest strainer plate. With the current St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 11 of 47 administrative RWT level, to be revised to the permanent level with an amendment to the Technical Specifications, the water level would be over 15 inches above the highest strainer plate. Under these conditions there would be virtually no debris load from the small break and HPSI flows would likely be throttled to maintain the RCS solid. It is further noted, that if reflood of the RCS is achieved after a small break LOCA, long-term core cooling would be provided by the secondary system via the steam generators or by the shutdown cooling system.As discussed and shown in the figures in the response to NRC Topic 3.j, Screen Modification Package., the newly installed strainer system contains two closely spaced sets of 4 strainer stacks connected to the top of the lower plenum. The lower plenum has an accordion perforated divider plate in the middle, and the ECCS/CSS recirculation suction flow comes off the ends of each plenum. The entire strainer system is located in the containment recirculation sump. The containment recirculation sump is open on both ends to a large trench, approximately 5 by 12 feet, that goes around the perimeter of containment and carries most of the recirculation flow to the sump. With screen perforation sizes of only 0.0625 inches and low constant approach velocities of only approximately 0.0034 ft/sec, formation of a vortex that can transport air into the system is fundamentally precluded by design and configuration.
Table A-2 of NRC Regulatory Guide 1.82, Revision 3, states that a 1 Y2 inch or deeper floor grating, or equivalent, that is at least 6 inches under water has the ability to suppress the formation of a vortex. The St. Lucie Unit 2 LBLOCA meets these criteria.Further, vortex testing of the Point Beach Nuclear Plant prototype strainer demonstrated that vortex characteristics were not present and no formation occurred even when the strainer was partially uncovered.
The St. Lucie Unit 2 strainer system is bounded by the Point Beach design.In accordance with Regulatory Guide 1.82, Rev 3, the St. Lucie Unit 2 strainer system limits air ingestion to less than 2% by limiting Froude Number to a maximum of 0.25.The collection and flow of post LOCA water in containment is analogous to that of open channel flow. Using the Froude Number equation for channel flow, along with conservative values for the strainer design, results in a.Froude Number of approximately 0.12, hence the strainer design will limit air ingestion below 2% in accordance with the Regulatory Guide.The potential for void formation below/downstream of the St. Lucie Unit 2 strainer system was evaluated using conventional hydraulic methods and NRC's NUREG/CR-6224 methodology.
The conventional analysis utilized Point Beach cold testing debris head loss results at 57.2 OF which were added to the St. Lucie Unit 2 clean strainer calculated head loss at 57.2 OF. This result was then multiplied by the ratio of the dynamic viscosity of water at 57.2 and 240 OF to result in a scaled total screen head loss of 1.443 ft of water. This technique is considered conservative because ratioing-up the highest cold test result for Point Beach in the same manner results in a total head loss of only 0.775 ft. for their prototype strainer.The NUREG/CR-6224 Correlation Methodology, also known as the NRC Head Loss Calculator, was used to further evaluate the potential for void formation downstream of the screens. The St. Lucie Unit 2 design parameters and the results from the ARL St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 12 of 47 testing were used to run the correlation which resulted in a strainer debris head loss of 0.0538 feet of water at 240 OF, and a related void fraction of 0.0% below the strainer screen.Both of these methods demonstrate that the potential head loss at the screens is very low, and that void formation would not be expected.
It is further noted, that with the centerline of the containment recirculation pipe inlet at elevation 9 feet, and the LB-LOCA sump water level of approximately 22.75 feet, there is well over 12 feet of head at the sump outlets. Hence, a void fraction of zero would be expected at the entrance to the ECCS/CSS recirculation pipe inlets for the design case strainer flow losses and the single failure case flow loss as presented below. Any temporary void formation at the top of the strainer would be collapsed soon after dropping into the strainer.[RAI 40] The very low strainer plate entrance velocity of approximately 0.0034 ft/sec, coupled with the approximately 12 inches of minimum water coverage at the top plates of the strainer system for the LBLOCA at RAS, will not allow floating debris to accumulate on the strainer system.[RAI 39] The newly installed St. Lucie Unit 2 strainer system is based on previous successful strainer prototype testing for the Point Beach Nuclear Plant. The St. Lucie Unit 2 strainer system is sized to assure a low approach inlet velocity of 0.0034 ft/sec based on 8570 gpm ECCS/CSS flow during the post-LOCA recirculation mode. The resultant strainer area is 5607.2 ft 2 with perforations of 0.0031 square inches. The low approach velocity allows the St. Lucie Unit 2 design to be correlated to, and compared with the Point Beach debris loading and prototype testing.An overview of the head loss calculations for the St. Lucie Unit 2 strainer system using the Point Beach testing results is provided below. A comparison of the available debris and coatings is also provided later in this section which shows that the debris load at Point Beach reasonably bounds St. Lucie Unit 2. Detailed discussion of the Point Beach prototype and test program is not provided in this submittal.
FPL will be conducting integrated chemical effects testing in a large flume on the St. Lucie Unit 2 design, using the calculated debris loading and post-LOCA chemistry conditions, with detailed debris characteristics for St. Lucie Unit 2. Hence, following this test program, a revision of this section will be provided to the NRC.The nominal design flow case for the design of the St. Lucie Unit 2 strainers assumed runout flow for two CSS pumps and two HPSI pumps. The head flow calculation that supported this case used detailed hydraulic calculations for the clean design and the results of Point Beach prototype testing for a strainer that employed the same design concept ( i.e., maintaining constant and small entrance velocities across the strainer surface area). This head loss calculation is considered to be conservative since it adds the clean head loss from the St. Lucie Unit 2 design to the total debris laden head loss from the Point Beach test. These results will stand in support of the St. Lucie Unit 2 design until testing for the St. Lucie Unit 2 design is completed and evaluated.
This test program will also include/address the actual debris loading and characterization of St.Lucie Unit 2 along with the actual post-LOCA chemistry conditions.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 13 of 47 The clean head loss calculations for the strainer stack internal components, lower plenum, and containment recirculation pipe inlet are summarized in Table 3.f 1 for a scaled temperature of 2100 F. These design features are shown in Figures 3.j -2 through 5. As concluded from these calculations, at 2100 F the strainer system with runout flow of a CSS and HPSI pump on the "A" and "B" train side, clean strainer head losses would be 1.21 feet of water on the "B" train side and 0.98 feet on the "A" train side.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 14 of 47 Table 3.f-1 *Calculated Clean Strainer Head Losses @ 210' F Two CSS Pumps and Two 1 CSP & 1 HPSI Pump -"B" 1 CSP & 1 HPSI Pump -HPSI Pumps at Runout Flow Train Strainer Stacks 1, 2, 3 "A" Train Strainer Stacks from the Sump & 4 5,6, 7 & 8 Parameter
@ 210°F @ 210-F Uncorrected CSHL for Stack 1 0.205 0.205 or 8 (includes 6% uncertainty)
Flow, Perforated Plate Head 0 0 Loss Corrections Strainer Length Head Loss 0.015 0.015 Corrections Disk Internal Flow Restriction 0 0 Head Loss Core Tube Exit Head Loss to Plenum (includes 10% 0.227 0.227 uncertainty)
Plenum Chamber Head Loss 0.021 0.017 (includes 10% uncertainty)
Square Orifice Restriction to Flow in Plenum (includes 10% 0.485 0.319 uncertainty)
Plenum Chamber Discharge
-Sump Head Loss (includes 0.125 0.058 10% uncertainty)
*Suction Pipe Entrance Head Loss (includes 10% 0.134 0.134 uncertainty)
Total Corrected Clean Strainer Head Loss 1.21 0.975 (TCCSHL) with Attached Piping -Ft of Water-Note, aoes not incluae piping ana other neaa piping to the suction of the ECCS/CSS pumps losses from the entrance oT me suction The debris laden calculations are summarized in Table 3.f 2 at three temperatures for the "B" side of the strainer system for the case where two CSS and two HPSI pumps are at runout flow from the sump. As indicated in the table, the worst case expected head loss on the St. Lucie Unit 2 screens for this condition would be approximately 1.72 feet of water at 2400 F and 1.82 feet at 2100 F.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 15 of 47 Table 3.f-2 Nominal Design Case -Calculated Debris Laden Strainer Head Losses Two CSS Pumps and Two HPSI Pumps at "B" Train Strainer Stacks 1, 2, 3 & 4 -Head Runout Flow from the Sump Loss at Calculated Temperatures Item Description 240OF 210°F **80OF PSL2 Calculated Clean Strainer System Head Loss With Temperature Compensation, 1.2 1.21 1.25 Ft of Water From Point Beach Design Basis Test Round 2 Testing -Head Loss With Temperature 0.515 0.608 1.769 Compensation, Ft of Water Total PSL2 Head Loss, Based on Sum of Clean Loss on PSL2 and Debris Laden Loss 1.715 1.818 3.019 From PB Test -Head Loss With Temperature Compensation, Ft of Water* Under these flow conditions, represents the most conservative side of the strainer system with the highest head loss**ECCS/CSS flows would have been throttled long before temperatures reach this level since containment pressure would be down and core decay heat would be lower.Under the conditions where the operator trips a CSS pump during the injection phase, calculations have determined that the train "A" side of the strainer system has the highest head loss. Similarly, for a single failure scenario for the highest flow offset from the sump, the "A" train side has higher head losses than the "B" train. The single failure assumes that the "A" train LPSI pump did not automatically trip when the RAS signal is generated on low RWT level. After RAS, the Operator will verify that RAS actions have occurred, and take the necessary action to trip the LPSI pump. The calculation results, provided in Table 3.f 3, show that this temporary head loss condition would result in a worst case head loss of 3.603 feet at 2100 F.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 16 of 47 Table 3.f-3 Worst Case Single Failure -Calculated Momentary Debris Laden Strainer Head Losses Worst Case Single 1 CSP & 1 HPSI & I LPSI Pump -"A" Train Strainer Stacks Failure of a LPSI Pump for 5, 6, 7, & 7 -Head Loss at Calculated Temperature to Trip on RAS Item Description 21 0°F PSL2 Calculated Clean Strainer System Head Loss With Temperature 3.603 Compensation, Ft. of Water (Including 10%Uncertainty Margin)*Represents the highest head loss side of the strainer system under this offset flow condition.
These head loss conditions would exist until the operator verified RAS actions and tripped the operating LPSI pump.A comparison has been completed that serves to demonstrate that the Point Beach testing results are applicable for St. Lucie Unit 2 since the amount of fiber, coatings, and chemical precipitates are bounding compared to that for St. Lucie. This is shown in Table 3.f 4 below, from which it is concluded that the types of materials and chemistry at Point Beach are sufficiently close to those at St. Lucie Unit 2, and the amount of fiber at Point Beach is bounding.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 17 of 47 Table 3.f-4 Summary Comparison of St. Lucie Unit 2 and Point Beach Debris Types and Amounts Debris Type St. Lucie Unit 2 Point Beach Fibrous Debris 1435.31 ft- 1,948.77 ft" Latent Fibrous Debris 10.1 Ibm 114.2 Ibm RMI 6067 ft 2  5386 ftW Calcium Silicate 362.5 Ibm. 1783.5 Ibm Foamglass 18.05 ft" *Insulation Jacketing, SS sheet 8487 ft" None Coatings (Qualified and Unqualified) 18.03 ftW 61.82 ftW Latent Debris Particulate 57.3 Ibm 427.5 Ibm Glass 46.082 ft*Labels, Stickers, Tape 24.4 ft" Adhesive .018 ft _Flex Conduit Jacket, PVC jacket 45 ft*Chemical Precipitates
****1138.2 Ibm *****1431.1 Ibm* None included in Point Beach testing, but based on the buoyant closed-cell structure of this type of insulation, it would be expected to float indefinitely.
** Point Beach does not employ stainless steel insulation jacketing, however, this jacketing is heavier than RMI type jackets and will not transport to the sump.*** Information from the Point Beach tests does not include these miscellaneous debris sources. The final St. Lucie Unit 2 testing program will assure that this type and amount of miscellaneous debris are accounted for.**** Data is from preliminary unverified calculations for St. Lucie Unit 2, and will be revised as a part of the future test program for the new strainer system.These are NaAlSi 3 0 8 precipitates only.[RAI 39] St. Lucie Unit 2 will be conducting an integrated test in a large flume. The results of the test program will be provided at a later date after the test program has been completed.
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[44 K< .*4444*14.*Figure Vf-1: ECCS/CSS Piping Schematic St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 19 of 47 Topic 3.Q: Net Positive Suction Head Available (NPSH)FPL Response Following a large break LOCA (LBLOCA) both trains of the Low Pressure Safety Injection (LPSI) pumps, Containment Spray (CS) pumps and High Pressure Safety Injection (HPSI) pumps are automatically started taking suction from the Refueling Water Tank (RWT). Prior to the end of the RWT injection phase, the Operator will shutdown one of the operating CSS pumps. This operation is conducted per procedural verification of proper containment pressure, containment fan cooler operation, and safety injection flow. Following trip of the CSS pump, the nominal flow rate from the RWT would be 4,970 gpm. When the RWT reaches low level, an automatic Recirculation Actuation Signal (RAS) is generated.
RAS shuts down the operating LPSI pumps and realigns the HPSI pump and operating CSS pump to take suction from the containment sump. At this point, the sump ECCS/CSS flow rate with one CSS pump and two HPSI pumps operating could be as high as 4,970 gpm.Based on an NRC audit finding at Waterford, an additional calculation for a LBLOCA was completed.
This calculation assumed a single failure of a LPSI pump to trip at the initiation of RAS. The Operator would take action to trip this pump manually during procedural verification of RAS actions. However, although this flow condition would be temporary, it would be the highest possible flow condition, 8,470 gpm from the containment sump. It is noted that the calculation assumes, under these temporary conditions immediately following RAS, that the strainers would remain clean with little or no debris head loss.Also as a result of the Waterford audit, revised post-LOCA sump calculations have been completed.
These calculations result in a minimum sump water level of 22.75 ft at 210&deg;F for a LBLOCA or SBLOCA, where the break flow rate provides adequate heat removal.For a SBLOCA that recovers RCS inventory the minimum sump level is 21.76 ft. The revised calculations consider:* Volume additions o RWT water level at minimum o Reactor Coolant System (RCS)o Other ECCS tanks at minimum level" Volume holdup from sump level o Empty spray piping o Spray droplets o Floor of the refueling cavity o Volume of water held up on horizontal and vertical surfaces o Steam in the containment atmosphere o RCS re-flood volume ECCS/CSS pump NPSH calculations have been conducted for numerous pump and* single failure scenarios for the LOCA where the break flow rate provides adequate means of heat removal from the RCS during long term cooling. Calculations use head losses for the sump strainers and friction/losses for the piping from the sump to the St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 20 of 47 ECCS/CSS pumps. ECCS/CSS pumps were calculated to be at or near run-out flows, even though containment and or RCS back pressure would be present. Further, the calculations were conducted in accordance with the conservative assumptions of Regulatory Guide 1.1, which does not allow credit for containment air heating and the accompanying additional partial pressure of air. It is noted that under sump water temperature conditions of 210&deg;F, that this additional pressure is approximately 5 ft.Hence there is significant conservatism using this methodology.
The minimum required NPSH for a HPSI pump with flow at 685 gpm is 23.5 feet of water, and the minimum for a CSS pump with flow at 3,600 gpm is 18.0 feet. Note that the calculations assume an additional 1% flow tolerance to bound the available pumps.As shown in Table 3.g-1, sufficient NPSH is available for the HPSI and CSS pump for the 4,970 gpm sump flow scenario.For the case where it is assumed that a single failure does not allow a LPSI pump to trip on RAS, and the operating CSS pump is on the same train as the LPSI pump, this CSS pump would have sufficient available NPSH. However, during this temporary flow upset, the opposite train HPSI pump would be relied upon as sufficient NPSH is available for this pump.As noted in Topic 3.o, Licensing Basis, the current administrative level of the Refueling Water Tank (RWT) will be made permanent with an amendment to the Technical Specifications to this higher level. At this higher level, the Minimum Available NPSH values in Table 3.g-1 would have an additional margin of 0.83 feet.&#xfd; St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 21 of 47 Table 3.g-1 Minimum Available NPSH Calculations
@ 210&deg;F with current RWT Technical Specification Minimum Level ()Pump Scenario (2)Sump IHPSINPSH CSP NPSH at RAS Initiation Flow Case Minimum Minimum Available Required Available Required LBLOCA one CSS and two HPSI 4,970 gpm (3)24.173 ft 24 ft (3)24.312 ft 18.3 ft Pumps -Debris Laden Strainers LBLOCA with (1),(4)20.902 ft LPSI Failure to 8,470 gpm 24 ft (4)18.742 ft 18.3 ft Trip on RAS -Clean Strainers (5)26.405 ft (') These calculations are based on the conservative assumptions of Regulatory Guide 1.1. It is noted that if the partial pressure of containment air heating were included in these calculations an additional 5 ft. of head would be available.
(2) These flows represent nominal runout values for the pumps. The NPSH calculations increased flow by 1 % to account for pump flow variability tolerance.
(3) HPSI pump is on the same train as the CSS pump (4) This is for the worst case with a LPSI, CSS, and HPSI pump on the same train. Under these temporary flow conditions, the available NPSH for the same train HPSI pump calculates approximately 3 ft below the required amount.(5) The available NPSH for the opposite train HPSI pump which is available and sufficient for long term cooling.Topic 3.h: Coatings Evaluation FPL Response Coatings inside containment are classified as Service Level 1 qualified, or unqualified.
Qualified coatings are defined as coatings that will remain in place under Design Basis Accident (DBA) conditions (temperature, radiation, humidity, and pressure).
The qualified coating systems used in the St. Lucie Unit 2 containment are listed in Table 3.h-1 below.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 22 of 47 Table 3.h-1 Qualified Coatings in the St. Lucie Unit 2 Containment Coating Application Substrate Application Product Thickness (mils)1st Coat Carboguard 890 6 2nn Coat Carboguard 890 6 1 st Coat Carbozinc 11 5 Steel 2 nd Coat Amercoat 90 8 Concrete 1 s7 Coat Carboguard 2011S 50 2 nd Coat Carboguard 890 7 Floor 3 rd Coat Carboguard 890 7 Concrete 1 st Coat Nu-Klad 11 OAA 125 Floor 2 nd Coat Amercoat 90 8 1st Coat Carboguard 2011S 35 Concrete 2 nd Coat Carboguard 890 7 Walls 3rd Coat Carboguard 890 7 Concrete 1 st Coat Nu-Klad 114 7 Walls and 2 nd Coat Nu-Klad 114 7 Ceilings 3 d Coat Amercoat 90 8[RAI 30] For St. Lucie Unit 2, the analyzed LOCA cases generated sufficient fiber to form a thin fiber bed. As discussed in previous sections, FPL will be conducting integrated chemical effects testing in a large flume on the St. Lucie Unit 2 strainer design. This test will cover the maximum debris generation-and a minimal debris generation case that can produce the "thin bed effect." Standard industry surrogates will be selected to assure that they meet specific characteristics of St. Lucie Unit 2 materials and coatings.
Following completion of this test program, a supplemental response will be transmitted to the NRC that provides the details of coating sizing, surrogates used, and test results.Selected features of the treatment of qualified and unqualified coatings in the determination of coating debris that reaches the sump strainers have been updated since the September 1 response.
These changes are discussed individually below.The qualified coating ZOI provided in the September 1 response for St. Lucie Unit 2 was 1 OD. The ZOI for qualified coatings has subsequently been reduced to 4D. The 4D ZOI is based on coatings performance testing that was completed during February of 2006.It is noted that the Amercoat 90 coating showed minor amounts of erosion in the testing, hence from a 4D to 1OD ZOI, it has been assumed that 1 mil of debris from Amercoat 90 is included in the debris generation.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 23 of 47[RAI 29] A description of the test, test data, and evaluation of the test data were previously provided to the NRC Staff for information on July 13, 2006 in FPL Letter L-2006-169 (R. S. Kundalkar (FPL) to M.G. Yoder (NRC), "Reports on FPL Sponsored Coatings Performance Tests Conducted at St. Lucie Nuclear Plant," July 13, 2006).The evaluation of the test results confirms that a 4D ZOI is applicable to the in-containment qualified coating systems at St. Lucie Unit 2, except as noted above for Amercoat 90. As stated in the test plan, heat and radiation increase coating cross linking, which tends to enhance the coating physical properties.
Therefore, since artificial aging, heat, or irradiation to the current plant conditions could enhance the physical properties and reduce the conservatism of the test, the test specimens were not aged, heated, or irradiated.
The coating thicknesses in the September 1 response were assumed to be 3 mils of inorganic zinc primer plus 6 mils of epoxy (or epoxy-phenolic) top coat for qualified coatings and 3 mils of inorganic zinc for unqualified coatings.
Subsequently, the analyses have been updated. The current debris generation model conservatively assumes the maximum thicknesses for each applicable coating system.The coating area in the ZOI in the September 1 response was assumed to be equal to the surface area of the ZOL. Subsequently, the updated debris generation calculations provide the quantity of qualified coatings for each break by using the concrete and steel drawings to determine the amount of coating that will be within the ZOI for each break.Coatings that are shielded from the jet by a robust barrier are not included in the total.The calculated volume of qualified steel coating is then increased by 10% to account for small areas of additional items such as piping, pipe/conduit/HVAC/cable tray supports, stiffener plates, ladders, cages, handrails, and kick plates.The estimated quantity of qualified and unqualified failed coatings for the S1 break in the September 1 response was 10 ft 3.With the changes discussed above, the estimated quantity of qualified and unqualified failed coatings for the S1 break is now 10.32 ft 3.The Coatings Specification has been enhanced and is used to control the quantity of degraded qualified coatings in containment.
The previous program for controlling in-containment coatings was described in the FPL response to NRC Generic Letter 98-04, "Potential for Degradation of the Emergency Core Cooling System and the Containment Spray System After a Loss-of-Coolant Accident Because of Construction and Protective Coating Deficiencies and Foreign Material in Containment" in letter L-98-277 on November 9, 1998. The letter summarized the program in place at that time for assessing and documenting the condition of qualified/acceptable coatings in primary containment at St. Lucie Unit 2.[RAI 25] The current program for controlling the quantity of unqualified/degraded coatings includes two separate inspections by qualified personnel during each refueling outage, and notification of plant management prior to restart if the volume of unqualified/degraded coatings approaches pre-established limits.The first inspection takes place at the beginning of every refueling outage, when all areas and components from which peeling coatings have the potential for falling into the St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 24 of 47 reactor cavity are inspected by the FPL Coating Supervisor.
The second inspection takes place at the end of every refueling outage when the condition of containment coatings is assessed by a team (including the Nuclear Coating Specialist) using guidance from EPRI Technical Report 1003102 ("Guidelines On Nuclear Safety-Related Coatings," Revision 1, (Formerly TR-109937)).
All accessible coated areas of the containment and equipment are included in the second inspection.
Plant management is notified prior to restart if the volume of unqualified/degraded coatings approaches pre-established limits.The initial coating inspection process is a visual inspection.
The acceptability of visual inspection as the first step in monitoring of Containment Building coatings is validated by EPRI Report No. 1014883, "Plant Support Engineering:
Adhesion Testing of Nuclear Coating Service Level 1 Coatings," August 2007. Following identification of degraded coatings, the degraded coatings are repaired per specification if possible.
For degraded coatings that are not repaired, areas of coatings determined to have inadequate adhesion are removed, and the Nuclear Coatings Specialist assesses the remaining coating to determine if it is acceptable for use. The assessment is by means of additional nondestructive and destructive examinations as appropriate.
Topic 3.i: Debris Source Term Refinements FPL Response None of the Guidance Report or Safety Evaluation debris source term refinements were used to reduce the debris sources on St. Lucie Unit 2.Topic 3.I: Screen Modification Package FPL Response The St. Lucie Unit 2 containment recirculation sump is open on both ends to a large recirculation trench that goes around the perimeter of the reactor containment and would carry most of the post-LOCA recirculation flow. Figure 3.j-1 provides a general overview of containment layout at the 18 ft elevation showing the trash racks which lead to the perimeter trench, and the general location of the containment recirculation sump. As shown in Figure 3.j-2, the bottom of the trench, approximately 12 ft elevation, is open to the containment recirculation sump which has a floor elevation of approximately 7 ft 7 inches.The containment recirculation sump contains the Reactor Drain Tank, related mechanical equipment, instrumentation and piping. This was also the location for the original containment recirculation sump screens and is the location of the new ECCS sump strainer system.The recently installed St. Lucie Unit 2 strainer system has eight separate vertically installed strainer stacks with a lower plenum box. This is mounted on the lower containment recirculation suction piping housing. Two separate recirculation intake pipes are located inside of the lower housing on the East and West ends of the recirculation sump. An instructional plan view, side view and isometric view of the strainer system are provided in Figures 3.j-2, 3, and 4, respectively.
Strainer stacks 5, 6, 7, and 8 service the East end of the containment recirculation sump, for the train "A" St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 25 of 47 recirculation pipe intake, and stacks 1, 2, 3, and 4 service the West end for train "B". An accordion divider plate with 1/16 inch holes is installed in the plenum which prevents any transport of large particles between the East and West strainer system. This helps to provide physical protection in the lower sump while still maintaining a degree of hydraulic coupling to balance head loss differences.
A strainer stack is an assembly of strainer modules generally with 11 or 15 disks, in each module. The modules have stiffener plates and are connected with tension rods into a strainer stack. Each of the disks is 1/2 inch thick with an internal separation gap between disks of 1 inch. The disks are hollow and have perforations of 1/16 inch diameter on the tops, bottoms and sides. A flow control tube with flow slots for each disk runs from the top disk to the bottom, and is of varying diameters for each of the modules as it progresses from the top to the bottom of the strainer stack. A typical end strainer stack is shown in Figure 3.j-5.As shown in Figure 3.j-4, the strainer stacks are of three basic designs. This was necessary to assure proper fit-up in the sump due to space interference limitations in the sump area. The hydraulic strainer designs of stacks 1 through 4 and 5 through 8 are all based on achieving a low approach velocity to the strainer perforations of approximately 0.0034 ft/sec, and closely balancing each ECCS/CSS train to a flow of approximately 4,250 gpm. Hence, the strainer area on each train is approximately equal to half of the total 5,607 square feet of strainer surface area.[RAI 32] The original sump screens have been replaced with the strainer system discussed earlier. The newly installed system is passive and does not rely on active features such as back flushing or other mechanical devices.The installation of the St. Lucie Unit 2 sump strainer system required the removal of the original sump screen system, relocation of Trisodium Phosphate Dodecahydrate (TSP)baskets, and the removal or modification of other in-sump piping and supports.
These included:* Removal of the original sump screens and most of the original framing.* Six of the TSP containers that were originally installed in the sump were removed and relocated to the recirculation trenches.* Three sections of Safety Injection System Piping were rerouted and re-supported.
* The Reactor Drain Tank level instrumentation tubing, nitrogen and primary makeup water supply lines, and drain and vent lines were modified including supports as necessary.
* Modification of the gallery steel and supports at the 23 foot elevation and the removal of an unneeded pipe whip restraint.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 26 of 47 FIGURE 3.j-1 UNIT 2 CONTAINMENT TRASH RACKS AND SUMP LOCATION r"-Q 5o&deg;w L 600 40/200 Refueling Cavity Area El 16---El 18.5'--(typ) <ECCSSump 18* El Outside of Primarv Shield 2(Trash Rack 2100 Door 2200 Azimuth Approximate 2300 240 <35*Primary hield Wall 01360'340*3300 EM C.320" 310&deg;250*260&deg;2800 St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 FIGURE 3.j-2 UNIT 2 CONTAINMENT RECIRC SUMP STRAINERS
-TOP VIEW L-2008-030 Attachment 3 Page 27 of 47 CO 9~U)U)9 N (0 (0 U)* (0 C0 (0 C?0 (0 CO U), (0-En 0)(0 (0 St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 28 of 47 FIGURE 3.j-3 UNIT 2 CONTAINMENT SUMP STRAINER SYSTEM -SIDE VIEW Grating and Support Beams El' 23'0"/Sump Floor E1' 77' 7L_ ... ... .Containment Sump Side View St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 29 of 47 FIGURE 3.j.-4 UNIT 2 CONTAINMENT SUMP East ECCS Suction Piping Outer Housing--. rr-ast  Weep holes (typ)Access hatches to ECCS suction piping o /ECCS'Sump Floor el i/L 717"~West ECCS Suction Piping Outer Housing St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 30 of 47 FIGURE 3.j-5 TYPICAL END STRAINER STACK 8-Nut Rod -15 Plate XD Plate XC-30 eXB aXA-22 (P, St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 31 of 47 Topic 3.k: Sump Structural Analysis FPL Response A general description of the strainers is provided in Topic 3.j, Screen Modification Package. Figures 3.j-3 and 4 show the strainer stacks, lower plenum box, and the east and west containment recirculation piping housings.
The recirculation piping housings, some of the original supporting members, and new support bracing were used in the installation of the strainer system. The new plenum box and strainer stacks are supported by this original and reinforced portion of the structural steel. As discussed below in greater detail, for structural analysis, two separate problems were evaluated using the GTSTRUDL Code: 1) the strainer stacks and their attachment to side walls and top of the plenum, and 2) the plenum box and lower piping housings were analyzed together as one integrated plenum assembly, and this is referred to as such in the balance of this discussion.
Strainer Stack Analysis: Each stack is essentially supported independently by the tube steel/angle iron supports and can be analyzed as an individual unit. Strainer Stacks #2 through #5 and #6 are all nearly identical overhanging strainer stacks, except that Stack #6 has five fewer disks.Hence, analysis of one of the other taller overhanging stacks bounds this stack. Stack#s 1, 7, and 8 are full stacks and are identical except for minor variances in the wall attachment assembly.
As discussed below, two analyses were conducted, one for an overhanging stack and the second for a full stack.The Strainer Assemblies are located outside of the concrete biological shield and are therefore not subject to pipe reaction forces or high energy line break jet loads from Reactor Coolant System or other ASME Code Class 1 piping. An evaluation of the ASME Code Class 2 and 3 piping in the general area of the strainers determined that there were no high energy line breaks that would result in a LOCA and require reliance on the strainer system. A two inch charging pump line that was located along the wall, did qualify as a high energy line. However, break cone analysis of the line shows no direct impact on the strainer assemblies.
Hence, it was determined that the structural load analysis of the Strainer Assemblies did not require consideration for pipe reaction loads or high energy line jets. Since the strainer system is outside the biological shield wall and down in the containment sump, there is no potential missile hazard from pipe breaks.It is further noted that the strainer assemblies are passive and do not employ mechanical or hydraulic cleaning or flushing following a LOCA, hence, there are none of these forces on the strainers.
The remaining potential loads for the Operating Basis Earthquake and Safe Shutdown Earthquake load combinations for the strainer system are provided in Table 3.k-1:
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 32 of 47 Table 3.k-1 Potential OBE and SSE Load Combinations Load Loads Allowable Applicable Environmental Combination Condition LC1 D + L 1.0 S Sump is dry or flooded LC2 D + L + E 1.0 S Sump is dry or flooded LC3 D + L + To 1.5 S Sump is dry or flooded LC4 D + L + To + E 1.5S Sump is dry or flooded LC5 D + L + To + E' 1.6S Sump is dry or flooded LC6 D + L + Ta 1.6S Sump is dry or flooded LC7 D + L + Ta + E 1.6S Sump is dry or flooded LC8 D D+L+Ta+E' 1.6S Sump is dry or flooded D = Dead Weight Load component L = Live Loads To = Thermal loads at maximum normal operating temperature Ta = Thermal loads at maximum accident design temperature E = Operating Basis Earthquake loads E' = Safe Shutdown Earthquake loads S = The required section strength based on elastic design methods and the allowable stresses Two load combination cases were analyzed in the GTSTRUDL strainer models to envelope the load combinations; an operating basis earthquake case and a safe shutdown earthquake case. Load Combination 4, LC4, bounds cases 1 and 3. In order to represent LC2 and LC4 in the calculations, the ratio of the yield stresses and water densities (at 80 OF and 240 OF) are used to calculate an allowable of 1.19 S. The use of this conservative Allowable and the LC4 load case in the strainer model runs conservatively bounds the service load conditions.
Load Combination 8, LC8, bounds the factored load conditions, cases 5 through 7, since it assumes higher temperature stresses and the earthquake stresses are higher than the operating basis earthquake.
The resulting load combinations used in the analysis are provided in Table 3.k-2:
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 33 of 47 Table 3.k-2 OBE and SSE Load Combinations for GTSTRUDL Models Load Loads Allowable Applicable Environmental Combination Condition LC4 D + Ldeb + Ldp + T. + Ew 1.19 S Sump is submerged
@ 120 'F LC8 D + Ldeb + Ldp + Ta + E'w 1.6 S Sump is submerged
@ 240 'F D = Dead Weight Load of strainer components Ldeb = Debris Weight Live Load Ldp = Differential Pressure Live Load (across a debris covered strainer)To = Thermal loads at 120 'F Ta = Thermal loads at 240 'F E = Operating Basis Earthquake loads E' = Safe Shutdown Earthquake loads S = The required section strength based on elastic design methods and the allowable stresses The strainer components are designed to meet code acceptance requirements of the AISC Manual of Steel Construction, 9th Edition, or the ASME Boiler & Pressure Vessel Code, Section III, 1971 Edition including 1973 Addenda for stainless steel. Other design and code usage for strainer components includes: Material Strengths at Elevated Temperatures:
The material properties for stainless steel materials are used at elevated temperatures associated with the load combination and are taken from ASME B&PV Code, Section II, Part D, Material Properties, 1998 Edition Plenum Plates and Side Channels:
Plate membrane stress and bending stress are-evaluated following the more limiting allowable stress in AISC or NC-3821.5-1.
Stainless Steel Members in Compression:
Allowable stresses for stainless steel members in compression are from ANSI/AISC-N690, and members in tension, shear, bending, or bearing are from AISC Strainer Perforated Plates: Equations from Appendix A, Article A-8000 of the ASME B&PV Code, Section III, 1971 Edition through Winter 1973 addenda (Ref.[3]) are used to calculate perforated plate stresses.Disk Rims: The disk rim and the attached perforated plate work as a combined section to resist bending loads and are based on the design guidelines of SEI/ASCE 8-02 Standard for Cold-Formed Stainless Steel Structural Members.Welds: Welds for non-pressure strainer support components are qualified per the AISC 9th Edition.Rivets: Rivet capacities are based on testing, with a factor of safety calculated according to Standard SEI/ASCE 8-02 as supplemented by AISI Specification for the Design of Cold-Formed Steel Structural Members, 1996 Edition.Mounting Hardware:
The analysis and design of expansion anchors is in accordance with Florida Power & Light Specification C2.24, "Drill-in Expansion'Anchors in Concrete St. Lucie Units 1 & 2 and Turkey Point Units 3 & 4," Revision 13 and FPL Standard STD-C-01 0, Appendix A, "Piping Seismic Analysis Methods", Revision 0.A figure representing the models for a tall overhanging stack and a full stack are shown in Figure 3.k-1. Each stack is essentially supported independently by the tube St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 34 of 47 steel/angle iron supports and can be analyzed as individual units. The disk faces, gap disks, gap rings, grill wire stiffeners, and end cover, are not included in the models (except for their mass)..The interaction ratios for the components in the models are provided in Table 3.k-3. The results of this calculation indicate the interaction ratios for the strainer assembly *components are below 1.0, and that the strainers meet the acceptance criteria for all applicable loadings.Table 3.k-3 Interaction Ratios for Strainer Assembly Components Strainer Component LC4-OBE LC8-SSE Intermediate Radial Stiffeners 0.57 0.72 Tension Rods 0.48 0.71 Spacers 0.97 0.97 Edge Channels 0.32 0.35 Core Tube (Biggest Holes) 0.07 0.09 Core Tube Mating Flange 0.09 0.13 Hex Couplings 0.07 0.07 Clip Angles 0.35 0.44 Vertical Angle Iron (support) 0.59 0.74 Tube Steel (support) 0.08 0.09 Disk Faces 0.60 0.52 Disk Rims 0.32 0.35 Wire Stiffener 0.46 0.50 Gap Disk (enveloping sleeve B) 0.12 0.11 Gap Disk stiffening ring 0.15 0.17 Sleeve C (enveloping sleeve A) 0.09 0.09 End Cover 0.12 0.13 Weld of Core Tube to Mating Flange 0.08 0.10 Weld of Tube Steel to Vertical Angle Iron 0.84 0.88 Weld of Tube Steel to Sump Wall Steel Plate 0.36 0.36 Clip Angle Bolts 0.07 0.13 Disk Face Rivets 0.17 0.18 Gap Disk Rivets 0.08 0.07 Sump Wall Steel Embedment Plate 0.47 0.75 Intearated Plenum Analysis: A figure representing the model for the integrated plenum assembly is shown in Figure 3.k-2. The interaction ratios for the components in this model are provided in Table 3.k-4. The results of this calculation indicate the interaction ratios for the plenum components are below one, and that the strainers meet the acceptance criteria for all applicable loadings.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 35 of 47 Table 3.k-4 Interaction Ratios for Plenum Assembly Components Plenum Component LC4-OBE LC8-SSE Channel Box Channels 0.62 0.66 Spacer Rods inside Plenum 0.19 0.20 Angle Framing 0.93 0.95 Support Plate Beams 0.16 0.33 W8x31, C.S. 0.07 0.18 Tube Steel Posts 0.04 0.09 Internal Pipe Posts 0.42 0.44 Stiffener Plates 0.90 0.94 Lower Internal C-shape Braces 0.31 0.32 Top Cover, Bottom Cover, Side Plates 0.83 0.92 Plenum Channel Web 0.53 0.59 Angle Local Flange 0.10 0.11 Plenum Channel Local Flange 0.31 0.31 Channel Splice Bolt 0.34, 0.55 Channel Splice Weld & Plate 0.44 0.69 Channel Corner Welds 0.55 0.54 Cover Plate Bolts 0.95 0.93 Cover Plate Hole Patches 0.63 0.91 Support Plate Bolts 0.41 0.78 Stiffener Angle End Bolting 0.99 0.96 Tube Steel End Welds 0.12 0.18 Support Plate-to-Plate Welds 0.28 0.35 Angle-to-Channel Welds 0.36 0.34 Channel Brace-to-Angle Welds 0.45 0.44 Corner Angle to Lower Angle Weld 0.34 0.35 Horizontal Angle to Angle Weld 0.78 0.76 Vertical Angle at Ledge to Lower Angle Weld 0.15 0.14 Stiffener Angle to Plate Weld 0.43 0.39 Stiffener Plate to Plate Weld 0.38 0.35 Plenum Flow Deflector 0.40 <0.4*.Concrete Expansion Anchors la 0.19 0.73 Concrete Expansion Anchors 2 0.20 0.49 Embedment Plate W2 on Ledge 0.23 <0.23*Corner Angle / Bolt at Ledge 0.53 0.64 Embedment Plate South Wall 0.13 0.42 WT6x13.5, C.S., Existing 0.23 0.36-NJote: interaction Ratio due to ioad case LUO-00,=-
is less than that due to these components LU+-Uti- Tor A special outage maintenance procedure is in place at St. Lucie Unit 2 to assure that the strainer system and trash racks are inspected.
The procedure addresses carefully accessing the sump area, installing railings on the upper deck of the Reactor Coolant Drain Tank, conducting initial and final inspections of the strainer system hardware and the trash racks. The procedure also calls for the installation of a temporary protective cover over the strainers at the beginning of the outage and the removal of the cover prior St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 36 of 47 to startup. A final inspection of the strainer system components and the trash racks is conducted prior to startup. As discussed in the procedure, any damage observed on the strainer system components or the trash racks is reported for evaluation and repair via Condition Reports.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 37 of 47 FIGURE 3.k.-1 Strainer Stacks #4 and #7 GTSTRUDL Models'4 Z, X St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 38 of 47 FIGURE 3.k.-2 Integrated Lower Plenum GTSTRUDL Model St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 39 of 47 Topic 3.1: Upstream Effects FPL Response[RAI 42] In the September 1 St. Lucie submittal it was noted that it was planned to obtain additional confirmation that there are no chokepoints.
This confirmation was obtained from a walkdown that was conducted in the St. Lucie Unit 2 containment specifically to evaluate recirculation flow paths. The walkdown utilized the guidance in Nuclear Energy Institute (NEI) Report 02-01, NEI Report 04-07, and the Staff's SE of NEI 04-07.As shown in Figure 3.j-1, there are 20 trash racks located at the biological shield wall on the 18 foot elevation.
ECCS flow from an RCS break would travel through these racks and dump into the recirculation trench that has a bottom elevation of approximately 12 feet. The trash racks prevent large debris from entering the recirculation trench and transporting to the recirculation sump screens. The newly installed strainer system is open to the trench on both ends of the containment recirculation sump. The openings in the trash racks between the steel bars are approximately 3/4 of an inch. A photo of typical trash racks at St. Lucie Unit 2 is shown in Figure 3.1-1. Similar structures are also utilized at the stairwell openings in the shield wall. Because of the large size of the racks, the quantity of them, and the relatively large size of the openings between slats, it is not probable that debris could fully block all of them and prevent the flow of water past the shield wall into the trench. A calculation was performed which estimated the flow rate, from the 18 foot elevation through the trash racks, at approximately 0.04 ft/sec. At this low flow rate it would be difficult for large debris to even reach the trash racks.Further, in the long term recirculation mode, only one CSS pump would be operating and much of this spray flow would enter the trench and sump from the 23' floor elevation outside of the bioshield wall, bypassing the trash racks. Hence, for long term cooling out of the break location, flows across thel 8 foot floor elevation would be limited to the HPSI pumps and a portion of one CSS pump. With a sump level for the large break LOCA at the 22.75 foot elevation, flow into the recirculation trench is not expected to be impeded at the trash racks. Large debris would likely gather at the bottom of the trash racks, allowing continued flow through the higher part of the racks.The walkdown also noted a second potential chokepoint in the recirculation trench near azimuth 225, which has a significant amount of piping, valves and pipe support. This region would be susceptible to clogging from large debris pieces. Since the trash racks inside the bioshield wall will remain unaltered, the recirculation trench is protected from large debris intrusion and is not a chokepoint.
[RAI 38] The information obtained during the walkdown confirms that water will not be held up by chokepoints or otherwise prevented from reaching the containment recirculation intakes via the strainer system. Special attention was paid to the fuel transfer canal, which is drained by two 6-inch nominal diameter pipes. These pipes are oriented horizontally with the bottom of the pipe approximately 3-inches above the transfer canal floor. They are not screened or capped. Because of the size and orientation of these drain pipes they will not create a chokepoint that would retain water in the fuel transfer canal. However, because the pipes are 3-inches above the floor, it is assumed that the water below 3-inches is held up and does not reach the sump.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 40 of 47 Other specific NEI and NRC recommendations that were addressed in the walkdown are itemized below.* All passages have sufficient flow clearances such that chokepoints are not expected." Curbs and ledges within the flow paths were found to be unable to retain water from returning to the sump area. Curbs at upper elevations had at least one open side to allow the free flow of water to the ground floor." No potential chokepoints were observed at upper elevations, including floor grates, which would be expected to retain fluid from reaching the containment floor." The containment floor was surveyed for chokepoints formed by equipment, components and other obstructions.
Where equipment congestion did occur, other flow paths were available so as to not restrict water transport.
* New scaffold and lead blanket storage boxes installed on the 23' elevation are expected to have no significant impact on flow modeling and do not create any new chokepoints due to their location and construction.
* The ECCS trench contains a significant amount of piping and pipe supports in some areas. Since the trench is protected from the intrusion of large debris by the trash racks on the 18' elevation, the trench is not expected to be clogged by debris. There is also a direct flow path from the inner annulus via a portal directly into the sump and grated areas above the sump from the 23' elevation.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 L-2008-030 Attachment 3 Page 41 of 47 FIGURE 3.1-1 Photo of Typical Trash Racks at the 18 foot elevation St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 42 of 47 Topic 3.m: Downstream Effects -Components and Systems FPL Response In the September 1 response it was noted that, at that time, the downstream evaluations identified instrumentation and six (6) components that required further evaluation.
Subsequently, as described in Topic 3.j., the strainer opening size has been reduced from an assumed square opening of 1/8th-inch by 1/8th-inch (diagonal dimension of 0.177-inch) to an actual round opening of 1/16th-inch diameter (0.0625-inch).
In addition, the HPSI pump seal water cyclone separators have been removed and the seals replaced, and the CSS pump seal water cyclone separators have been removed and the seals replaced.The original mechanical seals on the HPSI pumps incorporated injected fluid flushing with Safety Injection process fluid to augment the removal of heat generated by seal operation as well as heat conducted through the pump casing. Before the fluid entered the seals, pump discharge fluid was routed through a cyclone separator and external coolers to remove particulate and lower the fluid temperature.
Prior to entering the seals as injected flushing fluid, this Safety Injection fluid passed out of the HPSI pump at the pump discharge casing drain, through a cyclone separator to remove particulate and external coolers to lower the fluid temperature.
The HPSI pumps have been modified by removing the cyclone separator and associated piping, and replacing the mechanical seals with a new seal design that uses recirculated seal cavity fluid for flushing and cooling of the seal faces. Hence, HPSI pump seal injection no longer relies on process fluid via a cyclone separator.
Thus, the potential for debris clogging of the cyclone separator and related equipment has been eliminated as a GSI-191 downstream concern for the HPSI pumps.The original mechanical seals on the CSS pumps also relied on cyclone separators for removal of fluid particulate in seal injection water. The CSS pumps have been modified by removing the cyclone separator and associated piping, and replacing the mechanical seals with a new seal design that uses recirculated seal cavity fluid. Hence, CSS pump seal injection no longer relies on process fluid via a cyclone separator.
Thus, the potential for debris clogging of the cyclone separator and related equipment has been eliminated as a GSI-191 downstream concern for the CSS pumps.[RAI-31]With the exception of the ECCS/CSS recirculation pumps, downstream component analyses have been completed using the methodologies of WCAP-16406-P Revision 1 (WCAP-16406-P, "Evaluation of Downstream Sump Debris Effects in Support of GSI-1 91, Revision 1, August 2007). As discussed in our December 7, 2007, extension request, FPL plans on completing the remaining downstream analyses that support the demonstration of acceptability of the ECCS/CSS recirculation pumps to Revision 1 of WCAP-16406-P, by March 31, 2008. ECCS/CSS pump related analytical work to date, using Draft Revision 1 of WCAP-1 6406- P, May 2006, shows there is no need for additional pump changes.Consistent with the Staff's SE of NEI 04-07, the inactive volume in containment is less than 15% of the total volume. Consistent with the guidance in WCAP-1 6406-P Revision 1, the evaluation considered debris larger than the largest dimension of the sump St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 43 of 47 strainer opening, 1/16th-inch (62.5 mils). However, four (4) clarifications regarding the WCAP-1 6406-P methodology are provided below: Clarification 1 In lieu of the guidance provided in WCAP 16406-P regarding particle sizes, the analyses conservatively defined the "smaller" flow clearance as the circular dimension able to pass a 0.100-inch spherical particle.
The definition of "smaller" as 0.100-inch diameter sphere exceeds all dimensional attributes except for the length dimensions.
However the overall dimension (cross-sectional area) for a 0.100-inch diameter sphere is approximately 200% greater than the guidance provided in the WCAP. Therefore, this is considered conservative.
Clarification 2 The size distributions were calculated in lieu of the size distributions specified in WCAP-16406-P, Revision 1. However, for unqualified coatings, the size/mass distributions of WCAP-16406-P Draft Revision 1 are used.Clarification 3 All particulate debris is assumed to be spherical when calculating settling sizes and associated velocities.
Clarification 4 Only cold leg recirculation was modeled for settling velocities.
This flow path minimizes the debris settling and depletion, which maximizes the debris concentration over the mission time.Current evaluation results The results of the downstream evaluations of components that were completed with the WCAP-16406-P Revision 1 methodology are provided below.ECCS Valves ECCS valves in the recirculation path were evaluated with respect to erosion, plugging and the capability to change position per WCAP-16406-P.
It is noted that manually throttled valves are those requiring local Operator action. Remote operated throttle valves can be realigned from the control room in the event of some flow area induced erosion. Hence, erosion evaluations per the WCAP are not required for these valves.The analysis concluded that all valves in the ECCS flow path pass the WCAP criteria for erosion, plugging, and change of position.ECCS Relief Valves ECCS relief valves were evaluated with respect to erosion, plugging and debris interference with valve reseating.
Each ECCS relief valve on an ECCS/CSS recirculation flow path was evaluated by first comparing its set pressure to its recirculation mode pressure.
Where the set pressure is higher than the expected recirculation mode pressure, the valve does not have the potential to open during recirculation.
Based on a comparison of the valve set pressures to conservative expected recirculation-mode line pressures, no ECCS relief valve is expected to operate during recirculation.
Therefore, failure is precluded, and no further actions are'required to accommodate downstream effects on ECCS relief valves.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 44 of 47 ECCS Flow Restrictions The ECCS flow restrictions (orifices, flow elements, and spray nozzles) were evaluated with respect to plugging and erosion. Based on the results of the analyses, there are no downstream effects concerns due to wear or plugging for flow restrictions, and no further actions are required to accommodate downstream effects on ECCS flow restrictions.
ECCS Instrumentation The ECCS instrumentation was evaluated based on tap orientation and the velocity of the fluid passing the tap. The results of the evaluations confirm that no further actions are required to accommodate downstream effects on ECCS instrumentation.
ECCS Heat Exchangers The ECCS heat exchangers were evaluated with regard to erosion and plugging.
The results of the evaluations meet the acceptance criteria, and confirm that no further actions are required to accommodate downstream effects on heat exchangers.
As discussed above, with the exception of downstream effects on HPSI and CSS pumps, the results of these downstream evaluations on components provide assurance that, with the changes implemented at St. Lucie Unit 2, GSI-191 downstream equipment concerns have been satisfactorily addressed.
FPL plans to complete the downstream pump analysis by March 31, 2008 and will provide the results of that analysis in a future submittal.
As noted earlier, data from the testing of the St. Lucie Unit 2 strainer design will not be available until after March 31, 2008. Subsequently, an affirmation review will be conducted to assure that the conclusions and outcome of the downstream effects analysis remain valid.Topic 3.m: Downstream Effects -Fuel and Vessel FPL Response FPL is participating in the PWR Owners Group (PWROG) program to evaluate downstream effects related to in-vessel long-term cooling. The results of the PWROG program are documented in WCAP-16793-NP (WCAP-1 6793-NP, "Evaluation of Long-Term Cooling Considering Particulate, Fibrous and Chemical Debris in Recirculating.
Fluid," Rev. 0, May, 2007). The program was performed such that the results apply to the entire fleet of PWRs, regardless of the design (e.g., Westinghouse, CE, or B&W).The PWROG program demonstrated that the effects of fibrous debris, particulate debris, and chemical precipitation would not prevent adequate long-term core cooling flow from being established.
In the cases that were evaluated, the fuel clad temperature remained below 800 OF in the recirculation mode. This is well below the acceptance criterion of 2,200 OF in 10 CFR 50.46, Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors.
The specific conclusions regarding fiber debris reached by the PWROG include: Adequate flow to remove decay heat will continue to reach the core even with debris from the sump reaching the RCS and core. Test data has demonstrated that any debris that bypasses the screen is not likely to build up an impenetrable blockage at the core inlet. While any debris that collects at the core inlet will St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 45 of 47 provide some resistance to flow, in the extreme case that a large blockage does occur, numerical analyses have demonstrated that core decay heat removal will continue.Decay heat will continue to be removed even with debris collection at the fuel assembly spacer grids. Test data has demonstrated that any debris that bypasses the screen is small and consequently is not likely to collect at the grid locations.
Further, any blockage that may form will be limited in length and not be impenetrable to flow. In the extreme case that a large blockage does occur, numerical and first principle analyses have demonstrated that core decay heat removal will continue." Fibrous debris, should it enter the core region, will not tightly adhere to the surface of fuel cladding.
Thus, fibrous debris will not form a "blanket" on clad surfaces to restrict heat transfer and cause an increase in clad temperature.
Therefore, adherence of fibrous debris to the cladding is not plausible and will not adversely affect core cooling.WCAP 16793-NP Rev 0 concluded that the calculations, summarized above, for fiber debris are applicable to all PWRs, hence they are applicable to St. Lucie Unit 2.Using an extension of the chemical effects methods developed in WCAP-16530-NP to predict chemical deposition on fuel cladding, two sample calculations using large debris loadings of fiberglass and calcium silicate were performed and are discussed in WCAP 16793-NP Rev 0. The cases demonstrate that decay heat would be removed and acceptable fuel clad temperatures would be maintained.
However, as recommended in the WCAP-16793-NP, Revision 0, FPL has decided to perform a plant-specific calculation using St. Lucie Unit 2 parameters and the recommended WCAP methodology to confirm that chemical plate-out on the fuel does not result in the prediction of fuel cladding temperatures approaching the 800 OF value. It is planned that this assessment will be completed by March 31, 2008 and be reported to the NRC in the June 30, 2008 submittal.
Topic 3.n: Chemical Effects FPL Response As described in Attachment 1 of our December 7, 2007 extension request, St. Lucie Unit 2 integrated chemical effects testing in a large flume is expected to begin by the end of Ma}rch 2008 and be completed during the 2 nd quarter of 2008, including completion of analysis by June 30, 2008. The responses to the RAIs related to chemical affects will be provided in the June 30, 2008 submittal to the NRC.Topic 3.o: Licensing Basis FPL Response As discussed in other sections of this response, physical plant changes and procedural changes have been made to St. Lucie Unit 2 to resolve GL 2004-02 and GSI-191 concerns.
These are summarized in Topic 2 along with additional work that is planned to be completed.
A submittal will be made to the NRC providing responses to remaining St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 389 Attachment 3 Page 46 of 47 RAIs and describing final compliance with the regulatory requirements of GL 2004-02 by June 30, 2008.As noted in Topic 3.g, Net Positive Suction Head Available (NPSH), sump level calculations were revised to accommodate potential areas for water holdup based on lessons learned from the NRC audit of the Waterford sump program. This resulted in a lowering of post-LOCA containment sump levels for loss of coolant accidents, with a corresponding reduction in margin in NPSH for pumps in the recirculation mode.It is noted, that following the issuance of Bulletin 2003-01, St. Lucie Unit 2 put in place administrative controls to maintain a higher water level in the RWT than the required Technical Specification minimum. It is FPL's intent that this higher level would remain until such time as sump issues were completely resolved.
As described in Topic 3.f, Head Loss and Vortexing, and in Topic 3.g, Net Positive Suction Head Available (NPSH), calculations were also performed with this current/higher RWT level, resulting in an additional sump level margin. FPL has determined that an amendment to the Technical Specifications to raise the minimum allowable RWT level to the current/higher administrative level is warranted in order to regain margin for post-LOCA recirculation pumps. The amendment request for this increase in minimum Technical Specification RWT level will be submitted by June 30, 2008. The current/higher RWT level will remain in effect until the amendment request is reviewed by NRC, approved, and implemented on-site.Topic 3.p: Foreign Material Control Programs FPL Response Information related to programmatic controls for foreign materials was provided to the NRC in previous submittals.
Information was provided in FPL letter L-2003-201 which responded to NRC Bulletin 2003-01, and most recently in FPL letter L-2005-181, September 1, 2005 which responded to GL 2004-02. In general, the information related to programmatic controls that was supplied in these responses remains applicable.
The results of the walkdowns completed in 2006 to assess the quantities of latent and miscellaneous debris are discussed in the response to NRC Topic 3.d, Latent Debris.These walkdowns were conducted and consequently, the debris found during the walkdowns is considered representative of normal plant operation under the existing housekeeping programs.
Based on these walkdowns, it was determined that current housekeeping procedures were appropriate, hence no changes have been made to these procedures.
Procedural controls at St. Lucie Unit 2 ensure: i) that a Mode 1 through 4 containment restart cleanliness inspection is completed that verifies that no loose debris is present and, ii) restart readiness that further assures containment cleanliness.
These plant procedural requirements are further reinforced by written nuclear division policy regarding required plant readiness for operation.
Subsequent to the September 1 response, additional programmatic controls have been put in place or modified in support of the installation of the new strainer system.
St. Lucie Units 1 and 2 L-2008-030 Docket Nos. 50-335 and 50-389 Attachment 3 Page 47 of 47 Currently insulation and materials inside containment are controlled by procedures that require; (a) a review of changes to insulation or any other material inside containment that could affect the containment sump debris generation and transport analysis and/or recirculation functions and (b) a review of the effect of any change package for its impact on containment sump debris generation and transport.
This guidance has been enhanced by a new engineering specification that brings together, in one document, the insulation design documents that determine the design basis for the insulation debris component of the containment recirculation strainer design. This specification provides guidance for evaluating and maintaining piping and component insulation configuration within the containment building at St. Lucie Unit 2. In addition, the St. Lucie Plant procedure for controlling work orders was revised to assure that insulation work inside containment required signoff to the requirements of this specification.
The St. Lucie coatings specification assures that coatings and coating repairs inside containment are within the bounds of assumptions used in the applicable containment sump analysis.
Note that programmatic controls related to coatings are provided in Topic 3.h, Coatings Evaluation.
A new inspection procedure was implemented for new strainers.
The new procedure assures that the strainers are properly inspected and have no visible damage. The procedure also calls for the installation of protective covers to assure that outage related activities will not damage the strainers, and also calls for the removal of the covers prior to restart.}}

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