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{{Adams
#REDIRECT [[NOC-AE-10002562, Response to Request for Additional Information: Inservice Testing Program Description for the Third 10-Year Interval]]
| number = ML101750035
| issue date = 06/16/2010
| title = Project, Units 1 & 2 - Response to Request for Additional Information: Inservice Testing Program Description for the Third 10-Year Interval
| author name = Ruvalcaba M
| author affiliation = South Texas Project Nuclear Operating Co
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000498, 05000499
| license number =
| contact person =
| case reference number = G25, NOC-AE-10002562, TAC ME3515, TAC ME3516, TAC ME3517, TAC ME3518, TAC ME3521, TAC ME3522
| document type = Letter
| page count = 6
| project = TAC:ME3515, TAC:ME3516, TAC:ME3517, TAC:ME3518, TAC:ME3521, TAC:ME3522
| stage = Response to RAI
}}
 
=Text=
{{#Wiki_filter:Nuclear Operating Company South Texas Project Electric Generatmng Station PO. Box 289 Wadsworth, Texas 77483 -%NM-June 16, 2010 NOC-AE-10002562 File No.: G25 10 CFR 50.55a U. S. Nuclear Regulatory Commission Attention:
Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 South Texas Project Units 1 & 2 Docket Nos. STN 50-498, STN 50-499 Response to Request for Additional Information:
Inservice Testing Program Description for the Third 10-Year Interval (TAC Nos. ME3515, ME3516, ME 3517, ME3518, ME3521, ME3522)
 
==Reference:==
 
Marco Ruvalcaba, STP Nuclear Operating Company, to NRC Document Control Desk, "Inservice Testing Program Description for the Third 10-Year Interval," dated February 22, 2010 (NOC-AE-1 0002516) (ML1 00640120)Pursuant to 10 CFR 50.55a(f), STP Nuclear Operating Company submitted the referenced Inservice Testing (IST) Program plan for the South Texas Project third 10-year interval.
The IST program plan describes the programmatic aspects of IST examination of Class 1, 2, and 3 pumps and valves. Included are requests to use alternative examination or test requirements in place of certain examination or test requirements of the 2004 ASME OM Code. Attached are responses to questions provided by the NRC staff regarding those proposed alternative requirements.
There are no commitments included with this submittal.
If there are any questions, please contact either Mr. P. L. Walker at (361) 972-8392 or me at (361) 972-7904.I Marco Ruvalca ea Manager, Testing and Programs Engineering PLW
 
==Enclosure:==
 
Response to Request for Additional Information:
Inservice Testing Program Description for the Third 10-Year Interval STI: 32688078 NOC-AE-1 0002562 Page 2 of 2 cc: (paper copy)(electronic copy)Regional Administrator, Region IV U. S. Nuclear Regulatory Commission 612 East Lamar Blvd., Suite 400 Arlington, Texas 76011-8064 Mohan C. Thadani Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North (MS 8B1A)11555 Rockville Pike Rockville, MD 20852 Senior Resident Inspector U. S. Nuclear Regulatory Commission P. O. Box 289, Mail Code: MN116 Wadsworth, TX 77483 C. M. Canady City of Austin Electric Utility Department 721 Barton Springs Road Austin, TX 78704 Kevin Howell Catherine Callaway Jim von Suskil NRG South Texas LP A. H. Gutterman, Esquire Morgan, Lewis & Bockius LLP Mohan C. Thadani U. S. Nuclear Regulatory Commission J. J. Nesrsta R. K. Temple E. Alarcon Kevin Polio City Public Service C. Mele City of Austin Jon C. Wood Cox Smith Matthews Richard A. Ratliff Texas Department of State Health Services Alice Rogers Texas Department of State Health Services NOC-AE-10002562 Page 1 of 4 SOUTH TEXAS PROJECT UNITS I & 2 DOCKET NOS. STN 50-498, STN 50-499 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION:
INSERVICE TESTING PROGRAM DESCRIPTION FOR THE THIRD 10-YEAR INTERVAL RAI P-1-1: Pump Alternative Request -PRR-01 (Use of CodeeCase OMN-18)Please explain how the alternative in PRR-01 is acceptable and why this alternative is a reasonable alternative to the Code for Operation and Maintenance of Nuclear Power Plants (OM Code) requirements.
Please see the following documents (Agencywide Documents Access and Management System Accession Nos. ML090650668, ML091670464, ML092640690, ML093140302, and ML100820061) for examples of the information needed to evaluate this alternative request Response: Based on recent guidance from the ASME OM Code Committee regarding application of Code Case OMN-18, and as stated in PRR-01, the update of the Inservice Testing (IST) Program for the third ten-year interval reflects a more limiting upper bound Acceptable Range value of 1.06 versus 1.10 for flow and differential pressure.
Values above 1.06 would be in the Required Action Range. Tightening the Acceptable Range, in conjunction with using more precise pressure instruments during testing (an improvement in precision from +/- 2 percent to +/- 0.5 percent)'
provides more consistent trend results when comparing subsequent tests or test results in the aggregate.
Due to the improved precision, consistent testing methodology, and the addition of quarterly vibration monitoring for the former Group B pumps, deviations in actual pump performance indicative of impending degradation are more easily recognized during quarterly performance trending activities.
Additionally, declaring pumps inoperable for reasons other than actual equipment degradation can be avoided.The proposed quarterly testing methodology, in lieu of the current Code requirements imposed on quarterly pump testing, is expected to more accurately identify deviations and trends in actual pump performance and provides reasonable assurance of the operational readiness of the pumps.A similar application from the Perry Nuclear Power Plant, Unit 1, was approved by the NRC staff dated October 8, 2009 (ML092640690).
NOC-AE-1 0002562 Page 2 of 4 RAI P-1-2: Pump Alternative Request -PRR-03 (Alternate Test Frequency for the Residual Heat Removal Pumps)Regulatory Guide (RG) 1.175, "An Approach for Plant-Specific, Risk-Informed Decision-Making: Inservice Testing," August 1998, describes an acceptable alternative approach for applying risk insights from probabilistic risk assessment, in conjunction with established traditional engineering information, to make changes to a nuclear power plant's IST program. The approach described in RG 1.175 addresses the high-level safety principles specified in RG 1.174, "An Approach For Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes To The Licensing Basis," Revision 1, November 2002, and attempts to strike a balance between defining an acceptable process for developing risk-informed IST programs without being overly prescriptive.
It is intended that the approach presented in RG 1.175 should be regarded as an example of acceptable practices, and that licensees should have some degree of flexibility in satisfying regulatory requirements on the basis of their accumulated plant experience and knowledge.
As discussed in RG 1.175, please describe how the proposed alternative in PRR-03 is consistent with defense-in-depth philosophy and how the change maintains sufficient safety margins. Also describe the performance measure strategies for monitoring the proposed alternative in PRR-03.The use of Code Case OMN-3, "Requirements for Safety Significance Categorization of Components Using Risk Insights for Inservice Testing of LWR Power Plants," is conditionally approved in Regulatory Guide 1.192, "Operation and Maintenance Code Case Acceptability, ASME OM Code," Revision 0, dated June 2003. Please explain why you did not propose to use the provisions in Code Case OMN-3 to extend the test frequency for the residual heat removal pumps.Response: Defense-in-Depth Philosophy STP is unique in the design of its Residual Heat Removal (RHR) system. Whereas other plants have two trains normally installed, STP has three trains of RHR. This design overly satisfies Criterion 34, Residual Heat Removal, of 10 CFR 50, Appendix A.Further supporting the defense-in-depth philosophy, the NRC previously confirmed the three-train-based analysis for the percent change in system unavailability and core damage frequency.
See NRC correspondence dated February 17, 1994, "Issuance of Amendment Nos.59 and 47 to Facility Operating License Nos. NPF-76 and NFP-80 and Related Relief Requests" (ML021300134).
The results of the review indicate that the proposed changes in the RHR pump surveillance interval represent an insignificant change in system unavailability and no change in core damage frequency.
Based upon this review, it was concluded the alternative testing frequency for IST requirements specified in PRR-03 will provide an essentially equivalent level of safety for the RHR pumps.Safety Margin The initial relief request allowing a six-month test interval for the RHR system in lieu of the three-month interval required by the ASME Code was approved by the NRC correspondence of NOC-AE-1 0002562 Page 3 of 4 February 17, 1994. The RHR system, including the RHR pumps, continues to be used as designed with no change in function or performance.
The risk metrics for the RHR pumps remain consistent with the values used in the original risk analysis.
Therefore, the basis of the change in relation to the acceptance of minimal change in plant risk provided in RG 1.174 remains valid.Performance Measure Strateqies The performance measure strategies for monitoring the proposed alternative in PRR-03 include a Group A inservice test run on each RHR pump nominally every six months during normal plant operation.
This test frequency will be maintained during plant shutdown periods if it can reasonably be accomplished per the requirements of ISTB-5121.
A Comprehensive test per ISTB-5123 may be performed in lieu of a Group A test. A Comprehensive test shall be performed nominally every two years. Differential pressure, flow, and vibration measurements shall be acquired during the performance of both the Group A and Comprehensive tests.Code Case OMN-3 The RHR pump test frequency proposed for the third interval was previously approved by the NRC based on risk assessment methods generally applied to systems and components used at the South Texas Project. Risk-ranking criteria should be consistently applied across plant systems and components.
Applying OMN-3 to the RHR pumps and not to the rest of the risk-ranked applications would result internally inconsistent risk classifications.
This relief request is not intended to be a prompt for broad scope re-categorization of components using the risk-ranking guidelines provided in OMN-3.
NOC-AE-1 0002562 Page 4 of 4 RAI V-1-1: Valve Alternative Request -VRR-01 (Use of Code Case OMN-1)The OM Code does not consistently assign revision numbers to code cases that have been changed. For example, minor revisions were made to Code Case OMN-1 in the 2002 Addendum of the OM Code and Code Case OMN-1 was revised in its entirety in the 2006 Addendum of the OM Code. No revision numbers were assigned to OMN-1 in the 2002 or 2006 Addenda. There are two versions of OMN-1 in the 2009 Edition of the OM Code (OMN-1 and OMN-I-1).
OMN-I-1 is described as Revision I in the 2009 Edition of the OM Code. Please clarify which version of OMN-1 you plan to use to implement the alternative in VRR-01.Response: OMN-1, Revision 1 (OM Code 2009 Edition, OMN-1-1) will be used to implement the alternative in VRR-01.}}

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