ML20210S983
| ML20210S983 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 08/11/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20210S979 | List: |
| References | |
| NUDOCS 9908180251 | |
| Download: ML20210S983 (8) | |
Text
g M 406g't UNITED STATES g-J NUCLEAR REGULATORY COMMISSION
'2-WASHINGTON, D.C. 30eeH001
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' SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.182TO FACILITY OPERATING LICENSE NO. DPR-72 ADDITION OF A SAFETY-RELATED DIESEL-DRIVEN EMERGENCY FEEDWATER PUMP FLORIDA POWER CORPORATION CRYSTAL RIVER UNIT 3 DOCKET NO. 50-302
1.0 INTRODUCTION
By letter dated Ihvember 24,1998, and supplemented June 23,1999, Florida Power j
Corporation (FPC or licensee), the licensee for Crystal River Unit 3 (CR-3), submitted to the U.S. Nuclear Regulatory Commission (NRC) a proposal concoming the addition of a safety-related diesel-driven emergency feedwater (EFW) pump (EFP-3). This pump would take the place of the motor-driven EFW pump (EFP-1) for satisfying the improved technical specification (ITS) requirements in performing the required accident mitigation functions. The existing EFP-1 would be maintained in place and would serve as a safety-grade manual i
backup. This arrangement provides CR-3 with a reliable and diverse EFW system consisting of a safety-related turbine-driven emergency feedwater pump (EFP-2) and the new safety-related diesel-driven pump EFP-3. In addition, the safety-grade EFP-1 and a noneafety-
. related diesel-backed auxiliary feedwater pump (FWP-7) would be available, thus enhancing the defense-in-depth for the EFW system.
The addition of EFP-3 allows the EFW system to perform its functional goals without placing a significant load on the emergency dicsel generators (EGDGs). This reduction in loading will enable the EGDG-1 A to carry all Train A required emergency service loads during a postulated small break loss-of-coolant accident (SBLOCA) with a concurrent loss-of-offsite power (LOOP),
without the need forloei1 management. The proposed addition of EFP-3, according to the licensee, will also remove tfie cross-train dependencies in the EFW system during a postulated single failure of a DC bus or EFP-2. Various cycle-specific interim TS that provided for the licensee to manage the loads for EGDG-1 A would no longer be needed and will be deleted.
The June 27 1999, supplement did not affect the original proposed no significant hazards determination, or expand the scope of the request as noticed in the Federal Rooister.
2.0 BACKGROUND
Existmg load Imtabons on EGDG-1 A prohibit concurrent operation of EFP-1 with either the "A" train decay heat pump, which starts automatically on a low-pressure injechon (LPI) actuation signal with the reactor coolant pressure less than 500 psig, or the "A" train control complex chiller when the reactor buildmg spray pump is operateg. EFP-1 is interlocked with the LPI 9908190251 990011 PDR ADOCK 05000302 P
. actuation such that an LPI actuate occurring concurrently with a LOOP will automatically trip EFP-1 (LPl/EFP-1 trip interlock). FPC also identified several limiting single failures that required the EFW system to provide feedwater for the steam generators. As a result, FPC implemented a number of plant modifications and additional ope ator guidance for the operation of EFP-1 while providing sufficient margin for the EGDG-1 A to support emergency core cooling system (ECCS) piggyback operation. FPC implemented the following modifications and additional operator guidance:
G A non-safety-related diesel generator was installed to provide power to an auxiliary feedwater pump (FWP-7) during a LOOP event.
O Automatic opening of ASV-204 ("A" train steam block valve) was provided to start the steam-driven emergency feedwater pump (EFP-2).
G A cavitating venturi was installed at the discharge of both EFW system pumps to limit flow, thus providing protection against runout and inadequate net positive suction head.
O A motor-operated valve (EFV-12) was installed in the EFW system cross-tie line to
. establish a controlled and monitored flow path from EFP-2 to both steam generators by way of the "A" train power control valves; to close and de-energize the cycling EFW system block valves; and to stop EFP-1 (EGDG-1 A load management), which provides margin for EGDG 1A to supply power to start the LPI pump for ECCS piggyback operation and to start the control complex chiller.
O Pull-to-lock switches were installed on closed-cycle cooling water pumps (SWP-1 A and B) and their respective heat sink pumps (RWP-2A and B). These switches permit operator actions to stop the "A" train pumps (SWP-1 A and RWP-2A) and to keep them from starting, while the "B" train pumps continue to provide cooling to associated support components.' These actions constitute the EGDG-1 A load management required to maintain EFP-1 operating while providing enough margin to start the "A" train LPI pump to support ECCS piggyback operation.
O A switch was installed to defeat the LPl/EFP-1 trip interiock. This switch permits operator actions to defeat the interlock after EGDG-1 A load management is accomplished and permits continued operation of EFP-1 while the reactor coolant system pressure and temperature continue to decrease to the LPI actuation setpoint, it also permits starting of the "A" train LPI pump to support ECCS piggyback operation.
.The EFW system at CR-3 must support steam generator cooling for certain design basis accidents, which include a spectrum of SBLOCAs. Additionally certain single failures, when taken concurrently with a LOOP, require operator actions to maintain EFW system feedwater supply to the steam generators. The current EFW system consists of two 100-percent capacity pumps, one motor-driven and one steam turbine driven, and the emergency feed initiation and control (EFIC) system.
EFP-2 receives steam from either or both steam generators through parallel block valves ASV-204 and ASV-5. These valves receive an auto-open signal from the EFIC system if the demand for EFW system exists. EFP-1 is powered from EGDG-1A.
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3.0 EVALUATlON
. 3.1 Descnotion of Proposed Plant Chances The EFW system is designed to provide adequate flow to one or both steam generators (SGs) for decay heat removal with the generators at the maximum operating pressure of 1050 psig plus a suitable margin for post-accident pressure increases. The principal function of the EFW system is to remove decay heat fmm the reactor coolant when the normal feedwater supply is unavailable,' This is accomplished by supplying water from the emergency feedwater tank (EFT-2) to the once-through SG (OTSG) secondary side via the emergency feedwater nozzles.
Steam produced in the OTSGs is condensed in the main condenser via the turbine bypass valves or, if the evi,oepheric dump valves or main steam safety valves have actuated, discharged directly to the atmosphem.
In their submittal, the licensee states that EFP-3 will be a l:lirect replacement for EFP-1 to mitigate design basis accidents, and will satisfy all applicable requirements of the EFP-1 system design, as stipulated in the plant Final Safety Analysis Report (FSAR), Section 10.5.1.
EFP-3 will not be credited at this time for an attemate safe-shutdown capability in the event of j
a fire. EFP-1 will continue to provide the plant altamate safe-shutdown capability.
EFP-3 will have a nominal 100% capacity to meet EFW system requirements. The staff reviewed the Ingersoll-D! esser pump design curves for EFP-3. These curves indicate the power requirements, not positive suction head requirements and discharge pressures developed for various flow rates. Based on its review, the staff has determined that the pump
' is adequately sized to meet the discharge flow and pressure requirements. EFP-2 also has a nominal 100% capacity to meet the system requirements. EFP-2 can receive steam from either OTSG via connections upstream of the associated main steam isolation valve. The 1
diverse motive power of the two trains enhan::es both system availability and reliability.
The new diesel-driven pump EFP-3 will be housed in a new building which has been designed to meet seismic class I requirements and is watertight up to the elevation needed to protect against the design-basis flooding and extemal events. The building and structures were designed to minimize recirculation from the diesel exhaust to the diesel air intake. The building will house the pump, diesel engine, batteries and charging system, associated switchgear and a diesel fuel oil storage tank. EFP-3 will be installed in parallel with EFP-1 and will use the existing "A" train flow patn currently used by EFP-1. EFP-3 will have a cavitating venturl in its discharge line. This venturiis designed to limit flow to the OTSGs regardless of SG pressure and thus, protect the OTSGs and the pump from excessively high flow-induced operating conditions. In addition, EFP-3 will have a minimum flow recirculation line for pump protection, plus a full flow recirculation line for testing. The EFW flow control and block valves will continue to be powered by AC and DC power. The EFIC actuation signal (auto-start logic),
which normally starts EFP-1 will now actuate EFP-3. This EFIC actuation signal will be removed from EFP-1. The EFIC system will control the flow from EFP-3 just as it did for EFP-1.
EFP-3 has several design features that will allow it to be self-sufficient. The engine will be capable of starting and running without AC or DC power from station safety-related and non-safety-related busses. The self-contained battery and starting air systems will be sufficient to assure that EFP-3 is capable of starting. The indications and controls needed to
4 start and shut down EFP-3 will be located both in the main control room and in the EFP-3 building. These instruments will be powered by the dedicated EFP-3 DC bus. Once started, the pump can continue to run without starting air, AC or DC power. The cooling system for the
. EFW diesel engine is also self-sufficient. Cooling is provided by an attached radiator and shaft-driven fan.
In addition, an interlock will be installed to prevent both EFP-1 and EFP-3 from running at the same time. This interiock is based on the diesel speed and the discharge pressure of EFP-3. If EFP-1 is running and EFP-3 starts and meets the speed and pressure criteria, EFP-1 will trip. If EFP-3 is running and meets the pressure and speed criteria, EFP-1 cannot be started. Additionally, the EFP-1 control switch will be placed in the pull-to-lock position and will be maintained by administrative controls. This interlock is needed because the EFW system is not designed for concurrent operation of all three EFW system pumps.
EFP-3, with its subsystems, will be more self-sufficient than EFP-1. Industry data evaluated by the licensee and the staff showed that safety-related diesel-driven pumps are more than 98%
reliable. A sensitivity study was performed by the licenses to determine the potential impact that EFP-3 would have on the plant probabilistic safety assessment. The study determined that the addition of EFP-3 resulted in a not core damage frequency (CDF) decrease of approximately 3%. The primary factor driving the decrease in CDF is the addition of the third safety-grade EFW pump.
A motor-driven pump (with offsite power available and backup power from an EGDG during a LOOP)is more reliable than a self-contained diesel-driven pump. However, the self-contained diesel driving EFP-3 is of a simpler design compared to the EGDGs and is not affected by electrical failures. When considering overall EFW system reliability, the availability of EFP-l must also be considered. EFP-l will be maintained as a safety-grade component and its availability will be tracked under the maintenance rule program in accordance with 10 CFR 50.65. Therefore, EFP-1 is expected to be capable of delivering EFW flow if offsite power is available. As stated previously, EFP-1 is more reliable than EFP-3 when offsite power is available. In this circumstance, EFP-1 will remain available for use. EFP-3 is more reliable than EFP-1 if offsite power is not available. Therefore, the combination of both EFP-3 and EFP-1 provides greater overall system reliability than the existing EFW system whether or not offsite poweris available.
The normal water supply for EFP-3 will be the emergency feedwater tank (EFT-2), which contains a minimum water volume of 150,000 gallons. This is a seismic class I, missile protected, dedicated tank. The backup water supply will be from the condensate storage tank (CDT-1) and the fire service tanks (FSTs). The licensee has revised the calculation methodology to more accurately reflect the usable volumes for CDT-1 and the FSTs. The revised calculation also resulted in a change in the time required for natural circulation cooldown from 150 hours0.00174 days <br />0.0417 hours <br />2.480159e-4 weeks <br />5.7075e-5 months <br /> to approximately 7 days. The total water volume now required for natural circulation cooldown is 840,000 gallons, which is an increase from the previously reported required volume of 735,000 gallons. The change in tank volumes and coo!down time was evaluated and was determmed to have no impact on the design-basis analysis or the ability of CR-3 to perform a natural circulation cooldown coincident with a LOOP.
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5-EFP-3 cannot directly take suction from the condenser hotwell. The hotwell inventory is available to EFP-1, EFP-2 and FWP-7, which can either pump the hotwell volume directly to the OTSGs or to one of the tanks accessible to EFP-3. Even without this capability, EFP-3 has access to 870,000 gallons of water, which exceeds the 840,000 gallons required for a natural circulation cooldown with a LOOP. Approximately 600,000 gallons of this inventory is in the FSTs. These tanks are not designed to withstand a design-basis earthquake (DBE). During a postulated DBE, the water supply from the FSTs may not be available. During such an event, EFP-1 may be required to deliver the required hotwell volume to the OTSGs. Since EFP-1 will be maintained as a safety-related component and can be powered from EGDG-1 A, the staff finds this arrangement to be acceptable.
EFP-3 and its use to mitigate design basis accidents, instead of EFP-1, allow the EFW system to perform its functional goals without the need to manage the loads on the EGDGs. This load reduction will enable EGDG-1 A to carry all required emergency safety loads during a SBLOCA/ LOOP. Operator actions to cross-tie the EFW system and to stop EFP-1 for the loss of "B" train DC electrical or battery event, or to stop SWP-1 A and RWP-2A for the failure of EFP-2, will also no longer be required. The auto-open signal to ASV-204 to start EFP-2 as part of EGDG-1 A load management will no longer be required and will be removed.
On the basis of its review, as set forth above, the staff concludes that EFP-3 will meet the same system design requirements that are appscable to EFP-1 and will be able to mitigate design basis accidents. Therefore, the staff finds its proposed installation acceptable.
Additionally, the following events were analyzed by the licensee:
Station Biackout (SBO) l For an SBO event in which there are no onsite EGDGs and no offsite power available, EFP-3
. will be available in addition to the normally available EFP-2 to maintain the EFW level in the SGs for decay heat removal. EFP-3 is not affected by the SBO event, as compared to EFP-1, which is dependent on the EGDG and will not be available. The addition of EFP-3 increases a diverse capability of the plant to mitigate an SBO event. Because EFP-3 will be available during an SBO event, the staff finds this addition acceptable.
Post-Seismic Coolina Event For a post-seismic cooling event with a concurrent LOOP and a single failure of EFP-3, EFP-2 will automatically start and provide EFW to the steam generators. Defense in depth may be provided by FWP-7, if available, ' lthough it is not soismically qualified, to provide EFW to the a
steam generator from the condenser hotwell. Since both safety-related emergency diesel generators will start and energize their respective busses, wtnich are not significantly loaded, EFP-1 can be manually loaded on EGDG-1 A without the need to manage the loads on EGDG-1A to provide EFW system cooling.
If EFP-2 is lost due to a single failure, EFP-3 will automatically start and provide EFW to the steam generators. EFP-3 normally takes suchon from the designated EFT-2 and CDT-1, which contain 150,000 gallons and 120,000 gallons respectively. These sources of water provide approximately 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> of cooling in a post-seismic event. To continue to meet its
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'e commitment to Generic Letter 87-02, " Verification of Seismic Adequacy of Mechanical and Electrical Equipment in Operating Reactors, Unresolved Safety issue A-46," dated May 2, 1987, the licensee stated that its revised methodology will continue to provide natural circulation cooldown of the plant utilizing EFP-2 and EFP-3 with the same water sources
__(EFT-2 and CDT-1) in lieu of EFP-1. In the event that EFP-2 fails, EFP-1 will be utilized to deliver water from the condenser hotwell, which contains 150,000 gallons, since EFP-3 does not have a direct suction path from the condenser hotwell because of the system piping limitations. The EGDG-1 A load limitation is not a concem during a post-seismic cooling event.
Therefore, the load limitation will not affect the ability of EFP-1 to perform its function. As stated in this evaluation, EFP-1 will remain a safety-grade pump, and its availability to mitigate beyond design basis accidents will be maintained under the maintenance rule program in accordance with 10 CFR 50.65.
The licensee identified that failure of the "B" train DC power would result in a loss of all "B" train components, leaving EGDG-1 A to carry necessary loads to establish and maintain safe-shutdown conditions. Therefore, the EGDG load management strategy was devJ1oped, and some modifications to the plant were made to ensure continued EFP-1 operation and a capability to support ECCS piggyback operation.
With the use of EFP-3 in lieu of EFP-1, load management is no longer required for EGDG-1 A.
EFP-3 will automatically start in this event to provide EFW to the steam generators, taking suction from EFT-2 and CDT-1. Before exhausting the contents of these water sources, several options are available for the operators to continue to provide EFW to the steam generators, which include starting EFP-1 with the pump suction aligned to the condenser
- hotwell, starting FWP-7 with the pump suction aligned to the condenser hotwell, or starting EFP-2 with the pump suction aligned to the condenser hotwell and manually opening ASV-204, in view of the above, the staff finds these changes acceptable.
3.2 Proposed New Imoroved Technical Specifications and Revisions ITS 3.7.19 is being added to ensure that essential subsystems are within the limits needed to maintain the operational status of EFP-3. These specifications include a requiremont for diesel fuel oil, lube oil, and starting air, as well as a subsystem limiting condition for operation.
TS Bases 3.7.5 is also being revised to include discussion of EFP-3 design and limitstion. The new intended use of EFP-1 as a manual defense-in-depth pump is also discussed.
ITS 3.7.18 and its Bases will be retained with modifications to ensure two " trains" of Control Complex Cooling are Operable.
On the basis of its review, the staff concludes that the new additions of ITS and Bases, as well as surveillance requirements associated with EFP-3, would ensure the EFW system readiness to mitigate design-basis accident (DBA) events and some beyond DBAs, and are consistent with other similar ITS requirements and surveillances for similar components. Therefore, the staff finds them acceptable.
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A number of ITS and Bases that were approved for cycle-specific application will be deleted.
Related cycle-specific storim ITS and Bases changes are discussed in Attachment C of the licensee's submittal, in general, text marked " Note-Valid until Cycle 12 Only" will be deleted.
The original text before License Amendment No.163 was issued will be restored, except for some poitions of the text that are needed to help clarify ITS Bases 3.3.5, 3.5.2, and 3.7.5, which cover the background discussion on LPl concurrent operation limitation with reactor building isolation, SBLOCA, and ECCS, respectively.
On the basis of its review, the staff concludes that those cycle-specific interim ITS, as discussed in Attachment C of the licensee's submittal, are no longer applicable for the EFP-2 and EFP-3 system configuration, and finds the licensee's request to remove them accep:able.
l Changas such as Action letter designation, page numbers and other format changes are editorial in nature and are therefore acceptable.
4.0 STATE CONSULTATION
Based upon a letter dated March 8,1991, from Mary E. Clark of the State of Florida, Department of Health and Rehabilitative Services, to Deborah A. Miller, Licensing Assistant, U.S. NRC, the State of Florida does not desire notification of issuance of license amendments.
5.0 ENVIRONMENTAL CONSIDERATION
S The amendmer t changes requirements with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that this amsndment involves no significant hazards consideration and there has been no public comment on such finding (64 FR 2247). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmentalimpact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
6.0 CONCLUSION
S Based on its review of the licensee's proposal, the performance data for the proposed diesel driven EFW pump indicates that this pump is capable of delivering adequate flow to one or bout SGs during a worst case postulated accident condition. Thy staff has determined that EFP-3 will ri det applicable requirements as indicated in Section 10.5.1 of the plant FSAR, results in an enhancement to the defense-in-depth for the EFW system and is an acceptable replacement for the motor-driven EFW pump. Therefore, the licensee's proposed installation of EFP-3 and associated changes to the TSs are acceptable. Those changes which either involve delebons or replacements of cycle-specif'c requirements will retum the ITS to its previously approved version and are therefore acceptable.
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8-The staff concludes that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors: J. Rajan, D. Diec, S. Saba Date: August 11,1999 3
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