ML20012E713
| ML20012E713 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 03/28/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20012E712 | List: |
| References | |
| NUDOCS 9004060160 | |
| Download: ML20012E713 (4) | |
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- t, SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO FIRE PROTECTION PROGRAM PLAN PUBLIC SERVICE COMPANY OF COLORADO
_ ORT ST. YRAIN NUCLEAR GENERATING UNIT 1 F
DOCKET NO. 50-267 INTRODUCTION Company of Colorado (the licensee)s revised January 5,1990. Public Service By letter dated November 8 1989 a proposed Revision 3 to the Fort St. Vrain (FSV)FireProtectionProgramPlan(FPPP). The principal changes involved two use of one comon water supply (one pond) place tiree existing trains and the new fire protection cooldown trains to re instead of the existing two storage ponds.
C00LDOWN TRAINS Discussion The existing trains consist of two forced circulation trains (Train A and B)In A and one prestressed concrete reactor vessel (PCRV) liner cooling train. Tra consists of a condensate pump, which provides the flow from the condensate storage tank through a steam generator. The flow from the steam generator is recirculated through the decay heat removal (DHR) exchanger. This condensate pump also provides flow through a helium circulator. Train B consists of a diesel driven fire water pump which provides flow from the main cooling tower through a steam generator and a helium circulator.
The PCRV liner cooling is provided by the reactor plant cooling water pumps that are powered by a diesel generator.
In addition, this diesel generator supplies power to the service water system.
Evaluation The licensee proposed to replace the existing three trains with two redundant fire protection cooldown trains (Train 1 and 2). One train is sufficient to remove decay heat following a fire anywhere in the plant.
Proposed Train 1 Train 1 consists of a diesel generator and motor-driven fire water pump.
The diesel generator is the power supply for the fire water pump and other Train 1 electrical equipment. The motor driven fire water pump Ob0 M
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. l supplies cooling water to the Loop 2 PCRV liner cooling tubes. The liner cooling valves can be manually positioned in the " redistribute' mode to nc.xirrize cooling to the pCRV top head area. Af ter passing through the toop 2 PCRV liner cooling tubes, firewater is directed outside the reactor i
building to a yard drain in an open loop configuration.
l Makeus water is provided to the suction of the motor driven firtwater j
pump sy a circulator water makeup pump. Train 1 is used for cooldown following a fire in a congested cable area, since none of the Train 1 cables or components are located in any of the congested cable areas.
i Protesed Train ?
l The proposed Train 2 consist of a standby diesel generator and one of the Loop 2reactorglantcoolingwaterpumps. Train 2 electric equipment is powered by the 1B" standby diesel generator. One of the Loop 2 reactor i
plant cooling water pumps supplies the cooling water to the Loop 2 pCRV l
liner cooling tubes.
Train 2 is a closed loop, provided with a recircu-lating, cooling configuration, in which heat is removed by both Loop 2 reactor plant cooling water heat exchangers. These heat exchangers are i
cooled by service water. The service water system is o>erated in a closed i
loop mode, using either of the service water pumps or tie service water return pump. The makeup water is provided to the service water cooling tower basin by the domestic water supply.
Instrumentation l
The licensee has proposed the use of connon piping and instrumentation for both proposed new fire protection cooldown trains. Both of the proposed new fire protection cooldown trains supply the water to Loop 2 3
of the FCRV liner cooling tubes. This is acteptable because the water-filled piped is expected to survive a iire. The NRC acceptance criteria states:
' Water-filled mechanical components such as piping and valves necessary for safe reactor shutdown /cooldown which are within the area room, or zone encorpassed by a single postulated fire, shall not be i
consIdereddamagedbythefire. Water-filled valves and mechanical components with manue.1 operators in the fire area, room, or zone shall be considered to be manually operable within one hour after the start of the fire.'
i The monitoring instrumentation for Trains 1 and 2 is the same since both of the trains use Loop 2 pising in the PCRV liner cooling system. All the instrumentation for bot 1 the trains are local mechanical devices.
The instrumentation is located in different areas such that a postulated fire within the reactor building could not damage all the instrumentation.
Since both the pressure indicators are water filled, their failure in a fire is unlikely.
Furthennore the licensee has shown that the liner cooling (either Train 1 and 2),is not required until 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following a loss of forced circulation. The time duration is sufficient to assess the system's conditions and to replace the damaged instrumentation.
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Analysis f
The licensee analyzed a loss of forced circulation (LOFC) at 100 days af ter reactor shutdown following prolonged operation at 83.2 percent power. The initial decay heat generation rate used in this analyses was assumed to be 0.49 MW. The actual decay heat generation rates had decreased below 0.30 MW by Noveniber 27, 1989, 100 days after reactor shutdown. Therefore, the core heat generation rate used in the analysis was very conservative at 100 days and is even more conservative now with more than 200 days since FSV shutdown.
The analyses also assumed that one of two loops of PCRV liner cooling was placed in service within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following a LOTC, with flow redistributed to maximize cooling to the PCRV top head area and with only one of two PCRV liner cooling pumps in the operating loop.
The licensee's analysis showed that neither the PCRV liner nor the PCRV concrete temperatures exceed 113' F because of a postulated fire. On the basis of this review, the staff concluded that the proposed PCRV liner cooling using either Train 1 or 2 is adequate and acceptable.
STORAGE PONDS Discussion The licensee proposed to have one storage pond rather that the two existing i
storage ponds. The proposed storage pond contains approximately 12 million l
gallons of water which provides water to the circulating water makeup pump l
(CWMVP) structure. The three CWMVPs, each with a capacity of 5340 gallons, are available to pump water via two redundant discharge lines to both fire water pump suction pits. The proposed pond will have only one intake line, which supplies water to the circulating water makeup pump suction.
Evaluation This proposed change is a deviation from NRC acceptance criteria (BTP 9.5-1, Rev.1)whichstatesthatlakesorfreshwaterpondsofsufficientsizemay qualify as sole sources of water for fire protection, but there should be at least two intakes to the pump supply. The licensee has stated thet a minimum inventory of 10 million gallons of water will be maintained in one pond. Also, I
assuming 300,000 gallons could be exhausted in fire suppression activities, the remaining inventory can support PCRV liner cooling witi fire water for slightly over four days. On the basis of this review it is concluded that the minimum inventory of 10 million gallons and the use of a single intake is acceptable in view of the permanent shutdown status of FSV.
Conclusion The staff has concluded, based on the considerations discussed above, that:
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(1) there is reasonable assurance that the health and safety of the public will not be endangered by the proposed activities and (2) such activities will l
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be conducted in compliance with the Comission's regulations and the issuance of this amendment will not be inimical to the common defense and security nor th> health and safety of the public.
Principal Contributors: AmarjitSingh Peter B. Erickson Dated:
March 28,1990 4