ML19242A527
| ML19242A527 | |
| Person / Time | |
|---|---|
| Issue date: | 06/19/1979 |
| From: | Lainas G Office of Nuclear Reactor Regulation |
| To: | Vollmer R Office of Nuclear Reactor Regulation |
| References | |
| TAC-11094, TAC-11095, TAC-48143, NUDOCS 7908030084 | |
| Download: ML19242A527 (9) | |
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UNITED STATES f yQ h NUCLEAR REGULATORY COMMISSION y '/
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JUN 191979 MEMORANDUM FOR:
R. Vollmer, Assistant Di' rector for Systems and Projects, Division of Operating Reactors FRCM:
G. Lainas, Chief, Plant Systems Branch, Division of Operating Reactors
SUBJECT:
STAFF POSITICN - SAFE SHUTDOWN CAPABILITY At the present time, fire protection SER supolements must be issued for 45 reactor plants.
For 31 of the plants requiring SER supplements, we have required that the licensees provide additional inft mation to demonstrate safe shutdown capability for fires in certain plant areas and/or provide a propcsal fer an alternate shutdcwn capability. We have also required licensees to provide design details for alternate shutdown systems previcusly comitted in the initial SER's for 9 plants.
Tne attached staff position specifies the safe shutdown equiprent and their perfor-mance objectives that the licensees of these 40 plants should consider in demonstrating safe shutdown capability with existing or al ternate equipment.
We recommend that this staff position be sent to the licensees of those plants for which safe shutdown / alternate shutdown is being carried as an open item, except for these plants being reviewed in the Systematic Evaluation Program. The adequacy of the safe shutdown capability for the SE? plants will be determined as part of the SEP review.
Subsequently, Plant Systems Branch will evaluate the adequacy of the fira protection afforded safe shutdcwn systems in SEP plants.
F G. Lainas, Chief Plant Systems 3 ranch Division of Ccerating Reactors
Contact:
E. Sylvester, X27173
Enclosure:
As stated cc w/enclosura:
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D. Eisenhut D. Davis D. Ziemann G. Lainas P. Check R. Ferguson Y. McCre T. Watcach PSB Section C q (a.i
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STAFF POS! TION SAFE SHUTDOWN CAPABILITY Staff Concern During the staff's evaluation of fire protecticn programs at operating plants, one or more specific plant areas may be identified in wnich the staff does not have adequate assurance that a postulated fire will not damage both redundant divisions of shutdcwn systems.
This lack of assurance in safe snutdown capability has resulted from one or both of the following situations:
Case A:
The licensee has not adequately i dentified the systems and components required for safe shutdown and their location in specific fire areas.
Case B: The licensee has not demonstrated that the fire pr1tection for specific plant areas will prevent damage to both redundant divisions of safe shutdown components identified in these areas.
For Case A, the staff has required that an adequate safe shutdcwn analysis be performed.
This evaluation includes the identification of tne systens required for safe shutdcwn and the location of the system components in the plant. Where it is determined by this evaluation that safe shutdown ccmponents of both redundant divisions are located in the same fire area, the licensee is required to demonstrate that a postulated fire will not damage both divisions or provide alternate shutdown capability as in Case B.
For Case B, the staff may have required that an alternate shutdown capability be provided with is independent of the area of concern or the licensee may have proposed such a capability in lieu of certain additional fire protection modifications in the area.
The specific modifications casociated with the area of concern along with other systems and equipment already independent of the area form the al ternate shutdcwn capabili ty.
For each plant, the modifications needed and the combinations of systems which provide the shutdcwn functions may be unioun for eacn critical area; hcwever, the shutdcwn functions provided snou'a maintain plant parameters within the bounds of the limiting safety consequences deemed acceptacle for the design basis event.
Staf f Position Safe snutdcwn capacility snculd be demonstrated (Case A) or alternate shutdown capability orovided (Case 3) in accordance with the guidelines proviced belcw:
- 1. Cesign Basis Event The design basis event for considering the need for alternate shutdown is a posculated fire in a specific fire area containing redundant safe shutdcwn cables / equipment in close proximity anere it has been determined that fire protection means cannot assure that safe shutdown capability will be preserved.
Two cases should be considered:
(1) offsite acwer is available; and (2) offsite pcwer is not available, b'
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. 2. Limiting Safety Consecuences and Reoui red Shutdown Functions 2.1 No fissica product boundary integrity shall be affected:
a.
No fuel clad damage; b.
No rupture of any pr4 nary coolant boundary; c.
No rupture of the coni ainment boundary.
2.2 The reactor coolant system process variables shall be within those predicted for a loss of normal ac power.
2.3 The alternate shutdcwn capability shall be able to achieve and maintain subcritical conditions in the reactor, maintain reactor coolant inventory, achieve and maintain hot standby
- conditions (hot shutdcwn* for a BWR) for an extended period of time, acnieve cold shutdown
- conditions within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> ond maintain cold shutdown conditions thereafter.
As defined in the Standard Technical Specifications.
- 3. Performance Goals 3.1 The reactivity control functicn shall be capable of achieving and maintaining cold shutccwn reactivity ccnditions.
3.2 The reactor coolant makeup function shall be capable of maintaining the reactor coolant level above the top of the core for BWR's and in the pressurizer for PWR's.
3.3 The reactor heat removal function shall be capable of achieving and maintaining decay heat removal.
3.4 The process monitoring function shall be capable of providing direct readings of the process variables necessary to perform and control the above functions.
3.5 The sucporting function snc.ll be capable of providing the process cooling, lubrication, etc. necessary to termit the operation of the equipment used for safe snutdown by the systems identified in 3.1 - 3.4 3.6 The equipment and systems used to achieve and maintain hot standby conditions (hot snutdown for a 3WR) should be (1) free of fire damage; (2) capable of maintaining such conditions for an extended time ceriod longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if tne equipment required to acnieve and maintain cold shutdown is not available due to fire damage; and (3) powered by an ensite emergency pcwer system.
3.7 The equipment and systems used to achieve and maintain cold shutdcwn conditions should be either free of fire damage or the fire damage to such systems should be limited such tnat repairs can be made and cold shutdown concitions achieved within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
Equipment and systems used prior to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after the fire should be pcwered by an onsite emergency pcwer system; those used after 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> may be acwered by
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. offsite power.
3.8 These systems need not be designed to (1) seismic category I criteria; (2) sin,gle failure criteria; or (3) cope with other plant accidents such as pipe breaks or stuck valves
( Appendix A STP 9.5-1), except those portions of these systems which interface with or impact existing safety systems.
- 4. PWR Equipment Generally Necessary For Hot Standby (1) Reactivity Control Reactor trip capability (scram).
Boration capabili ty e.g.,
charging pump, makeup pump or high pressure injection pump taking suction from concentrated barated water supplies, and letdown system if required.
(2) Reactor Coolant Makeuo Reactor coolant makeup capability, e.g., charging pumps or the high pressure injection pumps.
Power operated relief valves may be required to reduce pressure to aiIow use of the high pressure injection pumps.
(3) Reactor Coolant System Pressure Control Reactor pressure control capability, e.g., charginj pumps or pressurizer eaters and use of the letdcwn sys, ems if required.
(4) Decay Heat Removal Decay heat removal capabili ty, e.g., power operated relief valves (steam generator) or safety relief valves for neat removal with a water supply and emergency or auxiliary feedwater pumos for makeup to the steam generator.
Service water or other cumps may be required to provide water for auxiliary feed pump suction if the condensate storage tank cacacity is not adequate for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
(5) Process wenitorina Instrumentaticn
?rocess monitoring capability e.g., pressurizer pressure and level, steam generator level.
(6) Succort The equipment required to support operaticn of the above described shutdown equictent e.g., component cooling water service water, etc. and cnsite pcwer sources ( AC, CC) witn their associated electrical distribution system.
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- 5. PWR Ecuicment Generally Necessary for Cold Shutdown *
(1)
Reactor Coolant System Pressure Reduction to Residual Heat Removal System ( RHR) CanaD111 y Reactor coolant system pressure reduction by cooldcwn using steam generator power operated mlief valves or atmospheric dump valves.
(2) Cecay Heat Removal Decay heat removal capab lity e.g., residual heat removal system, component cooling water system and service water system to removal heat and maintain cold chutdcwn.
(3)
Sucoort Support capability e.g., onsite pcwer sources ( AC & CC) or offsite af ter 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and the associated electrical distributicn system to supply the above equipment.
Equipment necessary in addition to that already provided to maintain hot standby.
- 6. BWR Ecuicment Generally Necessary For Hot Shutdown (1) Reactivity Control Reactor trip capability (scram).
(2) Reactor Coolant Makeup Reactor coolant inventory makeup capability e.g., reactor core isolation cooling system (RCIC) or the high pressure coolant injection system (HPCI).
(3) Reactor Pressure Control and Cecay Heat Removal Cepressuri:3 tion system valves or safety relief valves for dump to the sucoression pool.
The residual neat removal system in steam condensing nude, and service water system may also te used for heat remcval to One ultimate neat sink.
(4, Sucaression Pool Cooling Residual heat removal system (in sucoression cool cooling mode) service water system to maintain not snutocwn.
(5) Process Monito.ing Process mcnitoring capability e.g., reactor vessel levr.i and Dressure and suopression pool temperature.
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-S-(6) Succort Suoport capability e.g., onsite power source ( AC & DC) and their associated distribution systems to provide for the shutdown equipnent.
- 7. BWR Eouioment Generally Necessary For Cold Shutdown
- At this point the equipment necessary for hot shutdown has reduced the primary system pressure and temperature to where the RHR system may be placed in service in RHR cooling mode.
(1) Cecay Heat Removal Residual heat removal system in the RHR cooling mode, service water system.
(2) Succort Onsite sources ( AC & DC) or offsite af ter 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and their associated distribution systems to provide for shutdcwn equipment.
Equipment provided in addition to that for achieving hot shutdown.
- 8. Information Reouired For Staff Review (a)
Description of the systems or portions thereof used to provide the shutdown capability and modifications required to achieve the alternate shutdown capabilit; if requi red.
(b)
System design by drawings which show normal anu al ternate shutdown control and power circuits, location r; c.mponents, and that wiring which is in the area and the wiri'.g which is out of the area that required the alternate syst em.
(c) Verificaticn that changes to safety systems will not degrade safety systems.
(e.g., new isolation switches and control switches should meet design criteria and standaros in FSAR for electrical equipment in the system that the switcn is to be installed; cabinets that the switenes are to be mounted in snculd also meet the same criteria (?SAR) as otner safety related cabinets and Danels; to avoid inadvertent isolation frcm the control rocm, tne isolation switches snculd be keylocked, or alarmed in the control roca if in the " local" or "isclated" ocs i tion ;
periodic checks should be made to verify swi*.ch is in :ne p rocer position for nomal coeration; and a single tra 'sfer switch or other new device should not ce a source for a single failve to cause loss of redundant safety systems).
(d) Verification that wiring, including ocwer sources for the control circuit and equipment operation for the alternate shutdcwn method, is indeoendent of equiorent wiring in the area to be avoided.
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. (e) Verification that alternate shutdown power sources, including all breakers, have isolation devices on control circuits thit are routed through the area to be avoided, even if the breake r is to be operated manually.
(f) Verification that licensee procedure (s) have been developed which describe the tasks to be performed to effect the shutdown me thod. A summary of these procedures should be reviewed by the staff.
(g) Verification that spare fuses are available for control circuits where these fuses may be required in supplying pcwer to control circuits used for the shutdown method and may be blown by the effects of a cable spreading room fire.
The spare fuses should be located convenient to the existing fuses.
The shutdown procedure should inform the operator to check these fuses.
(h) Verification that the manpcwer required to perform the shutdown functions using the procedures of (f) as well as to provide fire brigaoe members to fight the fire is available as required by the fire brigade technical specifications.
(i) Verification that adequate acceptance tests are perforced.
These should veri fy that: equipment operates from tne local control station wnen the transfer or isolation switch is placed in the " local" position and that the equipment cannot be operated from the control room; and that equip-ment operates from the control rocm but cannot be operated at the local control station when the transfer or isolation switch is in the " remote" position.
(j) Technical Specifications of the surveillance requirements and limiting conditions for coeration for that equipment not already covered by existing Tech. Specs.
For example, if new isolation and c;ntrol switches are added to a service water system, the existing Tech. Scec. surveillance require-ments on the service water system should add a statement similar to the folicwing:
- Every third pump test snould also veri fy that tne cumo starts from the alternate shutdewn station af ter moving all service water system isolation switches to the local control position."
(k) Verification that tha systems availaole are adecuate to :erform the necessary shutduwn functions.
The functions required should be based on previcus analyses, if prssible (e.g.,
in the FSAR), such as a loss of normal a.c. pcwer or snutdcwn on a Group I isolation (3WR).
The equipment required for the alternate capability should be the same or ecuivalent to that relied on in the above analysis.
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.. (1) '/erification that repair procedures for cold shutdcwn systems are developed and material for repairs is maintained on site.
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