ML19308C980
| ML19308C980 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 01/17/1980 |
| From: | Lainas G Office of Nuclear Reactor Regulation |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8002130033 | |
| Download: ML19308C980 (14) | |
Text
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JAN 171980 MEMORANDUM FOR:
A. Schwencer, Chief Operating Reactors Branch #1 Division of Operating Reactors FROM:
G. Lainas, Chief Plant Systems Branch Division of Operating Reactors '
SUBJECT:
TROJAN FIRE PROTECTION - TRAIN B SWITCHGEAR ROOM Plant Name: Trojan Nuclear Plant Licensee: Portland General Electric Docket No.: 50-344 Project Manager:
C. Tramell Status: Fire Protection Review Complete; Draft SER i
Supplement being prepared.
Fire Protection for the Trojan train B switchgear room was identified l
as an incomplete item in our SER of March 9,1978 (item 3.2.2).
The enclosed staff requirement provides our evaluation of information submitted by the licensee on this item, and our requirement for additiona! modifications to resolve this item.
This requirement should be transmitted to the licensee. We request a response with 20 days that indicates which alternative will be satisfied; however, if the licensee chooses not to satisfy this requirement, a meeting should be arranged within the same 20 days with appropriate management individuals prior to initiating an order.
We are preparing a supplement to our SER on Trojan addressing the remaining incomplete items.
0 81 G. Lainas, Chief I
Plant Systems Branch Division of Operating Reactors
Contact:
H. George, X27136 i
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STAFF REQUIRENENT -
TROJAN TRAIN B SWITCHGEAR ROOM FIRE PROTECTION (Item 3.2.2 of F. P. SER)
Background
The Train B switchgear room predominantly contains cabling, switchgear, and other electrical equipment associated with safety train B.
The room also contains a small amount of train A equipment, including the preferred instrument a-c buses, battery chargers, inverters, and cabling routed to the train A battery. The train A cabling and equipment are generally well separated from train B equipment and cabling. However, due to the large amount of cabling in the room and the non-safety related cable trays that provided pathways for fire to be transmitted between safety divisions, the staff was concerned that a fire in one safety division could affect cabling in the redundant safety division. As noted in our fire protection SER of March 9,1978, PGE had committed to provide fire-stops in non-safety cable trays in this area that provided a pathway for fire to be transmitted between safety divisions. In addition, PGE had committed to provide an analysis based on cable tray tests to demonstrate the effectiveness of the room air coolers to remove heat from a fire and thus protect cables not involved in the fire from being damaged due to heat buildup.
The PGE letter of January 9,1979, indicated that adequate test data was available and that no tests would be performed. The staff then requested PGE to submit the promised analysis based on available data or to satisfy one of three alternatives for the train R switchgear room:
(a) Provide an alcernate shutdown capability independent of cabling and equipment in this room to achieve safe shutdown, or (b) Provide an automatic total flooding gas suppression system in this area, or (c)
Install a 3-hr rated barrier to separate the train A cabling and equipment in the room from the train B cabling and equip-ment.
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l i Evaluation j
By letter of July 30,1979, PGE submitted the results of an analysis of the j
capability of the air recirculation units in this area to protect cables and equipment in the safety division not involved in the fire. We have reviewed the assumptions used in this analysis and the conclusions made, and find the results unacceptable for the following reasons.
(1) The analysis is Iat conservative because it is a themal analysis that assumes unifom air mixing.
It does not consider localized higher temperatures, exposure fires from l
transient combustibles, and radiant energy effects. With l
these other considerations the temperature could increase much more rapidly.
(2) The electrical equipment in this room is designed to operate in a maximum ambient temperature of 104*F. The analysis I
indicates that 104*F would be reached in approximately 20 minutes and 180*F in 25 minutes with the air recirculation units operating in a fire. This means that tne air recir-culation units cannot overcome the heat generated by the fire prior to loss of vital equipment without intervention by the brigade to suppress the fire.
l (3) The credit in this analysis taken for the room air coolers is not conservative. They contain particulate type filters that could become clogged with smoke psrticles in a fire, i
thereby greatly reducing their heat removal capability.
These particulate filters are required to prevent dust buildup on the blower fan or heat exchanger fins during normal operation for heat loads in the room.
Staff Position j
Based on the above, we find the licensee's analysis unacceptable because there is not reasonable assurance that shutdown conditions can be achieved i
and maintained. We do not accept fire brigade actions as the only means of preserving safe shutdown capability where the separation between redundant systems is inadeouate. Passive protection, such as barriers, automatic suppression, and/or alternate shutdown capability are required where a fire could damage redundant safe shutdown cabling.
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To provide adequate protection for this area, we will require that one of the following be provided:
(1) An alternate shutdown capability independent of cabling and equip-ment in this room to achieve safe shutdown. This should be equivalent to the remote shutdown capability being provided for the control room and cable spreading room so that the staff's criteria for alternate shutdown (attached) are satisfied, or (2) An automatic total flooding gas suppression system. This system should: be actuated by smoke or rate-of-rise heat detectors located at the ceiling; have a minimum design concentration of 50% if CO2 and 20% if halon; have two-shot capability; be able to maintain a soak time of 30 minutes considering leakage through doors and ventilation dampers; and conform to NFPA 12 or 12A for deep-i seated fire conditions.
or (3) A 3-hour fire-rated barrier separating the train A cabling and equipment in the room from the train 8 cabling and equipment. This may be done by metal lath and plaster construction whose design has been tested to demonstrate a 3-hour fire-rating.
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STAFF POSITION SAFE SHUTDOWN CAPA8ILITY Staff Concern During the staff's evaluation of fire protection programs at i
operating plants, one or taart specific plant areas may be identified?
in which the staff does not have adequate assurance that a postulated i
fire will not damage both redundant divisions of shutdown systems.
l This lack of assurance in safe shutdown capability has resulted from one or both of the following situations:
Case A: The licensee has not adequately identified the' systems and components required for safe shutdown and their location in specific fire areas.
i Case B: The licensee has net demonstrated that the fire protection for specific plant areas will prevent damage to both redundant divisions of safe shutdown co=cenents identified in these areas.
For Case A. the staff has required that an adequate safe shutdown analysis be performed. This evaluation includes the identificaticn of the systems required for safe shutdewn and the location of the system components in the plant. Where it is determined by this evaluatien that safe shutdown components of both redundant divisions are located in the same fire area, the licensee is required to demonstrate i
that a pestulated fire will not damage both divisions or provide alternate shutdown capability as in Case 3.
t For Case B, the staff may have required that an alternate shutdown i
capacility be provided with is independent of the area of concern or the licensee may have proposed such a capability in lieu of i
certain additional fire protection modificaticns in the area. The specific modifications associated with the area of concern along with other systems and equipment already independent of the area form the l
alternate shutdown capability. For each plant, the modifications needed and i
the combinations of systems which provide the shutdown functions may be
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unique for each critical area; however, the shutdown functions provided should maintain plant parameters within the bounds of the limiting safety consequences dee.med acceptable for the design basis even Staff position Safe shutdown capability should be demonstrated (Case A) or alternate shutdcwn capability provided (Case B) in accordance with i
the guidelines provided belcw:
- 1. Desi;n Basis Event The design basis event for considering the need for alternate shutdown is a postulated fire in a specific fire area containing reduncant safe shutcown cables / equipment in close proximity where it has been deter tined that fire erotection means cannot ascurt that safe shutdewn capability will be preserved. Two cases should be considered: (1) offsite power is availeble; and (2) offsite power is not available.
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- 2. Limiting Safety Consecuences and Required Shutdown Functions 2.1 No fission product boundary integrity shall be affected:
a.
No fuel clad damage; b.
No rupture of any primary coolant boundary; c.
No rupture of the containment boundary.
2.2 The reactor coolant system process variables shali be within those predicted for a loss of normal ac power.
2.3 The alternate shutdown capability shall be able to achieve and maintain suberitical conditions in the reactor, maintain reactor coolant inventory, achieve and maintain hot standby
- conditions (hot shutdown
- for a BWR) for an extended period of time, achieve cold shutdown
- conditions within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and maintain cold shutdown conditions thereafter.
As defined in the Standard Technical Specifications.
- 3. Performance Goals 3.1 The reactivity control function shall be capable of achieving and maintaining cold shutdown reactivity conditions.
3.2 The reactor coolant makeup function shall be capable of maintaining the reactor coolant level above the top of the i
core for SWR'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
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providing direct readings of the process variables necessary to perform and control the above functions.
3.5 The supporting function shall be capable of providing th'e process cooling, lubrication, etc. necessary to permit the operation of the equipment used for safe shutdown by the systens identified in 3.1 - 3.4.
3.6 The equipment and systens used to achieve and maintain hot l
standby conditions (hot shutdown for a SWR) should be (1) free of fire damage; (2) capable of maintaining such I
conditions for an extended time period longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if the equipment required to achieve and maintain cold shutdown is not available due to fire damage; and (3) i powered by an onsite emergency power system.
l 3.7 The ecuipment and systems used to achieve and maintain cold shutdown conditions should be either free of fire damage er l
the fire damage to such systems should be limited such i
that recairs can be made and cold shutdown conditions achieved N-witnin 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Ecuipment 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 powered by an onsite emergency l
power 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 powered by
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3.8 These systems need not be designed to (1) seismic category I criteria; (2) single failure criteria; or (3) cope with other plant accidents such as pipe breaks or stuck valves (Appendix A BTP 9.5-1), except those portions of these systems which interface with or impact existing safety systems.
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- 4. PWR Ecuiement Generally Necessary For Het Standby (1) R'eactivity Control Reacter trip capability (scram). Boration capability e.g.,
charging pump, makeup pump or high pressure injection pump taking suction from concentrated borated water supplies, and letdown system if required.
(2) Reactor Ccolant Makeue Reactor coolant makeup capability, e.g., charging pumps or tne high pressure injection pumps.
Power ccerated relief valves may be required to reduce pressure to allow use of the high pressure injection pumps.
r (3) Reactor Ceolant System Pressure Centrol Reactor pressure centrol capability, e.g., charging pumps or pressurizer heaters and use of the letdown systems if required.
j (4) Decay Heat Remeval Decay heat removal capability, e.g., power operated relief valves (steam generator) or safety relief valves for heat removal with a water supply and emergency or auxiliary feedwater pumps for makeup to the steam generator. Service water or other pumps may be req - red to provide water for auxiliary
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feed pump suction if the cendensate storage tarik capacity is not adequate for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
i (5) Process Monitoring Instrumentatien l
t Process monitoring capability e.g., pressurizer pressure and level, steam generator level.
(6) Succort.
The ecuf pment required to support operatien of the above described shutdcwn equipment e.g., ccmcenent cooling water servi:e water, etc. and ensite power sources (AC, DC) with their associated electrical distributien system.
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- 5. PWR Equipment Generally Necessary For Cold Shutdown *
(1) Reactor Coolant System Pressure Reduction to Residual Heat Removal System (RHR) Capacility Reactor coolant system pressure reduction by cooldown using steam generetor power operated relief valves or atmospheric dump valves.
(2) Decay Heat Removal Decay heat removal capability e.g., residual heat removal system, compenent cooling water system arid service water system to removal heat and maintain cold shutdown.
I (3) Sucoort Support capability e.g., onsite power sources (AC & DC) l or offsite a'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 distribution system to sucoly the above equiernent.
l Equipment necessary in addition to that already provided to maintain hat stand::y.
- 6. BWR Ecuioment Generally Necessary For Hot Shutdown (1) Reactivity Control i
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Reactor trip capability (scram).
(2) Reactor Coolant Makeue Reactor coolant inventory makeup capability e.g., reactor core isolation cooling system (RCIC) or the high pressure coolant injection system (HPCI).
l (3) Reactor Pressure Control and Decay Heat Removal Depressurization system valves or safety relief valves for i
dump to the suppression pool. The residual heat removal system in steam condensing mode, and service water system may also be used for heat removal to the ultimate heat sink.
(4) Sueoression Pool Coolino l
Residual heat removal system (in suppression pool cooling mode) service water system to maintain hot shutdcwn.
(5) Process Monitorinc l
Process monitoring capability e.g., reactor vessel level and pressure and suppression pool temperature.
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(6) Support Support. capability e.g., onsite power source (AC & DC) and their asscciated distribution systems to provide for the shutdown -!quipinent.
- 7. BWR Equioment 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) Decay Heat Removal Residual heat removal system in the RHR cooling mode, service water system.
(2) Succort i
Onsite 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 tneir associated distribution systems to provide for shutdown equipment.
i Equipment provided in addition to that for achieving hot shutdown.
- 8. Information Recuired For Staff Review (a) Description of the systems or portions thereof used to i
provide the shutdown capability and modifications required to achieve the alternate shutdown capability if recuired.
(b) System design by drawings which shew normal and alternate snutdown control and power circuits, location of components, and
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that wiring which is in the area and the wiring which is out of the area that required the altemate system.
(c) Verification that changes to safety systems will not degrade safety systems.
(e.g.,newisolationswitches and control switches should meet design criteria and standards in FSAR for electrical equipment in the system that the switch is to be installed; cabinets that the switches are to be mounted in should also meet the same criteria (FSAR) as other safety related cabinets and panels; to avoid inadvertent isolation from the centrol l
room, the isolation switches should be keylocked, or alarmed in the centrol recm if in the " local" or " isolated" position; periodic checks should be made to verify switch is in the procer position for nor nal coeration; and a single transfer switch or otner new device should not be a scurce for a single failure to cause less of redundant safety systems).
(d) Verification that wiring, including power sources for the centrol circuit and equioment operaticn for the alternate shutdcwn methed, is independent of equipment wiring in the area to be avoided.
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6-(e) Verification that alternate shutdown power sources, ' including all breakers, have isolation devices on control circuits that are muted through the area to be avoided, even if the breaker is to be operated manually.
(f) Verification that licensee procedure (s) have been developed
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which describe the tasks to be performed to effect the shutdown i
me thod. A sumary of these procedures should be reviewed by the staff.
I (g) Verification that spare fuses are available for control circuits where these fuses,may be required in supplying power 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 manpower required to perform the shutdown functions using the procedures of (f) as well as to provide fire brigade members to fight the fire is available as required by the fire brigade technical specificatiens.
(i) Verification that adequate acceptanc'e tests are performed.
These should verify that: equipment operates from the local control station when the transfer or isolation switch
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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 room but cannot be operated at the local control station when the transfer or isolation I
switch is in the " remote" position.
(j) Technical Specificttions of the surveillance requirements and limiting conditions for operation for that equipment not already covered by existing Tech. Specs. For example, if new isolation and control switches are added to a service water system, the existing Tech. Spec. surveillance require-ments on the service water system should add a statement l
similar to the following:
"Every third pump test should also verify that the pump starts from the alternate shutdown station after moving all service water system isolation switches to the local control position."
(k) Verification that the systems available are adequate to perform the necessary shutdown functions. The functions required should be based on previous analyses, if possible (e.g.,
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in the FSAR), such as a loss of normal a.c. power or shutdown on a Group I isolation (SWR). The equipment required for the alternate capability shoulc be the same or ecuivalent to i
that relied on in the above analysis.
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(1) Verification that repair procedures for cold shutdown systems r
are developed and material for repairs is maintained on site.
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