ML20028C678
| ML20028C678 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 01/05/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20028C676 | List: |
| References | |
| TAC-11111, NUDOCS 8301130187 | |
| Download: ML20028C678 (13) | |
Text
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BEAVER VALLEY NUCLEAR POWER ST'ATION UNIT 1 SAFETY EVALUATION REPORT FOR APPENDIX R TO 10 CFR 50, ITEMS III.G.3 AND III.L INTRODUCTION On February 19, 1981, the fire protection rule for nuclear power plants, 10 CFR 50 and Appendix R to 10 CFR 50, became effective.
This rule requires alL Licensees of plants Licensed prior to January 1, 1979, to submit, (1) plans and schedules for meeting the applicable requirements of Appendix R, (2) a design descrip-tion of any modifications proposed to provide alternative safe shutdown capability pursuant to Paragraph III.G.3 of Appendix R, and (3) exemption requests for which the tolling provision of Section 50.48(c)(6) was to be invoked.
Section III.G of Appendix R is a retrofit item to atL pre-1979 plants regardless of previous SER positions and resolutions.
By submittals dated June 30, October 22 and October 28, 1982 the Licensee described the means by which safe shutdown can be l
l achieved in the event of fire,and proposed modifications to the Beaver Valley Nuclear Power Station Unit 1 to meet the requirements of Appendix R to 10 CFR 50, Items III.G.3 and III.L.
Additional i n f o rm at i on and clarification was obtained through a meeting held on November 30, 1982 and through telephone conference catts on December 6 and 9, 1982.
The Licensee subsequently documented his response in L ett ers dat ed December 10 and 21,1982.
8301130187 B30105 PDR ADOCK 05000334 F
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The licensee has provided safe shutdown analyses for the fire events and has demonstrated adequate redundancy in the proposed design of the Beaver Valley Nuclear Power Station Unit 1.
The oroposed modifications resolve previous SER open items on alternate shutdown, Our enslysis and evaluation of this follows.
SYSTEMS USED FOR POST-FIRE SAFF EWitTnnWM A.
Systems Required for Safe Shutdnun Safe shutdown of the reactor is initially performed by rod insertion from the control room.
Insertion can also be accom-plished by removing power to the rod drive in the motor-generator set area.
Reactor coolant inventory and subacquent reactivity control are maintained by one of the three high pressure charging pumps taking suction from the boric acid injection tank or the f
refueling water storage tank.
Reactor coolant pressure can be maintained by one set of pressurizer heaters and one of three charging pumps.
Overpressure protection is provided by safety,/ relief valves and code safeties on the pressurizer venting via pressurizer relief tank to the containment.
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. Decay heat removal can be accomplished by releasing steam from the steam generators via the atmospheric dump valves and the steam safety valves, Makeup water to the steam generators can be provided by the auxiliary feedwater pumps which take suction from the condensate sterope tank,or,as a backup,from the two demineralized. water storage tanks.
Cold shutdown conditions can be achieved and maintained by going to solid steam generator.
In this method, the steam generator receives makeup water f rom the auxiliary feedwater system and drains to the main condenser via steam bypass dump valves.
The two-inch bypass valves around the main steam isolstion valves (MSIVs) can be throttled in conjunction with auxiliary feedwater to stabilize the flow to the steam generators.
The main condenser can be drained to several locations.
A is available through safety _related piping backup river water source for this function to continue indefinitely.
The licensee wiLL the static install cradles on the main steam lines to support water loads.
The residual heat removal (RHR) system wilL be used, when avail-i abLe, for achieving and maintaining cold shutdown conditions.
The RHR system wilL not be available should a fire take place in the control room, process equipment room, cable spreading room, containment and cable vaults.
The Licensee does not be the RHR system if the control room cannot propose to use reentered and made available fotLowing a fire.
For this eventuality
.the solid ste3m generator wilL be used as the shutdown mode.
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B.
Areas Where Alternate Safe Shutdown Is Reauired The Licensee has provided alternate shutdown capability indepen-dent of cabling and equipment in the control room (CR-1),
cable spreading room (CS-1), relay room (CR-3), instrument rack room (CR-4), normal switchgear room (NS-1), pipe tunnel area (PT-1), CO storage /PG pump room (CO2), c ntainment-area 2
(RC-1), cable vaults (CV-1 and CV-2), auxiliary building area (PA-1A), emergency switchgear rooms (ES-1 and ES-2) and con-trol room A /C room (CR-2).
The alternate shutdown method wilL be accomplished by procedural means, with actions performed at ' Local shutdown stations or locally at the equipment.
The Licensee has provided a summary of the functions for which alternate shutdown methods may be needed, and the manual actions required to accomplish each of j
the identified functions which have been described.
Alternate process monitoring capability wilL be achieved through the installation of a backup indication panel in the ea'st cable vault.
The required instrumentation for process variables are available at the backup indication panel.
The Licensee wilL install a local steam pressure indicator in the atmospheric w
dump valve area for manual control of the steam pressure during i
post-fire shutdown.
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. Due to the close proximity of the three existing auxiliary feedwater pumps in the pipe tunnel area (PT-1),the Licensee has committed to install a new 100 percent capacity auxiliary feed-rater pump Located in a separate fire area in the turbine building.
The suction and discharge of this new pump wiLL tie into the existing auxiliary feedwater headers.
Also due to close proximity of motor-operated valves on the river water supply to the diesel generators, in the CO2 **
"*8'/
PG pump room (CO
),
the Licensee committed to relocate one 2
of the motor-operated valves to a separate fire area to eliminate 4
the possibility of coincident loss of cooling water to both diesel generators in the event of a fire.
The Li censee has proposed to use portable, gasoline-powered f ans as a means of providing essential ventilation in three areas in the event of fire damage to the normal HVAC equipment.
These three areas are the primary auxiliary building area (PA-1A) the emergency switchgear rooms (ES-1 and ES-2) and the control room A/C room (CR-2).
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. The Licensee has proposed modifications to the No. 2 diesel control circuit and wiring since redundant control circuits for the diesel generator were found to run in the same fire area.
The modifications are proposed in areas of normal switchgear, cable spreading room, instrument rack room, relay room and control room A/C room.
i The Licensee has also proposed to revise the circuits of all Category I, safety related motor control centers (480V) to
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provide current-Limiting devices f or the control transformers to prevent hot shorts from occurring.
C.
Remainino Plant Armam AlL other areas of the plant not required to have alternate safe shutdown wilL comply with the requirements of Section III.G.2 of Appendix R, unless an exemption request has been approved by the staff.
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EVALUATION i
A.
Performance Goals The performance goals for post-fire safe shutdown for reactivity control, reactor coolant makeup, reactor coolant pressure control and decay heat removal can be met j
using the existing systems and equipment listed in Section A above, including the new auxiliary feedwater pump.
The control of these functions can be accomplished using the alternate shutdown methods,or the control room, depending on the location of the fire.
The licensee's alternate shutdown method relies on procedures and actions at local shutdown stations or equipment.
The process-monitoring capability will be provided on the backup indication panet for reactor hot and cold leg temperatures, pressurizer pressure and level, steam generator level and source range flux monitor.
Steam 4
pressure will be monitored locally.
Requirements to read other local indications for tank levels and diagnostic pressure, temperature or flow indications of support systems will be included in the shutdown procedures.
The installed i
source range instrument drawer at the backup indication panel (BIP) witL have the ability to be hooked up to the' source range monitor within one hour.
The available support systems f or post-fire saf e shutdown l
are the redundant diesel generators, vital buses, reactor plant river water system, portable gaseline-powered fans for three areas and power supply for the backup indication panet.
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B.
72-Hour Recuirement Licensee stated that the plant can achieve cold sh'utdown without offsite power, but not necessarily within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
With RHR operational, the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> criterion wilL be met.
With RHR lost, the Licensee calculated that the capability exists to achieve cold shutdown within 127 hours0.00147 days <br />0.0353 hours <br />2.099868e-4 weeks <br />4.83235e-5 months <br /> without offsite power.
A backuo source of makeup water from the river is available for this function to continue indefinitely.
The Licensee has requested an exemption from the 72-hour requirement to achieve cold shutdown per Section III.L of Appendix R.
The Licensee proposed to use solid steam generator to achieve cold shutdown only when RHR system is not available.
Using solid steam generator method and with only onsite power available, the Licensee wilL need 127 hours0.00147 days <br />0.0353 hours <br />2.099868e-4 weeks <br />4.83235e-5 months <br /> to achieve cold shutdown. The actual granting 1
of this exemption, however, wilL be handled as a separate action.
C.
Reoairs The licensee stated that the only repairs necessary are connec-1 i
tions for source range flux monitor and cradle installation under the steam Lines for cold shutdown.
The equipment to effect these repairs wiLL be stored onsite.
In addition, procedures wilL be available for the repairs.
The staff considers this acceptable.
' D.
Associated Circuits and Isolation The licensee stated that atL circuitry, indicators, instru-ments and power supplies associated with the backup indi-cation panel wilL be independent from those of identified fire zones for which alternate shutdown capability is required.
The Licensee has not added any circuits other than alternate instrumentation at the backup indi ca t ion panet.
The switch to transfer the functions to the backup indication panel wilL be located in the east cable vault area in the vicinity of the backup indication panet.
1.
Common Power Source The Licensee stated that atL of the normal and control circuits are, or wiLL be provided isolation via electrically coordinated circuit breakers or fuses.
2.
Common Enclosure Nonsaf ety-related cabling does not run from one redun-l dant train to another.
The Licensee stated that associated circuits for common enclosures are Limited to switch' gear and Load center compartments or panels and boards in which safe shutdown circuits exist.
10-AlL circuits that did not have proper isolation were 1
reviewed for possible adverse effects on the circuits needed for safe shutdown.
The circuits which could safe shutdown wilL be provided with fuses or
)
a f fect breakers.
1 3.
Spurious Signal operation Spurious operations are prevented or corrected by disabling the output of the solid state pro-tection system (AC controls), and removing DC control power from AC switchgear.
The Licensee stated this action also prevents any logic from precluding or impairing safe shutdown.
A control room fire wiLL not affect the auto-start and sequencing functions of diesel control.
Loss of an automatic signal itself initiates the start sequence.
High/ Low Pressure Interface t
The Licensee has listed the following high/ Low pressure interfaces and how the spuricus operation of isolation valves is prevented:
Pressurizer Power-0perated Relief Valves and Associated Isolation Valves - Plant procedures vill require the closing of isolation valves upon detection of fire in i
specified areas and to rack out the respective circuit breakers.
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Reactor Coolant Supply to RH System - Plant procedures witL require the operator to rack out the respective circuit breakers whenever the reactor coolant temperature is greater than 350 F.
Volume Control Letdown Lines - Coincident spurious operation of at least three valves would be required to precipitate an uncontrolled discharge.
- Also, selective shorting between conductors in a mutti-conductor cable design is highty unlikely.
The loss of coolant associated with this multiple failure would be compensated by the operation of the charging pump.
Excess Letdown Flow Path - The three isolation valves associated with the flow are normalLy shut with their power supply racked out.
Primary Sample and Coolant Vent Systems - Flow is Limited by 3/8" restricted orifices, and is welL within the capacity of the chargingLpump.
12-E.
Safe Shutdown Procedures and Manenwar The Licensee stated that atL procedures are not yet written or up-to-date with respect to safe shutdown methods as currently proposed.
The Licensee's draft shutdown procedures provide instructions to the caerators on alternative methods of maintaining critical shutdown parameters by operating equipment locally.
Manual operations would require additional personnel (to achieve cold shutdown) beyond normat onsite shift complement.
The Licensee wiLL consider the timeliness of actions required, and personnet availability during the development of safe shutdown procedures.
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_LONCLUSION The goals of reactivity control, inventory control, decay heat removat and pressure control are met except for the deviation f rom the 72-hour cold-shutdown c rit erion (127 hours0.00147 days <br />0.0353 hours <br />2.099868e-4 weeks <br />4.83235e-5 months <br /> with only onsite power)
The staf f finds this extended time acceptable.
The goals of process monitoring and adequate support systems have been met.
Therefore, based on our review, we conclude that the proposed Beaver Valley Nuclear Power Station Unit 1 design meets the require-ments of Appendix R to 10 CFR Part 50 Items III.G.3 and
i III.L with respect to safe shutdown in the event of a fire, in the areas identified in the licensee's proposed modifi-cations.
This conclusion is contingent upon the granting of exemption to the 72-hour cold-shutdown requirement.
We further conclude that the alternate shutdown open items in our SER dated May 3, L979 are considered to be resolved.
Principal contributors R.
Goel V.
Panciera I
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