ML20079G948

Application for Amends to Licenses NPF-4 & NPF-7,changing Tech Specs to Ensure Design Basis Met for Svc Water Sys

ML20079G948
Person / Time
Site:	North Anna
Issue date:	10/03/1991
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20079G953	List: ML20079G948 ML20079G964
References
91-563, NUDOCS 9110100040
Download: ML20079G948 (9)

Text

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Yll:OIN I A lh.l!CTitlO A Nil " IWl:lt COMI'A N Y thennoso.Vonoxer unual October 3, 1991 U.S. Nuclear Regulatory Commission Serial No. 91563 Attentinn: Document Control Desk NL&P/JYR Washington, D.C. 20555 Docket Nos. 50 338 50 339 License Nos. NPF 4 NPF 7 Gentlemen:

ylRGINIA ELEQIBlq_ AND POWER COMPAR NORTH ANHA_EQY/fdLEIAllON .UNlIS_1.AUD._2 PROPOSED TECHMICAL SPEC 1ElGATION CHANGES Pursuant to 10 CFR 50.90, the Vlrginia Electric and Power Cornpany requests amendment., in the form of changes to the Technical Specificatlons, to Operating License Numbers NPF 4 and NPF 7 for North Anna Power Station Units 1 and 2, respectively. The proposed changes will revise the current Technical Specifications to encure the design basis is met for thu r.vice water system.

A discussion of ti.a proposed changes with the technical justificatica end safety evaluation of the propcsed changes is provided in Attachment 1. The proposed changes are presented in Attachments 2 and 3 for Units 1 and 2, respectively.

This request has been reviewed by the Station Nuclear Safety and Gr"ating Committee and the Management Safety Review Committee. It has bc0 determined that this request does not involve an unreviewed safety question as defined in 10 CFR 50.59 or a significant hazards consideration as defined in 10 CFR 50.92. The basis for our determination that no significant hazards consideration is involved is presented in Attachment 4.

Should you have any questions or require additional information, please contact us at your earliest convenience.

Very truly yours, n .

\ t N

\\ _xf s W. L. Stewart Senior Vice President - Nuclear

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Attachments j l

1. Discussion of Proposed Changes 2 Proposed Technical Specification Chango for North Anna Unit 1

3. Proposed Technical Specification Chango for North Anna Unit 2 4 10 CFR 50,92 Evaluation i

cc: U.S. Nuclear Roguintory Commission Region ll 101 Mariotta Stroot, N.W.

Suite 2000 Atlanta, GA 30323 Mr. M. S. Lessor NRC Senior Resident inspector North Anna Power Station Commissioner Department of Health Room 400 ,

109 Governor Street Richmond, Virginia 23219 1

COMMONWEALTH OF VIRGINIA )

)

COUNTYOF HENRICO )

The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by W. L. Stewart who is Senior Vice President - Nuclear, of Virginia Electric and Power Company. He is duly authorized to execute and file the foregoing document in behalf of that Company, and the statements in the document are true to the best of his knowledge and belief.

Acknowledged before me this @ Y day of ,_ d[of,J , 19f1L.

My Commission Expires: L 'fA _3/ ,199//_.

6 NSsl.Ihat._.

Notary Public (SEAL)

Attachment 1 Discussion of Proposed Changes North Anna Units 1 and 2 t

Virginia Electric and Power Company

t .

DISCUSSION OF PROPOSED CHAl{GES Introduction The proposed changes described herein are being made as a result of an NRC violation regarding the service water system. In the Notification of Violation (dated February 1,1991) the NRC identified that the operating procedures for the service water system were inadequate by not ensuring design basis flows to th9 recirculation spray heat exchangers during periods when a service water pump is inoperable. This indicated that our control of the service water system desi0n basis was inadequate. In our response to the Notice of Violation (dated March 1,1991) we committed to changes to the Technical Specifications to clarify the service water system operability requirements and, in the interim, to institute adequate administrative controls which will ensure the design basis is met.

DAtkground The service water system is common to both reactor units and is desl0 ned for the simultaneous operation of various subsystems and components of both units. The purpose of the service water system is to provide long term cooling after a loss of coolant accident (LOCA) and to supply cooling water to various safety related components during normal plant operation.

The sources of cooling water for the service water system are the service water reservoir or Lake Anna. These two, independent sources of water form the ultimate heat sink for the units.

The normal service water system alignment consists of four normal service water pumps taking suction from the service water reservoir, supplying various cornoonents through the supply header, and then returning to the service water reservoir through the return header to the spray arrays or bypass valves. A backup subsystem is available in the event of unavailability of the service water reservoir. This backup subsystem consists of two auxiliary service water pumps which take suction from Lake Anna supplying various components through the alternate supply header, and then returning to Lake Anna through the alternate return header.

The cooling capacity of the service water system is based on the cooling requirements assuming one unit sustains a LOCA with a simultaneous loss of offsite power to both units. The service water cooling requirements following a LOCA on one unit dictate that two normal service water pumps operate to supply adequate coohng flow to the affected unit and unaffected unit heat loads, in the event of a LOCA, a safety injection would be initiated. To ensure that sufficient service water cooling is available to both units, the safety injection signal actuates the following:

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a. - All four normal service water pumps start on receipt of a safety injection signal from either unit or on a loss of reserve i station service power. Operation of all four pumps provides <

maximum system cooling capacity and floxibility. -

b.~ The service water spray header isolation va!ves automatically open and the bypass. Isolation valves  ;

automatically close after receipt of a safety injection signal. l With all spray arrays in operation, the service water system '

can reject heat at the maximum rate. _

During a dwign basis accident, the supply valves from both loops of service-water to the .flectP's unit's recirculation spray heat exchangers are opened autom@cally tcon %ceipt of a containment depressurization signal. A safety injection sipal w2E occur prior to the containment depressurization signal.  ;

With four nov,ial zervice water pumps Of JRABLE, the unthrottled head loss of  !

the systerr., to components other than the recirculation spray heat exchangers,- .

is such that design flows are achieved through the recirculation spray heat  :

exchanger if a failure to a single pump or power supply occurs. With three ,

normal service water pumps OPERABLE, the flow of the system, to components l other than the recirculation spray heat exchangers, must be restricted to ensure  ;

that design flow will be available if a single pump or power supply. failure ,

occurs. This is achieved by reducing service water flow through tl's component cooling heat exenangers and must be dne if either or both of the units are in operating Modes 1 through 4. With two normal service wafer pumps OPERABLE, design' flows will not be achieved if a single normal service water ,

pump failure occurs. With one normal service water pump OPERABLE, design flows are not achieved. In the last two cases, more conservative actions are i required by the specifications. .

Technical Soicification Chrinaes General  ;

All Technical Specification changes described herein apply to North Anna Units -

1 and 2. ,

The current Action statements 3.7.4.1.a and 3.7.4.1.b =were renumbered to 3.7.4.1.c and 3.7.4.1.d, respectively - to allow additions of other Action -

. statements, i

- Technical Soecification 3.7.4.1 The numberitig of the Technical Specification was changed from 3/4.7.4 to -

3/4.7.4.1 to allow.for. the addition of a service water Technical Specification in modes 5 and 6 (which 'Is numbered 3.7.4.2). In addition. the title of this

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i Technical Specification was changed to add the word " operating" to identify that

- this specification applios to modes 1 through 4.

The Limiting Condition for Operation is changed to define what an operable service water loop consists of. Each service water loop must contain two OPERABLE service water pumps (excluding auxiliary service water pumps) with their associated normal and emergency power supplies, and an OPERABLE i flow path capable of providing cooling for OPERABLE plant compononts and  ;

transferring heat to the service water reservoir to ensure design basis flows are achlovable.

Tne Applicability statement is changed to clarify that this Technical Specification <

applios if 211tLE unit is in mode 1 through 4. This change will ensure that  ;

sufficient cooling capacity is available for both units during power operation. 7 Action statomont 3.7.4.1.a is added to require that if one of the four required l normal service water pumps becomes inoperable, that component cooling heat exchanger service water flows must be throttled, within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, to ensure that the normal service water pumps remain capable of providing design basis flows to the recirculation spray heat exchangers. This allow 3 design basis flows to be delivered by two normal service water pumps with the failure of the third OPERABLE normal service water pump.

Action statement 3.7.4.1.b is added to requito that if two of the four required service water pumps become inoperable Action 3.7.4.1.a must be periormed within one hour. Performing this action ensures the design basis flows can be rnet if no subsequent pump failures occur, in addition, at least one service water pump must be restored to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, or both units ,

shall be place in HOT STANDBY within the next six hours and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. The specified completion time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is consistent with other LCOs for the loss of one train of an ESF system and with MERITS. This completion timo is based on industry accepted practico, the low probability of an accident occurring during this time while one service water train in inoperable, and engineering Judgment considoring the number of available systems and the timo required to reasonably complete the required sction. The completion time of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> is a reasonable timo based on operating experience to reach HOT STANDBY from full power without challenging safefy '

systems or operators. Similarly, the completion time of 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> is reasonable censidering the unit can cooldown in such a timo frame. Those actions and completion times are consistent with MERITS.

1 Action statement 3.7.4.1.c was modified to add the phrase "except as provided in 3.7,4,1.a" for clarification, in addition, this action statement was changed to clarify that the inoperable loop must be returned to OPERABLE status within six hours or both units will be placed in HOT STANDBY.

j Action statement 3.7,4.1.d was modified to allow not having auto start capability on the third normal service water pump and require 2 out of 2 auxiliary service water pumps to be OPERABLE. Not requiring the third normal service water

6 pump to have an auto start capability is considorod a clarification of the current Technical Specification and is nooded to protect the normal service water pumps from a low flow condition when the throo pumps are aligned to the same supply header. The probabilistic risk assossment that was performed for the original amendment only required that the pump be available for service.

Requiring 2 out of 2 auxiliary servico water pumps will provido for a completo backup system to be available and will ensure that a manually initiated backup system exists which can deliver design basis flows during an accident condition. In addition, the footnoto for this action statement was modified to include the service water valvo house.

Action statomont 3.7.4.1.0 is added to require that if both service water loops become inoperable, that both units must be placed in HOT SHUTDOWN within-the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and that actions be initiated to placo both units in COLD SHUTDOWN within the next hour and continue to COLD SHUTDOWN. With two service water loops inoperable, the units are not prepared to respond to the design basis events for which the service water system is required. The units must be placed in a modo in which the risk to the unit and to the environment is minimized. Depending on the actual stato of the service water system, the recirculation spray heat exchangers may not have a safety grado heat sink and the unit should bo placed in HOT SHUTDOWN, a condition whero decay had can be removed by the steam generators. Twelve hours is a reasonable time, based on operating experience, to place the unit in HOT SHUTDOWN from full power conditions without challenging safety systems or operators. This Action statement is consistent with MERITS.

The action to place both units in HOT SHUTDOWN and continue actions until both units are in COLD SHUTDOWN addresses the condition if the service water system is unavailable to perform its intended function. In this situation, the unit may remain in HOT SHUTDOWN until a method to further cool the units becomes available. The actions and time intervals are consistent with MERITS.

Surveillance Requirement 4.7.4.1.c(2) was modified to clarify that the automatic service water valves should be verified to be in the correct position on a actual or simulated containment high high signal.

Surveillance Requirement 4.7,4.1.d was added to specify surveillance testing for OPERABILITY determination of the service water pumps in accordance with Specification 4.0.5, the AMSE Section XI program.

Technical Soecification 3.7.4.2 This Technical Specification was added to support the UFSAR design bases for both units in Modes 5 or 6. When both units are in COLD SHUTDOWN or REFUELING the design basis requires that the service water system be OPERABLE. This is to ensure an adequate heat sink is maintained for the residual heat removal system. This new specification,3.7.4.2, is proposed to address this condition.

The requirements for Modos 5 and 6 differ from Specification 3.7.4.1 by I requiring that one service water loop be OPERABLE. Service water is required .

to provido a heat sink for the residual heat removal system to removo decay heat from the roactor coro. Flowever, there is a significant reduction in potential heat loading on the service water system. Therefore, only one service water loop is required to be OPERABLE. Tho compononts requirod for ono loop to bo OPERABLE are the same as defined in Specification 3.7.4.1 except that crodit for the OPERABLE auxiliary servico water pump may be taken to satisfy the OPERABILITY requiroment of the LCO. This allows romoving the service water reservoir from service for maintenance and utilizing the Lake Anna reservoir as the heat sink for core heat removal. Requiring that two service water pumps be OPERABLE allows for a singlo pump or power falluto while still providing the heat sink for the residual heat removal system. This is consistent with the residual heat removal system requiroments.

Action Statomont 3.7.4.2.a requires that if there is only one OPERABLE service water pump, at least one inoperablo service water pump must be rostored to  ;

OPERABLE status within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. This is consistent with the action requirements for a partial loss of residual heat removal capability during shutdown conditions. >

Action Statomont 3.7.4.2.b requires that if no service water pumps aro OPERABLE, all operations involving an increase in the reactor decay heat load or a reduction in boron concentration of the R6 actor Coolant System must be immediately suspended because a total loss of shutdown cooling may have occurred. This is consistent with the action requirements for a total loss of residual heat removal capability during shutdown conditions. ,

Survolllanco requirements to demonstrate the OPERABILITY of one service water loop are proposed.

Bases Sections 3/4.7.4.1 and 3/4.7.4.2 The existing bases section (3/4.7.4) was expanded to provido a more detailed description of the service water system. This bases section was also split to i provido a description for operating and shutdown conditions (3/4.7.4.1 and 3/4.7.4.2, respectively).

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