ML20149M728

Proposed Tech Specs 3.5/4.5.C of TS Bases Describing Min RHR & RHRSW Pump Requirements for Post Accident Containment Heat Removal & Submit Update to Design Basis Accident Containment Temp & Pressure Response

ML20149M728
Person / Time
Site:	Monticello
Issue date:	01/23/1997
From:	NORTHERN STATES POWER CO.
To:
Shared Package
ML20149M719	List: ML20149M717 ML20149M722 ML20149M728 ML20149M736
References
NUDOCS 9701270125
Download: ML20149M728 (5)

Text

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3 Exhibit B Monticello Nuclear Generating Plant License Amendment Reauest Dated January 23,1997 Technical Specification Pages Marked Up With Proposed Working Changes Exhibit B consists of the existing Technical Specification pages marked up with the proposed changes. Existing pages affected by this change are listed below:

Paaes j 112 l 113 l

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J B-1

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9701270125 970123 PDR ADOCK 05000263 P PDR l- . _ _- _ -.

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Bases 3.5/4.5 Continued:

automatically controls three selected safety-relief valves although the safety analysis only takes credit for two valves. It '- *'- 7 days  ;

without materially t

B. RilR Interti' Two containment spray / cooling subsystems of the RHR system are provided to remove heat i I energy from the containment and control torus and drywell pressure in the event of a loss of An intertie 1 l c olant accident. A containment spray / cooling subsystem consists of 2 RHR service water j pumps, a RHR heat exchanger, 2 RHR pumps, and valves and piping necessary fcr Torus Cooling '

four-inch lin and Drywell Spray. Torus Spray is not considered part of a containment spray / cooling al r I

for water ham subsystem. Placing a containment spray / cooling subsystem into operation following a loss of i

recirculatior coolant accident is a manual operation.

he L RilR injection The most degraded condition for long term containment heat removal following the design allow the ope basis loss of coolant accident results from the loss of one diesel generator. Under these ,

receive a cle conditions, only one RHR pump and one RHR service water pump in the redundant division can .

be used for containment spray / cooling. The containment temperature and pressare have been there is a p analyzed under these conditions assuming service water and initial suppression pool  !

accident. S temperature are both 90"F. Acceptable margins to containment design coaditions have been demonstrated and the containment long term pressure is limited to less than 5 psig.

isolation val I Therefore the containment spray / cooling system is more than ample to provide the required ' ole t valve is close- heat removal capability. Refer to USAR Sections 5.2.3.3, 6.2.3.2.3, and 8.4.1.3. .alR  :

intertie line i small change in jet pu ,

j C. Containment Spray / Cooling Systems Re. ace Two containment spray /cco ig subsystems of the RilR system are vided to remove heat energy from the containment and control toru and drywell pressure in the eve of a loss of coolant accident. A ,

containment spray / cooling subs tem consists of 2 RilR Serv e Water Pumps, a lleat Exchanger, 2 RllR Pumps, j and valves and piping necessary i Torus Cooling and D well Spray. Torus Spray is not considered part of a containment spray / cooling subsyste For the flow pecified, the containment long term pressure is  ;

1imited to less than 5 psig and, there re, is mo than ample to provide the required heat removal [

capability. Reference Section 6.2.3.2.3 USAR.  !

Either subsystem is capable of performing e containment spray / cooling function. Loss of one RilR service water pump does not seriously jeopardize he co ainment spray / cooling capability as two of the remaining i three pumps can satisfy the cooling r uirements. Since there is some redundancy left, a 30 day repair period is adequate. Loss of I cont nment spray /co ing subsystem leaves one remaining system to perform  ;

the containment spray / cooling fut -ion. <

3.5/4.5 Bases 112 REV i

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Bases 3.5/4.5 Continued:

The RilR service water system provides c- 1- or the RilR heat exchangers and can thus maintain the suppression pool water within limits. Vi t low specified, the pool temperature limits are maintained as specified in Specification 3.7.A.

D. RCIC The RCIC system is provided to supply continuous makeup water to the reactor core when the reactor isolated from the turbine and when the feedwater system is not available. The pumping capacity of the RCIC system is sufficient to m- -'-- Tr the water level in rts.

The system me The llPCI s' During normal plant operation, the containment spray / cooling system provides cooling of the 1 feedwater suppression 3 7 A 1-pool water to maintain temperature within the limits specified in Specification system sho, The system surveillance requirements will be operable provide adequate assurance that the containment spray / cooling when required.

The survel The head and flow requirements specified for the RHR service water pumps provide assurance that the minimum required service water flow can be re9utred. supplied to the RHR heat exchangera. sgg 1 a test loop i ..smme r damage and -

E. Cold Shutd, The purpose of Specification J.a.c. in w ammum enac sutticient core cooling equipment is availablo at all times. It is during refueling outages that major maintenance is performed and during such time that all core and contal:unent spray / cooling subsystems may be out of service. This specification allows all core and containment spray / cooling subsystems to be inoperable provided no work is being done which has the potential for draining the reactor vessel. Thus events requiring core cooling are precluded.

Specification 3.5.E.2 recognizes that concurrent with control rod drive maintenance during the refueling outage, it may by necessary to drain the suppression chamber for maintenance or for the inspection required by Specification 4.7.A.I. In this situation, a sufficient inventory of water is maintained to assure adequate core cooling in the unlikely event of loss of control rod drive housing or instrument thimble seal integrity.

3.5/4.5 Bases 113 Rev

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t Bases 3.5/4.5 Continued:

automatically controls three selected safety-relief valves although the safety analysis only takes credit for two valves. It is therefore appropriate to permit one valve to be out-of-service for up to 7 days without materially reducing system reliability.

B. RHR Intertie Line An intertie line is provided to connect the RHR suction line with the two RHR loop return lines. This four-inch line is equipped with three isolation valves. The purpose of this line is to reduce the potential for water hammer in the recirculation and RHR system when required to cooldown with an

. isolated or idle recirculation system. The isolation valves are opened during a cooldown to ensure a f

uniform cooldown of the RHR injection piping. If one recirculation loop is isolated or idle, these valves and associated piping allow the operating loop to cool the isolated or idle loop. The RHR loop return line isolation valves receive a closure signal on LPCI initiation. In the event of an inoperable return line isolation valve, there is a potential for some of the LPCI flow to be diverted to the broken loop during a loss of coolant accident. Surveillance requirements have been established to periodically cycle the RHR intertie line isolation valves. In the event of an inoperable RHR loop return line isolation valve, either the inoperable valve is closed or the other two isolation valves are closed to prevent diversion of LPCI flow. The RHR intertie line flow is not permitted in the Run ,

Mode to eliminate 1) the need to compensate for the small change in jet pump drive flow or 2) a reduction in core flow during a loss of coolant accident.

C. Containment Spray / Cooling Systems ,

Two containment spray / cooling subsystems of the RHR system are provided to remove heat energy from the containment and control torus and drywell pressure in the event of a loss of coolant accident. A

• containment spray / cooling subsystem consists of 2 RHR service water pumps, a RHR heat exchanger, 2 RHR pumps, and valves and piping necessary for Torus Cooling and Drywell Spray. Torus Spray is not <

considered part of a containment spray / cooling subsystem. Placing a containment spray / cooling i subsystem into operation following a loss of coolant accident is a manual operation.

The most degraded condition for long term containment heat removal following the design basis loss of i coolant accident results from the loss of one diesel generator. Under these conditions, only one RHR ,

pump end one RHR service water pump in the redundant division can be used for containment i spray / cooling. The containment temperature and pressure have been analyzed under these conditions assuming service water and initial suppression pool temperature are both 90 F. Acceptable margins to containment design conditions have been demonstrated and the containment long term pressure is limited to less than 5 psig. Therefore the containment spray / cooling system is more than ample to provide the required heat removal capability. Refer to USAR Sections 5.2.3.3, 6.2.3.2.3, and 8.4.1.3. t 3.5/4.5 112 REV t

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Bases 3.5/4.5 Continued:

During normal plant operation, the containment spray / cooling system provides cooling of the suppression pool water to maintain temperature within the limits specified in Specification 3.7.A.1.

The surveillance requirements provide adequate assurance that the containment spray / cooling system  ;

will be operable when required. The head and flow requirements specified for the RHR service water  !

pumps provide assurance that the minimum required service water flow can be supplied to the RHR heat i exchangers.

D. RCIC  !

The RCIC system is provided to supply continuous makeup water to the reactor core when the reactor '

isolated from the turbine and when the feedwater system is not available. The pumping capacity of the RCIC system is sufficient to maintain the water level above the core without any other water system in operation. If the water level in the reactor vessel decreases to the RCIC initiation level, the system automatically starts. The system may also be manually initiated at any time.

The HPCI system provides an alternate method of supplying makeup water to the reactor should the normal feedwater become unavailable. Therefore, the specification calls for an operability check of the HPCI system should the RCIC system be found to be inoperable.

The surveillance requirements provide adequate assurance that the RCIC system will be operable when ,

required. All active components are testable and full flow can be denonstrated by recirculation ,

through a test loop during reactor operation. The pump discharge piping is maintained full to prevent  !

water hammer damage and to provide cooling at the earliest moment.

E. Cold Shutdown and Refueling Requirements l The purpose of Specification 3.5.E is to assure that sufficient core cooling equipment is available at all times. It is during refueling outages that major maintenance is performed and during such time that all core and containment spray / cooling subsystems may be out of service. This specification allows all core and containment spray / cooling subsystems to be inoperable provided no work is being  ;

done which has the potential for draining the reactor vessel. Thus events requiring core cooling are precluded.

i Specification 3.5.E.2 recognizes that concurrent with control rod drive maintenance during the i refueling outage, it may by necessary to drain the suppression chamber for maintenance or for the inspection required by Specification 4.7.A.1. In this situation, a sufficient inventory of water is maintained to ascure adequate core cooling in the unlikely event of loss of control rod drive housing or instrument thimble seal integrity.

3.5/4.5 113 REV i l

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