ML20042G700

Forwards Response to Generic Ltr 89-19, Request for Action Related to Resolution of USI A-47, 'Safety Implication of Control Sys in LWR Nuclear Power Plants.' Reactor Feedwater Pump Trip Sys for Water Overfill Protection Adequate

ML20042G700
Person / Time
Site:	Pilgrim
Issue date:	05/04/1990
From:	Gina Davis BOSTON EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-GTECI-A-47, REF-GTECI-SY, TASK-A-47, TASK-OR BECO-90-067, GL-89-19, NUDOCS 9005150308
Download: ML20042G700 (5)

Text

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O > Pilgrim Nuclear Power Station ,

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1 Plymouth, Massachusetts 02360 y

Q o. wee w. Devns BECo 90-067 E$.'r*Otreten May 4, 1990 U.S. Nuclear Regulatory C:mmist'.on Document Control: Desk Hashington, DC'~20555 License DPR-35 Docket 50-293 BOSTON EDISON COMPANY RESPONSE TO GENERIC LETTER 89-19,

" REQUEST FOR ACTION RELATED TO RESOLUTION OF UNRESOLVED SAFETY ISSUE A-47, SAFETY' IMPLICATION 9F CONTROL SYSTEMS IN LHR NUCLEAR POWER PLANTS"

Reference:

1. NRC l.etter to Boston Edison Company, dated February-1, 1978.

2. .BECo letter to NRC,' dated February 27, 1978 3.' NRC letter-to BEco, dated November 28, 1978 Generic Letter 89-19 requested Boston Edison Company (BECo) to provide information regarding our reactor water overfill protection capabilities under

~the provisions of 10CFR50.54(f) within 180-days of receipt of the letter. BEco received the subject letter on October 11, 1989. The requested response date was extended to May 4, 1990.by the NRC through the BHR Owners Group.

GL 89-19: requires the response to address whether BECo will implement the NRC proposed requirements related to reactor water overfill protection and propose a-schedule for the completion of the modification, or to provide appropriate justifications for not implementing the proposed requirements. The NRC's

, proposed requirements include hardware and operating procedure modifications, Loperator training and techni:al specification changes.

BECo has' assessed the Pilgrim Nuclear Power Statior. (PNPS) reactor water overfill protection features in itght of NRC proposed requirements and the NRC's regulatory analysis for proposed resolution of USI A-47 (NUREG-1218);

BEco has concluded the existing Reactor Feedwater Pump Trip System for reactor water overfill protection is adequate and meets the intent of the NRC's proposed requirements. This conclusion is based upon the following:

1. In response to the NRC's directive (Reference 1), BECo installed an automaib. Reactor Feedwater Pump (RFP) Trip system (Reference 2) as a part 'of -the feedwater control system for automatic reactor overfill protection. This RFP trip system was reviewed by the NRC in Reference 3.

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POSTON EDISON. COMPANY ,

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-V. S. Nuclear _ Regulatory Commission Page Two l 2 .~ PNPS.has implemented the BWR Owr.ic's Group symptom-based emergency ,

operating procedures 'EOPs) for controlling the reactor water level duri.ig off-normal events. .These procedures provide guidance to the plant operator H

for. corrective actions to be taken in high reactor water level events. The '

l operator training program includes classroom and simulator training on the  :

plant E0Ps. ..

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3. There are no existing surveillar r test requirements related to RFP trie 4 system in the PNPS Technical Specifications. However, we do perform a l channel calibration and functional test every six months, which includes '

testing of the circuit.and~all related relays up to but not including the  ;

relay contacts that trip the RFP breakers. He will modify our test  !

procedures to include testing of the untested relay contacts and breaker j trip mechanism by Refueling Outage #8. l e  ;

The attachment describes our assessment in detail. '

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Commonwealth of Massachusetts) i County of Plymouth )

Then perscnally appeared before me, Geoge H. Davis, who being duly sworn, did state that he is Vice President.- Nuclear Administration ol' Boston Edison Company and that he is duly authorized to execute and file the submittal contained herein in the name and on behalf of Boston Edison Company and that the statements in said submittal are true to the best of his knowledge and belief.

My' commission expires:

3 .

DATE I NOTARY PUBLIC cc: Mr.-R. Eaton, Project Manager

, Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Hall Stop: -1401 U. S. Nuclear Regulatory Commission <

1 White Flint North 11553 Rockville Pike Rockville, MD 02852 U. S. Nuclear Regulatory Commiss1on 4 Region I 475 Allendale Road King of Prussia, PA 19406 Senior NRC Resident Inspector Pilgrim Nuclear Power Station 1

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. ATTACHMENT j Reactor Overf111' Protection

Generic Letter 89-13 1:

' A. BACKGROUHQ The NRC staff-has concluded all BHR plants should provide automatic  ;

reactor vessel overfill protection to mitigate main feedwater overfeed {

everts during reactor power operation._ The system design and setpoints _;

'should be selected with the objective of minimizing inndvertent trips of

'." the main feedwater system during plant startup, normal operation,'.and  :

protection system surveillance. In addition. the staff recommends.all '

BWR licensee's reassess and modify, if needed, their operating  ?

procedures and operator training to assure operators can mitigate I reactor vessel overfill' events that may occur via the condensate booster pumps during reduced system pressure' operation.

B. PNPS REACTOR OVERFILL PROTECTION ASSESSMENT

1. Desian Batis

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I In response to NRC directives (see letter dated February 1, 1978)- .

and SIL No. 218 (dated March 31, 1977), BECo installed an automatic i Reactor Feedwater Pump (RFP) Trip system as a part of the feedwater control system for automatic reactor overfill protection. The RFP trip system is commercial grade and requires 2-out-of-2 reactor vessel high water level signals to initiate a feedwater pump trip.-

The overfill protection may be cancelled by the operator via'a '

reactor feed pump trip cutout switch on panel C905.

The overfill protective system signals originate at the feedwater control system's reactor Water level transmitters-which provide signals to the associated level switches. These switches are part -

.of the feedwater Control Circuitry. These switches are set to trip at +60 inches, 12 inches higher than the main turbine high water level. trip.

The Feedwater Control Circuitry, including the RFP. automatic trip system, could be disabled on loss of power, ventilation, or fire in the reactor water level feedwater control circuitry. This is i acceptable because the overfill protection system is provided as a-secondary method of overfill protection. Operator act,on is the primary method of overfill protection (see below). Therefore, a  !

failure due to loss of power, ventilation or fire in the Feedwater Control Circuitry has no safety consequence and will not prevent maintaining proper reactor water level. The existing PNPS RFP Trip design meets the intent of the NRC proposed requirements identified in Generic Letter 89-19. Therefore, as discussed in NUREG 1218, modifying the existing RFP trip system is not justified. -

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' ' N, '2.. Operator Actiont- )

C' In the' event reactor pressure vessel (RPV). water level exceeds normal operating. levels of +48 inches (normal operating RPV water  :

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7 level is between 27 and 30 inches), station procedures require the 0" , . control; room operator.to manually control the RPV fill' systems.and' 4 , manually trip the; reactor feed pumps if necessary. :To serve as a' uw ' backup toz such operator actions, the. reactor feed pump (RFP) auto jm ' trip system will trip the RFPs on the RPV Hater Level High (+60:  ;

inches) signal. These procedures are listed below with a brief Q -[

explanation of required control room operater actions, a EOP - 1 RPV Control The Emergency Operating Procedure directs the orarator to use1

. Group A injection systems to maintain RPV water tevel between

+9 inches and +48 inches. The condensate /feedwater system is a-Group A injection. system. Thus, this procedure does not allow (

the operator to exceed +48-inches of RPV water level..

b. 2.1.5. Controlled Shutdown from Power i

This procedure instructs the operator to remove one RFP from service at 60% reactor power and remove second RFP from service at 30% reactor power, in the case of: 1) a-controlled shutdown-with manual ~ SCRAM, 2) a controlled shutdown without a manual SCRAM, or.3) a controlled shutdown with one recirculation pump .t out of service. The operators are in control of and aware of the RPV water level throughout this procedure.

c. L1.6. Reactor SCMM In this procedure, following a SCRAM,.the operator is .

Instructed to ensure rer.irculation pumps are at minimum speed, q the main turbine is tripped, and to control-the RPV water level L between 49 inches and +48 inches by:

• Reducing the number of operating RFP and condensate pumps to l one each, and

• if water level is' increasing rapidly, secure tne RFP.  ;

The control room operators are trained to maintain the RPV wate, level between +9 inches and +48 inches during any unusual water level occurrences. The procedures listed above support the fact that the RFPs  !

are operator controlled in a systematic and reitable manner. This makes j the automatic actuation of the RFP auto trip system highly unlikely.

D. TECHNICAL SPECIFICATIONS REOUIREMENTS The PNPS Technical Specifications do not include surveillance test requirements specificelly related to the RFP trip syster. However, a calibration and functional test of the RFP trip system circuitry is performed under existing station procedures in conjunction with TS

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7'< surveillance testing performedLon other' reactor water level- l c sc ' instruments. The PNPS Master Surve111 ante Tracking System requires this. i fi ' testing be performed every six months. The procedure. tests the circuits 1 and all relays up to but not it.cluding-the relay contacts that trip the l RFP breaker-and the breaker trip function. BECo will modify our test '

procedures to include testing.of the presently Untested components by RF0 #8, l In addition..we have an ongoing program to improve our Technical )

Specifications. Once the improved BNR. Standard Technical. Specifications l (STS) have been approved by the NRC, we will evaluate the specific STS  !

requirements related to this system and include those that are-applicable to PHPS.

E. OPERATOR TRAINING-PNPS operatorsL are trained on the RFP Trip System, associated emergency  !;

operating procedures and receive simulator. training on the plant E0Ps.

No additional training on RFP system is considered necessary.

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