ML20116B558

Proposed Tech Specs Re Auxiliary Feedwater Pump Relay Response Time Testing

ML20116B558
Person / Time
Site:	North Anna
Issue date:	10/26/1992
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML20116B548	List: ML20116B544 ML20116B558
References
NUDOCS 9211020264
Download: ML20116B558 (7)

Text

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4 ATTACHMENT 3 PROPOSED TECHNICAL SPECIFICATION CHANGE UNIT 1 PhR bA 921026 P fffCK05000339 PDR

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TABLE 3.3-5 (Continued)

ENGINEERED SAEETY FEATURES RESPONSE TIMES INITIATING SIGNAL AND FUNCTION RESPONSE TIME IN SECONDS

6. Steam Flow in Two steam Unes-Hiah Coincident with Steam I he Pressure-Low

a. Safety injection (ECCS) s 13.0#/23.0##

b. Reactor Trip (from SI) s 3.0

c. Foodwater Isolation s 8.0 ~

d. Contal.iment isolation Pimse 'A' s 18.0#/28,0##

e. Auxilhry * 'evwater Pumps s 60.0

f. Essential Service Water System Not Applicable

g. Steam Line isolation s 8.0

7. COD'.ainment Pressure--Hiah-High

a. Containment Quench Spray s 60.0

b. Containment isolation-Phase "B' s 60.0

8. Containment Pronuto-intermediate Hiah-Hiah

a. Steam Line Isolation s 7.0

9. Steam Generator Water Level Low-Low

a. Auxiliary Feedwater Pumps s 60.0

10. Station Blackout

a. Auxiliary Feedwater Pumps s 60.0

11. Main Feedwater Pumn Trio

a. Auxiliary Feedwater Pumps s 60.0####

12. Sleam Generator Water Level--Hiah-Hiah

a. Turbine Trip Reactor Trip s 2.5 -

b. FeedwaterIsolation s 11.0 NORTH ANNA- UNIT 1 3/4 3-29 Amendment No.

TABLE.1;l*Eontined)

IABLE NOTATION Diesel generator starting and sequence load ng delays included. Response time lirnh includes opening of valves to establish Si path and attainrr.ent of discharge pressure for centrifugal charging pumps, and Low Head Safety injection pumps. y

1. Diesel generator starting and sequence loading delays not included. O'lsite power available.

Response timo limit incluoes opening of valves to establish Si path and attainment cf discharge pressure for contrif ugal charging pumps.

1. 1. Diesel generator starting and sequence loading delays included. Response time limit includes opening of valvts te establish Si path and attainment of discharge pressure for centrifugal charging pumps. -

1. 1. 1. The response times shown are based on the time from when the signal reachen the trip setting until the diesel generator is supplying the emergency bus.

1. 1. 1. 1. Rospunse time testing of the two relays in the auxiliary foodwater pump star' circuii (Relays 3-CKT 1FWSA05 and 3-CKT $ FWSB05) due 1:i a main foodwater pemp trip is suspended for the duration of Cycle 9.

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h NORTH ANNA - UNIT 1 3/4 3-30 Amendment No.

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ATTACHMENT 4 10 CFR 50.92 EVALUATION i

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1 SlGNIFICANT HAEARDS CONSip_EBATION EVALUATION Technical Specification surveillance requument 4.3.2.1.3, Table 3.3 5, item 11 requires Engineered Safety Feature (ESb response time testing of the auxiliary feedwater (AFW) pump circuit as a result of a main teedwater pump trip. The test is required at least once per 18 months. On October 91,1992 at 1245 hours0.0144 days <br />0.346 hours <br />0.00206 weeks <br />4.737225e-4 months <br /> it was determined that this requir ment had no, been met fo; North Anna Unit 1. (North Anna Unit 2 is in full compliance with the surveillance requirement.) The requirements of Technicci Specification 4.0.3 were immediately invoked which permit conducting the required surveillance test within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> folicwing discovery of the -missed surveillance.

The need for the Tschnical Specification change was identified durir g our programmatic revi^w of Technical Specification surveillance requirements as described in a letter to the NRC dated September 8,1992 (Serial No,92-482). Wnile preparing a test procedure to conduct the required surveillance, it v$ sishtmined that the actuation of two relays in the AFW pump start circuit (Relays 3a.r-1FWSA05 and 3 CKT-1FWSB05) due to a main feedwater pump trip would caug a turbine tr@

Lifting a lead to prevent relay actuation is possible, however, an error or an arc on the contacts could cause the relays tc actuate and cause a turbine trip / reactor trip.

On October 22,1992, we requested a temporary waiver of compliance from Technical Specification curveillance requirement 4 3.E1.3, Table 3.3 5, item 11 which requires Engineered Safety Feature (ESF) response time testing of the auxiliary feedwater (AFW) pump circuit as a result of a main feedwater pump trip. This was documented in a letter to the NRC dated October 22,1992 (Serial No. 92 687). The NRC verbally approved our waiver request on October 22,1992, and requested that we propose an emergency Technical Specification change by October 26,1992, to appropriately modify the Technical Specification surveillance requirement 4.3.2.1.3, Table 3.3 5, item 11.

This surveillance test is usually performed while the unit is in a shutdown condition.

Unit 1 is currently in coastdown operation at approximately 70% power and near the end of its cycle, prior to its 1993 Steam Generator Replacement Outage which is scheduled to begin January 2,1993. The Initiation of the outage prior to the scheduled date would result in inadequate resources being available to suoport the 1 outage, an unproductive period at the beginning of the obtage and substantial replacement power costs.

To better understand the basis for the Technical Specification change, a description of the .iffected ESF features is necessary. There are four events that automatically start the AFW pumps. These are: 1) safety injection, 2) steam generator low-low water -

level, 3) loss of offsite power, and 4) main feedwater pump trip. Response time testing is required to provide assurance that the protective and ESF actuation functions are completed within the time limits assumed in the accident ankyses. However, the main feedwater pump trip signal is anticipatory and no credit is taken in any safety analysis for that event. Technical Specification 4.3.2.1.3, Table 3.3-5, item 11 requires the initiation of the AFW pumps within 60 seconds of a main feedwater pump trip.

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4 The basis for suspending the response time test requirement for the two relays in the AFW pump start circuit for the remainder of the operating cycle involves several factors. First, the relays have' repeatedly been demonstrated to perform as expected during periodic functional testing as required by the Technical Specifications. (The only aspect not specifically addressed during the functional test has been the relay response time. The functionality of the system has been repeatedly demonstrated.)

Second, no credit is taken in the safety analysis for an AFW pump start on a main feedwater pump trip. Third, the affected relays are HFA relays, which are used throughout the plant. Responsa time testing of.those relays in other installed configmtions has censistently demonstrated a response time, typically much less than 0.1 seconw. 91 w!!hin that assumed in the response time acceptance criterion that forms the basis for the Technical Specification requirement. In addition,in August 1991, a safety injection occurred on Unit 1. The sequence of events recorder during that event documented that the required relay function occurred well within the Technical Specification requirement. Similar information is documented for an August 1992 safety injection on North Anna Unit 2. Although the sequence of events recorder only documented the first of the wo relays to actuate, it clearly showed that one relay functioned as expected and had a response time well within that required. Finally, the type of relays for which a Technical Specification change is being sought are reliable and generalry known to have acceptable response times.

Although the Technical Specification change does not pose a significant safety impact, several compensatory measures have been identified that will provide additior;al assurance of safe operation during the interval until the unit completes its current operating cycle. Therefore, for the remainder of the current Unit 1 operating cycle, the following compensatory measures will be in place:

1) The standby main feodwater pump will not be removed from service for-pre-planned maintenance. This will ensure that one standby main feedwater pump will be available to auto-start in the event of a loss of the other main feedwater pumps.

2) The Emergency Operating Procedures (EOPs) currently require the manual start of the AFW pumps in the event that all normal feedwater flow is lost. This requirement will be reviewad with operations personnel.

3) Operations will review the materiel condition of the main feedwater p' umps during each operating shift.

The Technical Specification change for excluding response time testing of the relays in the auxiliary feedwater (AFW) pumps start circuit due to a main feedwater pump trip, as required by Technical Specification surveillance requirement 4.3.2.1.3, Table 3.3-5, item 11, has been evaluated against the criteria in 10 CFR 50.92. Based on that-evaluation, we have determined that no significant hazards consideren exists. A summary of our evaluation is prcvided below.

1. The Technical Specificatio" dunge does not involve a significant'increa'sc in the probability or consequc% 4 an accident previously evaluated. No. credit is taken for the AFW pump u in the event of a main feedwater pump trip in the accident analysis. The typa af relay in question is used throughout the plant and

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z response time testing of HFA type relays _in other applications has consistently: a been well witnin specifications. Therefore, not response time testing the two relays-  ;

in the AFW pump _ start circuit during the interval until the unit shuts down _-roughly-  :

73 days- does not significantly affect the performance of the AFW system. Lastly, the survaillance test is normally conducted when the unit is shut down,_ Performing the surveillance during power operation has the potential for creating an cadesired transient or plant trip.

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2. The Technical Specification change does not create the possibility _of a new or different kind of accident from any accident previously evaluated. Since the change in the surveillancelequirement will require no nardware modification (i.e...

alterations to the plant _ configuration), ' operation of the facility _without those surveillance requirements does not create the possibility for any new or different kind of accident which has not already been evaluated in the Updated Final Safety Analysis Report (UFSAR).

Suspending the requirement for response time testing of the two relays will;not 'i result in any physical alteration to any plant system and there will not be a change in the method by which any safety related system performs its function. The design.

and operation of the AFW system, tn include an automatic pump start due to a main :

feedwater pump trip, remains unchanged. The type of relays for which a Technical' Specification change is_ being sought are reliable and generally known to have-acceptable response times.

3. The Technical Specification change does not involve a significantireduction in the margin of-safety. The design and operation of tho AFW system-is not being changed. The type of relays for which a Technical Specification change is-balng sought are reliable and geners!Iy known.to have acceptable response times.

-When compared to the entire circuit response time, the response time of the relays -

is insignificant. Further, the. margin of safety will not be reduced because the accident anclysis assumptions will continue to be met, i.e., the AFW pumps will start within the required response time initiated by a steam generator low low level:

. signal.

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