ML19210D033

Forwards Response to 791011 Ltr Re NRC Requirements for Auxiliary Feedwater Sys.Refueling Shutdown Will Commence on 791201.Some Testing Recommendations Will Not Be Scheduled Until Startup Testing Performed

ML19210D033
Person / Time
Site:	Beaver Valley
Issue date:	11/15/1979
From:	Dunn C DUQUESNE LIGHT CO.
To:	Eisenhut D Office of Nuclear Reactor Regulation
References
TAC-12520, TAC-44632, NUDOCS 7911200444
Download: ML19210D033 (4)

Text

'Af (412) 456-6000 ttSDurgh Pa Noverber 15, 1979 Darrel G. Eisenhut, Acting Director Division of Operating Reactors Office of Nuclear Reactor Regulatior United States Nuclear Regulatory Commission Washington, D. C. 20555

Reference:

Beaver Valley Power. Station, Unit No. 1 Docket No. 50-334 NRC Letter Dated October 11, 1979 - Requirements For Auxiliary Feedwater Systems

Dear Mr. Eisenhut:

The following response is submitted in reply to NRC Requirements For Auxiliary Feedwater Systems at Beaver Valley Power Station, KRC letter dated October 11, 1979.

At the present time, Beaver Valley Power Station is scheduled to commence its Refueling Shutdown on or about December 1, 1979. Therefore, some of the testing recommendations will not be scheduled until the station performs its startup testing.

As required by your letter, short term recommendations for procedure development will be completed prior to returning the station to power operation.

Specific replies to recommendations are included as an enclosure to this letter.

Should you have any questions or require additional information, please contact this office.

Very truly yours, N/ h C. N. Dunn Vice President, Operations Attachment g

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• DUQUESNE LIGHT COMPANY Beaver Valley Power Station Unit No. 1 REPLY TO NRC LETTER DATED OCTOBER 11, 1979

1. Response To Recommendation GS-3 This recommendation states that "the Licensee should re-examine the practice of throttling the Auxiliary Feedwater (AFW) System flow to avoid water hammer".

It should be noted that this practice is a result of a condition imposed by the Nuclear Regulatory Commission in the Beaver Valley Power Station (BVPS) Unit No. 1 Operating License and not because of any water hammer phenomena experienced during operation. This condition states in part "...whenever the secondary side water level in a steam generator is belou the level of the feedwater sparger, limit the secondary side water level rise rate in each steam generator to less than 1.2 inches per minute and shall reduce the rise rate to within this limit within two (2) minutes." This condition also states that it shall be removed "when Duquesne Light Company demonstrates to the satisfaction of the Commission that secondary side flew instability (water hammer) does not result in unacceptable consequences." An AFW System Transient Test Procedure was prepared to provide this demonstration but was postponed just prior to the test performance at the request of the Commission and was later cancelled. Since BVPS Unit No. I has the "J" tube modification to the Steam Generators feedwater ring and a loop seal at the feedwater inlet to the steam generators, it is felt that no AFW flow instabilities should be experienced. In addition, AFW Flow Transient Tests were performed at Trojan Nuclear Power Station, where the "J" tube modification to the steam generators were also installed, and satisfactorily demonstrated the lack of any feedwater flow instability. Therefore, it is requested that this condition be deleted from the Operating License.

The adequacy of the AFW System to supply on demand sufficient intial flow to the steam generators to assure adequate decay heat removal following a loss of main feedwater flow and reactor trip from 100% power with respect to AFW flow limitations was questioned. Since this limitation has been imposed as a condition of the Operating License, it is assumed the adequacy of these flow limitations concerning required core decay heat removal have already been addressed. The required minimum flow to the steam generators assumed in the BVPS FSAR, in the event of a station blackout or feedwater line break, is 350 gpm. BVPS procedures limit the flow to each steam generator at 150 gpm when the water level in the steam generator has decreased below 10% Narrow Range Level indication (Feedwater Ring sparger) and is increasing until the level is above 25% narrow range level indication.

2. Response To Recommendation GS-4 Response procedures will be developed to inform the operator when and in what order the transfer to alternate water sources should take place. These procedures will cover cases when the Primary Water Storage Tank (PWST) is not available and cases when the PWST water supply is being depleted. Procedures will be developed prior to return to power operation.

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Beaver Valley Power Station, Unit No. 1 Reply To NRC Letter Dated October 11, 1979 Page 2

3. Response To Recommendation GS-6 Procedures will be modified to require an additional operator to verify the AFW System valves are properly aligned. Procedures will be modified prior to returning the station to power operation.

Technical Specifications will be proposed to assure that prior to plant startup following an extended cold shutdown, a flow test will be performed to verify the normal flow path from the PWST to the steam generators. The Technical Specification will be submitted to the NRC prior to return to power operation.

4 Response To Recommendation GS-7 The licensee has verified that the automatic start AFW signals and asso-ciated circuitry are safety grade. The AFW system is initiated automatically by safety injection signal, loss of offsite power, and on low low steam generator level. These actuation signals are testable and these signals are the system actuations on which the FSAR Chapter 14 accident analysis is based.

The AFW system is also automatically initiated on loss of the main feedwater pumps in anticipation of low steam generator level. This anticipatory actu-ation is not testable during normal operation. All initiation signals and circuits are designed to prevent a single failure from causing a loss of the AFW system.

5.' The normally closed manually operated suction valves from the river water system will be periodically tested and their position verified. These pro-cedures will be approved prior to returning the station to power operation.

In addition, the licensee will propose Technical Specifications for NRC review prior to returning the station to power operation.

6. The locking of the AFW manual valves in their correct position as mandated by the administrative procedures for the staggered testing of the AFW system pumps has been implemented.

7. The licensee will review the present alignment of the AFW system discharge block valves for the normal, transient and accident conditions and modify as necessary prior to returning the station to power operation.

Additional Short-Term Recommendations

1. The present system at Beaver Valley Power Station has a redundant low level alarm to alert the operator of a condition when the PWST level is approaching the Technical Specification minimum. This allows the operator sufficient time to maintain the level above the minimum required. In addition, a design change requesting an additional low low level alarm will be submitted by December 1,1979

2. The 72-hour endurance test run will be performed upon completion of a design change to the AFW system which is currently scheduled for comple-tion during this refueling shutdown.

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Beaver Valley Power Station, Unit No. 1 Reply To NRC Letter Dated October 11, 1979 Page 3 Additional Short Term Recommendations (continued)

3. The AFW system was installed and designed to the 1970 standard which, at the time, was the highest grade available and is powered from the station vital bus which in turn is powered from the emergency diesel or the station battery.

4 Technical Specifications will be submitted to the NRC prior to the station returning to power operation to allow surveillance testing without realigning the manual valves.

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