ML18029A693

Forwards Addl Info in Response to Request Re NUREG-0737,Item II.K.3.28, Automatic Depressurization Sys Accumulator Qualification

ML18029A693
Person / Time
Site:	Browns Ferry
Issue date:	07/11/1985
From:	Domer J TENNESSEE VALLEY AUTHORITY
To:	Vassallo D Office of Nuclear Reactor Regulation
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.K.3.28, TASK-TM NUDOCS 8507180159
Download: ML18029A693 (10)

Text

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:8507180159 CeDATE: 85/07/11 NOTARIZ

YES, DOCKET FACIL:50-259 Browns" Ferry Nuclear Power Stations Unit ir Tennessee 05000259 50-260 Browns Ferry Nuclear Power Stations Unit 2i Tennessee 05000260 50"296 Browns Ferry Nuclear Power Stationi Unit 3~

Tennessee 05000296'UTH BYNAME AUTHOR AFFILIATION DOMEReJ ~ AD Tennessee Valley Authority RECIP ~ NAME RECIPIENT AFFILIATION VASSALLOiD ~ BE Operating Reactors Branch 2

SUBJECT:

Forwards addi info in response to request re, NUREG~0737i Item II' ',28'Automatic Depressurization Sys Accumulator Qualification."

DISTRIBUTION CODE:

A046D COPIES RECEIVED:LTR

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TITLE':

OR Submittal: TMI'ction Plan Rgmt NUREG-0737 8

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TENNESSEE VALLEYAUTHORlTY CHATTANOOGA. TENNESSEE 87401 400 Chestnut Street Tower II July ll, 1985 Director of Nuclear Reactor Regulation Attention:

Mr. Domenic B. Vassallo, Chief Operating Reactor Branch No.

2 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C.

20555

Dear Mr. Vassallo:

In the Matter of the Tennessee Valley Authority Docket Nos. 50-259 50-260 50-296 Enclosed is additional information regarding NUREG-0737, Item II.K.3.28, Automatic Depressurization System Accumulator Qual].fication, for the Browns Ferry Nuclear Plant.

This is in response to an informal request for additional information from your staff.

This information was provided informally to 'your staff previously.

If you have any questions, please get in touch with us through the Browns Ferry Project Manager.

Very truly yours, TENNESSEE VALLEY AUTHORITY J.

A. Domer, Chief Nuclear Licensing Branch Sworn t gpss subscribe be re me

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Notary Public My Commission Expires Enclosure cc:

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Director of Nuclear Reactor Regulation July 11, 1985 cc (Enclosure):

U.S. Nuclear Regulatory Commission Region II Attn:

Dr. J. Nelson Grace, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. R. J. Clark Project Manager Browns Ferry Nuclear Plant U.S. Nuclear Regulatory Commission 7920 Norfolk Avenue

Bethesda, Maryland 20814

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0 ENCLOSURE

RESPONSE

TO INFORMAL NRC-REQUEST FOR ADDITIONAL INFOR1fATION NUREG 0737 ITEM II.K.3.28 BROWNS FERRY NUCLEAR PLANT Question Clarify what portions of the existing and proposed ADS accumulator drywell air supply are seismically qualified.

~Res ense The system for supplying pneumatic pressure from the accumulator to the valve is seismically qualified for each ADS valve.

The system for supplying pneumatic pressure to the accumulators from any of. the pressure sources is not seismic.

Questi'on Considering that portions of the proposed modifications for providing 100 day recharge capability for the ADS accumulators will not be seismically qualified, clarify how the accumulators would be recharged should the non-seismic portions fail.

~Res onse In the current and proposed

systems, there is no way to recharge the accumulators assuming the failure of all nonseismic portions.

However, those portions will.be in two independant parts which both must fail in order to prevent charging of a sufficient number of accumulators.

Question Explain any other considerations such as risk, time and procedures available for repairs, or alternative means for cooling or depressurization that are germane in providing a basis. for your proposed modifications.

Resoonse Browns Ferry is equipped with HPCI and RCIC systems which are capable of providing adequate core cooling without, need for depressurization.

Both systems are capable of 100 day operation.

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0 Continued In the event that depressurization is required after a seismic event where all nonseismic equipment is assumed to fail, HPCI is capable of depressurizing the reactor vessel a short time after shutdown.

Startup test data indicates that HPCI consumes 155,000 LBm/hr of steam at full flow and 950 psig steam pressure at a pump discharge pressure 100 psi above the steam pressure.

Data at g~S~c~p pressures is not available.

The rated capacity of one ADS valve is approximately 897,000 lbs/hr.

However, for the same fluid power output (5000 gpm at 1109 psig) with the system operated in the test mode (condensate storage tank to condensate storage tank), the HPCI is expected to replace a proportion'ally increasing amount of ADS valve capacity as pressure decreases.

The HPCI system is designed to operate down to 100 psig vessel pressure.

F-Depressurization via the HPCI system is addressed in the BWR Emergency Procedure Guidelines which are being implemented at Browns Ferry.

Using procedures based on these guidelines HPCI, over a'period of days, is'apable of depressurizing the reactor vessel and maintaining it in the 100 to 200 psig range for 100 days.