ML20085E841

Final Deficiency Rept Re Potential for RHR Pump Operation in Excess of Design Runout.Initially Reported on 760203

ML20085E841
Person / Time
Site:	Browns Ferry
Issue date:	05/24/1976
From:	Gilleland J TENNESSEE VALLEY AUTHORITY
To:	Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20085E842	List: ML20085E841 ML20085E850 ML20085E861
References
10CFR-050.55E, 10CFR-50.55E, NUDOCS 8308160603
Download: ML20085E841 (3)

Text

.ptut to, . 830 Pow;r Bailding

, INNESSEE VALLEY AUTHcgY E FILE COFX l E g CHATTANOOGA. TENNESSEE 37401

% w.# f e MAY 211970

.256 Mr. Nornan C. Moseley, Director Office of Inspection and Enforcement U.S. Nucient Regulatory Co:: mission Region II - Suite 818 230 Peachtree Street, NW.

Atlanta, Georgia 30303

Dear Mr. Moseley:

BROUNS FERRY HUCLEAR PLANT UNIT 3 - REPORTABLE DEFICIENCY -

POTENTIAL FOR E1IR PU:!P OPERATION IN EXCESS OF DESIGN RUNOUT -

IE CONTROL NO. IIO1172F2 .

Initial report of the subject reportable deficiency was made to H. C. Dance, NRC-0IE, Region II, on February 3, 1976, and was followed by our March 4, 1976, letter, J. E. Cilleland to Donald F. Knuth. Enclosed is our final report concerning this deficiency (Enclosure 1) and a copy of TVA's nnalysis (Enclosure

2) relating to this deficiency.

Very truly yours, J. E. Cilleland Assistant Manager of Power I

Euclosures -

CC (Enclosures): .

Dr. E. Volgenau. Director Office of Inspection and Enforce:aent U.S. Nuclear Regulatory Cornission Washington, DC 20555 4

8308160603 760524 '

{DRADOCK 05000296  !

PDR i 4

An Equal Opportunity Employer

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, . v Et; CLOSURE 1 BROcil:S l'ElBY IlUCEAR PIAI.T UIIIT 3 POTEliTIAL FOR ImH M11' OERATIGII Ill EXCESS OF DESIGIl RUI!OUT DDR 224 FIIIAL REPORT On February 3,1976, an initial report was made by telephone to ImC-oe Region II Inspector, H. C. Dance, by C. Michelson, T. W. Barkalow, and R. D. Bradley in compliance with 1CCFR50 55(c). Subsequently, a written interim report on this deficiency was cutmitted to Dr. Lonald F. Knuth (IEC-0IE) from J. E. Gillelend (TVA) on March 4,1976. This is a final report on thic deficiency.

Description of Deficiency For a " Description of the Deficiency," refer to cection 2.0 of the report, "RHR Puup ' Protection Against operating In Excess of Design Runout,"

Enclosure 2.

Cause of Deficiency For the "Cause of the Deficiency," refer to section 2.1 of Enclosure 2.

' Safety Implications During a loss of coolant accident, the low pressure coolant injectica (LICI)

. logic for the RER System calls for the injection of water from four EIS pumps through an unbreken recirculation loop to the reactor vessel. A cingle active component failure in thic logic could result in incorrect loop selection and direct all four RHR pump to flow to the break. A break in the recirculation loop discharge line is the limiting situation. A significant increace in total system flow above the design condition will result due to the locc of recirculation loop jet pump flow recictance. The resulting flow hac been shown by calculations to exceed the runout capacity of the pu=ps, as deter-mined fram the pump manufacturer's test data. A single failure in the loCic could also result in four Rim pumps injecting into both recirculation loops simultaneously, with one loop broken. This is the limiting case.

Another single ctilure that was considered, and found to be less limiting was the case where the loop selection was performed correctly for a recirculation line break, but the recirculation pu=p diccharge valve in the unbroken loop fails to close. This results in an additional flow path through the recirculation pu=p to the reactor vessel. 'Ihis path is in parallel with the normal one throu6h the jet pu=ps, but has a much lower flow resistance. This could also result in RHR pu=p operation in excess of design runcut, but it is not the limiting case.

__________m _ - - - - - - - -

, 2 O O The RIIR injection mode is not needed for short-tem core cooling for either of the two cases as discussed above. IIcwever, the operation of the Rl!R pumps in excess of design runout presents a potential challenge to the availability of the pumps since they are needed for long-term containment cooling. A minimum of two RIIR pumps and associated heat exchangers must be operable to meet the long-term containment cooling requirements.

Description of Corrective Action For the " Description of Corrective Action 3 " refer to sections 3 0 and 3 1 of Enclosdre 2.---- ,

Means Taken to Prevent a Recurrence ,

For the "Means Taken to Prevent a Recurrence," refer to sections 3 2, 3 3, and 3.4 of Enclosdrs '27 i

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