ML19332A015

Deficiency Evaluation Rept Re Westinghouse Centrifugal Charging Pump Operation Following Secondary Side High Energy Line Rupture.Design Change Implemented to Remove Safety Injection Initiation Closure Signal from Isolation Valves

ML19332A015
Person / Time
Site:	Farley
Issue date:	08/20/1980
From:	Clayton F ALABAMA POWER CO.
To:
References
REF-PT21-80-219-003 10CFR-050.55E, 10CFR-50.55E, 80-874, NUDOCS 8009100363
Download: ML19332A015 (4)

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F. L CLAYTON, JR. b s.nior v,c. Pr.sid.nt P3; 1J Alabama Power August 20, 1980 rne ,wneer,,,c,re ,ys,,m Joseph M. Farley Nuclear Piant - Unit 2 Docket 50-364 Centrifugal Charging Pumps File: A-35.62.78 -

Log: 80-874 Mr. James P. O'Reilly U.S. Nuclear Regulatory Comission Office of Inspection and Enforcement 101 Marietta Street, N.W. - Suite 3100 Atlanta, Georgia 30303

Dear Mr. O'Reilly:

Alabama Power Company submits the attached deficiency (10CFR50.55(e)) evaluation report on the problem associated with the Westinghouse centrifugal charging pumps in the Joseph M. Farley Nuclear Plant-Unit 2. No 10CFR Part 21 report is being filed by Alabama Power Company since this problem was reported in Westinghouse le:ter NS-TMA-2245, dated May 8,1980 (letter addressed to Mr. Victor Stello, Director of Inspection and Enforcement).

This item was discussed with Mr. M. D. Hunt, U.S. NRC, on June 6,1980 and reported as a significant deficiency to Mr. Hunt on August 11, 1980.

If you have any questions, please let us know.

Very truly yours, kl'.

F. Clayto Jr.

FLC:WCP:sh Attachment xc +

Attachment:

U.S. Nuclear Regulatory Comission Attn: Mr. Victor Stello, Jr., Director Office of Inspection and Enforcement g9' Washington, D.C. 20555 g,/

Mr. M. D. Hunt, NRC, Region II

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t SIGNIFICANT DEFICIENCY EVALUATION FOR CENTRIFUGAL CHARGING PUMPS On May 8,1980 Westinghouse Electric Corporation wrote a letter (NS-TMA-2245) to the NRC concerning centrifugal charging pump (CCP) operation following secondary side high energy line rupture.

Westinghouse states "following a secondary side high energy line rupture and associated reactor trip, Reactor Coolant System (RCS) pressure and temperdture initially decrease. Safety injection is 'ctuated and the CCP's start to increase RCS inventor,. RCS pressure ar.. temperature subse-quently increase due to the loss of secondary inventory, steam line and feed line isolation, RCS inventory addition and reactor core decay heat generation.

The accident scenario may vary with rupture size and specific plant design, but it will develop into a RCS heat-up transient with accompanying increase in RCS pressure. As RCS pressure increases, the pressurizer power-operated relief valves (PORV's) are designed to limit RCS pressure to 2350 psia.

Although these valves are normally available, they are not designed as safety-related equipment. It can be postulated that due to either loss of offsite power, adverse environment inside containment, the pressurizer PORV in manual mode, or the PORV block valve in a closed position, due to PORV leakage, the pressurizer PORV's may not be operable. As a result of the RCS heatup and inventory increase, the RCS pressure could rise to the pressurizer safety valve set point of 2500 psia within approximately 200 seconds and remain at that pressure until transient " turnaround." Transient " turnaround" can occur between 1800 and 4200 seconds depending on operator action and available equipment. During the initial portion of this transient, the SI termination criteria tray not be satisfied. Consequently, the RCS pressure can reach the l I

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Significant Deficiency Evaluation for Centrifugal Page 2 -

Charging Pumps pressurizer safety valve relief pressure before CCP operation is teminated.

During this period, the minimum flow required for CCP operation must be satisfied by flow to the RCS since the CCP mini-flow isolation valves are automatically closed on safety injection initiation. This requires that the CCP's be able to deliver their minimum required flow to the RCS at the safety valve set point pressure."

An analysis was perfomed for the charging pumps used at Farley Nuclear Plant, Unit 2. The analysis indicated that minimum flow may not be adequate to ensure pump cooling, and potential pump damage could violate design criteria.

In reviewing this problem for reportability under Part 10 CFR 50.55(e),

it has been detemined that this condition represents a deficiency found in design and construction which, were it to have remained uncorrected, could have affected adversely the safety of operations of the nuclear power plant at any time throughout the expected lifetime of the plant. Additionally, this represents a deficiency in final design as approved and released for construction such that the design does not confom to the criteria stated in the Safety Analysis Report.

Alabama Power Company has implemented the following interim corrective action:

1. A design change to remove the safety injection initiation automatic closure signal from the CCP miniflow isolation valves has been implemented.

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Significant Deficiency Evaluation for Centrifugal Page 3 Charging Pumps

2. The plant emergency operating procedures have been modified to instruct the operator when to open and shut miniflow valves.

Tha above interim corrective action has been reviewed by Westinghouse, Southern Company Services. Inc. and Alabama Power Company. Long-term corrective action will be initiated after additional studies and analyses are performed by Westinghouse and Alabama Power Company.

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