ML18081A755

Interim Deficiency Rept Re Max Flow of RHR Pump During post- LOCA Mode.Caused by Low Sys Resistance to Pump Runout Conditions.Sys Resistance Increased by Placement of Resized Orifices

ML18081A755
Person / Time
Site:	Salem
Issue date:	10/04/1979
From:	Martin T Public Service Enterprise Group
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Shared Package
ML18081A754	List: ML18081A755
References
NUDOCS 7912140537
Download: ML18081A755 (3)

Text

Thomas J. Martin Public Service Electric and Gas Company 80 Park Place Newark, N.J. 07101 201/430-8316 Vice President Engineering and Construction October 4, 1979 Mr. Boyce H. Grier, Director

u. S. Nuclear Regulatory Commission Off ice of Inspection and Enforcement Region 1 631 Park Avenue King of Prussia, Pennsylvania 19406

Dear Mr. Grier:

MAXIMUM FLOW OF RHR PUMP DURING POST-LOCA RECIRCULATION MODE 10CFRSO.SS(e) "SIGNIFICANT DEFICIENCY" NO. 2 UNIT SALEM GENERATING STATION On August 30, 1979 a verbal report was made to Region'l, Office of Inspection and Enforcement representative Mr. B. Bateman, advising that a potential deficiency existed relative to the maximum flow of the RHR pumps during Post-LOCA recirculation mode (worst hydraulic configuration) . This report was provided in accordance with the provisions of 10CFRSO.SS(e). The following supplemental information is hereby submitted pursuant to our initial report (and our request for extension on 9-28-79 to Mr. R. w. McGaughy) and in accordance with the requirements of 10CFRSO.SS(e):

On July 13, 1979, Unit No. 2 RHR pumps were tested to establish the maximum flow for the worst hydraulic conf ig-uration and to evaluate the available NPSH based on that flow. The worst hydraulic configuration for NPSH evalua-tion (during recirculation mode} of the RHR pump is w~en one (ll RHR pump is feeding two (2) charging pumps, two (2) safety injection pumps and also feeding directly into the two (21 cold legs. The water source for the defined

.flow configuration* was the Refueling Water Storage Tank.

The results of this test were as*follows:

791214053 7

Mr. Boyce H. Grier 10/4/79 Pump No. Throttle Valve Position Flow (GPM) 2l 60% 4,132 22 60% 4,686 The test was stopped after the above results were reached because it was obvious that if the throttle valves were to be opened to 100% the pump would reach high runout con-ditions and the motor current readings would exceed that which is normally desired. The design runout flow for the RHR pump is 4500 gprn with the throttle valve full open.

Salem Unit No. 1 has an identical configuration and the reported deficiency and the corrective action on Unit 2 will be applicable to Unit No. 1.

2. Analysis of Safety Implications The configuration to which the RHR pumps were tested is not a design basis for Salem Nuclear Power Plant. The Salem plant design for cold leg recirculation phase operation with only one RHR pump consists of aligning the RHR discharge such that the running RHR pump is supply-ing the suction of.two charging pumps, two safety in-jection pum:r;sand the containment spray headers. There-fore the configuration to which the RHR pump was tested is not representative of the plari"t design. The purpose of the test was to establish the maximum flow for the RHR pump, and the flow path represented the worst hydraulic configuration for the pumps.

The test result demonstrated that the system resistance was lower than desired and there is a possibility of the pump reaching runout conditions during other modes of operation. However, to be conservative it was decided to increase the system resistance and decrease the maximum flow.

Mr. Boyce H. Grier 10/4/79

3. Corrective Action The system resistance on the discharge side of the RHR pumps was increased by changing the orifices on the flow elements that are located both upstream and downstream of the RHR heat exchangers.

The RHR pumps were retested with resized orifices in place, with the operating flow conditions described above. The test showed that with the throttle valve full open, the maximum flow was less than 4600 GPM. This test result is acceptable since the pump has adequate NPSH for flows up to 4800 GPM during recirculation phase. Westinghouse Electric Corporation evaluated the modified system for safety injection and concluded it to be above the refer-ence performance contained in the Salem FSAR.

Salem Unit 1 RHR system will be modified to include the resi.zed orifices before the plant returns to commercial operation.

Very truly yours, cc: Mr. L. J. Norrholm NRC, Hancocks Bridge