ML19345F664

Responds to IE Bulletin 80-24, Prevention of Damage Due to Water Leakage Inside Containment (Oct 17,1980 Indian Point 2 Event). Monitoring of Radioactivity Levels Permits Operator to Evaluate Leakage

ML19345F664
Person / Time
Site:	Pilgrim
Issue date:	01/15/1981
From:	Morisi A BOSTON EDISON CO.
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
81-09, 81-9, IEB-80-24, NUDOCS 8102180849
Download: ML19345F664 (2)

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b GOSTON EOlGON COMPANY orwcmat carica n saa sortstow statsv s a arO N, M a g g aC H U R CTTe 0 219 9 A. v. M D Ris t MANAGER NU C LEAR OPERATION S SUPPORT DEPARTM ENT January 15,1981 BECo. Ltr. #81-09 Mr. Boyce H. Grier, Director N

Office of Inspection and Enforcement Region I p

U.S. fluclear Regulatory Commission p

%gQ 631 Park Avenue C

i-King of Prussia, PA.

19406 p

A R License flo. DPR-35 9 Docket tio. 50-293 Response to IE_B thy

Dear Sir:

IE Bulletin #80-24, " Prevention of Damage Due to Water Leakage Inside Contain-ment (October 17, 1980 Indian Point 2 Event)" described circumstances which led to an accumulation of water on the containment floor at I.P.2 without the operator's knowledge.

Licensees were requested to review the circumstances and respond to those bulletin items applicable to their plants.

Item #3 is applicable for Pilgrim fluclear Power Station and our response is presented below:

Item #3_ For plants with closed cooling water systems inside containment provide a summary of experiences with cooling water system leakage into containment.

Response At Pilgrim Station, a reactor building closed cooling water system is provided to supply self-contained coolant to the reactor aux-iliary systens equipment and accessories (potentially radioactive) and to the residual heat removal system to remove heat during nonnal operation, shutdown, and accident canditions. The system consists of two independent loops, each ith three pumps,one heat exchanger and associatec: piping and valves. The loops are crosstied to pennit operation with various combinations of equipment.

A search of maintenance request records revealed no leaks of any major significance on this system.

In addition, as requested by D. L. Capton in a ctnversation with J. D. Keyes on this subject, we offer the following infonnation on the methods used to detect leakage in the drywell:

Leakage from the reactor pressure boundary inside the primary containment is measured by monitoring drywell floor and equipment drain sumps and measuring tunperature, pressure and humidity as well as the particulate, iod?ne and gaseous activity in the drywell atmosphere.

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The drywell equipment and floor sump flow monitoring system consists of three subsystems of redundant instrumentation monitoring:

(1) integrated sump flow, (2) the number of pump starts, and (3) sump pump running time.

The integrated sump flow is a direct measurement of leakage flowing out cf the sump. The number of pump starts allows the leakage to be calculated, since the volume 8102180 d Q

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i DOsTON EOlGON COMPANY Mr. Boyce H. Grier, Director 3_

January 15,1981 Page 2 between the high and low level switches is a known parameter, The timer allows calculation of the pump operating time during a given interval, which coupled with knowledge of the pump flow rate, allows calculation of the primary system leakage.

Conversely, the timer can be u<rd to determine the time between pump starts which also allows calculation of the leakage inflow, since the volume between the high and low level switches is known.

Air temperature and pressure monitoring of the drywell is used to infer possible Reactor Coolant Pressure Boundary leakage to the containment and an increase in humidity of the containment atmosphere would indicate release of water vapor to the containment.

The monitoring of airborne radioactivity levels in the contain-ment atmosphere permits the operator to evaluate leakage relative to the probable source.

The drywell sump flow monitoring system and the drywell atnospher;c activity monitoring system are checked on a daily basis to ensure that reactor coolant leakage remains within Technical Specification limitations.

If during your review of the above information you should have any further questions or concerns on the drywell leakage detection systens utilized at Pilgrim Station, please do not hesitate to contact us.

Very truly yours, 7)~" kM cc: Director Division of Reactor Operations Inspection Office of fiuclear Reactor Regulation U.S. fluclear Regulatory Ccmission Washington, D. C.

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