ML19208B755

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Responds to NRC 790716 Ltr Re Efforts to Improve Reliability of Target Rock Safety Relief Valves.Valves Currently in Original Design Configuration.Will Replace three-stage Topworks w/two-stage Topworks
ML19208B755
Person / Time
Site: Pilgrim
Issue date: 09/13/1979
From: Andognini G
BOSTON EDISON CO.
To: Grimes B
Office of Nuclear Reactor Regulation
References
79-182, NUDOCS 7909210342
Download: ML19208B755 (3)


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B O STO N E*DlB O N COMPANY GENER Ab OFFICE 5 B00 BovLs1DN STNCET BOSTON. Mas 3ACHUSETTs o2199 G. Camb ANDOGNING suPfalNTENDEIT MuCLEAN OPENAffCNS DEp44fMENT September 13, 1979 BECo. Ltr. #79- 182 Mr. Brian K. Grimes Acting Assistant Director for Systems Engineering Division of Operating Reactora Office of Nuclear Reactor Regulation U.S. Nuclear ReFulatory Commission Washington, D. C. 20555 License No. DPR-35 Docket No. 50-293 Information on Target Rock Safetv/ Relief Valves

Dear Sir:

In a letter sent to all Boiling Water Reactor Licenseei dated July 16, 1979, you concluded that increased surveillance testing of Tarp Rock Safety / Relief Valves is not the most effective method of assuring re:iiability for these valves, and requested specific information as to the efforts being made to improve the reliability of these valves at Pilgrim Station.

Our response to your questions is provided as follows:

1. What is the status of each of the Target Rock Safety / Relief Valves at your plant, i.e.:
a. Are they in their original design configuration?
b. What is the existing simmer margin?
c. What modifications have you implemented to improve reliability?
d. On what date were these modifications made?

Response

a. The Safety / Relief Valves are currently in their original design configuration.
b. With simmer margin defined as the difference between set point of the valves and normal full power operating pressure, three (3) safety / relief valves have a margin of 55 psi and one (1) has a margin of 65 psi (based on a normal operating pressure of 1030 i @g psig). 0 /

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gje BOSTON EDISON CO M PANY Mr. Brian K. Grimes September 13, 1979 Page 2

c. The following actions have been implemented to improve reliability:
1. Manual operation of valves is only performed when necessary.

At no time are these valves operated manually to clear a leak.

2. Valve operability tests are rotated to distribute wear evenly.
3. Valves are repaired at the earliest opportunity if the tail t pipe thermocouple shows high temperature (indicating excessive pilot leakage) .

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d. The actions listed above (c) have been implemented since early 1976.
2. What maintenance and testing do you routinely perform on these valves and how of ten is it performed?

Response

At least two (2) safety /re'.ief valves are checked or replaced with bench checked valves once per operating cycle.

All safety /tc31ef val'%s are tested every two cycles.

1 At least one safety / relief valve is disassembled and inspected each [

refueling outage.

The integrity of the safety / relief valve bellows is continuously mon-itored and the operability of the bellows monitoring system is demon-strated at least once every three (3) months.

3. What additional modifications and/or maintenance do you plan to implement in the future?

Response

The three (3) stage topworks will be replaced with two (2) stage top-works. Also, acoustic monitors will be installed on the tail pipes which will indicate if valves are open, closed, or leaking.

4. On what date will the modification (s) and/or maintenance in Item 3 be implemented?

Response

Boston Edison plans to complete these modifications by the end of the 1980 refueling outage.

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4 OcSTON EDISDN COMPANY Mr. Brian K. Grimes September 13, 1979 Page 3 We trust this information is responsive to your concerns and adequately demonstrates Boston Edison Company's efforts to provide assurance for safety /

relief valve operability and reliability. If you require further information or clarification, please contact us at your convenience.

Very truly yours,

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