ML19276G878

Provides Info Requested in NRC 781129 Ltr Re Containment Purging During Normal Plant Operation.Forwards List of Purge & Vent Valves Capable of Operation When Subjected to Dynamic Forces of a Design Basis LOCA

ML19276G878
Person / Time
Site:	Pilgrim
Issue date:	08/21/1979
From:	Andognini G BOSTON EDISON CO.
To:	Ippolito T Office of Nuclear Reactor Regulation
References
79-158, NUDOCS 7908280539
Download: ML19276G878 (2)

Text

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GosTcN EDiBON COMPANY GENERAL OFFICE 5 Goo GDYLSTON STREET S Q uTO N. N AE S ACNU SETTE O 219 9 e

G. Camb ANDOGN8N4 MANAGER NUCLEAS OPERADONe OEpANTMENT August 21, 1979 BECo. Ltr. #79-158 Mr. Thomas A. Ippolito, Chief Operating Reactors Branch #3 Division of Operating Reactors Of fice of Nuclear Reactor Regulation U.S. Nuclear Regulatory Cormtission Washington, D. C. 20555 License No. DPR-35 Docket No. 50-293 Containment Purging During Normal Plant Operation

References:

a) USh7C letter to Boston Edison Company dated November 29, 1978 b) Boston Edison Company letter to USNRC dated January 9, 1979 (BECo Letter #79-22)

Dear Sir:

In Reference a) you requested information concerning containment purging during normal plant operation. Reference b) provided our initial response to Item #3 (justify unlimited purging) of your letter. Included were the results of our review of electrical circuitry, the effect of containment purging ca the Appendix K ECCS Analysis, and a commitment to address the other concerns of Item #3 in a subsequent letter.

At that time Boston Edison Company planned to justify unlimited operation for all purge and vent valves, but now plans to justify unlimited operations for only those valves involved in the containment differential pressure operation.

All other purge and vent valves will be limited in their use to 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> per year during power operation. Therefore, this letter now provides the remainder of the information requested in Reference a) pertaining to Items 2 and 3.

Capability of Purge Valves to Close Azainst LOCA Force s We have reviewed the applicable design information anc have verified that the following valves are capable of operating when subject to the dynamic forces of a design basis loss-of-coolant accident.

so I

7g/i t 155 m eus0577

BOSTON EDISON COMPANY Mr. Thomas A. Ippolito, Chief August 21, 1979 Page 2 A05044A, A05044B, A05035A, A05035B, A05036A, A05036B, A05042A, A05042B, A05033A, A05033C, *A05043A, *A05043B,

• A05041A, *A05041B All valves have a temperature aad pressure rating Lt excess of the temperature and pressure conditions that would be experienced inside the reactor contain-ment following a design basis loss-of-coolant accident. Valves are located outside the reactor containment. The 20" valves are butterfly type. In our opinion any dynamic forces experienced during closure would be equal and oppo-site across the face of the disc, and thus would have little affect on the torque required for closing. The smaller 2" valves are globe valves and are designed to close against a larger differential pressure than LOCA differential pressure.

Radiological Evaluation Since we plan to justify unlimited operation for the valves involved in the containment delta P operation, our radiological evaluation provides justifica-tion on unlimited operation for the 2" valves only. Utilizing conservative X/Q values in our calculations, we concluded that the radiological consequences of a design basis accident would not result in doses in excess of 10 CFR 100 limits.

We feel that this letter in conjunction with our previous response Reference b) adequately address your concerns relating to containment purging. A technical specification change to reflect the 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> per year limitation on purge valves not associated with the containment differential pressure operation is being processed through our Operation Review Committee and Nuclear Safety Review and Audit Committee and will be forwarded in the near future. Should you have any further questions on this subject please contact us.

Very truly yours,

• Valves used for containment differential pressure control 204i 156