ML20137L863

Submits Addl Info Re Generic Ltr 83-28,Item 4.2.1, Periodic Maint Program for Reactor Trip Breakers & Item 4.2.2, Trending of Reactor Trip Breakers, Per 850827 & 28 Telcons

ML20137L863
Person / Time
Site:	Yankee Rowe
Issue date:	09/10/1985
From:	Papanic G YANKEE ATOMIC ELECTRIC CO.
To:	Zwolinski J Office of Nuclear Reactor Regulation
References
FYR-85-97, GL-83-28, NUDOCS 8509130079
Download: ML20137L863 (3)

Text

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O Tc'=pho"' (6 ") "' 'o YANKEE ATOMIC ELECTRIC COMPANY TWX 710-380-7619 3 1671 Worcester Road, Framingham, Massachusetts 01701 2.C.2.1 g ( FYR 85-97 September 10, 1985 United States Nuclear Regulatory Commission Washington, DC 20555 Attention: Mr. John A. Zwolinski, Chief Operating Reactors Branch No. 5 Division of Licensing

References:

(a) License No. DPR-3 (Docket No. 50-29)

(b) USNRC Letter to All Licensees, dated July 8, 1983, CL-83-28)

(c) YAEC Letter to USNRC, dated November 5, 1983 (d) YAEC Letter to USNRC, dated January 13, 1984 (e) USNRC Letter to YAEC, dated December 17, 1984 (f) YAEC Letter to USNRC, dated February 21, 1985 (g) YAEC Letter to USNRC, dated March 19, 1985 (h) Telephone Communications Between Mr. J. Clifford (USNRC) and Mr. G. Papanic, on August 27 and 28, 1985

Subject:

Ceneric Letter 83-28, items 4.2.1, Periodic Maintenance Program for Reactor Trip Breakers and 4.2.2, Trending of Reactor Trip Breakers

Dear Sir:

This letter provides additional information requested by Reference (h) for items 4.2.1 and 4.2.2. This information contained in Attachment A supplements our previously submitted responses.

Very truly yours, (2 au4 George P6 panic, Jr Senior Project Engineer - Licensing CP/dps Attachment fo

$9230079e5090 P ADOCM 05000029 PDR

l September 10, 1985 ATTACHMENT A Generic Letter 83-28 Items 4.2.1 and 4.2.2 USNRC Ouestion 1 Have the DB-25 reactor trip switchgear circuit breakers at Yankee been open-closed cycled more than two hundred times between refueling outages?

Response 1 The DB-25 circuit breakers are not equipped with an open-close cycle counter.

However, we can estimate the number of open-close cycles for the breakers between refueling outages as follows:

1. The breakers are required to be cycled once after refueling maintenance is performed but prior to plant startup.

2. Prior to Cycle 10, the breakers were cycled once per plant scram or shutdown.

3. Since Cycle 10, the breakers are cycled once per plant scram or shutdown if Procedure OP-4611 has been performed within 7 days, or 21 times if Procedure OP-4611 has not been performed within 7 days.

The following Table lists the number of plant scrans or shutdowns per plant operating cycle and the corresponding estimate of the number of open-close cycles of the DB-25 circuit breakers:

No. of Plant Scrams Estimated No. of YWPS Operaton Cycle or Shutdowns DB-25 Cycles 1 13 14 2 8 9 3 6 7 4 5 6 5 3 4 6 5 6 7 4 5 8 6 7 9 6 7 10 15 316 11 7 148 12 9 190 13 5 106 14 9 190 15 5 106 16 14 195 17 6 127

September 10, 1985 Based on the above, only Cycle 10 (1973-1974) is estimated to have exceeded 200 open-close cycles of the DB-25 circuit breakers. This particular cycle had 15 scrans or shutdowns, nine of which can be attributed to new flow instrumentation installed in the plant during the refueling outage.

USNBC Question 2 What is the possibility of YNPS exceeding 200 DB-25 circuit breaker open-close cycles between refueling outages in future operation?

Response 2 In our answer to Question 1. Yankee estimated that only once in 25 years of operation have we exceeded 200 open-close cycles of the DB-25 circuit breakers between refueling outages. This particular operation cycle is considered an unusual case. Thus, Yankee does not anticipate that we will exceed 200 open-close cycles of the DB-25 circuit breakers between refueling outages in future operation.

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