ML20213F890

Forwards Response to IE Bulletin 86-003.Problem Does Not Exist at Plant.No Addl Work or Response Required

ML20213F890
Person / Time
Site:	Yankee Rowe
Issue date:	11/07/1986
From:	Heider L YANKEE ATOMIC ELECTRIC CO.
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
DCC-86-174, FYR-86-110, IEB-86-003, IEB-86-3, NUDOCS 8611170233
Download: ML20213F890 (2)

Text

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q Telephone (617) 872-8100

,. TWX 710u380 7619 YANKEE ATOMIC ELECTRIC COMPANY

'.MLAj 1671 Worcester Road, Framingham, Massachusetts 01701 DCC e6-174

.Yauxes< '*

November 7, 1986 FYR 86-110 United States Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406 Attention: Dr. Thomas E. Murley Regional Administrator

References:

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

(b) I.E. Compliance Bulletin No. 86-03, NYR 86-227, dated October 8, 1986

Subject:

Response Required to I.E. Compliance Bulletin No. 86-03

Dear Sir:

The attachment to this letter contains a complete response to the information requested in Reference (b). As is shown in the attachment to this letter, the problem identified in Reference (b) does not exist at Yankee, and therefore no additional work or further response is required.

We trust this information is satisfactory; however, if you have any questicas, please contact us.

Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY f d4 L. H. Heider Vice President and Manager of Operations SPF/bil Attachment COMMONWEALTH OF MASSACHUSETTS)

)ss MIDDLESEX COUNTY )

Then personally appeared before me, L. H. Heider, who, being duly sworn, did state that he is Vice President and Manager of Operations of Yankee Atomic Electric Company, that he is duly authorized to execute and file the foregoing document in the name and on the behalf of Yankee Atomic Electric Company and that the statements therein are true to the best of his knowledge and belief.

Robert H. Groce Notary Public My Commission Expires August 29, 1991 8611170233 861107 PDR ADOCK 05000029 hl! '%

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r ATTACHMENT Yankee Response to I.E. Bulletin No. 86-03 The Yankee Emergency Core Cooling System (ECCS) contains three trains of pumps. Each train consists of one high pressure and one low pressure pump.

All six pumps have orificed minimum recirculation lines, which connect to a common header to return the recirculation flow to the safety injection tank.

The common recirculation line is isolated by series valves upon the initiation of recirculation from the containment sump. This is where the similarity between the Yankee design and that discussed in I.E. Compliance Bulletin (IECB) No. 86-03 ends.

The single failure concern of IECB No. 86-03 was an input into the Yankee minimum recirculation line isolation design. A single failure will not cause an inadvertent isolation of the Yankee ECCS pumps' minimum recirculation line for the following reasons:

1. The minimum recirculation line is isolated by two Motor-Operated Valves (MOVs) in series. Upon a loss-of-power, a MOV fails as is. These valves are normally open, which would be their failed position on a loss-of-power.

2. These two valves are powered by diverse emergency power supplies. A loss-of-power would only affect one valve. The second valve would be available to perform the isolation function during the recirculation phase.

3. Each motor operator is provided with dual contactors which provide a single failure proof design. This design requires one failure in the control circuitry of the valve closing contactor, and a second failure in the control circuitry of the dual contactor before the valve would go closed. By design, the operator is required to operate the two control switches, one of which is key-locked to close the valve. An inadvertent closure would require two separate actions by the operator.

4. The switchover from injection to recirculation is performed manually by the opscators in the Control Room. There are no automatic control signals to these valves that could result in a single failure that would operate both contactors on one valve. In fact, there are no common connections between the control circuits of two contactors that could cause a common mode failure between the two contactors and cause an inadvertent valve closure.

. Based upon the single failure-proof design of the Yankee minimum recirculation line isolation valves, the concern identified in IECB No. 86-03 does not exist at Yankee. Therefore, no further actions are required.

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