ML19260C222

Forwards Criteria Re Electrical Override/Bypass for Use in Review of Operating Reactors.Maintaining Purge Valves Closed Does Not Resolve NRC Concern W/Purge Valve Circuitry

ML19260C222
Person / Time
Site:	Millstone
Issue date:	12/11/1979
From:	Reid R Office of Nuclear Reactor Regulation
To:	Counsil W NORTHEAST NUCLEAR ENERGY CO.
References
TAC-42588, NUDOCS 7912260083
Download: ML19260C222 (5)

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December 11, 1979 Docket No. 50-366 Mr. W. G. Counsil, Vice President Nuclear Engineering & Operations Northeast Nuclear Energy Company P. O. Box 270 Hartford, Connecticut 06101

Dear Mr. Counsil:

By letter dated January 3 and April 27, 1979, you responded to our November 29, 1978 letter on Containment Purging at Millstone, Unit No. 2.

Your commitment to not purge the Millstone, Unit No. 2 containment in Modes 1 through 4 was found acceptable on an interim basis as documented in our October 30, 1979 letter.

Issuance of your proposed Technical Specifications, as modified to meet our requirements, at a later date will resolve our concern in regards to containment purge valve mechnical operations. However, our concern regarding the design of all safety actuation signal circuits, as expressed in our November 29, 1978 letter, remains unresolved.

As a result of this generic review, we have established criteria regarding electrical override / bypass for use in the review of all operating reactors.

These criteria are presented in Enclosure 1.

Please note that criteria 4 and 5 overlap with our lessons learned requirements; and your system will be evaluated during that review, also We have determined that the Millstone, Unit No. 2 d'esign is not in conformance with at least the first three of these criteria and you have indicated that no design changes are being considered, because the purge valves are to be maintained in the closed position.

Maintaining the purge valves closed does not resolve our concern with the purge valve circuitry. As a matter of general safety principles, it is the staff's position that such unacceptable circuitry should not be left intact. The potential for a repeat situation developing either during Modes 5 and 6 or during some future operation in Modes 1 through 4 is considered to be an unnecessary and unacceptable risk to public health and safety. Therefore, we request that you:

(1) Electrically disconnect and/or remove any bypass / override circuitry that does not safisfy the Enclosure 1 criteria, and (2) modify the basis for proposed Technical Specification (Section 3/4.6.1.7) to make explicitly clear that the purge isolation valves are required to be closed for two reasons -

mechanical operability and electrical override considerations.

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Mr. W. G. Counsil December 11, 1979 You are requested to provide infonnation on the proposed modifications to the containment purge circuitry and propose changes to the basis of the Technical Specifications within 30 da.ys from receipt of this letter.

The resolution of our concerns regarding the mechanical and electrical problems with the containment purge valve operation does not eliminate our concerns related to other ESF equipment / component design.

In light of the Enclosure 1 criteria, you are requested to provide your response to the Enclosure 2 request for additional information within 30 days from receipt of this letter.

Sincerely,

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Robert W. Reid, Chief Operating Reactors Branch #4 Division of Operating Reactors

Enclosures:

1.

Containment Isolation Electrical Override /

Bypass Design Criteria 2.

Request for Additional Information cc: w/ enclosures See next page

Northeast Nuclear Energy Company cc:

William H. Cuddy, Esquire Day, Berry & Howard Counselors at Law One Constitution Plaza Hartford, Connecticut 06103 Waterford Public Library Rope Ferry Road, Route 156 Waterford, Connecticut 06385 Northeast Nuclear. Energy Company ATTN:

Superintendent Millstone Plant Post Office Box 128 llaterford, Connecticut 06385 Northeast Utilities Service Company ATTN: Mr. Janes R. Himmelwright Nuclear Engineering and Operations P. O. Box 270 Hartford, Connecticut 06101 Anthony Z. Roisman, Esq.

Natural Resources Defense Council 917 15th Street, N.W.

Washington, D.C.

20005 Mr. John T. Shediosky Nuclear Regulatory Commission, Region I Office of Inspection and Enforcement 631 Park Avenue King of Prussia, Pennsylvania 19406 1616 079

CONTAINMENT ISOLATION ELECTRICAL OVERRIDE / BYPASS DESIGN CRITERIA 1.

The overriding of one type of safety actuation signal (e.g., radiation) should not cause the blocking of any other type of safety actuation signal (e.g., pressure) to the isolation valves.

2.

Sufficient physical features (e.g., key lock switches) should be provided to facilitate adequate administrative controls.

3.

The system-level annunciation of the overridden status should be provided for every safety system impacted when an override is active.

4.

At least two diverse signals should be provided to initiate isolation of the containment ventilation system.

Specifically, containment high radia-tion, safety injection actuation, and/or containment high pressure should automatically initiate containment isolation.

5.

The instrumentation and control systems provided to initiate containment isolation should be designed and qualified as safety-grac' equipment.

6.

The overriding or resetting of the isolation actuation signal should not cause the automatic reopening of any isolation / purge valve.

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RE00EST FOR ADDITIONAL If;FORIMTI0ft MILLST0flE, UNIT !!0. 2 1.

The design feature of cycling of the normal control switch for ESF equipment / component (e.g., isolation valve) to override a safety actuation signal to the equipment does not facilitate an acceptable degree of administrative control over the use of the override.

Describe the design changes you propose to rectify this deficiency.

2.

The fact that a safety actuation signal to ESF equipment is over-riden must be "annuniciated" at the systea level whenever such an override is active.

Valve position (" status") lights are not sufficient.

Describe the design changes you propose to rectify the present deficiency.

3.

All equipment which senses plant conditions and initiates operation of ESF systems shall be designed and appropriately qualified as Class lE equipment. T)iscuss the qualification of all such equip-ment at Millstone, Unit No. 2.

Describe any changes necessary to achieve full compliance with this requirement.

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