ML20041C647

Forwards Eg&G Final Technical Evaluation Rept, SEP Topic III-10.A,Thermal Overload Protection for Motors of Motor Operated Valves. Need to Implement Changes Will Be Determined During Integrated Plant Safety Assessment

ML20041C647
Person / Time
Site:	Millstone
Issue date:	02/26/1982
From:	James Shea Office of Nuclear Reactor Regulation
To:	Counsil W NORTHEAST NUCLEAR ENERGY CO.
Shared Package
ML20041C648	List: ML20041C647 ML20041C649
References
TASK-03-10.A, TASK-3-10.A, TASK-RR LSO5-82-02-122, LSO5-82-2-122, NUDOCS 8203020413
Download: ML20041C647 (4)

Text

.,, 4 February 26, 1982 e\\ & ?:

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Docket No. 50-245 g

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LS05-82-02-122

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Mr. W. G. Counsil, Vice President c3 Nuclear Engineering and Operations Northeast Nuclear Energy Company

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i Post Office Box 270 Hartford, Connecticut 06101

SUBJECT:

SEP TOPIC III-10. A, THERMAL-0VERLOAD PROTECTION FOR MOTORS OF MOTOR-0PERATED VALVES, SAFETY EVALUATION REPORT FOR MILLSTONE UNIT 1

< is our contractor's final Technical Evaluation Report on this topic for your facility. is a revised Safety Eval-uation Report that is based on Enclosure 1.

Both enclosures have been revised to reflect the additional information provided by your August 28, 1 981 letter.

The staff still proposes changes to the overload protection of 12 motor-operated valves.

The need to actually implement these changes will be determined during the integrated plant safety assessment.

This topic assessment ma" he revised in the future if your facility design is changed or if NRC 3 Cd 6

criteria relating to this topic are modified before the integrated assessment is completed.

8 Sincerely,

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lWot James J. Shea, Project Manager G 5) E/

Operating Reactors Cranch No. 5 D. h2si.,go Division of Licensing

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Mr. W. G. Counsil cc William H. Cuddy, Esquire State of Connecticut Day, Berry & Howard Office of Policy & Management Counselors at Law ATTN: Under Secretary Energy One Constitution Plaza Division Hartford, Connecticut 06103 80 Washington Street Hartford, Connecticut 061.15 Natural Resources Defense Council 917 15th Street, N. W Ronald C. Haynes, Regional Washington, D. C.

20005 Administrator Nuclear Regulatory Commission Northeast Nuclear Energy Company Region 1 Office ATTN: Superintendent 631 Park Avenue Millstone Plant King of Prussia, Pennsylvania 19406 P. O. Box 128 Waterford,' Connecticut 06385 Mr. Richard T. Laudenat Manager, Generation Facilities Licensing Northeast Utilities Service Company P. O. Box 270 Hartford, Connecticut 06101 Resident Inspector c/o U. S. NRC P. O. Box Drawer KK Niantic, Connecticut 06357 Waterford Public Library Rope Ferry Road, Route 156 Waterford, Connecticut 06385 First Selectman of the Town of Waterford Hall of Records 200 Boston Post Road Wat.erford, Connecticut 06385 John F. Opeka Systems Superintendent Northeast Utilities Service Company

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P. O. Box 270 Hartford, Connecticut 06101 U. S. Environmental Protection Agency Region I Office ATTN:

Regional Radiation Representative JFK Federal Building Boston, Ma'ssachusetts 02203

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SYSTEMATIC EVALUATION PROGRAM TOPIC lil-10.A MILLSTONE 1 i

TOPIC:

III-10. A, THERMAL-0VERLOAD PROTECTION FOR MOTORS OF MOTOR-OPERATED VALVES e

I.

INTRODUCTI'ON The primary objective of thermal overload relays is to protect motor windings of motor-operated valves (MOV)~ agaihst excessive heating.

This feature of thermal overload relays could, however, interfere with the successful functioning of a safety related system.

In nuc-lear plant safety systens applicatien, the ultimate criterion sho01d -

' be to drive the valve-to its proper position to mitigat'e the conse--

quences of an accidents, rather than to be concerned with degradation or failure o'f the motor due to excessive heating.

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II..' REVIEW CRITERIA The primary revien' criteria are:

1.

IEEE Std. 279-1971, and

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2.

Regulatory Guide 1.105.

As a result of numerous operating plant events resulting from torque switch problems the following supplemental criterion was used:

"(3)

In MOV designs that use a torque switch to limit the opening or closing of the valve, the automatic opening or closing s.ignal

• should be used in conjunction with a corresponding limit switch."

III.

RELATED SAFETY TOPICS AND INTERFACES There are no safety areas related to the scope of this review that are addressed by other SEP Topics nor are any.other topics dcpendent on ene results of this review.

9 IV.

REVIEW GUIDELINES The review should assure that:

(1) thermal overload protection, if provided, for MOV's should have the trip setpoint.at a value high enough to prevent spurious trips due to design inaccuracies, trip set-point drif t, or variation in the ambient temperature at the installed location; (2) the circuits that bypass the thermal overload ' protection under accident conditions are designed to IEEE Std. 279-1971 criteria,

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as appropriate for the rest of the safety related system; and (3) in MOV designs that use a torque switch instead of a limit switch to limit the opening or closing of. the valve, the automatic opening or closing signal should be used in conjunction with a corresponding limit switch and thermal overload should remain as backup protection over the first 10i of valve travel.

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V.

EVALUATION The design provisions for motor-operated valve protection are described in EG&G Report EGG-EA-5748, " Thermal-Overload, Protection for Motors of Motor-Operated Valves."

Th' rmal-overload protection for motors of motor-operated valves at e

Millstone 1 does not comply with current licensing criteria. Thermal-overload protection devices are not bypassed in.21 valves and no information is available to support adequacy of trip setpoints. Nine of these valves are normally closed containment isolation valves.

'VI.

CONCLUSIONS The Millstone 1 design does not satisfy the current licensing criteria for 21 safety related valve functions. Because poor valve reliability may lead to the failure of more than one valve during emergency condi-tions, and mul,tiple valve failures have not been analyzed for their affect upon system performance and plant safety, the staff recommends that action should be taken to improve valve reliability (i.e., bypas-sing torque switches with a limit switch during automatic actuation of the valve and bypassing thermal overloads with an ECCS signal) for the 12 motor-operated valves that are not normally in their emergency position and have thermal overloads that are not bypassed by an emer-gency signal.

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