ML20010E133
| ML20010E133 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 08/28/1981 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Counsil W CONNECTICUT YANKEE ATOMIC POWER CO. |
| References | |
| TASK-03-10.A, TASK-3-10.A, TASK-RR LSO5-81-08-070, LSO5-81-8-70, NUDOCS 8109030129 | |
| Download: ML20010E133 (4) | |
Text
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August 28, 1981 Docket Nc, 50-213 3
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Mr. W. G. Counsil, Vice President Nuclear Engineering and Ooerations q u.t g p @
Connecticut Yankee Atonic Power Co.
sA Post Office Box 270 h
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Hartford, Connecticut 06101
Dear Mr. Counsil:
SUDJECT: SEP T0nIC III-10. A. THEPJtAL-0VERLOAD PROTECTIOil FOR fiOTORS OF MOTOR-OPERATED VALVES, SAFETY EVALUATI0fl REPORT FOR MILLST0tlE V' LIT 1 The enclosed staff safety evaluation suoplenents our contractor's evaluation that has been nade available to you previously. This evaluation supports the fin;iings of the enclosed staff safety evaluation on Tonic III-10. A that proposes modifications to the valve protective trips.
The need to actually imlenent these chances will be deternined during the integrated plant safety assessnent.
This tooic assessnent ray be revised in the future if your facility design is changed or if 'iRC criteria relatinq to this topic are nodified before the integrated assessnent is completed.
Sincerely,
(
Dennis M. Crutchfield, Chief Operating Reactors Branch !!o. 5 l
Division of Licensing 1
Enclosure:
As stated
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OFFICIAL RECORD COPY m : r.
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I HADDAM NECK Docket No. 50-213 I
Mr. W. G. Counsil CC Day, Berry & iloward Counselors at Law One Constitution Plaza llartford, Connecticut 06103 Superintendent Haddam Neck Plant i
RFD #1 Post Of fice Box 127E East Hampton, Connecticut 06424 Mr. Richard R. Laudenat Manager, Generation Facilities Licensing I
Northeast Utilities Service Company P. O. Box 270 Hartford, Connecticut 06101 Russell Library 119 Broad Street Middletown, Connecticut 06457 Board of Sclectmen Town Hall Haddam, Connecticut 06103 Connecticut Energy Agency ATTN: Assistant Director Research and Policy Development Departnent of Planning and Energy Policy 20 Grand Street l
Hartford, Connecticut 06106 U. S. Environmental Protection Agency Region I Office i
ATTN: EIS COORDINATOR JFK Federal Building Boston, Massachusetts 02203 l
Resident Inspector Haddam Neck Nuclear Power Station l
c/o U. S. NRC t
East Haddam Post Office East Haddam, Connecticut 06423 1
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I SYSTEMATIC EVALUATION PROGRAM TOPIC III-10.A MILLSTONE 1 TOPIC:
III-10.A, THERMAL-0VERLOAD PROTECTION FOR MOTORS OF MOTOR-OPERATED VALVES I.
INTRODUCTION The prirary objective of 11 erml overload relays is to protect rcotor windings of motor-cperated valces (M3V) against excessive heating.
This fcature of thermal overload relays cculd, however, interfere with the successful functicning of a safety related system.
In nuc-icar plant safety system appli:aticn, the ultirate criterion should -
be to drive the valve-to its propcr position to mitigate the conse-qucnces of an accidents, rather than to be concerned with degradation or failure of the motor due to excessive heating.
II.
REVIEW CRITERIA The primary review criteria are:
1.
IEEE Std. 279-1971, and 2.
As a result of numerous operating plant events resulting from torque switch problems the follcwing supplemental criterion was used:
"(3)
In M3V 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 addrossed by cther SEP Topics nor are any.other tcpics dependent on the results of this review.
IV.
REVIEW GUIDELINES The resiew should assure that:
(1) thermal overload protection, if Provided, for M3V'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 in IEEE Std. 279-1971 criteria, 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 10% of valve travel.
i 2
V.
EVALUATIO" The design pt avisions for motor-operated valve protection are described in EG&G Report 1651F, " Thermal-Overload Protection for Motors of Motor-Operated Valves."
Thermal-overlaad protection for motors of notor-operated valves at Millstone 1 does not comply with current licensing criteria.
Thermal-overload protec-tion devices are not bypassed, no information is available to support adequacy of trip setpoints, and for most of the valves, torque switches rather than linit switches are used to terminate valve travel.
VI.
CONCLUSIONS The Millstone 1 design does not satisfy the current licensing criteria for safety related valve functions.
Because poor valve rei ability may lead to the failure of nore than one valve during emergency conditions, and multiple 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., bypassing torque switches with a limit switch during automatic actuation of the valve and b:.oassing thermal overloads with an ECCS signal).