ML20041C649
| ML20041C649 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/31/1982 |
| From: | Farmer F EG&G, INC. |
| To: | Scholl R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20041C648 | List: |
| References | |
| CON-FIN-A-6425, TASK-03-10.A, TASK-3-10.A, TASK-RR EGG-EA-5748, NUDOCS 8203020417 | |
| Download: ML20041C649 (6) | |
Text
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-EGG-EA-5748
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JANUARY 1982 SYSTEMATIC EVALUATION PROGRAM, TOPIC III-10.A, THERPAL-0VERLOAD PROTECTION FOR MOTORS OF MOTOR-0PERATED VALVES, MILLSTONE NUCLEAR POWER l
STATION, UNIT NO. 1 F. G. Farmer U.S. Department of Energy Idaho Operations Office
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1 This is an informal report intended for use as a preliminary or working document Prepared for the U.S. Nuclear Regulatory Commission Under DOE Contract No. DE-AC07-761001570 FIN No. A6425 0
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FOKW EG4G 3fse (Rev 1g Pg INTERIM REPORT Accession No.
Report No. EGG-EA-5748 i
Centract Program or Project
Title:
Electrical, Instrumentation, and Control Systems Support for the Systematic Evaluation Program (II)
Subject of this Document:
Systematic Evaluation Program, Topic III-10.A, Thermal-Overload Protection 3
for Motors of Motor-Operated Valves, Millstone Nuclear Power Station, Unit No. 1 Type of Document:
Informal Report Author (s):
F. G. Farmer D te of Document:
January 1982 Rssponsible NRC Individual and NRC Office or Division:
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Ray F. Scholl, Division of Licensing This document was prepared primarily for preliminary orinternat use.it has not received full review and approval. Since there may be substantive changes,this document should not be considered final EG&G Idaho, Inc.
Idaho Falls, Idaho 83.415 Prepared for the U.S. Nuclear Regulatory Commission Washington, D.C.
Under DOE Contract No. DE AC07 761D01570 NRC FIN No. A6425 INTERIM REPORT
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SYSTEMATIC EVALUATION PROGRAM TOPIC III-10.A THERMAL'-0VERLOAD PROTECTION FOR MOTORS OF MOTOR-0PERATED VALVES MILLSTONE NUCLEAR POWER STATION, UNIT N0. 1 Docket No. 50-245 January 1982 F. G. Farmer EG&G Idaho, Inc.
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ABSTRACT g
This SEP technical evaluation, for the Millstone Nuclear Power Station, Unit No. 1, reviews the application of thermal-overload protection devices'to motors associated with safet -related motor-operated valves.
FOREWORD This report is supplied as part of the " Electrical, Instrumentation, and Control Systems Support for the Systematic Evaluation Program (II)"
being conducted for the U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, Division of Licensing by EG&G Idaho, Inc.,
Reliability and Statistics Branch.
The U.S. Nuclear Regulatory Commise ided the work under'the authorization B&R 20-10-02-05, FIN A64E
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4 TOPIC III-10.A THERMAL-0VERLOAD PROTECTION FOR MOTORS OF MOTOR-OPERATED VALVES Mlu. STONE NUCLEAR POWER STATION, UNIT NO.1 o
INTRODUCTION The objective of this review is to provide assurance that the applica-tion of thermal-overload protection devices to tnotors associated with saf'ety-related motor-operated valves does not result in needless hindrance
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o'f the valves perfo' ming their safety functions.
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In accordance with this objective, the application of either one of the two recommendations contained in Regulatory Guide 1.106, " Thermal-Overload Protection for Electric Motors on Motor-Operated Valves," is adequate.
These recommendations are as follows:
(1) Provided that the completion of the, safety function is not jeop-ardized or that other safety systems are not degraded, (a) the thermal-overload protection devices should be continuously bypassed and temporarily placed in force only when the valve notors are undergoing periodic or maintenance testing, or (b) those thermal-overload protection devices that are normally' in force during plant operation should be bypassed under accident conditions.
(2)
The trip setpoint of the thermal-overload protection devices should be established with all uncertainties resolved in favor of completing the safety-related. action. With respect to those uncertainties, consideration should be given to (a) variations in the ambient temperature at the installed location of the overload prote'ction devices and the valve motors, (b) inaccuracies in motor heating data and the overload protection device trip char-acteris tics and the matching of these two items, and (c) setpoint drift.
In order to ensure continued functional reliability and the accuracy of the trip point, the thermal-overload protection device should be periodically tested.
In addition, the current licensing criteria require that-7 (3)
In MOV designs that use a torque 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.
DISCUSSION On February 7,1980, Northeast Utilities submitted a list of all safety-related motor-operated valves and the electrical schematics for 1
those valves.4 The licensee subsequently re valves and supplying additional information.gised the list, deleting six Of 59 safety-related MOVs, 38 have thermal-overload devices which provide alarm only; the TOLs are not in the valve control circuits. The remaining 21 valves have thermal-overload protection devices which are not bypassed; there is no docketed information to indicate that TOL trip setpoints have been set to comply with all the variables of Criterion 2, above. Nine of these valves are for containment isolation and are normally closed; they should not be required to operate during an accident. Seven valve open functions and 54 valve close functions are terminated by torque switches rather than limit switches; 41 valve open functions are termin oratorqueswitch(switchesareinseries).gtedbyeitheralimitswitch Automatic open or close signals are used in conjunction with limit switches which bypass the torque switches at the beginning of travel.
EVALUATION Thermal-overload protection for. motors of motor-operated valves at Millstone 1 does not comply with current licensing criteria. Thermal-overload protection devices are not bypassed and no information is available to support. adequacy of trip setpoints. The use of limit and torque switches on these valves meets current licensing criteria.
REFERENCES 1.
IEEE Standard 179-1971, " Criteria for Protection Systems for Nuclear Power Generating Stations."
2.
Branch Technical Position EICSB-27, " Design Criteria for Thermal Over-load Protection for Motors of Motor-0perated Valves."
3.
Regulatory Guide 1.106, " Thermal Overload Protection for Electric Motors on Motor-0perated Valves."
4 Letter, Northeast Utilities (Counsil) to NRR (Ziemann), dated February 7, 1980.
5.
Letter, Northeast Utilities (Counsil) to NRR (Crutchfield), dated April 16, 1981.
6.
Letter, Northeast. Utilities (Counsil) to NRR (Crutchfield), dated August 28, 1981.
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