ML20039G782
| ML20039G782 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 11/30/1981 |
| From: | Udy A EG&G, INC. |
| To: | Scholl R Office of Nuclear Reactor Regulation |
| References | |
| CON-FIN-A-6425, TASK-06-04, TASK-6-4, TASK-RR EGG-EA-5671, NUDOCS 8201190131 | |
| Download: ML20039G782 (9) | |
Text
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/,,i Bd SYSTEMATIC EVALUATION PROGRAM TOPIC VI-4, ELECTRICAL,
- 5) Sit INSTRUMENTATION, AND CONTROL ASPECTS OF THE OVERRIDE N TIS OF CONTAINMENT PURGE VALVE ISOLATION, BIG ROCK POINT PLANT j)5vf {f to d
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w This is an informal report intended for use as a preliminary or working document 4
Prepared for the U.S. Nuclear Regulatory Commission Under DOE Contract No. DE-AC07-76ID01570 FIN No. A6425 g
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- c. u ni INTERIM REPORT Accession No.
Report No. EGG-EA-5671 Contract Program or Project
Title:
Electrical, Instrumentation, and Control Systems Support for the Systematic Evaluation Program (II)
Subject of this Document:
Systematic Evaluation Program Topic VI-4, Electrical, Instrumentation, and Control Aspects of the Override of Containment Purge Valve Isolation, Big Rock Point Plant Type of Document:
Informal Report Author (s):
A. C. Udy Date of Document:
November 1981 Responsible NRC Individual and NRC Office or Division:
Ray F. Scholl, Jr., Division of Licensing This document was prepared primarily for preliminary or internal 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.
Prepared for the U.S. Nuclear Regulatory Commission Washington, D.C.
Under DOE Contract No. DE-AC07 7SID01570 NRC FIN No. A6425 t
INTERIM REPORT l
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0 SYSTEMATIC EVALUATION PROGRAM TOPIC VI 4 ELECTRICAL, INSTRUMENTATION, AND CONTROL ASPECTS OF THE OVERRIDE OF CONTAINMENT PURGE VALVE ISOLATION BIG ROCK POINT PLANT Docket No. 50-155 November 1981 A. C. Udy Reliability and Statistics Branch Engineering Analysis Division EG&G Idaho, Inc.
e ABSTRACT This SEP technical evaluation, for the Big Rock Point Plant, reviews the design capacity of the electrical, instrumentation, and control systems of the containment ventilation isolation system and other related engineered safety feature functions.
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 & Statistics Branch.
The U.S. Nuclear Regulatory Commission funded the work under the authorization B&R 20-10-02-05, FIN A6425.
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C6T; TENTS 1
1.0 INTRODUCTION
0 I
2.0 EVALUATION OF THE BIG ROCK POINT PLANT..........................
2.1 Review Gu.idelines.........................................
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2.2 Cont 2cnment Ventilation Isolation Circuits Design 2
Description...............................................
2.3 Containment Ventilation Isolation System Design Evaluation................................................
3 2.4 Other Related Engineered Safety Feature System Circuits..................................................
3 4
3.0
SUMMARY
4.0 REFERENCES
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SYSTEMATIC EVALUATION PROGRAM TOPIC VI-4 ELECTRICAL, It!STRUMENTATION, AND CONTROL ASPECTS OF THE OVERRIDE OF CONTAINMENT PURGE VALVE ISOLATION BIG ROCK POINT PLANT
1.0 INTRODUCTION
Based on the information supplied by the Consumers Power Company (CPCo), this report addresses the electrical, instrumentation, and control systems design aspects of the Containment Ventilation Isolation (CVI) system and other related Engineered Safety Feature (ESF) functions for the Big Rock Point Plant.
Several instances have been reported where the automatic closure of the containment ventilation or purge isolation valves would not have occur-red because the safety actuation signals were manually overridden or blocked during normal plant operations. Lack of proper management controls, pro-cedural inadequacies, and circuit design deficiencies contributed to these instances. These events also brought into question the mechanical oper-ability of the valves themselves. These events were determined by the Nuclear Regulatory Commission (NRC) to be an Abnormal Occurrence (#78-05) and, accordingly, were reported to Congress.
The NRC is now reviewing the electrical override 6spects of containment purging and venting for all operating reactors. On November 28, 1978, the NRC issued a letter, " Containment Purging During Normal Plant Operation" to all Boiling Water Reactor and Pressurized Water Reactor licensees. This required a review of these systems by the licensee. CPCo responded on 19782 stating that the revi6w was in process. On Septem-December 29,3 ber 11, 1979 and March 14, 1980,4 CPCo supplied analysis and circuit details for this review. CPCo supplied additiondl information for this review on September 24, 1981.5 2.0 EVALUATION OF THE BIG ROCK POINT PLANT 2.1 Review Guidelines. The intent of this evaluation is to determine if the actuating signals for the ESF equipment meet the following NRC criteria:
1.
Guideline No. 1--In keeping with the requirements of General Design Criteria 55 and 56, the over-ridea 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.,
a.
The following definition is given for clarity of use in this evaluation:
j 1
l Override:
the signal is still present, and it is blocked in order to l
perform a function contrary to the signal.
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pressure) for those valves that have no function besides containment isolation.
2.
Guideline No. 2--Sufficient physical features (e.g.,
t key lock switches) are to be proviced to facilitate adequate administrative controls.
3.
Guideline No. 3--A system level annunciation of the overridden status should be provided for every safety system impacted when any override is active.
Additionally, this review uses the following NRC design guidelines:
1.
Guideline No. 4--Diverse signals should be provided to initiate isolation of the containment ventilation system. Specifically, containment high radiation, safety injection actuation, and containment high pres-sure (where containment high pressure is not a portion of safety injection actuation) should automatically initiate CVI.
2.
Guideline No. 5--The instrumentation and control systems provided to initiate the ESF should be designed and qualified as safety grade equipment.
a of the 3.
Guideline No. 6--the overriding or resetting ESF actuation signal should not cause any valve or damper to change position.
Guideline 6 in this review applies primarily to other related ESF f
systems because implementation of this guideline for containment isolation will be reviewed by the Lessons Learned Task Force, based on the recomien-dations in NUREG-0578, Section 2.1.4.
When containment isolation is not involved, consideration on a case-by-case basis of automatic valve reposi-tioning upon reset may be considered acceptable. Acceptability would be dependent upon system function, design intent, and suitable operating pro-cedures.
'2.2 Containment Ventilation Isolation Circuits Design Description.
The containment purge and vent isolation valves use solenoid-operated pilot valves for actuation. Loss of power or instrument air pressure will cause the isolation valves to close. Automatic closure of the isolation valves will occur on any of the following signals:
reactor scram, containment highpressure,lowreactorwaterlevel(thesamesetpgintusedforcore spray), containment high radiation'and loss of power.
The purge and vent isolation valves are also used for containment c
vacuum relief. The control system will not adversely affect both series a.
The following definition is given for clarity of use in this evaluation:
Reset:
the signal has come and gone, ar.d the circuit is being cleared in order to return it to the normal condition.
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i valves concurrently on a single random failure. However, the system will override any signal that closes the containment ventiletion isolation valves.
It is not expected that a vaccum condition will exist concurrent with a design basis accident. Even in long term cooling, should the vacuum relief system operate, the air flow would be into containment. -Therefore, no radiation would escape while the vacuum is being relieved. The valves reclose, due to the same signal, when the. vacuum has been relieved.
2.3 Containment Ventilation Isolation System' Design Evaluation.
Guideline 1 requires that no signal override can prevent another safety actuation signal from functioning. The Big Rock Point Plant has no manual override of the isolation' signal for the containment ventilation isolation valves. This guideline is satisfied.
Guideline 2 requires that reset and override switches have physical provisions to aid in the administrative control of these switches. With no 1
override possible for the containment ventilation isolation valves, this guideline is not applicable.
Guideline 3 requires system level annunciation whenever an override affects the performance of a safety system. This guideline'is also not j
applicable to the containment ventilation isolation valves.
f Guideline 4 requires that isolation of the CVI valves be actuated by several diverse signals. This guideline is met in that:
i 1.
Reactor scram, i
2.
Containment high pressure, 3.
Law reacter water level (this also actuates the core spray system),
J 4.
Containment high radiation and 5.
Loss of power all will cause the containment ventilation isolatio.n valves to close.
Guideline 5 requires that isolation actuation signals be derived from qualifiedsafety-gradeequipment.jcatesthatallarederivedfromfully safety grade equipment. CPCo ind The radiation monitors, when described, were "not class lE" equipment.5 SEP Topic III-12 will further examine the environmental qualifications of the radiation monitors.
i Guideline 6 requires that no reset of isolation logic will automatic-ally open the isolation valves. CPCo indicates that after the initating 2
isolation signal is cleared, that no isolation valve will atomatically i
reopen.
This guideline is satisfied.
2.4 Other Related Engineered Safety Feature System Circuits. A review of other related ESF circuits was also made.- Control switches that are pull-to override, are used for the functions a) reactor emergency cooling back-up 3
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spray valves, b) reactor building emergency spray valve, c) reactor gency cooling spray valves and d) emergency condenser. outlet valves.gmer-These circuits have been modified 't'o provide annunication upon an ovtreide 5
. condition and now comply with the applicable guidelines.
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l No other manual overrides in existing' circuits.have been identified in
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the review of-the material submitted for this audit.
3.0 '
SUMMARY
~
The NRC issued a letter, " Containment Purging During Normal Plant Operation," which requested CPCo to revi2w purging requirements, controls, and procedures for purging at the Big Rock Point Plant.
The electrical, instrumentation, and control design aspectsaof the containment ventilation isolation valves for the Big Rock Point Plant were evaluated using the design guidelines stated in Section 2.1 of this report.
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' Except-for non-class lE radiation monitors, these guidelines -are satisfied.
SEP Topic III-12 will examine the environmental qualifications of the radi-ation monitors.
4.0 REFERENCES
l 1.
NRC/ DOR letter (A..Schwencer) to CPCo and all BWR and PWR licensees,
" Containment Purging During Normal Plant Operation," dated November 28, 1978.
2.
CPCo Ietter, D. A. Bixel to Director, Nuclear Reactor Regulation, NRC, i
" Containment Purging During Normal Plant Operation," December 29, 1978.
3.
CPCo letter, D. A. Bixel to Director, Nuclear Reactor Regulation, NRC, "Results of Review of Safety Circuit Overrides," September 11, 1979.
4.
CPCo letter, D.'P. Hoffman to Director, Nuclear Reactor Regulation, j
NRC, " Containment Purge System, Single Failures," March 14, 1980.
1 5.
CPCo letter, R. A. Vincent to Director, Nuclear Reactor Regulation, NRC, "SEP Topic VI-4, Containment Isolation System," September 24, 1981.
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