ML19254D735
| ML19254D735 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 02/28/1979 |
| From: | Cleveland C EG&G, INC. |
| To: | |
| Shared Package | |
| ML19254D733 | List: |
| References | |
| CON-FIN-A-6256 RE-A-79-045, RE-A-79-45, NUDOCS 7910300024 | |
| Download: ML19254D735 (9) | |
Text
RE-A-h-045 For U. 5. Nuclear Regula c:y co nission ATTACHMENT I CODE ASSESSMENT AND APPLICATIONS PROGRAM i
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2 Nfl TECHNICAL EVALUATION REPORT BIG ROCK POINT PLANT CONTAINMENT ISOLATION SYSTEM g
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Accession No.
Report No. RE-A-7e-045 Code Assessment and Applications Program Centract Program or Project
Title:
Technical Evaluation Report of Big Rock Point subject of this Document:
Containment Isolation System i
Code Assessment and Applications Technical Evaluation Rep:-
Type of Document:
Author (s):
C. J. Cleveland Date of Document:
February, 1979 Respensible NAC Individual and NRC Office or Division:
Paul Shemanski, NRC-DOR This document was prepared primarily icr prehminary or internal use. It has not received f ull review and approval. Since there may be substantive changes.this document should not be considered final.
EG&G Idaho. Inc.
Idaho Fa!!s. Idaho E3401 Prepare:: f:r t,e U.S. Nuclear Fegu.a 0. Cemrnission anc the U.S De:a me-t of Energy icanc Opera: :~.s Ofbce Unce* Contract Nc. EV-75-C-07-157C NR C P. '.c A6255 INTERIM REPORT "8
188
CONTENTS 1
1.0 INTRODUCTION
1 2.0 SINGLE FAILURE ANALYSIS GUIDELINES..,.............
2 3.0 EV ALU AT I O N.............
2 3.1 Mod if i c at i on s.......................
2 3.2 Dis cu ssien 5
4.0 CON CLUS ION. '..........................
5 REFERENCES.................'..........
5.0 N.
e 1
TECHNICAL EVALUATION REPORT SIG ROCK POINT PLANT CONTAINMENT ISOLATION SYSTEM 1.0 IN1RODUCTION Centained in this evaluation are the results of a single f ailure analysis of the Censumers Power Company's Big Rock Point nuclear plant These containment air supply and exhaust lines valve centrol circuits.
valves are used to block radioactive releases to the at:nosphere in the t
,ent (FH AIC).
event of a postulated fuel handling accident insice conta The Consumers Power Company, in May 1978, was requested to furnish additional information relating to the design of the containment isola-tion system (CIS) including a description as to what extent the system will comply with the current criteria for engineered safety systems The licensee's listed in the NRC Standard Review Plan, NUREG 75/087.
29,1978 (Reference 5) response letter and attachments dated November
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were reviewed in performing this evaluation.
2.0 SINGLE FAILURE ANALYSIS GUIDELINES Consumers Power Company was requested by the NRC to provide inf or,
mation relating to the engineered safety features available to mitigate This evaluation is based on the guidelines for performing a a FMAIC.
single f ailure analysis of instrumentation and control systems contain-ed in the NRC Standard Review Plan, Section 7.3 (NUREG 75/087; Refer-ence 1), as well as IEEE Standard 379-1977 (Reference 3) and Regulatory Guide 1.53 (Ref erence 2).
e:ui;: ment f ailures Exa ples of the specific tges :f system a :
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c:nsidered include (a) relay f ailures, (b) solenoi: f ailure4, ar.d (3) hot shorts, h
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190 I
3.0 EVALUATION Th.is section provides (a) a brief description of the containment isolation system design features. available at the Big Rock Point plant to mitigate the consequences of a FHAIC, and (b) a discussion of our single f ailure analysis of the system.
To mitigate a FHAIC the licensee has two (2) 3.1 Modifications.
series redundant contacts from two (2) containment radiation monitors which deenergize a relay (SVX5) causing two (2) series redundant con-tacts of th s relay to open the negative leg of the 125 V DC control power to Relays SVX1, SVX3, SVX6, and SVX4 (see Reference 5, Attach-The deenergization of these relays removes power to the air ment I).
inlet, exhaust, and f an control air valves causing them to f ail closed 5
and thus i,solating the containment.
Another modification was made to the CIS just prior to the FHAIC The licensee inTtaTied an automatic vacuum reli.ef system modificati on.
The circuitry for this vacuum relief system is for the containment.
integrated into the CIS system to open the inlet and exhaust isolation This valves which, in turn, relieve a vacuum to a preset pressure.
vacuum. relief circuitry will override an isolation signal from a FHAIC
or a SCRAM until the preset pressure of the vacuum relief system is s atisfi ed.
The two (2) series rtdundant sr7ely air valves and their associ-ated vacuum relief instruments, as well as the two (2) series redundant f an air sucply control valves are supplied from a single 125 V DC The two (2) series redundant air exhaust valves and their source.
ass:ciated vacuum relief instruments are supplied frem a single 120 V AC source.
T 3.2 Discussier.
Upon performing a single f ailure analysis of the C'. 5 sy s tar., several scstulate: f ailures we-e f ound that wculc creclude a c:ntai-ment isolation signa' resulting f-cm a FEAIC, Inus causing a It should be noted that the pessi:le release to the atmescherc, 2
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licensee, in his submittal and analysis (Reference 5), has recognized some single f ailures. These f ailures are mechanical f ailure of the solenoid valves, " hot shorts" in wiring to those solenoid valves, and stuck contacts of Relays SVX1, SVX2, SVX6, and SVX7.
The following single f ailures were found in the CIS:
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(1)
Solenoid valve malfunctions (a) A f ailure of any one of the air pilot solenoid val.es to close on deenergization would cause the related pair of isolation valves to remain This condition can' be the result of open.
foreign objects in the air supply; corrosion, or malfunctioning springs or plungers in the solenoid valve.
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(2) Occurrence of hot shorts (a) Although unlikely, the occurrence of a " hot short" in the control wiring could allow the solenoid valves discuss,ed in (1) above to remain energized or be:cce energized while an isolation signal is present.
(3) Relay failures
( a) A failure of the armature of Relay SVXS to open its contacts would bicci ; containment isolati:n signal. This ::tI: result if the amature or amature spring are to f ail
( b ';
If the cor. tacts of ei:be-Relay SVX1 cr SVX2, v".icn are paralisi, were ::.celd er st'.ek the inlet isciaticn vaives would remain
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(c) An amature or amature spring f ailure of Relays SYXI or SVX2 could cause their associ-ated contacts to remain closed and keep the inlet isolation valves open A welded or stuck contact of either of the (d) parallel contacts of Relays SVX6 or SVX7 or armature or amature spring f ailure of these relafs would cause the exhaust isolation valves to remain open.
t Because of the automatic vacuum rel'ef system circuits being integrated into and being para 11r.1 to the CIS system, there are several other single f ailures in the vacuum relief system that could block an isolatien These signai resulting from a FMAIC or a SCRAM signal.
include:
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2 304 a (1) Relay f ailures If either of the two (2) parallel contacts of (a)
Auxiliary Relay PI5X2, which are in parallel with the aforementioned relays SVXI and SVX2, or the contacts of Auxiliary Relay PI5XI were to weld or stick shut after the removal of a vacuum relief signal, a FHAIC signal would not close the inlet isolation valves An amature er amature spring f ailure of (b)
Auxiliary Relay FI5X1, PI5X2 could also cause their centacts nct to ocen.
t Vacuum relief instrument f ailures c 'nte-nal (a)
Stuck contacts, set point c-i#:,
f ailure cf Pressure Switch FIS173,,' vid necate 4
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an isolation signal and keep the inlet isola-tion valves open (b)
Stuck or welded contacts (6-4), set point drif t, or internal f ailure of' Pressure Switch PI5187 could defeat the isolation signal to the exhaust isoletion valves.
While the f an con
- ol air supply valves have not been adcressed by the licensee in his analysis, he has included them in the isolation circuit Contacts of Relay SVX4 could stick or become welded, or for a FHAIC.
the armature or amature spring could f ail causing the valves to remain cpen.
None,of the above cited f ailures can be manually overridden by any tripping the associated supply breake-or by discon-means short c,T necting an energized wire.
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4.0 CONCLUSION
As shown in Section 3.2, the lack of redundancy and independence it.the air supply and exhaust portion of the CIS and its integrated vacuum relief system leaves this system subject to numerous disabling single f ailures.
It b theref ore concluded that the design modifi-cations to the CIS to mitigate the consequences of a FHAIC do not meet the single f ailure criteria.
5.0 REFERENCES
U5t3C Standard Review P",an for the Review cf Safety Analysis Re-1.
ports f or Nuclear Power cl ants (Lk'R Editi cr', NUREG 75 /CS7, Sec-tien 7.3. Containment Isclation System.
Regulatcry Guide 1.53, Acolicaticn cf the Sin;'.e Failure Criterion 2.
to Nuclear Power Pian: Prctection Systems.
" 3 194 3
h Standard Application of the Single Failure IEEE Standard 379-1977, 3.
Criteria to Nuclear Power Generating Station Class IE Syste s.
10 CFR 50, Appendix A, General Design Criteria, Criterion 21, 4.
Protection System Reliability end Testability.
29, 1978 Consumers Power Company letter Sixel to Ziemann, November 5.
and attachments.
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N.
48 b
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CRITERIA FOR EVALUATION OF CONTAlfNENT PURGE SYSTEM ELECTRICAL DESIGN The primary intent of this evaluation is to determine if the following requirements are met for the safety signals to all purge and ventilation isclation valves:
(1) Overriding of one type of safety actuation signal (e.g.,
radiation) must not cause the blocking of any other type of safety actua' ion signal (e.g., pressure) to the
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isolation valves.
(2)
Sufficient physical feature s (e.g... key lock switches,)
are provided to facilitate adequate administrative controls.
(3)
System-level annunciation of the overridden status is provided for every safety sptem impacted when any override is active.
The following definitions are given for clarity of use in this evaluation:
(1)
Reset:
The signal has come and gone, and circuit is being cleared in order to return it to the normal condition.
(2)
Overri6:
The signal is still present, and it is blocked in order to perfonn a function contrary to the signal.
Incidental to this review, consideration was also given to the following:
(1)
Diverse signals should be pmvided to initiate isolation of the containment ventilation system.
Specifically, containment radia-tion, safety injection actuation, and containment pressure should automatically initiate CVI.
(2) The instrumentation and control systems provided to initiate CVI should,be designed and qualified as safety,-grade e:iuipment.
(3) The overriding or reseting of the isolation actuation sional should not cause the automatic.re-opening of any isolation /
purge valve.
" 3 196,
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