ML17258A729
| ML17258A729 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 01/12/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17258A728 | List: |
| References | |
| TASK-06-04, TASK-6-4, TASK-RR NUDOCS 8101280423 | |
| Download: ML17258A729 (13) | |
Text
ENCLOSURE SAFETY EVALUATION REPORT GINNA PLANT OVERRIDE OF CONTAINMENT PURGE ISOLATION AND OTHER ENGINEE D S FETY FE TURE C
U 10N SIGNALS Introduction As a result of Abnormal Occurrence 878-5, the NRC issued a generic letter requesting each licensee to take certain actions.
Evaluation The enclosed report was prepared for us by EG&G, Idaho, as part of our technical assistance program for SEP.
This report provides a technical evaluation of the electrical, instrumentation and control design aspects of the override of containment purge valves isolation and other engineered safety feature actuation signals and is based upon review of these design aspects against the six NRC criteria provided for the review.
The technical evaluation concludes that the modifications made by the licensee at the plant have not brought the designs into conformance with our review criteria.
Conclusion Based upon our review of the consultant's technical evaluation, we, conclude that the electrical, instrumentation and control design aspects of the override of containment purge valves isolation and other engineered safety feature actuation signals are not acceptable, The licensee must promptly modify his design such that:
1.
For the override capability for individual containment isolation valves:
(a)
Manual isolation is never bypassed, and (b)
Only high containment radiation or safety injection signal, but not both, are bypassed by a single operation action of a switch, 2.
An annunciation is activated when a bypass condition is established, and 3.
The feedwater isolation valve control system prevents valve motion when the isolation logic is reset or overridden,
We also require that the licensee commit to replace the containment radiation channels that initiate containment isolation when Regulatory Guide 1.141 is approved by the NRC.
The staff also disagrees with the contractor and has concluded that, with the exception of the feedwater isolation valves, the modifications made as a result of the Lessons Learned from TNI provide adequate augmentation of the administrative controls against reopening containment isolation valves.
In that this review was initiated as a follow-up to an Abnormal Occurrence and the deficiencies identified in this review are both numerous and significant, we recommend that immediate corrective action be required of the licensee.
1947F SEP TECHNICAL EVALUATION TOPIC VI-4 ELECTRICAL) INSTRUMENTATION) AND CONTROL ASPECTS OF THE OVERRIDE OF CONTAINMENT PURGE VALVE ISOLATION R. E.
GINNA NUCLEAR POWER PLANT Docket No. 50-244 Draft 10-16"80
As a result of the short-term lessons
- learned, the CVI valve control circuits have been modified to provide individual resetting of each isola-tion valve.
Resetting a valve after automatic closure now requires opera-tion of a key-locked reset switch and a valve reset (guarded) pushbutton switch.
The valve then goes to the position the valve control circuit requires.
Administrative procedure requires the valve controller to be in the closed position before resetting the valve logic.
2.3 Containment Ventilation Isolation S stem Desi n Evaluation.
Guideline 1 requires that no signal override can prevent another safety actuation signal from functioning.
Ginna has override provision in the reset switches.
The override is over the safety injection signal and the radiati.on signal, as well as manual actuation.
Additionally, since high containment pressure is part of the safety injection signal, it is also overridden.
This design is not in conformance with this guideline.
Guideline 2 requires that reset and override switches have physical provisions to aid in the administrative control of these switches.
The reset switches are keylocked.
The individual valve reset switches are guarded.
This guideline is satisfied.
Guideline 3 requires system level annunciation whenever an over-ride affects the performance of a safety system.
This guideline is not satisfied by the Ginna design; however, individual status lights moni-tor the status of each individual valve override.
Guideline 4 requires that isolation of the CUI valves be actuated by several diverse signals.
This requirement i.s met in that:
1.
Safety injection will initiate isolation.
2.
High pressure in the reactor building will ini:tiate safety injection.
3.
High-level radiation trips will initiate isolation.
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Guideline 5 requires that isolation actuation signals.'be derived from safety grade equipment.
The radiation monitors used to initiate isolation are not class lE equipment.
This guideline is not completely satisfied.
Guideline 6 requires that no reset of isolation logic will, of itself, automatically open the isolation valves.
While an attempt was made to comply with the guideline as a result of short-term lessons
- learned, opera-ting procedures are still required at the Ginna station to return the indi-vidual valve controllers to the closed position prior to resetting the individual valve isolation logic.
This is not in compliance with this guideline.
2.4 Other Related En ineered Safet Feature S stem Circuits.
Guide-line 1 requires that no signal override can prevent another safety actuation signal from functioning.
Manual containment spray and manual containment isolation are prevented from functioning when an override is established.
The NRC should require RGE to make the circuit changes necessary
.so the Ginna plant will conform to guideline l.
Guideline 2 requires that reset and override switches have physical provision to aid in the administrative control of these switches.
Other ESF override (reset) switches are pushbutton, with no physical restraint.
The NRC should require that RGE install any additional provisions needed to conform to guideline 2.
Guideline 3 requires system level annunciation whenever an override affects the performance of a safety system.
RGE feels that annunciation is not necessary, "since the reset remains actuated only if the input signals causing the automatic safety actuation signal persist."
Therefore, the Ginna plant does'ot annunciate when an override is established.
The HRC should require that RGE provide the annunciation needed to conform to guideline 3.
Guideline 6 requires that no reset of isolation logic will, of itself, automatically open the isolation valves.
The main feedwater isolation valvaes do not conform with this guideline.
The NRC should require RGE
to make the circuit changes necessary so that guideline 6 is conformed with at the Ginna plant.
No other manual overrides have been identified in 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 RGE to review purging requirements,
- controls, and procedures for purging at the R. E. Ginna Nuclear Power Plant.
The electrical, instrumentation, and control design aspects of the containment ventilation isolation valves for the Ginna station were evalu-ated using the design gudelines stated in Section 2.1 of this report.
These guidelines are satisfied except:
1.
The override capability for individual valves overrides all automatic and manual isolation signals.
2.
Audible annunciation is not provided when this override is established.
3.
The radiation channels used to initiate isolation of the CVI system are not qualified as class 1E equipment.
4.
The valve control system is not interlocked with the isolation reset control system to adequately (i.e., not rely on administrative procedures) prevent valve motion when the isolation logic is reset or overridden.
The NRC should require that these deficiencies be corrected.
Other ESF systems have deficiencies as outlined in Section 2.4.
The NRC should also require that these be corrected.
4.0 REFERENCES
1.
NRC/DOR letter, A. Schwencer, to RGE and all BWR and PWR licensees, "Containment Purging During Normal Plant Operation," dated November 28, 1978.
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2.
RGE letter, L. D. White> Jr., to Director of Nuclear Reactor Regula-tion, U.S.
NRC, "Containment Purging During Normal Plant Operations,"
January 2, 1979.
3.
RGE letter, L. D. White, Jr., to Director of Nuclear Reactor Reg61a-tion, U,S.
NRC, "Review of Safety Actuation Circuits with Overrides,"
February 16, 1979.
4.
RGE letter, L. D. White, Jr.,
to Director of Nuclear Reactor Regula-tion, U.S.
NRC, "Review of Safety Actuation Circuits with Overrides,"
March 30, 1979.
5.
RGE letter, L. D. White, Jr.,
to Director of Nuclear Reactor Regula-tion, U.S.
- NRC, "SEP Topic VI-4, Containment Isolation System,"
March 17, 1980.
6.
Drawing, Westinghouse Logic Diagram No. 882D612 Sheet 6
Revision 5
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Safeguards Actuation Signals."
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CONTENTS 1 ~ 0 INTRODUCTION e
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2 ~ 0 EVALUATION OF THE R E ~
G INNA NUCLEAR POMER PLANT
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2 2.1 2.2 2.3 2.4 Review Guidelines Containment Ventilation Description Containment Ventilation Evaluation Other Related Engineered
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Safety Feature System Circuits 4
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2 Isolation Circuits Design
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3 Isolation System Design
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4.0 REFERENCES
6 1'1
SEP TECHNICAL EVALUATION TOPIC VI-4 ELECTRICAL, INSTRUMENTATION, AND CONTROL ASPECTS OF
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THE OVERRRIDE OF CONTAINMENT PURGE VALVE ISOLATION R. E.
GINNA NUCLEAR POWER PLANT
1.0 INTRODUCTION
Based on the information supplied by the Rochester Gas and Electric Company (RGE) this report addresses the electrical, instrumentation, and control system design aspects of the Containment Ventilation Isolation (CVI) system and other related Engineered Safety Feature (ESF) functions for the Ginna 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 opera-bility of tne valves themselves.
These events were determined by the Nuc-lear Regulatory Commission (NRC) to be an Abnormal Occurrence (878-05) and accordingly, were reported to Congress.
The NRC is now reviewing the electrical override aspects 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, which required a review of these systems by the licensee.
RGE responded on February 16, 1979
, March 30, 1979
, and March 17, 1980
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o Safety Analysis Report (FSAR) and Westinghouse Drawing No. 882D612,'Sheet 6 6 also contain design information reviewed for this report.
2.0 EVALUATION OF THE R. E. GINNA NUCLEAR POWER PLANT 2.1 Review Guidelines.
The intent of this evaluation is to determine if the actuating signals for the ESF equipment meet the following kRC requirements:
1.
Guideline No.
1In 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'he blocking of any other type of safety actuation signal (e.g.,
pressure) for those valves that have no function
.besides containment isolation.
2.
Guideline No.
2Sufficient physical features (e.g.,
key lock switches) are to be provided 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:
Guideline No. 4Diverse 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.
5The instrumentation and control systems provided to initiate the ESF should be designed and qualified as safety grade equipment.
3.
Guideline No.
6the overriding or resettinga of the ESF actuation signal should not cause any v'alve or damper to change position.
a.
The following definitions are given for clarity of use in this evaluation:
Override:
the signal is still present, and it is blocked in order to perform a function contrary to the signal.
Reset:
the signal has come and gone, and the circuit is being cleared in order to return it to the normal condition.
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Guideline 6 in this review applies primarily to other related ESF systems because implementation of this guideline for conta'inment isolation will be reviewed by the Lessons Learned Task Force, based on the recom-mendations in NUREG-0578, Section 2.1.4.
Mhen containment isolation is not involved, consideration on a ease-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 procedures.
2.2 Containment Ventilation Isolation Circuits Desi n Descri tion.
Automatic closure of the four containment purge valves, the two containment depressurization
- valves, and the two radiation monitor valves will occur on any of the following conditions 1.
High containment radiation 2.
Safety injection signal (high containment pressure can initiate a safety injection signal).
RGE has indicated that these signals are derived from equipment "designed and constructed as a class 1E system."
- However, the radiation channels have not been shown to be class 1E.
These eight valves (except for the radiation monitor valves) are air-operated butterfly valves and are used so that one is redundant for another on the same air line.
Valve position lights show the actual valve posi-tion.
The solenoid valves fail closed on loss of air or on loss of power.
The radiation monitor valves are air-operated diaphragm valves which have either a check valve or a manual valve for redundancy.
7 The logic of the. containment isolation and the CVI valves is shown in reference 6.
In both systems, the manual actuation is overridden alon'g with the automatic actuation signals by operation of a reset switch (one per safeguards train).
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