ML20084E676
| ML20084E676 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 01/31/1984 |
| From: | Jacoby K, Kountanis B ENERGY ENGINEERING GROUP |
| To: | NRC |
| Shared Package | |
| ML20084E669 | List: |
| References | |
| CON-FIN-A-0231, CON-FIN-A-231 EGG-1183-4217, EGG-1183-4217-R01, EGG-1183-4217-R1, NUDOCS 8405020443 | |
| Download: ML20084E676 (12) | |
Text
EGG 1183-4217 May 1981 n EUUU Revision 1 CCENERGY MEASUREMENTS GROUP January 1983 TECHNICAL EVALUATION OF THE ELECTRICAL, INSTRUMENTATION, AND CONTROL DESIGN ASPECTS OF THE OVERRIDE OF CONTAINMENT PURGE VALVE ISOLATION AND OTHER ENGINEERED SAFETY FEATURE SIGNALS FOR THE PILGRIM NUCLEAR POWER STATION, UNIT 1 (DOCKET NO. 50-293)
By K. D. Jacoby/B. Kountanis Approved for Publication AP Jf R. Radosevic, Department Manager t
This document is UNCLASSIFIED
. Derivative
' Classi fier: ) 6 y [y j N. E. Broderick, Department Manager 1
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ABSTRACT This report documents the technical evaluation of the electrical, instrumentation, and control design aspects of the override of containment purge valve isolation and other engineered safety feature signals for the Pilgrim Nuclear Power Station, Unit 1.
The review criteria are based on IEEE Std-279-1971 requirements for the safety signals to all purge and ventilation isolation valves.
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FOREWORO This report i s supplied as part of the Selected Electrical, Instrumentation, and Control Systems Issues (SEICSI) Program being con-ducted for the U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, Division of Operating Reactors, by Lawrence Livermore Laboratory, Field Test Systems Divi sion of the El ectronics Engineering Department.
The U.S. Nuclear Regulatory Commission funded the work under an authori zation entitled "El ectrical,
Instrumentation and Cont rol System Support," B&R 20 19 04 031, FIN A-0231.
Work for revision 1 was authorized
' by FIN A-0250. - Revised portions are identified by vertical marks in the margin.
The work was performed by EG8G, Inc., Energy Measurements Group,
- San Ramon Operations, for Lawrence.Livermore Laboratory under U. S. Depart-ment of Energy contract number DE-AC08-76NV01183.
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TABLE OF CONTENTS Page 1.
INTRODUCTION.
1 2.
EVALUATION OF PILGRIM NUCLEAR POWER STATION, UNIT 1.
3 2.1 Review Criteria 3
2.2 Containment Ventilation Isolation Circuits Design Description 4
2.3 Containment Ventilation Isolation System Design Evaluation.
5 2.4 Other Engineered Safety Feature System Circuits 6
3.
CONCLUSIONS.
9 REFERENCES.
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a TECHNICAL EVALUATION OF THE ELECTRICAL, INSTRUMENTATION, AND CONTROL DESIGN ASPECTS OF THE OVERRIDE OF CONTAINMENT PURGE VALVE ISOLATION AND OTHER ENGINEERED SAFETY FEATURE SIGNALS FOR THE PILGRIM NUCLEAR POWER STATION, UNIT 1 (Docket'50-293)
K. D. Jacoby/B. Kountanis EG&G, Inc., Energy Measurements Group, San Ramon Operations 1.
INTRODUCTION Several instances have been reported where automatic closure of the containment ventilation / purge valves would not have occurred because the safety actuation signals were either manually overriden or blocked during normal pl ant operations.
These events resulted from procedural inadequacies, design deficiencies, and lack of proper management controls.
These. events also-brought into question the mechanical operability of the containment isolation valves themselves.
These events were determined -by
.the U.S. Nuclear Regulatory Commission (NRC) to be an Abnormal Occurrence
(#78-5) and were, accordingly, reported to the U.S. Congress.
As a foll ow-up on this Abnormal Occurrence, the NRC staff is reviewing the electrical override aspects and the mechanical operability aspects of containment purging for all operating power reactors.
On November 28, 1978, the NRC issued a' letter entitled " Containment Purging
'During Normal Plant Operation" [Ref.1] to all boiling water reactor (BWR) and pressurized water reactor (PWR) licensees.
In a letter [Ref. 2] dated January 9,1979, the Boston Edison Company (BECo), the licensee for the Pilgrim Nuclear Power Station, Unit 1, replied to the NRC generic letter.
_ The evaluation of other eng.ineered safety feature (ESF) systems was sub-mitted in response to I&E Bulletin 79-08 [Ref. 3].
The licensee met [Ref.
4] with the NRC in Bethesda, M.D.,
on December 11, 1979, to discuss this
. issue further.
References 5 through 12 list the - additional correspondence be-tween-the NRC and the licensee on this subject.
Reference 13 is a conference call made to the licensee to discuss this subject.
This document addresses only the electrical, instrumentation, and control- (EI&C) design aspects of the containment ventilation isolation
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2.
EVALUATION OF PILGRIM NUCLEAR POWER STATION, UNIT 1 2.1 REVIEW CRITERIA The primary intent of this evaluation is to determine that the following NRC staff criteria are met for the safety signals to all ESF equipment:
(1)
Criterion no.1 - In keeping with the requirements of General Design Criteria 55 and 56, the overriding
- 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.,
pressure) for those valves that have no function besides containment isolation.
(2)
Criterion no. 2 - Sufficient physical features (e.g.,
keylock' switches) are to be provided to facilitate adequate administrative controls.
(3)
Criterion no. 3 - A system-level annunciation of the overridden status should be provided for every safety system impacted when any override is active.
(See R.G. 1.47).
Incidental to this review, the. following additional NRC design criteria were used in the evalution:
(1)
Criterion 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 pressure (where containment hi gh : pressure is not a portion of safety injection actuation) should auto-matically initiate.CVI.
(2)
Criterion no. 5 - The instrumentation and control systems ~ provided to initiate the ESF should be de-signed and qualified as safety-grade equipment.
- The following definition is 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.
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2 (3)
Criterion no. 6 - The overriding or resetting
Criterion 6 in this review applies primarily to other related ESF systems because implementation of this criterion for containment isolation has been reviewed by the Lessons Learned Task Force, based on the recom-mendations in NUREG-0578 Section 2.1.4 [Ref.14].
Automatic valve reposi-tioning upon. reset may be acceptable when containment isol ation is not involved; consideration will be given on a case-by-case basis.
Accept-ability would be dependent upon system function, design intent, and suit-able operating procedures.
2.2 CONTAINMENT VENTILATION ISOLATION CIRCUITS DESIGN DESCRIPTION Pilgrim Nuclear Power Station, Unit 1, has two ESF trains which can cause isolation of the containment ventilation system, which is labeled Primary Containment Isolation System (PCIS) on this unit.
One train con-trols the inboard containment ventilation / purge isolation valves, and the other train controls the outboard isolation valves.
The initiating con-tacts for each train are described below:
(1)
Automatic Contacts (all one-out-of-two, - taken twice logic)
(a)
Refueling 1 floor ventilation exhaust high radia-tion (b)
High drywell pressure (c)
Low reactor water level 3
(d)
Reactor building high radiation 5
(2)
Manual Contacts (a)
Keylock system-level _ switches-(b)
Individual PCIS valve manual switches The relays for each of the _ monitored plant conditions havb con-
. tacts ini each of the t'wo trains that control the PCIS valves.
Each train is powered by a different - electrical ' bus..
The PCIS circuits contain a reset switch, which returns the circuit to the normal condition once the initiating signal is no longer present.
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- The following definition is given for clarity of use in this. evaluation:
Reset:
The signal has 'come and gone, and the circuit is being cleared to return'it to the normal condition.
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When a monitored pl ant condition calls for isolation, electric power is removed from the actuation relays (e.g., relay RPWAO), which in turn provides electric power to operate the slave relays (e.g.,
relay RPWA1).
The slave relay contacts open to remove electric power from the solenoid valves, causing the isolation valves to close.
The slave relay circuit contains a seal-in contact which main-tains this relay in an energized state after it has received a trip signal, until the initiating condition has been corrected and the system has been reset.
With the slave relay energized, the PCIS valves will remain closed and cannot be opened even by their manual switches (with the exception of the valves in the bypass circuit described below).
There are four valves which can be opened by overriding an isola-tion signal.
These are the two isolation valves in series in a two-inch line venting the suppression chamber and two isolation valves in series in a two-inch line venting the drywell to the Standby Gas Treatment System.
The control logic for these valves allows an override of the contairment isolation signal if the keylock control switches for these valves are in the " emergency open" position.
With the switches in this position, how-ever, the valves will reisolate upon receipt of a low-low reactor water trip signal.
The PCIS signal cannot be cleared until the initiating ccq-dition(s) is cleared.
When all initiating conditions are cleared, the system may be reset by first placing the manual switches for each of the following valves -into the " closed" position:
drywell and torus air inlet valves; drywell and :orus nitrogen inlet valves; and, drywell and torus exhaust valves (all two-inch and 20-inch valves).
Once these control switches have all Nen placed in the " closed" position, the reset switches may momentarily be switched to the " reset" position to reset the system.
Upon system reset, the valves listed above will not reopen until their control switches are-returned to the "open" position.
All 'other PCIS valves will reopen, however, upon reset of the system if their control switches are left in the "open" position.
2.3 CONTAINMENT VENTILATION ISOLATI0' SYSTEM DESIGN EVALUATION The PCIS actuation system has a reset switch, but does not have-an override capability.
However, four of the PCIS valves can be opened by overriding an isolation signal as discussed in Section 2.2.
This override will cause the blocking of all other types of' safety ' actuation si gnal s,
with the exception of reactor low-low water level.
The four valves which -can. be opened by overriding an isolation I
signal are two isolation valves (SV5041A and SV5041B) in series in a two-J
_ inch line venting the suppression chamber and two _ isolation valves (SV5043A
)
and -SV5043B)'in series in a two-inch line venting the _drywell to the Stand-J by Gas Treatment System.
The control logic _ for these valves allows an j
override 'of the containment isolation signal if the keylock control 2
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2 switches for these valves are in the " emergency open" position.
With the switches in this position, however, the valves will reisolate upon receipt of a low-low reactor water trip signal.
After reviewing the material submitted by the licensee, we recom-mend that the licensee:
1) remove the bypass of the automatic isolation signals;
- 2), show-that the low-low-water level isolation signal provides all the protection required by the criteria when the normal isolation signals are bypassed; or 3) modify the design to ' satisfy' review criterion number 1.
The existing PCIS signal override (" emergency open") for those valves which have the override capability uses a keylock control switch.
We conclude that NRC staff criterion no. 2 regarding physical features that facilitate _ administrative controls is satisfied by this design.
The PCIS signal override 'for those valves which have' the override capability is annunciated.
We conclude that NRC staff criterion no. 3 is satisfied.
The PCIS automatic _~ actuation signal is derived from diverse s.i g nal s.
. Currently,. no containment radiation monitoring instrumentation which provides a signal to the PCIS-is installed at Pilgrim, Unit 1.
As a result of this review, the licensee stated that they plan to install
-safety-grade radiation monitors which will. provide a signal to the PCIS
[Ref. 123 Based on this commitment, we. conclude' that NRC staff criterion no. 4 will be satisfied.
The licensee-indicated [Ref.11] that the instrumentation chan-nels and logic associated with the PCIS are safety.-grade. 'We conclude that NRC staff criterion no. 5 is. satisfied.
When all initiating isolations conditions have-been cleared, and when ' the control' switches for the - drywell' and torus. air inlet valves, drywell and. torus nitrogen inlet valves, and.drywell and torus' exhaust valves 'have been placed in the " closed". position, the > PCIS actuation. signal can be-reset.
Upon ' resetting, any of the other -PCIS = valves '_with their manual., switch left in the "open"- position - will automatically reopen.
The
-PCIS reset 11ogic will be evaluated by the 'NRC staff as - part of-the I&E -
Bulletin 80-06 review; therefore, no conclusions regarding: compliance with NRC staff criterion no. 6.will-be made in this report.
2d
- OTHER ENGINEERED SAFETY FEATURE SYSTEM CIRCUITS As.part of this review, the-High Pressure _ Core Injection (HPCI)-
system was selected'for evaluation.. It was: determined from the information-
. submitted; by;the licensee' that both :the ' HPCI ' auxiliary Loil ~ pump andt the -,
HPCI gland seal condenser blower will stop once the initiating signal is no longer present and the reset pushbutton is depressed, returning the circuit
.to the normal condition.
We conclude that all criteria except criterion no. 6 are satisfied for HPCI.
4 The HPCI reset logic will be evaluated by the NRC staff as part of the I&E Bulletin 80-06 review as will the reset logic for other ESFs.
Therefore, no conclusions regarding compliance with NRC staff criterion no.
6 will be made in this report.
On the basis of this audit review, we conclude that there is reasonable assurance that other ESF systems comply with the remaining NRC staff criteria.
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CONCLUSIONS The EISC design aspects of containment purge valve isolation and other ESF signals for the Pilgrim Nuclear Power Station, Unit 1,
were evaluated using those design criteria stated in Section 2.1 of this report.
We conclude that the licensee should take appropriate action regarding the four isolation valves described in Section 2.3 so that the l
PCIS system will satisfy review criterion number 1.
As discussed in Section 2.4 of this report, separate evaluation will be made by the NRC staff for criterion no. 6 as applicable to HPCI.
Therefore, no conclusions regarding compliance with this criterion were made in this report.
For the purposes of this report, we conclude that, with the installation of the safety-grade radiation monitors committed to by the licensee and with appropriate action on the PCIS, both the PCIS and the other ESFs will meet all the NRC staff criteria.
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REFERENCES 1.
NRC letter (A. Schwencer) to Boston Edison Company (BECo), "Contain-ment Purging During Normal Plant Operation," dated November 29, 1978.
2.
BECo letter (G. C. Andognini) to NRC (T.
A.
Ippolito), " Containment Purging During Normal Plant Operation," dated January 9,1979.
3.
BECo letter (G. C. Andognini) to NRC (B. H. Grier), " Response to I&E Bulletin 79-08," dated April 25, 1979.
4.
NRC memorandum (J.
N.
Hannon) to distribution, " Meeting Summary,"
dated December 13, 1979.
5.
BECo Letter (G. C. Andognini) to NRC (T. A. Ippolito), " Supplementary Information to I&E Bulletin 79-08," dated August 21, 1979.
6.
BECo letter (G. C. Andognini) to NRC (T. A. Ippolito), " Supplemental Response to ISE Bulletin 79-08," dated November 6,1979.
7.
BEco letter (J. E. Howard) to NRC (T. A. Ippolito), " Interim Positions for Containment Purge and Vent Valve Operation," dated December 19, 1979.
8.
BEco letter (G. C. Andognini) to NRC (D. G.
Eisenhut), " Containment Purge and Vent Valve Operability," dated May 27, 1980.
9.
BECo letter (G. C. Andognini) to NRC (T. A. Ippolito), " Supplemental Response to Containment Purge and Vent System Mechanical Review Ouestions," dated May 27, 1980, 10.
BECo letter ( A. V. Morisi) to NRC (T. A. Ippolito), " Additional In-formation on Bypass and Reset on Engineered Safety Features," dated September 28, 1980.
11.
BECo letter ( A. V. Morisi) to NRC (T. A.
Ippolito), " Supplement to Information on Bypass and Reset of Engineered Safety Features," dated October 10, 1980.
12.
BEco letter (W. J. Merritt) to NRC (D. G. Eisenhut). "TMI NUREG 0737 Commitments," dated February 27, 1981.
13.
NRC. conference call with BEco and EG8G, subject: " Questions on CVI and Other ESF Circuit Designs," February 10, 1981.
14 U.S. Nuclear Regulatory Commission, "TMI-2 Lessons Learned Task Force Status Report and Short-Term Recomendations," NUREG-0578, published July 1979.
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