ML17083A319
| ML17083A319 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 04/01/1980 |
| From: | Stolz J Office of Nuclear Reactor Regulation |
| To: | Furbush M PACIFIC GAS & ELECTRIC CO. |
| References | |
| NUDOCS 8004240520 | |
| Download: ML17083A319 (20) | |
Text
District~ on:
] ]98O NRR Reading NSIC TIC TERA LWR 81 File D. F.
Ross D. B. Vassallo S.
A. Varga J.- F. Stolz B.
C. Buckley H. Rushbrook E.
G. Hylton ELD IE (3)
, ACRS (16)
APR Docket Nos:
0- 75 and 50-323
Dear Hr. Furbush:
Hr. Halcolm H. Furbush Vice President - General Counsel Pacific Gas 5 Electric Company 77 Beale Street San Francisco, California 94106 E ~ Christenbury, ELD Generic Ltr. File SUMECT:
POTENTIAL DESIGN DEFICIENCIES IN BYPASS, OVERRIDE, AND RESET CIRCUITS OF ENGINEERED SAFETY FEATURES-DIABLO CANYON 1
AND 2 Discussion Of Deficiencies Several instances have been reported where automatic closure of the containment ventilation/purge valves would not have occur red because the safety actuation signals were either manually overriden or bypassed (blocked) during normal plant opera'tions.
In addition, a related design deficiency with regard to the resetting of engineered safety feature actuation signals has been found at several operating facilities where, upon the reset of an ESF signal, certain safety related equipment would return to its non-safety mode.
Specifically, on Dune 25, 1978, Northeast Nuclear Energy Company discovered that intermittent containment purge operations had been conducted at Hillstone Unit No. 2 with the safety actuation signals to redundant containment purge isolation valves (48 inch butterfly valves) manually overriden and inoperable.
The isola-tion signals which are required to automatically close the purge valves to assure containment integrity were manually overriden to allow purging of containment with a high radiation signal present.
The manual override circuitry designed by the plant's architect/engineer defeated not on'1y the high radiation signal but also all other isolation signals to these valves.
To manually override a safety actuation signal, the operator cycles the valve control switch to the closed position and then to the open position.
This action energized a relay which blocked the safety signal and allowed manual operation independent of any safety actuation signal.
This circuitry was designed to permit reopening of certain valves after an accident to allow manual operation of required safety equipment.
OFFICE SURNAME
. DATE/...~.........
NRC FORM 318 (9 76) NRCM 0240
.............s.oops 4+ S.Q,o 4 U.Si GOVERNMENT PRINTING OFFICE: 1979.289.369 '
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1)
The overriding'f one type of safety acutation signal (e.g., parti-culate radiation) should not cause the blocking of any other type of safety actuation signal (e.g., iodine radiation, reactor pressure) for those valves that have no function oCher than containment isolation.
2)
Physical features (e.g., key lock switches) should be provided to en-sure adequate administrative controls.
3)
A system level annunciation of the overridden status should be provided for every safety system impacted when any override is acti ve.
(See Regulatory, Guide 1.47).
4)
The following diverse signals should be provided to initiate isolation of the containment purge/ventilation system:
containment high radiation, safety injection actuation, and containment high pressure (where con-tainment high pressure is not a portion of safety injection actuation).
5)
The instrumentation systems provided to initiate containment purge ventila-tion isolation should be designed and qualified to Class 1E criteria.
6)
The overriding or resetthng2 of the ESF actuation signal should not cause any equipment to change position.
Accordingly, you are requested to review your protection system design to deter-mine its degree of conformance to these criteria.
You should report the results of your review to us by April 5, 1980, describing any departures from the criteira and the corrective actions to be implemented.
Design departures for which no corrective action is planned should be justified.
Please advise ifyou have any questions on this matter.
This request for generic information was approved by GAO under blanket clearance number 8180225 (R0072).
This clear ance expires July 31, 1980.
Sincerely, 01 igirg3. sign o'g py
~'o.1-"1P. StO1 John F. Stolz, Chief Light l<ater Reactors Branch No.
'l Division of Project Management "See previous yel1ow for previous concurrence cc:
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order to return it to the normal condition.
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Q AS YOU CONPLETE YOUR REVIEW OF THE KENENY CONNISSION'S REPORT ON TNI-2 AND PREPARE RECONNENDATIONS FOR SUBNITTAL TO THE PRESIDENT>
I URGE THAT YOU CONSIDER A PROCEDURE TO PERNIT THE EARLY LICENSING OF THOSE NUCLEAR PLANTS WHICH WO'ULD NOW BE LICENSED BUT FOR THREE NILE ISLAND.o THERE.ARE SEVERAL POWER 'PLANTS CURRENTLY AWAITING.OPERATING LICE NSES
'FRON THE NRC I NCLUDI NG OUR ' I AB LO CANYON PLANTe THESE PLANTS WOULD IN ALL LIKELIHOOD BE OPERATING TODAY IF IT WERE NOT FOR THE ACCIDENT AND RESULTANT LICENSING DELAYS~
SEVEN YEARS AGO WE FILED FOR A N OPERATI NG LICENSE FOR UNIT
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THE PLANT HAS BEEN CHARACTERI'ZED BY THE ASLB AS THE NOST INTENSIVELY REV IEWED PLA NT I N HISTORY o WE HAVE ALREADY INITIATED CHANGES AS A RESULT OF LESSONS LEARNED ~
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THE PLANT MILL ENABLE US TO REDUCE OUR DEPEhDENCE UPON INPORTED OIL BY. 20 NILLIONBARRELS A YEAR WHEN BOTH UNITS ARE IN OPERA TIO No FURTHERNORE t DELAY COSTS 0 UR GUSTO NER S OVER $ 60 NILLI0 0 A NONTH IN ADDITIONAL COSTS ~
THANK YOU FOR YOUR CO NSID ERATIO N 0 F 'HiS INPORT ANT NATTER o BARTO N Mo S HAGKELFORD PRESIDENT AND CHIEF OPERATING OFFICER PACIFIC. GAS AND ELECTRIC CONPANY 77 BEALE STREET SF 1201 (R549)
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ter. Malcolm H. Furbush APR 1 ]gap On September 8, 1978, the-staff was advised that, as a matter of routine, Salem Unit No.
1 had been venting the containment through the containment ventilation system valves to reduce pressure.
In certain instances this venting has occurred with the containment high particulate radfatfon monitor isolation signal to the purge and pressure-vacuum relief valves overridden.
The ovenfde of this containment isolation signal was accomplished by re-setting the train A and S reset buttons.
Under these circumstances, six valves in the containment vent and purge systems could be opened with the radiation isolation signal present.
This override was performed after verffyfng that the actual containment particulate levels were acceptable for venting.
The licensee, after further fnvestfgatfon of this practice, determined that the reset of the particulate radiation monitor alarm also overrides the containment isolation signal to the purge valves such that the purge valves would not have automatically closed on an emergency core cooling system
{ECCS) safety injection signal.
A related design deficiency was discovered during a review of system operation following a recent unit trip and subsequent, safety inJectfon at North Anna Ho. l.
Specifically, it was found that certain equipment important to safety (for example, control room habitabi lity system dampers) would return to its non-safety mode following the reset of an ESF signal.
In addition, many utilities do not have safety grade radiation monitors to initiate containment isolation.
Safet Siqnificance The overridfng of, certain containment ventilation isolation signals could also bypass other saftty actuation signals and thus prevent valve closure when the other isolation signals are present.
Although such designs may be acceptable, and even necessary, to accomplish certain reactor functions, they are generally unacceptable where they result in the unnecessary bypassing of safety actuation signals.
Where such bypassing is also inadvertent, a more serious situation is created especially where there is no bypass indication system to alert the operator.
Where the resetting of ESF actuation signals, such as safety injection, directly causes equipment important to safety to return to its non-safety mode, protec-tive actions of the affected systems could be prematurely negated when the
'ssociated actuation signal is reset.
Prompt operator action would be required to assure that the necessary equipment is returned to its emergency mode.
The use of a non-safety.
grade monitor to inftfate containment isolation could seriously degrade the reliability'f the fsolation system.
St'aff Position It is our position that, in addition to-other applicable criteria, the following should be satisiffed for all operating license applications currently under revi ew:
OFFICE SURNAME DATE)..
NRC FORM'318 (9-76) NRCM 0240
~
~
O,U.S. GOVERNMENT PRINTING OFFICE: 1979 289369
0 ti
Hr. Malcolm H. Furbush 3
1)
The bverrfdfngi of one type of safety actu fon signa'I (e.g., parti-cu'Iate radiation) should not cause the bl king of any other type of
- ~safety actuation signal (e.g., iodine ra iatfon, reactor pressure) fb those valves that have no function ther than conta1nment isolation.
4 2)
Physical features (e.g., key lock s tches) should be provided to en-sure adequate administrative contr s.
3)
A system 1%eve annunclatlon of e overridden status shouId be provided for every safet system impact d when any override is active.
(See Regulatory Guide
. 7).
4)
The following diverse s qn s should be provided to initiate isolation of the contafnment purge qntflatfon system:
containment high radiation, safety injection actuati n,Mnd containment high pressure (where con-tainment high pressure s not portion of safety injection actuation).
5)
The instrumentation tfon fsolation shou stems provf ed to initiate containment purge venti la<<
be desfgned and qualified to Glass 1E criteria.
6)
The overriding or esetting of the ES actuation signal should not cause any equipment to hange positfon.
Accordingly, you ar requested to review your pr ectfon system design to deter-mine its degree of conformance to these criteria.
ou should report the results of your review to us by April 15, 1980, describing a
departures from the criteria and th corrective actions to be implemented.
Design departures for which no correc ive action is planned should be justffie Please advise if you have any questions on this matter.
Sincerely, cc:
See next page John F. Stolz, Chief L1ght Water Reactors Branch N.
1 Division of Project Management fMN i
f d
ly.
>Override:
The signal ls stl11 present, and lt Is b'locked In order to perf q a function contrary to the signal.
2Reset:
The signal has come and gone, and the circuit is being cleared 1n order to return ft to the normal condition.
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SURNAME DATE$
NRC FORM'318 (9.761 NRCM 0240, OU.S. GOVERNMENT PRINTING OFFICE: 1979 289'369
/
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Mr. Malcolm H. Furbush l""3 I '9"r)
CC:
Philip A. Crane, Jr.,
Esq.
Pacific Gas
& Electric Company 77 Beale Street San Francisco, California 94106 Janice E. Kerr, Esq.
California Public Utilities Commission 350 McAllister Street San Francisco, California 94102 Mr. Frederick Eissler, President Scenic Shoreline Preservation Conference, Inc.
4623 More Mesa Drive Santa
- Barbara, California 93105 Ms. Elizabeth E. Apfelberg 1415 Cazadero San Luis Obispo, California 93401 Ms. Sandra A. Silver 1760 Alisal Street San Luis Obispo,'alifornia 93401 Mr. Gordon A. Silver 1760 Alisal Street San Luis Obispo, California 93401 Paul C. Valentine, Esq.
321 Lytton Avenue Palo Alto, California 94302 Yale I. Jones, Esq.
19th Floor 100 Van Ness Avenue San Francisco, California 94102 Mr. Richard Hubbard MHB Technical Associates Suite K
1723 Hamilton Avenue San Jose, California 95125 Mr. John Marrs=
Managing Editor San Luis Obispo County Telegram - Tribune 1321 Johnson Avenue P. 0.
Box 112 San Luis Obispo, California 93406 Elizabeth S.
Bowers, Esq.,
Chairman Atomic Safety
& Licensing Board U.
S. Nuclear Regu)afory Cqmmlssion Washington, D.
C.
20555 Mr. Glenn 0. Bright Atomic Safety
& Licensing Board U.
S. Nuclear Regulatory Commission Washington, D.
C.
20555 Tolbert Young P. 0.
Box 219 Avila Beach, California 93424 Richard S.
- Salzman, Esq.,
Chairman Atomic Safety
& Licensing Appeal Board U.
S. Nuclear Regulatory Commission Washington, D.
C.
20555 Dr.
W.
Reed Johnson Atomic Safety
& Licensing Appeal Board U.
S. Nuclear Regulatory Commission Washington, D.
C.
20555 Alan S. Rosenthal, Esq.
Atomic Safety
& Licensing Appeal Borad U.
S. Nuclear Regulatory Commission Washington, D.
C.
20555 Ms.
Raye Fleming 1920 Mattie Road Shell Beach, California 93440 Bren'ushforth, Esq.
Center for Law in the Public Interest 10203 Santa Monica Boulevard Los Angeles, California 90067 Arthur B. Gehr, Esq.
Snell
& Wilmer 3100 Valley Center Phoenix, Arizona 85073 Mr. James
- 0. Schuyler, Nuclear Projects Engineer Pacific Gas
& Electric Company 77 Beale Street San Francisco, California 94106
s
Nr. Malcolm H. Furbush cc:
Bruce Norton, Esq.
3216 North 3rd Street Suite 202 Phoenix, Arizona 85012 Nr.
W.
C. Gangloff Westinghouse Electric Corporation P.
0.
Box 355 Pittsburgh, Pennsylvania 15230 Nichael R. Klein, Esq.
Wilmer, Cutler 5 Pickering 1666 K Street, N.
W.
Washington, D.
C.
20006 David F.
Fl ei schaker, Esq.
Suite 709 1735 Eye Street, N.
W.
Washington, D.
C.
20006 Dr. William E. Martin Senior Ecologist Battelle Memorial Institute
- Columbus, Ohio 43201 W. Andrew Baldwin, Esq.
124 Spear Street San Francisco, California 94105 Resi.dent Inspector/Diablo Canyon NPS c(o U,
S.
NRC P. 0.
Box 219 Avila Beach, California 93424
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