ML20127B978
| ML20127B978 | |
| Person / Time | |
|---|---|
| Issue date: | 06/01/1984 |
| From: | Spessard R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20127B981 | List: |
| References | |
| NUDOCS 8408230490 | |
| Download: ML20127B978 (10) | |
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NUCLEAR REGULATORY COMMISslON
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, Fk MEMORANDUM FOR: D. G. Eisenhut, Director, Division of Licensing, NRR FROM: R. L. Spessard, Director, Division of Engineering
SUBJECT:
UNMONITORED FAILURES OF CLASS 1E SAFETY-RELATED SWITCHGEAR CIRCUIT BREAKERS AND POWER SUPPLIES (AITS-F03052383)
REFERENCE:
AEOD/C301 Study, Failures of Class 1E Safety-Related Switchgear.
Circuit-Breakers to Close on Demand, dated April 29, 1983 Task Interface Agreement, Susquehanna 1 - MOV Thermal Overload Design (Task No.83-113) dated December 8,1983
- As a result of our interest in the subject matter, a survey and review was performed at selected Region III nuclear plants to determine the potential for unmonitored failures of Class 1E safety-related switchgear circuit breakers and power supplies. The results of this review and our recommenda-tions are provided as an attachment to this memorandum.
This information is provided for consideration during NRR's on going reviews l regarding this matter',and it was discussed with G. Holahan of your staff.
We consider this informatio.n to be particularly important because of the potential safety significan~c e 1of this type of'unmonitored failure, i.e., a ,
l single unmonitored failure can prevent a safety system from functioning -
(high or low pressure safety injection pump, auxiliary feedwater pump, .
i emergency diesel generator output breaker, engineered safety features motor l operated valve, eter).
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W\OS23 OHRD &
D. G. Eisenhut 2 Further questions regarding this matter should be , directed to R. D. Walker (FTS 388-5565) of my staff. .
yae R. L. Spessard, Director Division of Engineering
Enclosure:
As Stated cc w/ enc 1:
A. B. Davis, DRA, RIII - -
C. E. Norelius, RIII B. Jorgensen, SRI, Palisades R. H. Vollmer, NRR H. L'. Thompson, NRR -
R. J. Matson, NRR T. P. Speis, NRR R. Wessman, NRR C. J. Haltemes, AEOD E. L. Jordan, IE J. N. Grace, IE
- T. T. Martin, RI J. A. 01shinski, RII R. Denise, RIV
'T. W. Bishop, RV 2
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SURVEY OF SELECTED REGION III FACILITIES FOR UNMONITORED FAILURES OF CLASS IE SAFETY-RELATED SWITCHGEAR
SUMMARY
Region III performed a survey and review of selected nuclear _ plants regarding the potential for unmonitored failures to occur in Class 1E ' safety-related switchgear circuit breakers and power supplies. The effort was initiated
- following the review of AEOD study (C301), dated April 29, 1983, regarding
. unmonitored failures of Class 1E safety-related breakers to close on demand.
j Additionally, Region III had a similar long-standing concern identified at the Palisades nuclear plant in.1978 by Region III inspectors. The AEOD study
- suggested that monitoring of safety-related closing circuits would be appr.o-
.priate.
4 The potential unmonitored failure modes, as stated in the AE00 study, exist'in the nuclear industry because of the long-standing, normal design practices ,
regarding electrical equipment and the noted lack of specific regulatory guidance in this area. We agree with this assessment and our. experience has also revealed that the same or equivalent criteria has not been applied to the r Class IE switchgear and power supplies as has been applied to mechanical equipment, such as valves - verified and locked in the " operable" position.
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DISCUSSION The Region III survey and review and the AEOD study revealed that the elec-trical switchgear purchased by the nuclear, industry was not, in all cases, designed with adequate consideration regarding the monitoring of failures as -
required by _the general design criteria as stated in Criterion 23 of Appendix
-A to 10 CFR 50. Historically the control circuits for electrical circuit breakers and power supplies have been designed to provide the monitoring and accomplishment of the "0 PEN" function and not the "CLOSE" function. In the
[' nuclear industry the "CLOSE" function is often the action required to suc-l cessfully accomplish the-safety function. Additionally, in certain cases l either or both of the "0 PEN" or "CLOSE" functions are required to fulfill the
!- safety function and neither of these control circuits are adequately monitored for failures. Furthermore, our ~ survey and review revealed that the same' level
~o f importance is apparently not applied to electrical and mechanical components in all cases. Mechanical valves are in almost all cases monitored and verified I to be in the position to accomplish a safety function, and sometimes locked in l that position to ensure continued operability.- Electrical circuit breakers and power supplies are not provided the equivalent level of importance and verifi-cation in all cases. Most electrical breakers are subject to only routine
, surveillance, testing, maintenance, and preventative maintenance activities.
- Verification for operability is not generally performed on the equipment.
! The survey and review revealed a number of existing conditions which indicated
, - the basic failure mode design requirements were not adequately' addressed I regarding the closing of a breaker or the starting of a component on demand. ,
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, Further, the inoperable equipment may remain in that condition for a period of i
time between surveillance tests. These potential unmonitored failures at the
- surveyed nuclear plant,s included, but were not limited to, the following items (Refer to Tables I, II,'and III).
Lack of equipment position or status in the control room - continuously occupied area. In most all cases indication provided was locally.
. Breaker "CLOSE" cibcuit fuses and control circuitry not monitored and i indicated or anyiunciated in the control room - continuously occupied
[ area. 'In some casts these are indicated locally, remotely, or annunciated.
i
, . Locally mounted " toggle-type" switches which provide power to the breaker
" charge" spring motor not monitored in the control room - continuously occupied area. Access to these switches is not specifically limited.
. Locally mounted breaker trip or lockout devices not monitored in the control room - continuously occupied area. In most cases indication j is provided locally.
. Local breaker " cell" or " connect" switches not monitored in the control room - con'tinuously occupied area. In most cases no indication is provided locally or remotely.
l . Status of the breaker "close" springs not monitored in the control room -
r continuously occupied area. In most cases indication is provided locally
' and in some cases they are monitored.
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Local breaker or starter fixed trip devices (thermal or magnetic) not monitored in the control room - continuously occupied area. In most cases this is indicated locally.
As noted, all the conditions could be verified locally at th'e breaker or panel; however, a few could not be verified (breaker cell switches, control circuit continuity, etc.). The actual conditions vary with the equipment manufacturer, -the licensee or the Architect Engineer.
The'above listed design deficiencies built into the standard electrical switchgear and power supply equipment appear to fall within General Design Criteria, GDC-23, " Protection System Failure Modes" - which requires in part, that the protection system "shall be designed to fail into a safe state or into a state demonstrated to be acceptable on some other defined basis if conditions such as disconnection of the system, loss of energy (e.g., elec-trical power, instrument air), ...are experienced." IEEE 279-1971 states that "the' nuclear power generating station protection system shall, with precision and reliability, automatically initiate protective action whenever 3
a condition monitored by the system reaches a preset level." The accepted, .
standard design of the electrical switchgear and power supply equipment does not, in all cases, appear to meet these basic design requirements. This matter appears to be a generic issue as' indicated by the noted failures recorded in the AE00 report and the survey performed by Region III.
g Additionally, the Region III survey noted whether the licensees were per- '
forming additional surveillance or monitoring of the electrical switchgear or [
power supply equipment in order to ensure the continued operability of the affected safety-related equipment to reduce the incidence of these type events.
.With only a few exceptions the licensees were not providing additional sur-veillance or monitoring of the electrical equipment to verify operability or to detect unmonitored. failures. I Three tables provided iridicate hhe specific results of the findings by .
Region III to. provide the bases for our findings and recommendations, and to assist with the NRC's review. Although the tables are not complete in all cases, it is apparent that the potential for unmonitored failures exist in the state-of-art electrical equipment presently installed in the nuclear plants. The tables include the fo'11owing information in most cases for Class 1E 4160 volt circuit breakers, 480 volt load center circuit breakers, and 480 volt motor control center circuit breakers:
. Nuclear-facility site
!.. .- Circuit Breaker make and model l . . Circuit breaker position indication locally and in the control room l . Power availability to the "CLOSE" circuit in the control room l
. Annunciation available in the control room
. Additional surveillance performed
. Thermal overload / fuses monitored locally and in the control room
. General remarks 3 .
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CONCLUSIONS
-The AEOD study and the Region III survey and review indicate that many types of unmonitored failure modes exist within.the electrical switchgear and power supplies; few licensees perform additional surveillance to limit the incidence of these type failures; the situation has been the result of the provision of inadequate guidance and design requirements; and the same or equivalent criteria are not placed on both electrical and mechanical equipment.
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RECOMMENDATIONS Because the AEOD study and the Region III survey and review indicate that the condition has resulted from inadequate guidance regarding design requirements, it is recommended that consideration be given to establishing clear design requirements and provide the appropriate industry guidance to ensure equivalent importance to safety be placed on both electrical and mechanical equipment.
Since the Region III survey and review were limited, consideration should be given to performing an industry-wide / Region-wide survey, if necessary to establish the full safety significance and to provide additional information regarding this matter from other licensees.
Consideration should be given to establishing requirements for additional-4 I
.turveillance and monitoring to be implemented during the interim period while the overall design and safety significance of this matter is being established.
These requirements may establish permanent surveillance and monitoring activi-ties to replace design inadequacies in older plants or cause upgrade of the original design in order to reduce the incidence of unmonitored failures in safety-related systems.
Consideration should be given to requiring each licensee to review the design requirements and failure modes inherent in the design and present in the facility and develop and implement appropriate corrective actions.
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/ ~/ / / / / / -
/ / / */ / l /
/ / / / / / / '
/ / / / CLOSE CIRCUIT / / / . .
/ / / POSITION / POWER / / /
/ / / INDICATION / INDICATION / / /
/ CIRCUIT / CIRCUIT / / / CONTROL / /
l /BP.EAKER / BREAKER / / AT / / AT / ROOM / /
OPERATING / MAKE
/MODEL / / CONTROL / / CONTROL / ANNUN / SURV /
l SITE / / / LOCALLY / ROOM / LOCALLY / ROOM / / / REMARKS l ll l l l l l l l l BIG ROCK" ll l 1 .I l l l l l 13.8KV, 6.9KV j ll l l l . l l l l NORM & l.CHG SPRING FLAG ON BREAKER
]). C. COOK ll ITE l 5HK l YES l YES l YES I NO l YES I PMs I. TOGGLE SWITCH TO DISENGAGE
! ll l l l l 1 l l l SPRING MOTOR ON BREAKER I
il I l l ~~l I i l NORM & 1 tAVISBESSE (L W l 50DHP l YES I YES' , I- NO I N0 l*YES l PMs l* NO REFLASH FOR SECOND BRKR l li l l I l l l l NORM & l DRESDEN ll GE I 4KV l YES l YES l YES l NO l N0 i PMs l I ll l MAGNA I i l l l i NORM & I DUANE ARNOLD ll GE l SLAST l YES l YES I YES l YES I *NO l PMs l*EDG AND STDBY XFMR ONLY L li BROWN I l i I l l l NORM & l. TOGGLE SWITCH TO DE-ENERGIZE JERMI ll BOVERI l SHK l YES I YES I YES I YES l YES l PMs l SPRING MTR ON BRKR l ll l l l 1 1 I I NORM & 1 KEWAUNEE ll ME l PSD I YES l YES l YES I YES l*YES l PMs l* TRIP ONLY *
, llITE/GULDI SHK l i ! l l l NORM & I LASALLE ll GE I PSD l YES I YES 1 YES YES l YES I: PMs l ,
LACROSSE ^ ll l l I l IANOT UTILIZED AT THIS SITE l 1l l MAGNA l l l l l NORM & l MONTICELLO ll GE I BLAST l YES l YES l YES l NO l YES PMs l I il l l l l l l SHIFT I PALISADES ll 2400V l MA-250Bl YES I YES l YES l N0 l HO l CHECKS I l ll 1 I l l I I I NORM / l POINT BEACH ll W l DH 350 l YES l YES l YES I YES l YES l PMs l Il I I i l I I i NORM / I PRAIRIE ISLAND ll ITE l SHK l YES I YES l YES I YES I YES l PMs l
, II I l l l l l l NORM / I QUAD CITIES ll l ' YES YES YES l YES NO I PMs .I
- ZION ll l YES YES YES l' NO 'l "D:ta Not Available At This Time -
TABLE I CLASS IE 4160 VOLT CIRCUIT BREAKERS
/ / , / / / / / / -
/ . / / / / / / / ,'
/ / / / / / / / -
/ / / / / / CLOSE CIRCUIT / / ;
/ / / POSITION / / / POWER / /
/ / / INDICATION / / SPRING / INDICATION / / '.
/ CIRCUIT / CIRCUIT / / CONTROL / MOTOR / / /
/ BREAKER / BREAKER / / AT / ROOM / TOGGLE / / AT / /
JPERATING / MAKE / MODEL / / CONTROL / ANNUN / SWITCH / / CONTROL / SURV /
SITE / / / LOCALLY / ROOM / / / LOCALLY / ROOM / / REMARKS ll l 1 ! 1 l l l l l ll l l l l l l l l TESTED- l ll l 1 1 I I I I IEVERY 3 l lIG ROCK
- ll l l 'I l l l l DAYS LEDG BRKR ll l l l .
l.
l I l l NORM & I
). C. COOK ll ITE lK1600S l YES l YES l NO l YES I YES l NO l PMs l ll l l l YES l l l l l NORM & l*MTRS SOL OP
) AVIS BESSE 11 GE l*AK-3A i YES l(SUPPLY'l**YES i N0 i N0 i NO l PMs l**NO REFLASH ll l l l ONLY) sl- l l l l 1
11 1 I l l l l l l NORM & 1
)RESDEN ll GE l AK-2A I YES I YES l NO l NO I YES I l PMs l 11 AC 1 LH600 l l l l l l 1 NORM & 1
)UANE ARNOLD 11 ITE l K600 l YES l YES l NO _ l NO l YES I YES l PMs l ll BROWN l TYPE I i l l l l l NORM & I ERMI ll BOVERI l K l YES l YES l YES l YES l YES l YES l PMs I ll l l l l l l l l NORM & l* TRIP ONLY CHG CEWAUNEE ll AC l LA600 l YES l YES l*YES I YES l YES I YES I PMs ISPRING FLAG ON BRKR ll l l l l MAIN l l l l l ll 1 AK-2A l l lBKRS NOTl l l l NORM & l ,
_ASALLE ll GE lAKAR5AEl YES l YES I ALL l NO l YES l YES l PMs [
ll l l l 1 l l l l NORM & l* LIGHTS ON ALL - SOME
.ACROSSE ll AC l LA600 l YES l YES [*YES l YES l YES l N0 l PMs lANNUNCIATED ll l 1 1 I I I I I NORM / I 10NTICELLO ll GE I ACB ' YES YES l N0 l l YES I l PMs l ll 1 K-225 I I I I I NORM / I
'ALISADES ll ITE I K-600 I YES l N0 i NO l YES l YES I NO l PMs I il i I I ,
I I i l NORM / l
'0 INT BEACH ll U l 0850 l YES I YES l YES l N0 i NO l YES l PMs i 11 1 I I I I I I I NORM / I
'RAIRIE ISLAND ll AC l LA600 I YES I YES l YES l NO l NO l YES I PMs 1 ll l l l l l l l l NORM / l
!UAD CITIES ll l l YES l l NO l NO l l PMe,
.10N ll l l YES l YES l l l YES NO l
'D:ta Not Available At This Time TABLE II CLASS IE 480 VOLT LOAD CENTER CIRCpIT BREAKERS
o
/ -
/ / /- / / / * '
/ / / /
/ / < s
/ / / / / /
/ / / . THERMAL
/ / / POSITION
/ / ,, / CLOSE CIRCUIT / / ;
/ OVERLOAD / / /
/ POWER- / '
/ / INDICATION / FUSES / / SPRING /
/
/ CIRCUIT / CIRCUIT / INDICATION / /
/ / CONTROL / MOTOR /
/ BREAKER / BREAKER / / AT /
/ /
i OPERATING / ROOM / TOGGLE / / AT
/MAKE /MODEL / / CONTROL /
/ /
SITE / / / SERIES /ANNUN / SWITCH / / CONT 90L/SURV /
/ LOCALLY / ROOM / USED / PARALLEL / /
ll l l l l 1 I
/ LOCALLY / ROOM / / REMARKS BIG ROCK' ll l l I I l l l l l l l ll t
l l l l 1 1 I I l D. C. COOK I I l 11 WEST I K 600 l YES I YES l YES l SERIES I *NO 1 1 INORM i *SOME ll l HFB I NO l YES I NO l& PMsl ANNUNCIATED i 1- I l l l DAVIS BESSE ll WEST I HKA l l l lNORN l l YES l NO. I N0 . I ----
I NO i NO ll l 1 I NO I NO l& PMsl 1 I I i DRESDEN ll GE I 7700 l YES l YES I YiS l SERIES 1 N0 l
l l l NORM i DUANE ARNOLD ll l i NO T YES I YES l& PMsl l l l ll BRN l TYPE 1 i L l l l I I F l FERMI l l l ll BVGI i HE l YES I YES I YES l l NORM i I SERIES 1 YES l --- l YES l YES KEWAUNEE ll AC l LA600 I YES l YES l l !
l& PMsl ll KM ! I i l I i I T l l LASALLE ll ISC 1 --- l YES I YES I YES I l i INORM i *SOME ll 1 l l lPARALLEll *NO I --- I YES I YES l& PMsl ANNUNCIATED l I l l LACROSSE ll AC l LA600 l YES l YES l NO ---
l l l NORM 1 *LIGHIS ON ALL -
I l*YES I NO I NO 1 YES 11 .I I I I I l& PMsl SOME ANNUNCIATED MONTICELLO ll GE i i l l l i YES l YES INORM/l I l l NO l N0 l NO I NO lPMs I il i I I I I PALISADES I I ll W lFA-3035MI YES l YES I YES i l l NORM /l ,,
l SERIES l NO l N0 i NO l N0 IPMs 11 i L I I I I
I I POINT BEACH ll W l DBSO I YES l YES l N0 ----
I l INORM/l ll l I YES I N0 i NO I YES IPMs l l l 1 l I
l 1 I i PRAIRIE ISLAND ll GE l 7700 l YES l YES I YES l NORM /l ll I SERIES I N0 i NO 1 YES I N0 IPMs !-
1 1 I I
]UAD CITIES I I I l ll l l YES l l NORM /l I l YES l SERIES I l NO EION ll l l YES I YES l l l lPMs l l l NO l YES l YES
'D:tc Nat Available At This Time I NO l l TABLE III CLASS IE 480 VOLT MCC CENTER CIRCUIT BREAKERS ,
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