ML20136G446
| ML20136G446 | |
| Person / Time | |
|---|---|
| Issue date: | 11/08/1985 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Heltemes C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| References | |
| TASK-2.E.6, TASK-TM NUDOCS 8511220350 | |
| Download: ML20136G446 (4) | |
Text
._
[samee\\
UNITED STATES
[
p, NUCLEAR REGULATORY COMMISSION ms uwarow. o. c. noses
\\..... /p r.
sw as MEMORANDUM FOR:
C. J. Heltemes, Jr., Director Office for Analysis and Evaluation of Operational Data a
FROM:
Harold R. Denton, Director Office of Nuclear Reactor Regulation i
SUBJECT:
EVALUATION OF RECENT VALVE OPERATOR MOTOR BURNOUT EVENTS l
1 j
i The Office of Nuclear Reactor Regulation has reviewed the Special Study Report
" Evaluation of Recent Valve Operator Motor Burnout Events" transmitted in your
]
memorandum dated September 19, 1985. The report pointed out several generic i
problems regarding the use, misuse or non-use of thermal overload protective (TOL) devices for valve motor operators in nuclear power plants.
It was noted l
that valve motor operators are burning out at an increasing rate and that this t
is a significant generic safety concern due to the number of valves involved, their use in safety systems, and the potential for comon mode failures. The i
special report recomended that NRR expedite implementation of the proposed action plan to address valve motor burnout, which includes a reassessment of Regulatory Guide 1.106 (T0L Protection for Electric Motors on M0Vs).
NRR notes that the special study report identifies a significant increase in valve operator motor burnout events in recent years. We believe that part of this increase results from the more extensive data and searches consulted by this study as compared to that used in the May 1982 study on the same subject.
Also, part of the increase may be attributed to the increase in the number of i
operating reactors since 1982. Nevertheless, NRR is in agreement with the AE00 assessment of this concern.
~
- This concern is one of a number of valve surveillance testing concerns being i
addressed in accordance with the Action Plan for the resolution of Generic i
Issue !!.E.6.1, "In-Situ Testing of Valves." To conserve resources in NRR and l
to expedite resolution of !!.E.6.1, it was decided to utilize a DOE contractor j
tJ perform many Of the significant milestone tasks in the Action Plan.
Brookhaven National Laboratory (BNL) has been selected as the contractor and is i
i scheduled to begin work on these tasks in November 1985. Earlier comencement l
of this task had been deferred due to funding limitations, which are expected f
to be resolved with approval of the FY 86 NRR budget.
MP**
l'.v.
" m k,gy a m ou fgf*g o
C i
IA 4
C. J. Helteres l The BNL work effort is scheduled to be completed in about 18 months and will include a review and evaluation of industry practice in bypassing thermal overload devices. BNL is to provide recommendations for possible staff action, such as revising Regulatory Guide 1.106. Other concerns previously raised by AEOD will also be addressed by BNL. These concerns include inadequate torque and limit switch adjustments and the possible use of valve signature tracing techniques, such as MOVATS.
NRR will keep AE00 informed as BNL evaluations are completed and recommendations are developed.
Our comments have been discussed with Earl Brown of your staff.
If you have l
anyquestions,pleasecontactW.Swenson(x27876)oftheOperatingReactor Assessment Branch.
f f
1 Mnny
.,xnse t9"~
Har61d R.
enton, Director Office of Nuclear Reactor Regulation cc:
K. Seyfrit E. Brown R. B. Minogue, RES l
l I
l l
l
. =
I' NOV a 1985 i
l The BNL work effort is scheduled to be completed in about 18 months and will include a review and evaluation of industry practice in bypassing thermal J
overload devices. BNL is to provide recommendations for possible staff action, such as revising Regulatory Guide 1.106. Other concerns previously raised by AE00 will also be addressed by BNL. These concerns include inadequate torque i
and limit switch adjustments and the possible use of valve signature tracing l
techniques, such as MOVATS.
NRR will keep AE00 informed as BNL evaluations are completed and recommendations are developed.
Our comments have been discussed with Earl Brown of your staff.
If you have i
any questions, please contact W. Swenson (x27876) of the Operating Reactor j
Assessment Branch.
I Original signed by Darro110. Einenhut atf Harold R. Denton, Director i
l Office of Nuclear Reactor Regulation I
cc:
K. Seyfrit E. Brown DISTRIBUTION YELLOW TICKET 859245 j
Central File w/ incoming i
NSIC w/ incoming NRC PDR w/ incoming 4
ORAB Reading i
- 0. Rothberg l
F. Cherny i
W. Swenson i
R. Wessman I
G. Holahan D. Crutchfield l
F. Miraglia/H. Thompson D. Eisenhut l
H. Denton l
H. Smith w/ incoming PPAS
- Previously concurred 1
0 l
ORAB:DL*
SL:0RAB:DL*
C:MEB:DE*
AD:CSE:DE*
/V@RAB:DL:BC WSwenson:mk RWetsman FCherny RBosnak Ab1hhan 10/18/85 10/18/85 10/21/85 10/21/85 10/t.Y/85
(
g Cf M D:DL[
p DD:
),
Tchfield HThompson DE t
ttrn 1
10gg85 IQ/g/85
$/p/85
@/g /85 r
i 1
_ - ~ ~
i l
l
{
NRR will keep AE00 informed as BNL evaluations are completed and recommendations j
are developed. Also, NRR will coordinate with AE00 in the development of a final resolution to Generic Issue !!.E.6.1.
{
i Our coments have been discussed with Earl Brown of your staff.
If you have i
anyquestions,pleasecontactW.Swenson(x27876)oftheOperatingReactor j
Assessment Branch.
i j
Harold R. Denton, Director j
Office of Nuclear Reactor Regulation 4
cc:
K. Seyfrit E. Brown DISTRIBUTION YELLOW TICKET 859245 j
Central File w/ incoming NSIC w/ incoming i
NRC PDR w/ incoming 1
ORAB Reading 1
- 0. Rothberg j
F. Cherny W. Swenson i
R. Wessman G. Holahan D. Crutchfield i
F. Miraglia/H Thompson D. Eisenhut H. Denton H. Smith w/ incoming PPAS ORAL}p SL:
L C:MEB:D
,A
- DE ORAB:DL:BC WSwenson:mk RWessman rny' Rilost ak GHolahan FChe//8510/g/85 10/ /85 j
10 @ 85 10/g85 10/J 4
AD:SA:DL D:DL DD:NRR D:NRR i
DCrutchfield HThompson DEisenhut HDenton 10/ /85 10/ /85 10/ /85 10/ /85
}
i i
1 i
i i
i
A j!.
e 8
0 UNITED STATES MM {'
[
r'i NUCLE AR REGULATORY COMMISSION 5-t WASHING TON, D. C. 20*A5 c.,
%...../
September 19, 1985 AE00/5503 MEMORANDUM FOR:
H. R. Denton, Director Office of Nuclear Reactor Regulation FROM:
C. J. Heltemes, Jr., Director Office for Analysis and Evaluation of Operational Data
SUBJECT:
EVALUATION OF RECENT VALVE OPERATOR MOTOR BURNOUT EVENTS We have continued to monitor operatinq experience reports involving valve failure to operate associated with valve operator motor burnout since this l
subject was addressed in the AE00 Case Study C203, issued in May, 1987. This Case Study covered valve operator events during 1978, 1979, and 1980 and recommended that Regulatory Guide 1.106 be reassessed based on a relationship i
between valve operator motor burnout and the guidance in the Regulatory Guide to bypass motor thermal overload devices. The enclosed Special Report provides a limited review and evaluation of valve operator motor burnout events subseouent to the 1980 time frame addressed by C203.
References 3 and 4 of the enclosed AE00 Special Report indicate that NRR I
developed a proposed action plan to address the AE0D recommendations in Case Study C203 concerning bypassing of motor thermal overload devices, but the proposed plan has not yet been approved.
This Special Report illustrates that operating plants have not corrected this problem and thus corroborates the origiral recommendation. Although only a few events were reviewed and analyzed, the report identifies more than 200 valve operator motor burnout events including more than 180 events durirg the approximate four year time frame from 1981 to early 1985. The number of events during the most recent four years is significantly greater than the 19 events reported in AE00/C203 for the preceding three years (1978, 1979, and 1980).
This number of events raises potential significant safety issues for the following reasons: (1) Motor l
operated valves are used extensively in safety systems where performance of the I
safety function requires that valves must open and/or closet (2) the motor i
failure mechanism can be common mode based on an overall plant philosophy covering tnermal overload devices and surveillance procedures; (3) the failed motors can remain undetected for long periods of tinct and (4) motor burnout l
has resulted in damage to the valve operator in a manner that prevented vnho i
operation by either motor or manual drive mechanisms.
In view of this situation, we recomend that you consider the findings of this report to expedito implementation of the NRR proposed plan to address motor burnout, including reassessment of Regulatory Guide 1.106.
l l()Di O f
i
=.
l l
H. R. Denton i 1
1 l
Should you or your staff have any questions or require additional information, please call Mr. Karl Seyfrit or Mr. Earl J. Brown of my staff. Mr. Seyfrit can be reached at X24440 while Mr. Brown can be reached at X24437.
l l
l
/
h L / of'd N h &
C. J./
f Heltemes, JP., Directnr Office for Analysis and Evaluation of Operational Data i
Enclosure:
i As stated cc w/ enclosure:
R. B. Minogue, RES l
l
[
1 l
l l
l l
i 1
f i
i I
AE00/5503 l
EVALUATION OF RECENT VALVE OPEPATOR MOTOR BURNOUT EVENTS l
l Special Study Report Office for Analysis and Evaluation of Operational Data f
I September 1985 l
l t
Prepared by: Earl J. Brown i
I t
i l
l NOTE: This report documents results of studies completed to date by the Office for Analysis and Evaluation of Operational Data with regard to particular operating events. The findings, conclusions and i
recomendations contained in this report are provided in support of other ongoing NRC activities concerning these events. Since the studies are ongoing, the report is not necessarily final, and the i
findings and recomendations do not represent the positions or requirements of the responsible program office of the Nuclear-Regulatory Comission.
I f
ggod**((ptf'
r e
TABLE OF CONTENTS
.P.1E l
SUMMARY
1
[
1 BACKGPOUND 1
DISCUS $10N FINDINGS AND CONCLUSIONS 3
5 REFERENCES FIGURE 1 FAILED SMB 0 MOTOR OPERATOR............
6 FOR VALVE 39A APPEN0!X A MOTOR OPERATED VALVE EVENTS INVOLVING THERMAL 7
OVEPLOAD DEVICES AND MOTOR DURNOUT APPENDIX 0 A00!T!0NAL VALVE OPEPATOR MOTOR BURNOUT EVENTS 10 1
I l
l l
l l
1 l
i.
i EVALVATION OF RECENT VALVE OPERATOR l
MOTOR BURNOUT EVENTS
SUMMARY
AEOD has been monitorino operating events pertaining to motor operated valves since the issuance of AE00 Case Study C203 in May,1982, which reviewed events L
during 1978, 1979, and 1980. One issue covered by that report was a recomendation addressing valve operator motor burnout. Because of recent events AE00 conducted a limited review and evaluation of a few events.
Based on the limited review, it has been concluded that valve operator motor burnout continues to pose a potential safety problem. The data corroborates the original AE00 recomendation in C203 relative to a reassessment of Regulatory Guide 1.106 concerning bypassing of thermal overload (TOL) devices.
Although only a few events were reviewed and analyzed, additional search techniques have identified more than 180 events subsequent to the oriainal 19 events in C203. These additional events cover the time frane from 1981 to early 1985. Accordingly, it is recommended that the Office of Nuclear Reactor Regulation use this report as a basis to expedite implementation of the NRR proposed plan to address valve operator motor burnout and a reassessment of Pegulatory Guide 1.106.
hAckCD0VND ApreviousAE00studyissuedinMay,1932(Reference 1.AE00/C203)provided recommendations addressing several deficiencies pertaining to valve assembly inoperability. One of those recomendations involved reassessment of the guidance in Regulatory Guide 1.106 (Reference 2) concerning bypassing thermal l
overload devices because of valve operator motor burnout events experienced from 1978 through 1980.
This reco mendation has been under consideration in NRR and would be addressed by the proposed task action p1An that Was developed inJuly,1984(References 3and4)toresolveGenericIssue!!.E.6.1. This proposed action plan, however, has not yet been approved.
The primary purpose of the thermal overload (TOL) device is to protect the valve operator motor from dwage and degradation due to overheating and to provide an alert of an off normal situation by trippino and stopping operation of the motor.
In contrast, the underlying concern of Regulatory Guide 1.106 was to prevent valve inoperability due to spurious tripp'ng of the thermal overload device by guidance to bypass the device and/or use conservative sirirg with respect to motor current. Therefore, the intent for both the presence of l
the TOL device and the guidance in the Regulatory Guide is to ensure that the valve operator motor is capable of operating When needed. But, in practiCA1 terms, operating plants have experienced premature valve operator motor burnout which illustrates a lack of motor protection.
Ol5005510N Since the issuance of At0D study C203, At00 has bnn monitoring oseratina events involving motor burnout.
This monitoring indicated that tiese events were continuing and increasing in frecuency. As a result, we initiated a Ilmited evaluation of data accumulater subsequent to that used for the study in
I 2
Reference 1 which covered the years 1978, 1979, and 1980. Data involving TOL devices associated with motor burnout that was obtained from the Sequence Coding and Search System (SCSS) is presented in Appendix A.
The data, consisting of 14 events, is arranged by plant docket number, LER number, and a brief description based on a review of each LER ard all attached dncuments.
One event, item 14, was obtained from an inspection report rather than SCSS (the event was not reported by LER). Since the purpose of the valve operator l
motor TOL device is to protect the motor and alert plant staff of potential valve operability problems, the event description concentrates on available information concerning motor protection, nature of damage, TOL bypass features, and control room alares, t
Whereas past studies had identified valve motor burnout as predominantly occurring at BWRs, the recent data covers both BWRs and PWRs. Additionally, a recentAE00studyonvalveoperatorhammering(Reference 5) identifies 17 events that involved motor burnout (five events are also part of Appendix A).
Also, Peference 6 identifies four motor burnout events that involve premature l
degradation of motors due to oversized TOL devices. Hence, the data in Appendix A, and References 5 and 6 represent 30 new valve operator motor burnout events since the initial 19 failures analyzed in the 1902 Case Study l
(Reference 1).
These recent events continue to support questions concerning the effectiveness of the TOL device in providing protection to the valve operator motor. Post of the events in Appendix A indicate that the TOL device was not providing l
pretection because it did not trip prior to motor damage.
In fact, several of the event reports identify concurrent TOL trip or TOL burnout and discovery of i
motor burnout. Also, several of the events indicate the valve operator motor i
continued to run after completion of the intended operation which culminated i
with eventual motor burnout without TOL protection or alarm in the control
~
l room.
The events in Appendix A corroborate the previous conclusion that valve j
operator motors continue to burn out and are not being protected and failures t
can be undetected. The burnout events include situations in which the TOL device was always in the valve circuit or there was permanent bypass of the TOL device or bypass of the TOL device at some time.
In particular, item 12 is an example of undetected motor burnout shortly af ter a surveillance test (a few seconds or minutes) cven though the explicit guidance in Regulatory Guide 1.106 was utilizedt i.e., the TOL device was continuously bypassed and only placed in force during periodic or maintenance testing.
The reason for lack of detection was that there was no TOL alam in the control room with the test / bypass switch i
in the bypass position prior to actuation of the TOL device.
The other items in Appendix A appear,to indicate lack of TOL protection because t
either the TOL device was overstred (such as 300% of full load current) or the TOL devices were routinely reset af ter the trip without an attempt to determine the root cause of the TOL trip.
In addition to lack of T0L protection, item 14 i
illustrates a >otentially serieus side effect of the motor burnout mode of l
4 fatture.
In t$at event, the closing torque switch did not stop the motor when r
the valve reached the fully closed position. Also, the TOL device was sized at 3001 of the full load current and did not trip to stop the motor. The motor i
housingwasfoundcrackedopen(seeFloure1)anddislocatedsufficientlyto cause the internal mechanism to jam wh'ch also prevented manual operation of l
i I
. the valve. Hence, motor burnout resulted in loss of, both motor and manual operational modes of the valve. This aspect could have serious implications involving several safety systems that have valves outside containment where valve operability may have been presumed assured by manual means (although possibly delayed) even if the valve operator motor was damaged. Therefore, I
this event appears to represent a potential generic failure mechanism which l
could prohibit both remote and manual valve operation.
The operating experience reviewed and analyzed in AE00 reports (References 1 l
5, 6, and this report) represents approximately 50 events (19 during 1978 to 1980 and about 30 during 1981 to early 1985) associated with valve operator motor damage or burnout. Although these approximately 50 events provide a sufficient basis to draw conc %sions and raise safety concerns, they do not and were never intended to represent a comprehensive list of such events.
In order to identify other motor burnout events, additional data searches were conducted and resulted in an additional 150 burnout events. These searches covered the time period 1981 to early 1985 and utilized data sources as follows:
(1) Events reported by LER as retrieved from SCSS and RECON, and a limited review of LER abstracts for four plants in the DCS (see Appendix B for a list of events);
(2) Limited search of the NPPDS.
Thus, the more than 200 motor burnout events clearly indicate a lack of valve operator motor protection which illustrates that TOL devices are not being used effectively to provide protection against motor overheating. This situation, therefore, suggests that the failure mechanism (burnout) is potentially a common mode failure for a given plant because it appears related to an overall l
attitude or modus operandi concerning the design and operation of MOVS, and the l
valves' TOL sizing, bypassing of TOL devices, alarms, and surveillance pro-cedures in use at the plant. The apparent increasing rate of burnout events suggests a need to at least determine the primary root causes of valve operator motor burnout even though it would seem unlikely that licensees could identify and correct all causer of failure. Therefore, available devices that protect against valve operator motor burnout should be correctly utilized as a means to reduce the number of burnout events.
Burnout of valve operator motors is a potentially significant safety concern i
for the following reasons:
(a) Motor operated valves are used extensively in safety systemst (b) motor failure can be a common mode mechanism for a given plant based on their overall philosophy covering TOL devices and survelliance procedurest fc) the failed motors can remain undetected for long periods of times and (dJ motor burnout has resulted in damage to the valve operator that prevented valve operability by both motor and manual drive mechanisms.
EINDINr5 AND CONCLUSIONS The total number of events (200) reviewed in this report provide conclusive i
evidence that valve motor burnout is a serious problem. The motor burnout events illustrate that ineffective ut11tration of TOL devices has resulted in situations that (al remove or severely linit TOL protection for the value operator motor or hb) prohibit detection of failed valve operator motorn. The
[
following findings are provided:
1
t (1) Valve operator motor burnout is still occurring and it appears to 4
occur more frequently (180 events identified for the most recent 4 l
years compared to 19 events for the 3 year span 1978,1979, and j
1980).
(2) Motor burnout is a potentially significant safety concern because:
l (a Motor operated valves are used extensively in safety systems, 1
(b for a given plant, the mechanism can be common mode failure; i
1 (c failure can be undetected for long periods of time; and (d) the i
1 failure could prevent both motor and manual operation of the valve, i
This also suggests a need to determine the root cause of motor burnout.
(3) Although the root cause (or causes) of motor burnout may be complex and not fully understood, it is evident there is a lack of valve l
1 operator motor protection.
Hence, there is a need to further address
)*
motor burnout including reassessment of Regulatory Guide 1.106 as i
recommended in AEOD Case Study C203 (Reference 1).
i In view of this situation, we recomend that NRR consider the findings of this i
report to expedite implementation of the NRR proposed plan to address valve t
j operator notor burnout, including reassessment of Regulatory Guide 1.106, i
i J
l l
i i
i j
i l
I l
I J
l l
i I
l
L s r
REFERENCE!
1.
NRC, E. J. Brown and F. S. Ashe, " Survey of Valve Operator Pelated Events Occurring During 1978, 1979, and 1980," AE0D/C203, May 1982.
2.
NRC, Regulatory Guide 1.106, " Thermal Overload Protection for Electric Motors on Motor-Operated Valves," Revision 1, March 1977.
3.
NRC, R. J. Bosnak to W. Minners, " Status of Potential Generic Issue 54, Valve Operated Related Events Occurring During 1978, 1979, and 1980."
March 26, 1984.
l 4
NRC, J. P. Knight to R. H. Vollmer, "MEB Task Action Plarc~f r Resoiution h
of Generic Issue II.E.6.1, In Situ Testing of Valves," July 30, 1984.
1 5.
NRC, M. Chiramal " Motor Operated Valve Failures Due to Hammering j
Problem," AE0D/E501, January 17, 1985.
6.
NRC, E. J. Brown and F. S. Ashe, " Inoperable Motor Operated Valve j
i Assemblies Due to Premature Degradation of Motors and/or Improper Limit j
Switch Torque / Switch Adjustment," AE0D/E305, April 18, 1983.
i l
I I
1 i
j a
p.n 7
i l
a 3
W-(
l i
(
Valve Motor j
in back of Operator I
,' ?
Stem of Valve 39A Handwheel for manual
,,f operation I
h Fig. 1 Failed SMB-0 Motor Operator For Valve 39A l.--
_j
7 Appendix A
~
MOTOR OPERATED VALVE EVENTS INVOLVING THERMAL OVERLOAD. DEVICES AND MOTOR BURNOUT-
' Docket and Plant LER No.
Event Description 1
1.
237 83-024 Core spray valve failed to open. After several attempts TOLS tripped.
Dresden 2 Motor was found burned out.
'l I
2, 245 84-015~
While restoring valve lineup after an Isolation Condenser Functional and Millstone 1 Calibration Test, the isolation condenser isolation valve,1-IC-3, motor TOL and 125 volt dc ground alarms annunciated in the control room.
Out-of-adjustment limit switch caused motor to run after disc reached full closed position and motor was extensively damaged, and subsequently failed in full closed position.
3.
245 84-018 Operation of outboard isolation condenser condensate return valve, Millstone 1 1-IC-3,~became erratic.
Subsequently, the motor overloaded and the circuit breaker began to smoke. Out-of-adjustment limit switch caused-motor to run beyond the full closed position with extensive e
motor damage and the valve failed in full closed position.
i 4,
271 82-014 Outboard RWCU system isolation valve, V12-18, would not open.
The TOL Vermont-Yankee was found tripped. Valve was manually lifted off the seat. One half j
hour later.the TOL was reset and the valve opened electrically. About 10 minutes later there was loss of indication on V12-18 and an RWCU pump trip.
[
The valve breaker was tripped and the motor had failed.
1-5.
~272 84-021 Containment isolation valve received close signal but would not reopen on Salem 1 operator demand (open light did not come on).
The TOL device was jumpered in the control circuit which implied no TOL protection.
The stem nut was not staked such that valve never closed and motor kept running and burned out.
k:
i 1
Docket and Plant LER No.
Event Description 6.
293 82-042 During a surveillance timing test, HPCI torus suction valve, M0-2301-35 Pilgrim did not operate.
An open field winding was found on the operator motor. Due to its required service, the motor has no TOL or torque switch protection.
7.
298 81-003 During surveillance test on 2/23/81, the outboard drywell spray Cooper isolation valve, RHR-MO-26B, motor current increased and remained high when the valve reached the closed position.
If the motor breaker had not been manually tripped, the motor would have overheated and failed in the closed position.
(Test procedure appears to have detected high current before TOL tripped.)
Similar event occurred on 11/3/80.
8.
302 83-009 During surveillance testing on 2/22/83, the emergency feedwater pump Crystal River failed to start because the steam supply valve, ASV-5, failed to open.
The cause was reported as motor burnout due to a failed torque switch.
Discussions with the licensee revealed that subsequent investigation determined the TOL was sized for continuous duty which was a misappli-cation, the torque switch was set incorrectly, and the TOL is not alarmed on a trip (see LER 83-042 also).
9.
302 83-042 During surveillance testing on 9/27/83, the motor on steam supply valve, Crystal River ASV-5, for EFW pump 2 burned up.
The cause was initially reported as a faulty torque P. witch.
A subsequent LER revision 1 identified the cause as a stuck contactor believed to be caused by a sticky substance such as cable pulling lubricant.
10.
369 81-152 Steam Generator 1C main feed to AFW nozzle isolation valve would not McGuire 1 operate and was manually shut.
Both the motor and TOL device were i
found burned out.
The motor was replaced and a functional verification perfonned. After canpletion of the timing test, a TOL alarm was received.
The second failure involved a mechanical latch malfunction causing internal canponents to fail and the actuator hammered until it broke.
- 9.-
/
Docket and Plant
.LER No.
Event Description-
,[
- 11.. 387 83-111 With the unit at 100% power, it was found that.the cooling water' supply Susquehanna 1 valve, HV-156F059, to the.HPCI lube oil' cooler and barometric condenser would not cycle.
The valve motor was burned out due to insulation break-down.
- 12. 387 83-129
~
Motor operated valve, HV-156F059, would not operate from the control room.
Susquehanna.1
-The torque switch failed to open at the specified torque.
The motor
~
continued to run and burned up on over torque with a locked rotor.
' The TOL bypass. circuit design was found to give an erroneous.
indication in the control romn in that 'if the MOV test / bypass switch were to be returned to the bypass position prior to actuation of the.
[
TOL, then no alann would occur.
(IE IN 84-13 was issued 'on this event.)
\\
[
Susquehanna 1 and barometric condenser would not operate.
This is additional i
information about LER 83-129. TOL, motor windings, armature and I
brushes were burned. Torque switch failed to open due to grease,.
.one spring pack Belv111e washer was installed backwards, and the thrust washer / sleeve gap was too small.
l
- 14. 271 Inspection Torus cooling was secured by closing upstream isolation valve
' Vermont Yankee
-Report V10-39A.. Approximately one minute after closing, a 125% overload 50-271/84-08 condition was annunciated in the control room and the circuit breaker i
tripped open. Torque switch had not stopped motor.when valve closed.
[
Motor circuit shorted and caused magnetic overcurrent trip. The TOL y
was set at 300% and did not actuate to de-energize the motor to provide
.t protection.
Motor operator housing was cracked and prevented both motor and manual operation of the valve.
t i
~.
~
10 -
Appendix B ADDITIONAL VALVE OPERATOR MOTOR BURNOUT EVENTS (LER NUMBER BY DOCKET NUMBER) 237/83-052, Rev. 1 328/81-115 237/83-052 334/80-011 245/84-014 361/82-103, Rev. 2 245/81-040 361/82-103 259/80-072 362/83-022, Rev. 1 263/82-017, Rev.1 362/83-022 271/81-023 366/79-086 278/81-018 366/80-109, Rev.1 280/81-075 366/80-109 281/81-052, Rev.1 366/80-089 281/81-052 366/80-101 291/83-026 366/81-074 293/80-044 366/81-088 293/81-008 366/81-117 315/81-004 366/81-114 320/80-048 366/79-114, Rev.1 321/82-088 366/81-142 321/82-041 368/81-026 324/81-013 369/81-159 324/81-082 369/81-150 324/81-029 369/81-121 324/81 -019 ~
369/81-120 325/81-014 416/83-168 325/81-013 t
-