ML18101A839
| ML18101A839 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 07/18/1995 |
| From: | Ruland W, Scholl L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML18101A837 | List: |
| References | |
| 50-272-95-12, 50-311-95-12, NUDOCS 9507260112 | |
| Download: ML18101A839 (10) | |
See also: IR 05000272/1995012
Text
DOCKET/REPORT NOS:
LICENSEE:
FACILITY:
DATES:
INSPECTOR:
APPROVED BY:
U. S. NUCLEAR REGULATORY COMMISSION
REGION I
50-272/95-12
50-3'11/95-12
Public Service Electric and Gas Company
Salem Nuclear Generating Station, Units 1 and 2
Hancocks Bridge, N.J.
May 15 - June 8, 1995
Larry choll, Reactor Engineer
Electrical Section
Division of Reactor Safety
~Ur.kl.IL
Electrical Section
Division of Reactor Safety
7//o/9S-
Date
7/q/rr
Date
Areas Inspected:
The areas examined during this inspection included a review
of the operation and maintenance of the 4.16 kV and 230/460 volt air circuit
breakers.
The itispection included a review of established maintenance
procedures, breaker reliability, corrective actions taken for breaker failures
and actions taken in response -to industry and NRC information.
The inspector also performed a review of active operability determinations for
Salem Units 1 and 2 to evaluate the quality of these determinations and to
ensure that the evaluations had an adequate bases to support the conclusion
that the safety components were operable.
Results:
Refer to Executive Summary
9507260112 950718
ADOCK 05000272
Q
EXECUTIVE SUMMARY
Circuit Breaker Inspection
The inspectors found that preventive maintenance programs and procedures have
been established for the 4.16 kV and 230/460 volt air circuit breakers.
A good training course has been established to train the electricians on the
operation and maintenance of the various types of circuit breakers.
The
training facility was found to be excellent.
The 4.16 kV circuit breaker reliability has been generally good.
However, the
230/460 volt ITE circuit breakers have experienced numerous failures due to
hardened and/or dirty grease in the operating mechanisms.
The failure of
circuit breakers to operate properly can result -in the loss of safety systems.
Also, the slow closing of a circuit breaker could increase safety system
response times and change emergency diesel generator loading sequences.
The
licensee is presently attempting to resolve this problem.
Since this
condition has been allowed to exist for several years, a violation has been
cited for the failure of the licensee to take corrective action to prevent
repetitive failures.
The licensee review and disposition of industry information regarding circuit
breaker problems was found to be good.
The inspectors found the operability determinations to be of a variable
quality.
In some cases, the documented bases for the operability conclusions
were not complete, and it was necessary for the inspectors to obtain
additional information to assess the operability determination conclusion.
In
several cases, actions necessary to monitor degraded conditions to ensure
continued operability were not clearly specified.
PSE&G issued a new
procedure for the performance of operability determinations on May 25, 1995.
Unresolved Item 50-272/95-80-01;50-311/95-80-0l (regarding the adequacy of
operability determinations) will remain open pending NRC review of future
operability determinations performed using the new procedure .
ii
DETAILS
1.0
SCOPE/BACKGROUND (NRC INSPECTION PROCEDURE 62705)
The purpose of this inspection was to review the operation and maintenance of
the circuit breakers utilized in the 230, 460, and 4160 volt electrical
systems.
The inspection included a review of breaker reliability, preventive
maintenance (PM) program and procedures, corrective actions taken for breaker
deficiencies and failures and actions taken in response to industry
information associated with circuit breakers.
The inspector also interviewed
members of the -plant technical and maintenance departments involved in
activities associated with the circuit breakers.
The types of circuit breakers used at the Salem Units 1 & 2 plants are General
Electric (GE) Magne-Blast for the 4.16 kV buses and primarily ITE K-Series
breakers for the 230 and 460 volt buses.
The emphasis of this review was to identify possible problems associated with
the circuit breakers that could result in a common mode failure of more than
one breaker.
2.0
PREVENTIVE MAINTENANCE PROGRAM AND PROCEDURES
Preventive Maintenance Program
A PM program has been established for all safety and nonsafety breakers and
the frequency for each of the breakers was based on a reliability centered
maintenance study.
Preventive maintenance is performed on all of the circuit
breakers on a minimum frequency of every five years. Certain circuit breakers
had preventive maintenance performed on a more frequent bases.
For example,
the containment fan coil unit breakers have preventive maintenance performed
every 18 months since they are operated more frequently than other breakers.
The breaker preventive maintenance is normally performed by PSE&G
electricians.
In addition to the preventive maintenance performed by PSE&G,
the 4 kV breakers are returned to the vendor (GE} every nine years to receive
a more comprehensive overhaul and refurbishment.
Maintenance Procedures
Maintenance procedures are in place to control work on each type of breaker
used at the Salem plants. The inspector reviewed portions of the procedures
and found that the vendor recommendations had been appropriately incorporated
into the procedures.
One procedural weakness that was identified was that the
circuit breaker lubrication recommendations were not clearly specified and
therefore the extent to which each breaker's moving parts were cleaned and
lubricated was left to the discretion of the particular electrician performing
the maintenance.
As discussed in Section 3.0 of this report, the lack of
proper lubrication has resulted in performance problems with the 230/460 volt
breakers .
2
Due to an unplanned Unit 1 outage, a planned PM activity on an ITE breaker was
canceled and the inspector did not have the opportunity to observe in-progress
circuit breaker maintenance.
The inspector interviewed two electricians and
found them to be very knowledgeable on the operation and maintenance of the
circuit breakers.
Training
The inspector toured the training facility and discussed the circuit breaker
training program with one of the electrical instructors. The inspector found
that a good training facility is utilized to provide thorough training on all
of the various circuit breakers utilized in the plant. The lesson plans are
detailed and a significant amount of time is dedicated to the circuit breaker
portion of the electrician training.
3.0
CIRCUIT BREAKER FAILURE HISTORY
4.16 kV Magne Blast Circuit Breakers
The 4.16 kV circuit breaker performance has been generally reliable and there
were no significant trends noted in a review of the breaker failure histories.
230/460 Volt ITE Circuit Breakers
A review of the failure histories for the ITE 230/460 volt breakers revealed
that numerous failures (failure of a breaker to close) were attributed to
hardened and/or dirty grease in the operating mechanism.
The licensee was
currently investigating a recent problem associated with a breaker failure
that was attributed* to hardened grease, but had not yet determined the root
cause or the corrective actions necessary to preclude repeat failures. The
inspector reviewed the problem with the circuit breaker lubrication in more
detail and determined the following:
The system engineer had reviewed the circuit breaker failure history and
found two similar failures in the recent data (approximately two years).
The inspector reviewed the failure reports for the past five years and
identified 13 cases where a safety-related circuit breaker failed to
close and the cause was attributed to hardened and/or dirty grease.
(The 13 included additional recent failures not yet added to the data
base reviewed by the system engineer.)
Plant operators, engineers, and maintenance personnel were aware of
instances where there was a delayed response to a breaker close signal.
One incident report stated that the delay could be as much as 30
seconds.
Corrective actions for the doc~mented breaker failures were to clean and
lubricate the particular circuit breaker, but the corrective actions did
not address generic implications .
3
The electricians that were interviewed were aware of the slow close
problem and had observed the slow close when doing as-found trip tests
of the breakers during the PM process. However, their experience was
that the breakers would always close and had not seen any breakers stay
open indefinitely.
The PM procedure had been revised in January 1992 to provide more
guidance as to what actions were specifically required to be performed
during a PM.
Previously, the procedure instructed the electrician to
inspect the breaker and perform cleaning and lubrication as necessary
but did not specify mandatory lubrication points.
A review of the current PM procedure showed that although there is more
specific guidance to the electricians, the specific roller that appears
to cause the slow and/or failure to close is not one of the specified
mandatory clean and lubrication points.
At the time of the inspection, the licensee had not performed any
documented safety assessment and/or operability determination to address
the implications of the breakers slow closing or failing to close.
An
operability evaluation was subsequently performed and addressed
considerations such as the effects of slow closure on system time
responses and emergency diesel generator load sequencing. Also, actions
were taken to ensure all circuit breakers were recently operated with
satisfactory results.
There did not appear to be a clear correlation between the timing of the
circuit breaker failures relative to when the breaker PM was last
performed or to whether or not it was last performed using the new
procedure.
The inspector found that the electrical systems engineer was developing a plan
to resolve the problem with the hardened grease and associated circuit breaker
failures. Actions included in this plan were:
Two tubes of the grease (Anderol 757) used to lubricate the breakers
were sent to the manufacturer for analyses.
One tube was from the
storeroom and the other was one that had been in use by the maintenance
department.
A sample of grease from an inservice circuit breaker will be sent to the
vendor for analysis.
The circuit breaker vendor (ABB) will be requested to review/observe the
PSE&G maintenance practices to assess their adequacy.
Circuit breaker operating times will be checked before and after
maintenance to evaluate the effectiveness of the preventive and/or
corrective maintenance .
4
The system engineer was also in the process of reviewing an incident report
developed by the operations department that documents numerous failures of the
circuit breakers for the primary water pumps.
During this review, the system
engineer found that a significant number (approximately 40%) of the
maint~nance work orders listed the cause of the failure as "unknown".
The
system engineer issued Engineering Memo #95-150 to the operations engineers to
ensure that the plant operators were aware of the hardened grease problem and
to request that the operators initiate actions to troubleshoot breaker
problems before any actions are taken that may disturb the conditions at the
time of malfunction.
For example, breakers should not be racked out of the
operate position before as-found data is documented and any possible
troubleshooting has been performed.
Although the licensee is currently investigating the breaker failures caused
by hardened grease, the failure to identify the cause of the problem that has
existed for several years and the failure to take corrective actions to
prevent repetitive failures is a violation of 10 CFR 50, Appendix B, Criteria
XVI corrective action requirements.
(50-272/95-12-01; 50-311/95-12-01)
4.0
PSE&G REVIEW AND RESPONSE TO INDUSTRY INFORMATION
The inspector reviewed the actions taken by PSE&G in response to the following
NRC Information Notices (INs):
'
General Electric Magne-Blast Circuit Breaker Problems
BBC Brown Boveri Low-Voltage K-Line Circuit Breakers with
Deficient Overcurrent Trip Devices
Potential Failure of ASEA Brown Boveri Circuit Breakers
During Seismic Event
Failures Caused By An Improperly Adjusted Test Link in 4.16
kV General Electric Switchgear
Inoperablity of General Electric Magne-Blast Breaker Because
of Misalignment of Close-Latch Spring
The inspector found that PSE&G had appropriately evaluated the above
information and had implemented hardware and/or procedure changes to address
the applicable issues.
5.0
WALKDOWN OF SWITCHGEAR AND MAINTENANCE AREA
The electrical equipment was found to be in good condition during a walkdown
of the switchgear areas. Housekeeping was very good in the switchgear areas
and th~re were not an excessive number of equipment trouble tags.
The
deficiencies identified on trouble tags were minor .
5
6.0
MANAGEMENT OVERSIGHT AND SELF-ASSESSMENT
Following the initial inspection activities and NRC identification of concerns
with the lack of timely resolution of the circuit breaker lubrication issue, a
quality assurance (QA) audit report was provided to the inspector that had
identified concerns with the failure of the containment fan coil unit (CFCU)
circuit breakers.
The QA audit identified that there were repeat failures of
the CFCU circuit breakers and that an adequate cause determination or actions
to prevent recurrence had not been established.
The report also noted that
the generic implications of the failure had not been addressed nor was there a
documented safety evaluation to assess the effects of a slow start during an
event.
The inspector found the QA audit findings to be excellent. However, the
maintenance department was allowed the routine time of 30 days to respond to
the findings.
The inspector concluded that a more timely safety assessment
would have been appropriate to ensure that the problems with the circuit
breakers did not affect the operability of safety equipment.
7.0
OPERABILITY DETERMINATION (OD) REVIEWS (NRC INSPECTION PROCEDURE 71707)
(UPDATE UNRESOLVED ITEM 50-272/95-80-01; 50-311/95-80-01)
During a special NRC team inspection conducted April 26 - May 12, 1995, the
inspectors identified nine examples where the station had been operated with
degraded equipment for which operability determinations had been prepared.
The technical bases for the operability determinations were found to be
deficient and inappropriately justified operability based upon equipment
redundancy, the lack of technical specification or Updated Final Safety
Analysis Report documentation, the lack of effect on the reactor protection
system, and fail safe positioning. Subsequent to the departure of the
inspection team from the site, PSE&G committed to completing a review of all
active ODs by May 19, 1995.
The results of the PSE&G review were forwarded to
the NRC during the week of May 22, 1995.
The inspectors reviewed the adequacy of the bases for the active ODs during
this inspection and found that the quality of the ODs was variable and in
several cases the inspectors required additional information to reach a
conclusion regarding equipment operability.
Some of the ODs clearly stated
what the safety functions of the components and systems were and others only
listed reference documents that described the safety functions.
The higher
quality ODs clearly listed the safety functions and then addressed the effects
of the degraded condition against each of the safety functions. Another
weakness was that the bases for operability did not clearly specify what
periodic inspections, measurements and/or tests were necessary* to ensure
continued operability. The inspector also noted that several of the ODs
provided addressed conditions that had already been resolved by component
replacement and as such were not active ODs.
')
6
Examples of these findings:
The OD associated with bolt failures on the emergency diesel generator
(EOG) fuel inlet block stated that "the risk of additional bolt failures
was low due to *the large number of bolts for all six engines and their
large number of operating hours".
The OD did not contain a discussion
on how the number of operating hours correlated to the observed bolt
failures. Data provided to the inspector indicated that the bolt
failures had occurred on the Unit 2 EDGs that had approximately 1300
operating hours while the Unit 1 EDGs had approximately 800 operating
hours. This data could suggest that the Unit 1 EDGs would experience
bolt failures when additional operating hours accumulate on the EDGs.
The documentation provided in the OD did not indicate that the root
cause of the failures had been identified and corrected.
During followup discussions with the system engineer and maintenance
personnel, the inspector obtained additional information regarding the
suspected cause of the bolt failures and corrective actions taken.
The
root cause of the failures was believed to be a deficiency in the
machining of the fuel pump inlet counterbore area. This deficiency
resulted in some of the mounting bolts bottoming out in the mounting
hole and caused insufficient bolting forces on one side of the fuel pump
inlet face. This condition caused higher forces to act on the other
bolt and resulted in fatigue failure of the bolt. Dimensional checks
have been made on the counterbore area and bolt holes to verify that all
bolts are fully seated during torquing and where necessary the bolt
holes have been tapped to provide full bolt seating.
Based on the
additional information provided, the inspector concluded that
operability concerns had been appropriately addressed.
The operability determination for a battery cell that had a portion of
scavenger post-seal lead broken loose from the positive post-seal did
not address the long term effects of the missing scavenging lead. The
purpose of the scavenger lead is to protect the current carrying lead
post from corrosion. The operability determination only addressed the
effects of the piece of lead having landed on the top of adjacent plate
separators. Since the affected cell was subsequently replaced, this was
not an active OD; however, this is an example of an OD that lacked a
thorough technical bases.
The OD for battery cells that experienced copper contamination did not
address the long term effects of this condition. The contamination may
have been the result of copper being displaced from the current carrying
insert in the battery post and the time dependent effects of this copper
displacement was not addressed.
The affected cells have been replaced
and therefore this is no longer an active OD.
However, it is an example
where the bases did not adequately address how long the condition could
exist without impacting operability or what inspections, measurements
and tests were necessary to ensure continued operability .
_!
v
7
The inspector noted that on May 24, 1995, Procedure SC.OP-DD.ZZ-OD02(Q) -
Revision O, "Operability Determination," was issued.
The purpose of this new
procedure is to provide guidance to the station personnel for conducting
operability determinations of structures, systems, and components and
documenting the results of the review.
Conclusions
The inspectors did not identify any examples where component operability could
not be justified, although process weaknesses were identified as discussed
above.
The effectiveness of the new procedure could not be assessed at this
time due to the recent issuance and lack of a significant number of
operability determinations that were performed under this procedure. This
unresolved item remains open pending additional NRC review of the adequacy of
operability determination performed utilizing the new procedure.
8.0
EXIT MEETING
Exit meetings were held on May 24 and June 8, 1995, with members of the
licensee's staff noted in Attachment 1.
The inspector discussed the scope and
findings of the inspection. The licensee had no disagreements with the
findings.
Proprietary information was reviewed during this inspection;
however, no proprietary information is contained in this inspection report.
Attachment:
Exit Meeting Attendees
-~
'
ATTACHMENT 1
EXIT MEETING ATTENDEES
MAY 24, 1995
Public Service Electric and Gas
R. Chranowski, Technical Department
B. O'Grady, Operations Department
L. Hayos, Nuclear Engineering Department
G. Madsen, Technical Department
R. Malone, Licensing Department
M. Morroni, Maintenance Department
D. Tauber, Quality Assurance Department
Atlantic Electric
M. Sesok, Site Representative
J. Janocha, Lead Engineer
Public Service Electric and Gas
C. Bersak, Staff Engineer
R. Brown, Strategic Planning
E. Harkness, Planning Department
JUNE 8, 1995
M. Metcalf Sr., Maintenance Department
P. Moeller, Licensing Department
J. Morrison, Corrective Actions
B. Preston, Engineering Department
J. Ranalli, Technical Department
P. Steinhauer, Technical Department
J. Summers, General Manager, Salem Operations
D. Tauber, Quality Assurance Department
Atlantic Electric
M. Sesok, Site R~presentative
PECO Energy
R. Kankus, Joint Owners Affairs
Delmarva Power
P. Duca, Site Representative