ML20210H408
| ML20210H408 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 03/20/1986 |
| From: | Brownlee V, Bryant J, Sasser M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20210H360 | List: |
| References | |
| 50-269-86-01, 50-269-86-1, 50-270-86-01, 50-270-86-1, 50-287-86-01, 50-287-86-1, IEIN-85-094, IEIN-85-94, NUDOCS 8604030056 | |
| Download: ML20210H408 (10) | |
See also: IR 05000269/1986001
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION
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101 MARIETTA STREET, N.W.
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Report Nos.: 50-269/86-01, 50-270/86-01, and 50-287/86-01
Licensee: Duke Power Company.
422 South Church Street
Charlotte, N.C.
28242
Facility Name: Oconee Nuclear Station
Docket Nos.: 50-269, 50-270, 50-287
-License Nos.: DPR-38, DPR-47, and DPR-55
Inspection Conducted: Jgnuary 14 - February 10, 1986
Inspectors: bi
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Approved by:
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V. l. Bgowiniee, Section Chief, ( Acting)
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Division of Reactor Projects
SUMMARY
Scope:
This routine, announced inspection entailed 270 insoector-hours on site
in the areas of operations, surveillance, maintenance, followup of events, cold
weather preparations, reactor shutdown margin, and prepr. rations for refueling.
Results:
Of the seven areas inspected, no violations were identified in six
areas.
One violation was found in one area (Failure to follow procedure during
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surveillance test, paragraph 11).
0604030056 B60321
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REPORT DETAILS
1.
Licensee Employees Contacted
- M. S. Tuckman, Station Manager
J. N. Pope, Superintendent of Operations
- T. B. Owen, Superintendent of Maintenance
R. T. Bond, Compliance Engineer
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- T. C. Matthews, Technical Specialist
- D. E. Havice, I&E Engineer
B. G. Davenport, Performance Engineer
-J. W.~ Collier, Reactor Engineer
Other licensee employees contacted included technicians, operators,
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mechanics, security force members, and staff engineers.
- Attended exit interview.
2.
Exit Interview
The inspection scope and findings were summarized on Feburary 11, with those
persons indicated in paragraph 1 above. The licensee did not identify as
proprietary any of the materials provided to or reviewed by the inspectors
during this inspection.
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3.
Licensee Action on Previous Enforcement Matters
-Not inspected.
' 4.
Unresolved Items
Unresolved items were not identified on this inspection.
5.
Plant Operations
The inspectors reviewed plant operations throughout the reporting period to
verify conformance with regulatory requirements, technical speci ficatior.s
(TS), and administrative controls.
Control room logs, shift turnover
records, and equipment removal and restoration records were reviewed
routinely.
Interviews were conducted with plant operations, maintenance,
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' chemistry, health physics and performance personnel .
Activities within the control rooms were monitored on an almost daily basis.
Inspections were conducted on day and on night shifts, during week days and
on weekends.
Some inspections were made during shif t change in order to
evaluate shif t turnover performance.
Actions observed were conducted as
required by Operations Management Procedure 2-1.
The complement of
licensed personnel on each shift inspected met or exceeded the requirements
of TS.
Operators were responsive to plant annunciator alarms' and were
cognizant of plant conditions.
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Plant tours were taken throughout the reporting period on a routine basis.
The areas toured included the following:
Turbine Building-
Auxiliary Building
Units 1, 2, and 3 Penetration Rooms
Units 1,2, and 3. Electrical Equipment Rooms
Units 1,2, md 3 Cable Spreading Rooms
Station Yard Zele within the Protected Area
Standby Shutdown Facility
Units 1 and 2 Spent Fuel Pool
During the plant tours, ongoing activities, housekeeping, . security,
equipment status, and radiation control practices were observed.
Unit 1 operated at essentially full power until 3:48 a.m. on January 31,
when the unit 1 output breaker, PCB-20, failed, causing its ceramic
insulator to explode.
This caused the breaker to open, resulting in a
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turbine trip and an anticipatory reactor trip.
During and following the
reactor trip all systems performed as required to stabilize the reactor at
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hot shutdown conditions.
The main feeawater pumps tripped due to high
discharge pressure following the reactor trip, however; the emergency
feedwatar pumps supplied feedwater to the steam generator as designed.
There was no ESF actuation.
The fault in the 230 Ky switchyard caused the yellow bus to become isolated,
rendering the overhead path from the Keowee emergency power supply
However, the underground power path was not affected.
Emergency power was not required during or after the unit trip. As required
by TS, the Keowee emergency power path through the underground feeder was
operability tested within I hour. The inoperability of the Keowee overhead
emergency power path placed all three Oconee units in a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> action
statement.
The yellow bus was re-energized at approximated 6:30 p.m., ending the action
statement. Unit I was critical at 8:14 p.m. with power operations resuming
at 3:23 a.m. on February 1.
The unit remained at full power through the end
of the report period.
Unit 2 operated at essentially full power until 11:31 a.m. on January 31,
when the unit tripped from 100% power following a load rejection which
caused a turbine and anticipatory reactor trip. At the time, electricians
were performing maintenance and testing of microwave circuits in the 230 Kv
switchyard. Input of signals into an electrical circuit unexpectedly caused
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a breaker fault relay on PCB-23 to actuate.
This relay signal was an indication that a fault had occurrad on the.
breaker, the breaker then opened causing a generator lockout.
All systems performed as required during the reactor trip.
continued to be supplied to the steam generators by the main feedwater
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pumps.
No actuation of engineered safety features (ESF) occurred.
Following reset of the breakers in the switchyard, the reactor was returned
critical at 3:00 p.m.
Power operations resumed when the turbine was placed
on-line at 12:04 a.m. on February 1.
Full' power operations continued until 3:30 p.m. on February 4 when the unit
tripped on reactor power imbalance.
Cause of the trip was the reactor
protection system (RPS) channels C and D trip breakers opening during the
performance of a surveillance test.
This trip is discussed in greater
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detail in paragraph 11.
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Following evaluation and determination of the reason for the trip, the
reactor was taken critical at 8:19 p.m. on February 4.
Power operation was
. resumed and the- unit remained at full power through the end of the report
period.
Unit 3 operated at essentially full power until 6:00 a.m. on January 30,
when power reduction began in order to repair a turbine reheat stop valve
which had closed. Power was reduced to 15% and the turbine taken' off line
at 10:53 a.m. The turbine was placed back on line and power ascension began
at 3:59 a.m. on January 31.
At 7:08 a.m.
on January 31, the reactor tripped from 57% power on high
pressure. The trip was caused when a main feedwater pump flow transmitter
failed high, causing a feedwater runback and the subsequent reactor high
pressure trip.
Only one feedwater pump was operating at the time. All
systems responded normally and there was no ESF actuation. The unit was
made critical at 10:49 a.m. on January 31 and returned to power the same
day. Unit 3 continued operation at full power through the remainder of the
report period.
6.
Surveillance Testing
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The surveillance tests listed below were reviewed and/or witnessed by the
inspectors to verify procedural and performance adequacy.
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The completed tests reviewed were examined for necessary test prerequisites,
instructions, acceptance criteria, technical content, authorization to begin
work, data collection, independent verification where required, handling of
deficiencies noted, and review of completed work.
Tha tests witnessed, in whole or in part, . wore inspected to determine that
approved procedures were available,
test equipment was calibrated,
prerequisites were met, tests were conducted according to procedure, test
results were acceptable and systems restoration was completed.
Surveillances witnessed in whole or in part are as follows:
CP/1/A/2002/01 Unit 1 Primary Sampling System
CP/0/A/2004/6B Determination of Fluorides, Unit 2 RCS and PZR
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CP/0/A/2004/2B Determination of Boron, Unit 2 RCS and PZR
CP/0/A/2004/3E Determination of Chlorides, Unit 2 RCS and PZR
PT/0/A/290/04
Turbine Stop Valve Movement, Unit 1
PT/0/A/290/03
Turbine Control Valve Movement, Unit 1
PT/1/A/251/02
SF Cooling Pump A Performance Test
PT/2/A/1103/15 . Reactivity Balance Procedure
Surveillance tests reviewed are as follows:
PT/0/A/620/09
Keowee Hydro Operation
PT/2/A/600/10
Reactor Coolant Leakage
PT/1/A/600/10
Reactor Coolant Leakage
PT/2/A/600/01
Periodic Instrument Surveillance
PT/1/A/1103/15 Reactivity Balance Procedure, Unit 1
PT/2/A/1103/15 Reactivity Balance Procedure, Unit 2
PT/3/A/1103/15 Reactivity Balance Procedure, Unit 3
No violations or deviations were identified.
7.
Maintenance Activities
Maintenance activities were observed and/or reviewed during the reporting
period to verify that work was performed by qualified personnel and that
approv'ed procedures in use adequately described work that was not within the
skill of the trade. Activities, procedures end work requests were examined
to verify proper authorization to begin work, provisions for fire,
cleanliness, and exposure control, proper return of equipment to service,
and that limiting conditions for operation were met.
Maintenance witnessed in whole or in part:
WR 27182B Repair 2 RIA-10
WR 27807B Repair of 28 RBCU Motor Starter
Replace 3CA Gattery
8.
Starting of Low Pressure Injection (LPI) Pump With Suction Valve Closed
Report No. 269/85-38 discussed the starting of IC LPI pump with the suction
valve,
.P-7,
closed. The error was detectsd itmediately and the pump was
not damaged. The inspectors have reviewed the event in greater detail to
determine just how it occured.
PT/1/A/0203/06, Low Pressure Injection Pump Performance Test, has several
functions and references different sections on enclosures, depending on _the
purpose of using the procedure. As stated in the earlier report, the system
was prepared soon after midnight for testing on the following shift. The
final part of the preparation performed by the night shift was a section of
an enclosure which required, in three steps, opening the suction valve,
opening the vent valve, and when venting was complete, closing the vent
valve. These steps were performed and verified. The next step would be to
return to the body of the procedure and resume the test.
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The nuclear equipment operator (NEO), knowing that no further work was to be
done, requested the reactor operator (RO) to close LP-7, which is the tormal
action after merely venting the pump and returing it to its normal mode.
Without referencing the procedure, the R0 did as requested. Note that LPI
pump C has no automatic ESF function. Twelve hours later the performance
group began performing the test. The enclosure, since there was no step to
close the valve and sign completion, indicated that LP-7 was open.
The error apparently resulted from the time lag between setting up the
system and performing the test, the configuration of the procedure, and the
NEO, in effect, adding a step which was not in the procedure. The residents
were made aware of the error;
the error was noted immediately and
corrective action taken which prevented damage to the pump; and the
procedure has been modified to add a step req" iring verification that valve
LP-7 is open prior to starting the pump.
The licensee is reviewing other
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procedures and the practice of performing valve lineups a considerable
period of time before a test is performed. Due to the circumstances and the
corrective action taken, this event was not cited as a violation.
.The inspector followup item, IFI 269/85-38-01, is closed.
9.
Determination of Reactor Shutdown Margin (61707)
An inspection of the licensee's. program for . determining shutdown margin
(SDM) was performed to verify that SDM calculation is technically correct
and in accordance with TS and station procedures.
Technical review of procedures verified that the most recent critical
conditions prior to unit shutdown are used in the SDM calculation.
The
factors which must be considered are the core reactivity changes due to fuel
burnup, power, temperature, boron, xenon, samarium, and control rod
position.
On January 31, Oconee taits 1, 2,
and 3 each tripped off-line duc to
different reasons. The inspectors reviewed the specific SDM calculations
performed for those reactor trips.
SDM is calculated using procedure
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PT/A/1103/15, Reactivity Balance Procedure, with curves specific to each
unit based on prior core reload data for the unit cycle.
Following a reactor trip the Performance reactor engineer calculates a
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reactor SDM for het shutdown conditions with all control rods inserted for
the specific conditions of burnup, boron concentration, xenon, and others as
appropriate.
All calculations are independently verified by a second
individual on a separate sheet. Subsequent calculations for SDM, shutdown
boron concentration, or estimated critical rod position (ECP) are performed
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based on changing conditions as required by the appropriate startup or trip
recovery procedure.
The inspectors reviewed all the calculations performed following the unit
trips of January 31. One minor discrepancy was noted and discussed with
appropriate licensee staff.
Following the trip of unit 3, the ECP was
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calculated in preparation for restart. During the approach to criticality,
the reactor did not go critical within the required window on rod position.
As required by the startup procedure, all control rods were inserted for
re-evaluation of the ECP.
It was determined that the boron concentration
existing at the time of startup was higher than that used for the initial
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ECP calculation because water from the concentrated boric acid storage tank
(CBAST) had been used for makeup durino the previous 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period since
the last chemistry sample.
'Although a procedural violation did not exist, the inspectors discussed with
the licensee the importance of ensuring the use of accurate existing reactor
conditions for all calculations in the reactivity balance procedure.
The
inspectors will review future reactivity balance calculations to verify that
this type of problem does not continue.
No violations or deviations were identified.
10.
Preparation for Refueling (60705)
For the unit 1 outage, scheduled to begin on 2/13 the residents reviewed the
licensee's preparations for refueling, including the controls on receipt,
inspection, and storage of new fuel. An inspection tour of the units I and
2 spent fuel pool (SFP) was taken to assess cleanliness, the storage area
for new fuel, empty space available to off-load the core, and the general
condition of the pool area and equipment.
Procedure OP/0/A/1503/04, New Fuel Assembly Inspection and Storage, was
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reviewed to ensure that an adequate, approved procedure is available for
receipt, inspection, and storage of new fuel.
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The inspectors selected a recent shipment of new fuel from Babcock & Wilcox
(B&W), for review of all the completed documentation.
This shipment
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included six containers each containing two fuel assemblies.
The documents
reviewed were:
Performance memo to Operations specifying the correct location for
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each new fuel assembly and its components.
Completed procedure OP/0/A/1503/04 for the shipping containers and
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fuel assembly.
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All documents either received from B&W or completed by Operations
which trace the new fuel from the supplier to its location in the
SFP.
Inc!uded are bill of lading, NRC/D0E Form 741, shipping
notice, emergency instructions to driver, and fuel assembly
storage notification.
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All the documentation reviewed was found to be in order.
The fuel
assemblies were traced from the supplier, B&W, to the receiver and
subsequently to specific storage locations in the SFP. The inspectors found
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that adequate procedures exist to control the receipt, inspection, and
storage of new fuel.
Following the inspection of new fuel receipt the inspectors reviewed the
licensee's program for refueling. The sequence for refueling the reactor is
as follows:
1.
Offload of the entire reactor core into the SFP.
2.
Component shuffle in the SFP to match up components with correct
fuel assemblies.
3.
Verification of correct assemblies and components in the SFP.
4.
Reload of the reactor core.
5.
Core. verification of correct fuel assemblies and core alignment.
The inspectors verified that adequate. procedures exist to control the above
activities. .The procedures which determine the reload sequence, identifying
specific core locations, 'are developed by station and general office
engineering personnel and formally transmitted tc t,perations personnel for
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implementation.
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No violations or deviations were identified.
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11.
Unit 2 Trip Due To Personnel Error
Unit 2 tripped from 100% power at 3:30 p.m. on February 4, apparently due to
a' personnel error during performance of a surveillance test.
The unit
tripped on power imbalance when safety rods trip breakers were in
advertently left opened, driving the rods into the reactor. All safety
systems performed as required and there was no engineered safety system
actuation. Steam generator levels were maintained at the post trip startup
levels.
At the time of the trip, I&E technicians were performing ' procedure
IP/2/A/305/3C, RPS Channel
'C'
Calibration and Functional Test, when a
personnel error.resulted in breakers CB-3 and CB-4 (associated with Channel
D) mistakenly being tripped and left open at the local shunt trip instead of
the Channel C breakers, CB-1 and CB-2.
The error was not realized at the
time and when subsequent steps in . testing of the Channel C trip logic
resulted in opening of CB-1 and CB-2, the rods drove in on 2 out of 4 RPS
logic.
Critical steps in the test procedure being followed required independent
verification.
All steps in the procedure were . properly signed off,
indicating that correct actions were taken and verified to be correct. The
mechanics stated that they did not believe an error had been made; however,
the events recorder shows the sequence of events leading to the trip.
While the licensee reported the event and all actions taken after the event
were correct, this will be cited- as a violation for failing to follow
procedure since the critical steps in the procedure had been signed and
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independently verified to be correct.
(Violation
failure to follow
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procedure during surveillance test 50-270/86-01-01).
12.
Emergency Drills
On January 29 the residents participated in a practice emergency drill on
Unit 3.
During the simulated accident, in which a simulated site area
emergency was declared, the techincal support center (TSC) and operational
support center were actuated.
On February 2 the residents participated, at the TSC and the crisis
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management center, in a practice drill in which general emergency was
simulated.
In the early phases of the drills the inspectors' observed the drill from the
control rooms to verify that the drills did not impart negatively on routine
operation of the reactors. The inspectors determined that all phases of the
drill were handled professionally and.in a controlled manner.
13.
Information Notice 85-94 - Minimum Flow Paths
IE Notice 85-94: Potential for loss of Minimum Flow Paths Leading to ECCS
Pump Damage During a LOCA, alerted licensee's of recent problems discovered
at some plants which found that minimum flow requirements might not be met
for some emergency core cooling system (ECCS) pumps under some accident
conditions.
In summary, the information notice stated that some pumps had
inadequate flow paths due to system design or valve problems.
The
inspectors reviewed the recirculation flow paths for Oconee safety related
pumps, both independently and with licensee personnel.
The high pressure injection (HPI), low pressure injection (LPI), emergency
feedwater, and reactor building spray (RBS) systems were reviewed. Results
of _ the residents' review, as summarized below, indicated that problems of
the kind presented in the IE Notice are not present at Oconee.
For each HPI pump there is a one and one half inch minimum flow recirc line
with 35-40 gpm flow directed to the letdown coolers and back to the letdown
storage tank.
There are two manual block valves in each recirc line,
however these are always open by procedure.
There are no procedures which
require these to be closed.
Pumps 'always have minimum recirc while
operating.
Each LPI pump- has a one inch recirc line back to the pump suction with no
cooling.
The recirc lines have no block valves and cannot be isolated.
Because the recirc line provides no heat sink, the LPI pump (s) can only be
run for a short period of time while dead headed.
This is controlled
administratively in the emergency operating procedure (EOP) through a note
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that states that LPI cannot operate without flow for more than 30 minutes.
The coerator is directed to establish flow or secure the pump (s).
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For the reactor building spray (RBS) pumps there is no recirc path. Pump
suction is always open by procedure. The pump discharge valve op~ ens and the
pump starts on the same signal, ESF and containment high pressure. The pump
discharge pressure is 250 psig; the only restriction is the containment
pressure.
Since containment design pressure is 60 psig there is adequate
margin to ensure pump flow.
For the motor driven emergency feedwater pumps (EFW) there is an automatic,
self contained, minimum recirc valve incorporated into the discharge check
valve. All other valves in the recirc lines are locked open by procedure.
The turbine driven EFW pump has a recirc line which is always open to the
upper surge tank. All valves in the line are locked open by procedure.
No violations or deviations were identified.
14.
Licensee Event Reports
The inspectors reviewed nonroutine event reports to verify the report
details met license requirements, identified the cause of the event,
described corrective actions appropriate for the idenfified cause, and
adequately addressed the event and any generic implications.
In addition,
as appropriate, the inspectors examined operating and maintenance logs, and
records and internal investigation reports.
Personnel were interviewed to- verify that the report accurately reflected
the circumstances of the event, that the corrective action had been taken or
responsibility assigned to assure completion, and that the event was
reviewed by the licensee, as stipulated in the Technical Specifications.
The following event reports were reviewed:
(0 pen) LER 270/82-10 Stuck Suction Relief on the "2B" MFWP, After a
Reactor Trip. This incident resulted in the upper surge tank level
falling below technical specifications limits.
Only one outstanding
commitment remains. Station Modification 1584 has been installed, but
does not work satisfactorily. Until oparational problems are resolved
the LER will remain open.
(Closed) LER's 269/83-17 and 269/83-20 Delayed trip on CRD DC Breaker.
Several modifications have been completed on reactor trip breakers, and
changes have been made to preventive maintenance procedures. There
have been no recent failures and there are no further modifications in
work. These items are closed.
(0 pen) LER 269/83-12 Emerr~.1cy Discharge Valve Opened Without Ccmmand
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Due to Component Malfunct.on.
Corrective action was taken which
restored the equipment to operability and heaters were ins *.alled to
disipate moisture. A final change to relocate power cables in order to
prevent spurious operation is scheduled to be completed by August 1,
1986.
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