ML16148A527
| ML16148A527 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 07/12/1991 |
| From: | Belisle G, Binoy Desai, Poertner W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML16148A525 | List: |
| References | |
| 50-269-91-12, 50-270-91-12, 50-287-91-12, NUDOCS 9108120225 | |
| Download: ML16148A527 (9) | |
See also: IR 05000269/1991012
Text
1 REG&
UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTA STREET, N.W.
ATLANTA, GEORGIA 30323
Report Nos.:
50-269/91-12, 50-270/91-12 and 50-287/91-12
Licensee: Duke Power Company
P. 0. Box 1007
Charlotte, NC 28201-1007
Docket Nos.:
50-269, 50-270, 50-287, 72-4
License Nos.:
DPR-38, DPR-47, DPR-55, SNM-2503
Facility Name:
Oconee Nuclear Station
Inspection Conducted: May 26 - June 29, 1991
Inspector:
_
_
_
. K. P ertner, Act ng Sen r es
t Inspector
Date Signed
B. B. Desai, Residen
Insp t rgned
Approved. by:
__
_
_
__
_
_
_
G. A.B 1Tsle, S
n Chief
at
Division of Reactor Projects
SUMMARY
Scope:
This routine, announced inspection involved inspection on-site in
the areas of operations, surveillance testing, maintenance
activities, spent fuel transfer cask inspection and inspection of
open items.
Results: Two violations were identified.
The first violation involved the
loss of configuration control of flow instrumentation (paragraph
2.d).
The second violation involved the operation of safety-related
systems without procedural guidance (paragraph 2.e).
0D
ADO:K 05000269
0
PDR-
REPORT DETAILS
1. Persons Contacted
Licensee Employees
- H. Barron, Station Manager
D. Couch, Keowee Hydrostation Manager
- T. Curtis, Compliance Manager
J. Davis, Technical. Services Superintendent
D. Deatherage, Operations Support Manager
B. Dolan, Design Engineering Manager, Oconee Site Office
- W. Foster, Maintenance Superintendent
T. Glenn, Engineering Supervisor
- 0. Kohler, Compliance Engineer
- .C. Little, Instrument and Electrical Manager
H. Lowery, Chairman, Oconee Safety Review Group
- B. Millsap, Maintenance Engineer
M. Patrick, Performance Engineer
D. Powell, Station Services Superintendent
- G. Rothenberger, Integrated Scheduling Superintendent
- R. Sweigart, Operations Superintendent
Other licensee employees contacted included technicians,
operators,
mechanics, security force members, and staff engineers.
NRC Resident Inspectors:
- P. Harmon
- W. Poertner
- B. Desai
- Attended exit interview.
2. Plant Operations. (71707)
a.
General
The inspectors reviewed plant operations throughout the reporting
period to verify conformance with regulatory requirements, Technical
Specifications (TS), and administrative controls.
Control room logs,
shift turnover records,
temporary modification log and equipment
removal and restoration records were reviewed routinely. Discussions
were conducted with plant operations, maintenance, chemistry, health
physics, instrument & electrical (I&E), 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
weekdays and on weekends.
Some inspections were made during shift
change in order to evaluate shift turnover performance.
Actions
2
observed were conducted as required by the licensee's Administrative
Procedures.
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.
Plant tours were taken throughout the reporting period on a routine
basis.
The areas toured included the following:
Turbine Building
Auxiliary Building
CCW Intake Structure
Independent Spent Fuel Storage Facility
Units 1, 2 and 3 Electrical Equipment Rooms
Units 1, 2 and 3 Cable Spreading Rooms
Units 1, 2 and 3 Penetration Rooms
Units 1, 2 and 3 Spent Fuel Pool Rooms
Station Y'ard Zone within the Protected Area
Standby Shutdown Facility
Keowee Hydro Station,
During the plant tours, ongoing activities, housekeeping, security,
equipment status, and radiation control practices were observed.
Within the areas reviewed, licensee activities were satisfactory.
b.
Plant Status
Unit 1 operated at power for the entire reporting period.
Unit 2 operated at power for the entire reporting period.
Unit 3 operated a.t power until June 9, 1991, when it automatically
tripped on low pressure/temperature due to the Group 5 control rods
dropping into the core. The Unit was returned to service on June 10,
1991.
c. Unit 3 Reactor Trip.
At 3:06 p.m.,
on June 9, 1991,
Unit 3 experienced an automatic reactor trip from 100 percent power.
The automatic actuation of
three of the four channels of the Reactor Protection System (RPS)
on
Low Pressure/Temperature and the subsequent reactor trip was caused
by the Group 5 control rods dropping into the core during movement of
Rod 12 in Group 5. A-
blown fuse in the absolute position indication
instrumentation required Instrumentation and Electrical
(I&E)
personnel to. enter the Control
Rod Patch Panel.
Following the
replacement of the blown fuse, operations performed OP/0/A/1105/09,
4.
3
Patch Panel Verification at Power,
as required by Technical
Specification (TS) 4.7.2.1. Rod 12 of Group 5 was transferred to the
auxiliary power supply to make adjustments to its position. When the
rod was moved, .the entire Group 5 bank dropped into the core and
subsequently the reactor tripped on
Low Pressure/Temperature.
Further investigation by the licensee determined that the transfer
from the regulating to the auxiliary power supply was not complete,
leaving both power supplies connected to the control rod drives.
This resulted in four phases of the rod contactors being energized
instead of two phases.
The magnetic fields produced by the rod
contactors were 180 degrees out of phase, effectively cancelling each
other.
As a result, the contactors opened and the rods in Group 5
dropped into the core. The failure to fully transfer to. the Auxiliary
power supply was due to the transfer switch for Rod 12 of Group 5
failing in the mid-position.
The switch was replaced prior to
startup.
-Maintenance engineering personnel are investigating
possible ways to change the transfer logic to alert the operator that
the transfer has not fully occurred.
The possibility of replacing
the transfer switch with an
improved version is also being
investigated.
The post trip response was normal; however, the following exceptions
were noted:
RPS channel "A" did not trip.
The trip setpoints for all four
channels were checked and found to be within tolerance. The "A"
channel was found to be calibrated towards the lower tolerance
limit, while the other three channels were calibrated toward the
upper limit.
Therefore, the plant had already tripped before
the setpoint .was reached for the "A" channel.
Following the trip, MS-19 (Turbine Bypass Control Valve A) was
continuously cycling even though steam pressure remained
constant. The valve was found to be cycling about 4.5 inches,
and sticking about 1 inch from the closed position. Adjustments
were made and the cycling of the valve was terminated.
As a
result of MS-19 opening and closing, MS-5 (Main Steam Relief
Valve) seated, then re-lifted following the trip. In addition,
the line from MS-19 to the condenser experienced large swings
due to a water hammer. One axial support and one spring support
bed plate were damaged and two elbows were slightly distorted.
The licensee attributed the water hammer to a temporary
modification
which
installed
a
condensate/feedwater
recirculation line to the turbine bypass line.
This source of
water, in addition to leakage by the turbine bypass valves, was
postulated to
be more than the drain line capacity.
Consequently, water accumulated at the bypass line low point.
The licensee has rerouted the recirculating line to the turbine
building drains. In addition, the.licensee has plans to replace
the turbine bypass lines during the next refueling outage.
4
The licensee conducted an investigation of the trip and'events that
occurred as part of this trip.
The inspectors witnessed actions
taken by the operators as well as participated in the post trip
meeting. No problems were identified. The licensee notified the NRC
as required by 10 CFR 50.72 (b)(2)(ii).
Unit 3 was returned to power operation on June 10, 1991.
d. Low Pressure Injection (LPI) Flow Instrument 2FT-4A Inoperable.
On May 30,
1991,
during performance of PT/2/A/0203/6A,
LPI Pump
Performance Test, the 2B LPI header flow instrument 2FT-4A on the
Unit 2 control panel did not indicate flow when the 2B LPI pump was
started.
Subsequent investigation by the licensee determined that
the instrument was valved out of service.
The instrument was
returned to service and an investigation was initiated to determine
how configuration control of the flow instrument was lost. The LPI
flow instruments had been calibrated less than a week prior to the
.pump performance test due to problems identified with the span values
used to calibrate the instruments.
Flow instrument 2FT-4A had been
independently verified at that time as being returned to service in
the controlling procedure.. The licensee was unable to conclusively
determine that the flow instrument had been left valved out of
Il
service after the instrument was calibrated; however,
the most
probable cause was determined to be oversight on the technicians part
when the work control copy of the procedure was combined with the
official copy of the procedure in the control room.
The failure to
maintain configuration control
on flow instrument 2FT-4A is
identified as Violation 50-270/91-12-01: Inoperable Flow Instrument.
The operators did not declare train "B" of the low pressure injection
system inoperable when the flow instrument failed to indicate flow.
-When questioned by the inspector the control room SRO stated that the
system was still operable because flow indication was available on
the plant computer. The LPI flow instruments on the Unit 2 control
board are non-seismic, non-class 1E, air operated instrumentation and
are scheduled to be replaced during the next refueling outage with
instrumentation that meets the requirements of Regulatory Guide 1.97.
The computer point flow indication is also a non-class 1E indication.
The licensee's position is that use of the computer point for
operability of the LPI system is acceptable until the flow
instrumentation is upgraded to meet the requirements of Regulatory
Guide 1.97.
The inspectors have expressed concerns in previous
inspections about the adequacy of the ECCS flow instrumentation. and
the amount of time. that has elapsed without upgrading the instru
mentation.
The instrumentation on Unit 3 was replaced during the
last refueling outage and Units 1 and 2 are scheduled to have the
instrumentation replaced during the next scheduled refueling outage.
Within this area, one violation was identified.
5
e. Core Flood Tank (CFT) Level Problems.
On May 25, 1991., during calibration of the Unit 3 "B" CFT channel 2
level instrument, the indicated level changed from 12.76 feet to
12.54 feet after the channel was calibrated. Channel 1 indicated
13.04 feet.
The channel 2 level instrument had been calibrated due
to the mismatch in indicated level between the two level instruments.
The Technical Specification (TS) lower limit for CFT level is 12.56
feet. Based on the channel 2 level instrument being less than the TS
limit the operators decided to add water to the "B" CFT.
The
operators attempted to makeup to the CFT per OP/3/A/1104/01,
Core
Flooding System; however,
the boric acid mix tank pump would not
pump.
The operators decided to crossconnect the "A" and ."B" CFTs
through the 1 inch sample lines to sluice water from the "A" CFT to
the "B" CFT.
The valves were opened and water level increased to
12.59 inches in the "B" CFT.
OP/3/A/1104/01 did not contain
procedural guidance for sluicing CFTs and a procedure change to
incorporate this method of increasing CFT level into the procedure
was not initiated. The procedure for sampling the CFTs specifically
requires that the non sampled CFTs sample valve be verified shut.
The failure to meet the procedural requirements of OP/3/A/1104/01 for
makeup to the "B" CFT is identified as Violation 50-287/91-12-02:
Failure to Follow Procedure.
The inspector also questioned the, acceptability of crossconnecting
CFTs during normal power operation.
TSs require that both CFTs be
operable when the unit is at power.
If the break location during a
loss of coolant accident was on a core flood tank injection line the
unaffected CFT would be crossconnected to the faulted CFT through the
1. inch sample line.. Based on the inspectors concern, the licensee
performed an engineering evaluation and determined that 25 percent of
the water volume in the non-faulted CFT would not be injected into
the core, however the core would remain covered under this condition.
The inspectors still question the acceptability of crossconnecting
the CFTs.at power since 25 percent of the non-faulted CFT would not
inject into the core and the sample valves do not receive power from
a safety related power supply and by design could not be shut during
a design basis accident.
The licensee is evaluating whether. a
procedure change to allow sluicing the CFTs should be included in the
controlling procedure.
Within this area, one violation was identified
f. Failure of Keowee Unit 1 to Start during Performance Test.
During the performance of PT/0/A/620/09, Keowee Unit 1 failed to
start due to failure of the generator breaker to close. The unit was
declared inoperable, a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> action statement was entered, and an
investigation into the. cause was initiated by the licensee.
The
failure of the generator breaker to close was attributed to the
X-relay contacts not closing at set turbine speed.
A pivoting
6
mechanical finger within the X-relay was found not reset causing the
X-relay contacts to remain open upon energization of the coil.
The
mechanical finger was physically reset and the performance test was
successfully run.
The licensee in conjunction with the manufacturer
is investigating the cause of the failure.
Pending further
evaluation, the licensee is visually verifying that the X-relay is
reset, following each shutdown of the Keowee units and logging that
the relay is reset in the Keowee operators log. The inspectors will
continue to monitor the licensee's actions regarding this issue.
g. Motor Control Center (MCC) Breaker Coordination Problems.
On May 29, 1991, the licensee determined that a breaker coordination
problem existed on MCCs 1, 2, and 3XS2. If an'overcurrent condition
occurred on non-safety panelboards 1, 2, or 3KM during an accident
the feeder breaker to the respective XS2 MCC could trip open prior to
the supply breaker to the non-safety panelboard tripping.
The
licensee found this problem as a result of an ongoing design review
of breaker and relay trip settings to address previously identified
problems in this area.
The panelboard supply was removed from the
safety-related MCC and transferred to a non-safety-related MCC. The
inspectors followed the licensee's immediate corrective actions to
resolve the breaker coordination problem and will followup on this
item via the licensee'.s LER.
3. Surveillance Testing (61726)
Surveillance tests were reviewed by the inspectors to verify procedural
and performance adequacy. 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. The tests witnessed, in whole or in part, were 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 reviewed and witnessed in whole or in part:
IP/O/A/0400/11
Keowee 125V DC Control Battery Test
PT/3/A/0251/01
LPSW Pump Performance Test
PT/O/A/600/19
Surveillance of 4160 and 600 Volt. Breakers
PT/3/A/0150/22L
Functional Test for HPSW Supply to TDEFW Pump
PT/3/A/6O0/01
Periodic Instrument Surveillance
PT/2/A/600/01
Periodic Instrument Surveillance
PT/1/A/600/01
Periodic Instrument Surveillance
PT/2A/0/600/13A
MDEFW Pump Performance Test
PT/1/A/251/01
LPSW Pump performance Test
Within the areas reviewed, licensee activities were satisfactory.
No violations or deviations were identified.
7
4. Maintenance Activities (62703)
Maintenance activities were observed and/or reviewed during the reporting
period to verify that work was performed by qualified personnel and that
approved procedures in use adequately described work that was not within
the skill of the trade.
Activities, procedures, and 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 reviewed and witnessed in whole or in part:
WR 52049J
Replace CRD Breaker CB-2
Exempt Change to Route KM from 1XS2 to 1XO
Replace Transfer Switch between Auxiliary and
Normal Power Supply
Troubleshoot Sullair Primary Instrument Air Compressor
Within the areas reviewed, licensee activities were satisfactory.
No Violations or deviations were identified.
5. - Spent Fuel Transfer Cask Inspection (55050)
On May 29, 1991, the inspector met with licensee representatives to review
the status of a spent fuel canister which was rejected by the licensee.
It was rejected during receipt inspection due to code rejectable lack of
fusion (LOF)
indications depicted in vendor supplied radiographs.
The
canister in question (DSC-1) had been fabricated by Equipos Nucleares SA
(ENSA), of Spain in accordance with ASME Code Section III, NC (83W85), see
NRC Inspection Report Nos. 50-269,270,287/90-21, paragraph 5, for further
details.
Since the close of the inspection discussed in the referenced
Inspection Report, the licensee met and discussed the problem with the
vendor,
re-radiographed the weld in question repeatedly in order to
duplicate shooting techniques and film sensitivity and attempt to locate
the rejectable indication. When none of these attempted was successful in
locating.the indication, the licensee performed a detailed review of the
fabrication records and discovered that the weld in question, (LW-205-1),
had been ground/dressed following radiography, to prepare it for surface
examination. Therefore, on the basis of the on-site radiographs, and the
recently discovered grinding records, the licensee concluded that the
indications observed in the vendor radiographs were no longer there as
they had been removed during the grinding of this weld.
By memorandum,
the licensee's Level III Examiner indicated the on site radiographs meet
code requirements and do not show rejectable indications.
The inspector
reviewed the vendor' and licensee produced radiographs, reviewed the vendor
documents presented and concurred with the licensee's decision that the
subject canister meets applicable code standards and is therefore
acceptable for the application.
No violations or deviations were identified.
8
6.
Inspection of Open Items (92700)(92701)(92702)
The following open items were reviewed using licensee reports, inspection,
record review, and discussions with licensee personnel, as appropriate:
(Closed) Violation 50-269,270,287/89-05-02:
Failure to follow
Procedures Due to Inadequacies in CMD Training and Qualifications.
The inspector reviewed the licensee response dated April 13, 1989,
and supplemental response dated October 2, 1990.
The licensee is
scheduled to complete the training and qualification of Construction
Maintenance Division personnel performing Nuclear Modification Work
in December 1992.
Based on the scheduled completion date, this item
is closed.
7. Exit Interview (30703)
The inspection scope and findings were summarized on July 3, 1991, with
those persons indicated in paragraph 1 above. The inspectors described
the areas inspected and discussed in detail the inspection findings. The
licensee did not identify as proprietary any of the material provided to
or reviewed by the inspectors during this inspection.
Item Number
Description/Reference Paragraph
50-270/91-12-01
Violation -
Inoperable Flow
Instrument, paragraph 2.d.
50-287/91-12-02
Violation -
Failure to Follow
Procedure,.paragraph 2.e.