IR 05000458/1990008
| ML20034C556 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 04/24/1990 |
| From: | Constable G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML20034C554 | List: |
| References | |
| 50-458-90-08, 50-458-90-8, NUDOCS 9005040135 | |
| Download: ML20034C556 (9) | |
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APPENDIX U.S. NUCLEAR REGULATORY COMMISSION
REGION IV
NRC Inspection Report:
50-458/90-08'
Operating License:
NPF-47 Docket: 50-458 L
Licensee: Gulf States Utilities Company (GSU)
l P.O. Box 220
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St. Francisville, Louisiana 70775 Facility Name: River Bend Station (RBS)
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Inspection At: RBS, St. Francisville, Louisiana Inspection Conducted: March 1-31, 1990 Inspectors:
E. J. Ford, Senior Resident Inspector W. B. Jones, Resident Inspector Approved:
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m L constable, cnlet, Project bect1on G fte Division of Reactor Projects i
Inspection Sumary i
Inspection Conducted March 1-31. 1990 (Report 50-458/90-08)
.i Areas Inspected:
Routine, unannounced inspection including followup of events, operational safety verification, maintenance observation, surveillance test observation, and followup of previously identified items.
Results: Within the areas inspected, no violations or deviations were identified.
Good operator actions prevented-possible severe damage to the 230KV/13.8KV Freferred Transformer "F."
By being properly attentive to equipment cond(tion during outside-rounds, the operator was able to alert plant management to.
arcing problems on the transforner.
A complex work activity on Residual Heat Removal "A" Suppression Pool. Test Return Valve IE12*M0VF0024A was well controlled with systematic corrective
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actions. The job plan utilized was properly revised as the work scope expanded. The maintenance process was well implemented for this activity.
9005040135 900426 PDR ADOCK 05000458 O
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DETAILS
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1.
Persons Contacted i
d GSU
- D. L. Andrews, Director, Nuclear Training
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W. J. Beck,. Supervisor, Balance of Plant Design J. E. Booker, Manager, Nuclear Industry Programs -
G. Bysfield', Supervisor, Control Systems:
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- E. M.. Cargill, Director, Radiation' Programs i
- J. W. Cook, Technical Assistant
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- J. C. Deddens, Senior Vice President, River Bend Nuclear. Group; i
- L. A. England Director,~ Nuclear Licensing-l A. 0. Fredieu,~ Supervisor, Operations
- P. D. Graham, Plant Manager l
J. R. Hamilton, Director ' Design: Engineering
- L. G. Johnson, Site Representative,-Cajun
- D N. Lorfing, Supervisor, Nuclear. Licensing
- J.-C. Maher, Licensing Engineer
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~J. Mead, Supervisor. Electrical Design ' __
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- J. hiller, Director, Engineering Analysis
- W. H. Odell, Manager, Oversight
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- T. F. Plunkett,-General Manager. Business-Systems and Oversigit
- J. P. Schippert, Assistant Plant Manager, Operations, Radwaste and j
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Chemistry-
.j J. Venable, Assistant Operations Supervisor
- R. G. West, Assistant Plant Manager,' System Engineering
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The inspectors also interviewed additional licensee: personnel during the -
inspection period.
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- Denotes those persons that attended. the exit interview conducted on April 9,1990.
2.
Plant Status i
The unit operated at essentially 100 percent-thermal power du' ring the.
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j first half of this' inspection period. ' _0n March 11 and March.29.1990,-the 7
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unit experienced large electrical grid transients with minimal effect on j"
-_the plant..0n March 14, 1990, the. licensee began. reducing power in
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. preparation for a planned midcycle. outage. On March 15,-1990, the reactor
scrammed from 42 percent thermal power when the main generator tripped on'
an' apparent loss of field. Subsequent investigation determined the
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generator: loss of field relay to be faulty. The licensee commenced a-
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14-day outage involving:
feedwater nozzle inspection; maintenance on
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drywell' coolers, main steam isolation ' valve. ASCO solenoid: valve,'and
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service water valves; required cold shutdown-surveillance testing; and:
I work on TOPAZ (instrument panel)-inverters and' associated chargers..
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j On March 27, 1990, the licensee began a startup of'the unit and synchronized the main generator to the electrical grid on March 28, 1990.-
The unit was essentially ~ at 100 percent thermal power for the remainder of the month.
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3.
Followup of Events -(93702)
During this. inspection' period, the inspector reviewed licensee condition-reports (CRs) 'and 10_CFR 50.72 reports'and held discussions with various
plant personnel to ascertain the sequence, cause, and corrective actions
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taken for plant events. Discussion of selected events are given below:
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-Scram 90-01 On' March 15, 1990, at 9:40 p.m., the reactor scrammed from 42 percent-thermal power. The-licensee was performing-a controlled shutdown at the
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time to begin a planned midcycle outage.
The scram was initiated by a
main turbine control valve-fast closure resulting from a main generator trip.. The reason for the generator trip was subsequently determined' to be caused by a-faulty loss of Field Relay KLF40.
The plant responded as expected following the scram with the exception of the reactor recirculation Flow Control Valve <"A" and Feedwater' Pump "C".
The flow control valve failed _ to run back (to 42 percent open) following
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.the expected reactor vessel' Level 4 signal. _ Troubleshooting activities later revealed a loose connecting plug.inian electronics cabinet. The inspector subsequently reviewed the maintenance work package for:the i
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troubleshooting activity, Maintenance Work. Order-(MWO)-R135760, and did-not note any discrepancies. The reactor recirculation flow control system is nonsafety-related. The failure of a reactor flow controlled valve to i
run back-is analyzed in'the RBS Updated Safety Analysis Report.
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Main Feedwater Pump "C" experienced an inboard seal leak'which required the pump to be shutdown. The seal was replaced and the pump aligned during the outage.
The-inspector reviewed the cause of the scram and the failure mechanism of-Relay KLF40 with the plant manager and other licensee personnel prior to the restart of the unit.
Grid Disturbances
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On March 29, 1990, the licensee had completed a 2-week'midcycle outage on schedule and was in the process of returning to full power operation.. The operators'had increased power to approximately 15 percent thermal power when a 100 megawatt electrical transient was observed at RBS when five Louisiana Power & Light Company units tripped due to a grid fault near Taft, Louisiana, on the southwest power grid. The transient had minor
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-4-effects on RBS and did not produce any engineered safety feature actuations or isolations.
An earlier grid disturbance occurred on March 11, 1990, when a failed
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transformer at the nearby Formosa Chemical Plant caused the RBS main generator power output to swing between 850 MWe and 1050 MWe.
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-the-event RBS was operating at 980 MWe. The voltage transient caused the'
Division II-control building emergency ventilation system to actuate. The associated control building air intake Radiation Monitor RMS-RE13B spiked high because of the voltage transient. After verifying no actual high
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radiation. condition existed, the operators restored the air handling i
system to its normal lineup.
The operators responded to both transients in an alert and thorough manner verifying that all instrumentation and systems were in their proper condition. They also took the conservative action of reviewing computer archived data to assure there were no discrepancies in-plant response to the transients.-
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Nonsafety-Related Load Center Failure
On March 26. 1990, whiletheunitwasincoldshutdown.(Mode 4)forthe midcycle outage, a fault developed in the 13.8KV/480V (NJS-X1A)
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transformer. This transformer normally supplies nonsafety-related Switch-Gear NJS-SWGRA. The failure occurred shortly after cross-tieing the
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nonsafety-related 480V Switchgears NJS-SWGR "A" and "B."
This switchgear
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is located in the auxiliary building. The transformer failure caused the associated 13.8KV feeder breaker (ACB-16) to the switchgear to trip, j
i Switchgeer (NJS-SWGR "C" and "D"), located in the normal switchgear-I building, had also been crosstied and fed through ACB-16. These are all nonsafety-related boards;- however,: one of the loads:is-the normal supply -
to Division Il reactor protection system (RPS), When the Division II-RPS deenergized, a Division II isolation was received'resulting in the-l as-designed actuations of, standby gas treatment, annulus mixing, fuel building filtration, and standby service water systems. Also', Residual Heat Removal Pump "B" tripped because of the Division.II isolation causing a loss of shutdown cooling for approximately 10 minutes. During this time, the reactor coolant temperature remained constant at 122 F.
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i licensee subsequently determined the cause of the transformer failure to
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be an internal fault.
The licensee verified that there was no damage to the associated switchgear. A spare transformer, located on site, was used to replace the damaged transformer.
The inspector monitored this event and observed the corrective maintenance activities on the transformer. A corona arcing problem on Preferred Transformer "F" (startup transformer) had led to the' unusual breaker lineup. The arcing was caused by an insulation breakdown on an instrument i
line. The line has been repaired.
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f-5-Battery Charger END*CHGRIB l-
l On February =11,- 1990, with the reactor at 100 percent thermal power, the unit experienced a. partial engineered safety features (ESF) actuation of-Division 11 systems and the opening of the Residual-Heat Removal "B"
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L and "C" injection valves. The event occurred when a scheduled electrical-
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l preventative meintenance procedure was being performed on the Division II
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battery charger (ENB*CHGRIB). When.the electrician switched to.the i
equalize position.on the charger, an apparent high voltage spike was
experienced which caused a downstream Topaz inverter to trip.
i This event is ' discussed further in NRC Inspection Reports 50-458/90-04 and-
- 50-458/90-05.
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The licensee suspended further use of the procedure and mainta'ined the
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~ chargers in the float position pending the results of an engineering
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investigation. The inspector verified by observation that the. Division I',
, II, and.III chargers were properly tagged with RBS Clearance 90-0160, dated'
February 11, 1990.
During.this report period the licensee completed the1r investigation. The licensee and a vendor representative determined that ChN3er ENB*CHGRIB
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had performed properly. However, some of the Topaz inverter's trip set)oints had drifted low. This had caused the Topaz inverter associated wit 1 Charger ENB*CHGRIB to trip when the charger was taken tu equalize.
The inverters were recalibrated and are now in the preventative maintenance program. Additionally, Topaz inverter. loads were compiled and incorporated
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by Temporary Change Notice (TCN) 90-0212 into Abnormal Operating Procedure A0P-0014. " Loss of 125VDC." The inspector reviewed the A0P and i
noted load lists for the following inverters:
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1E51-K600(providespowertoRCICinstrumentation)
E22-PSI (provides power to HPCS instrumentation)
E21A-PSI (provides power' to Division I and RCIC instrumentation))
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E12A-PSI (provides power to Division'II and RCIC= instrumentation i.
This inspector noted that the charger had beenithoroughly. tested and
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monitored and-that the load lists for the Topaz inverters were developed
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and implemented in a-timely manner.
This satisfies the licensee's statements that corrective actions would be.
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performed'on the battery charger, that the charger would be checked weekly for proper outputs, and that load lists would be developed for the Division.I and II Topaz inverters and incorporated into applicable procedures.
l No violations or deviations were identified.
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4.
Operational Safety Verification (71707)
l Throughout the inspection period the inspectors observed operational
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activities and monitored operational events.. The conduct of control room
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activities. and access to the control room was properly controlled in -
accordance with administrative requirements. Control room staffing met 'or o
exceeded minimum requirements. Several shift briefings were observed by the inspectors, it was noted'that detailed information concerning plant status and'pending special tests or plcnt evolutions was covered. When-questioned by the inspectors,;the operators were aware of plant configuration and why alarms were lit.
Information obtained by control;
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board walkdowns and discussions with operators regarding plant conditions-and events were adequately identified in the main control room log. The
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inspectors noted-that the operators appropriately considered inoperable
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equipment for any applicable limiting conditions for operation and t
maintained tracking logs.
Subsequent _to the end of the outage on March'27. 1990,- the inspector verified by control-board _ walkdown, electrical panel observations, and
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i verification of flow path valve lineup that the high pressure core spray,
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automatic' depressurization system, low pressure core spray, low pressure coolant injections systems,' reactor core isolation cooling system, and the emergency diesel generators were in their required standby _ lineup.
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On March 26, 1990, while on normal rounds of outside' equipment, an alert operator detected an arcing problem onLthe Preferred Transformer "F."
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13.8KV instrument:line had suffered. insulation breakdown. The operator promptly inforned the control room. This allowed _ plant managenent the
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opportunity to deenergize the transfonner prior to failure.
L The inspectors observed security personnel perform their duties of personnel and package search. Vehicles were properly authorized and controlled 'or escorted within.the protected area (PA).
Personnel access
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was observed to be controlled in.accordance with established procedures.
The inspector conducted site tours to ensure compensatory posts.were properly. implemented as required because of. equipment failure or i
degradation. The PA barriers were adequately illuminated and the
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isolation zones were free'of transient materials.
No violations or deviations were identified.
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Maintenance Observation ' (62703)
On January 10,.1990, the licensee performed'a'shheduled surveillance test on the Residual Heat Removal (RHR) "A" Suppression Pool' Test Return i-Valve 1E12*M0VF024A. During the performance of this test, the valve failed to fully close against the system pressure.- The licensee initiated CR 90-0022 to document'the investigation as to why the valve failed to-
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operate as expected. The inspector reviewed prompt MWO R056366 which was l
initiated and performed on-January 10, 1990.
(This review is documented o
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in NRC Inspection Report 50-458/90-03.) This-MWO authorized the performance _
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of _an "0ATIS" signature test of the valve which was successfully completed i
on January 11, 1990, and the valve returned to service. No cause for the j
valves' _ failure to close could be detemined.
- MWO R121893 was subsequently initiated by field engineering on January 31,-
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1990, to disassemble and inspect the valve internals, the limitorque actuator, and repack and'11ve-load the valvei This action'was-in response tolCR 90-0022 to try and determine the root cause for.the valve failing to
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completely close on January 10, 1990.
On March 22, 1990, during the planned midcycle maintenance outage,. the
'i licensee performed the maintenance activities authorized by the MWO._ The L
initial maintenance activity consisted of replacing the torque switch and spring pack. The. inspector noted that-the maintenance activity was well
planned. and the procedures-referenced in the MWO were assembled in the
- work package. The inspector l verified that the protective clearance tagging had been properly placed.
Electrical leads lifted during the maintenance activity were properly identified in accordance with GMP-0042,
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" Lifted Lead and Jumper Control."
After the maintenance activity was completed on March 23, 1990, the inspector observed the performance of "0ATIS" signature testing on
1E12*M0VF0024A. The valve was' cycled.'several, times to ensure that the
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- data obtained during the signature' test was consistent.- No problems.with-the valve were noted during'the performance of the signature testing.
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The 1icensee then performed the required operability test as specified in
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the maintenance package. The operability test consisted of stroking the valve through several cycles to verify valve stroke times and current-draw. The ~ acceptance criteria has been established in CMP-1253, l
"Limitorque Motor Operated Yalves."' LDuring closure stroke, the valve l
failed to completely close. The valve was cycled two additional times with the valve failing to_ completely close each time.
The job plan for MWO R121893 was then revised to disassemble and inspect
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the _ valve intervals.
Applicable repair procedures.were also-included in
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the revised job plan. The valve intervals' were inspected and clearance
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measurements taken for the guide rib areas. The wedge guide and guide' rib
areas were then dressed in accordance with the job plan, Revision 4.
The valve disc seat was also beveled in accordance with the job instructions.
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After reassembling the valve, additional "0ATIS" signature tests were performed. The test results showed that the required torque to close the j
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valve against the system pressure'.had been. reduced. The valve was then
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local-leak rate tested and functionally tested-in"accordance with
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_ CMP-1253. The valve was returned to service on March 26, 1990, after
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successful completion of each of these tests.
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The inspector found the licensee's corrective actions to be systematic and
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well controlled.. An appropriate job plan was developed for the maintenance activity. As. the job scope changed during the maintenance activity,. the job plan was also revised.
The. inspector believes the maintenance process was well implemented during this maintenance' activity.
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No violations or deviations were identified.
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Surveillance Test Observation (61726)
' On March 1,1990, the inspector observed a licensed operator _ conduct-t F
portions of Surveillance' Test STP-204-3305, " Loop C RHR Valve Operability Test." This-test-verifies that valve operability and isolation times are
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within the limits of Technical Specification 3/4.6.4.3, " Primary
Containment and Drywell. Isolation Valves." The STP_was performed with the
reactor in Operational Condition 1-as required.: The ins)ector determined
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through discussions with the operator. and observations t1at the-required
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prerequisites had been met. The inspector independently verified that the-minimum number of emergency core cooling systems were operable during the-
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perfonnance..of Step 7.3.1 of the STP. This step requires closing the RHR "C" Pump Suction Valve IE12*MOVF105 which renders the subsystem
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inoperable. The' test was conducted in accordance'with the surveillance
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i procedure. The stroke time data and valve operability of Valves 1E12*M0VF105'and IE12*MOV64C were within acceptance limits.
The inspector observed portions ~ of the performance of Surveillance Test STP-209-4205, "RCIC Actuation - Condensate Storage Tank Water Level-Low Monthly Chfunct (E51-N635E),"'on March 21, 1990 The purpose of-
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this surveillance is to perform a channel functional test of -
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instrumentation as-required by Technical; Specification 3/4.3.5.1,
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Table 4.3.5.1-1.c.
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Prior to beginning the test, the technicians received authorization from
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The inspector questioned.both technicians
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and found them to be cognizant of the surveillance test requirements. The inspector observed that the procedure was being followed.1 verified ~that
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lifted leads were properly controlled in accordance with General Maintenance Procedure 0042,. " Circuit. Testing ~and Lifted Leads and'
Jumpers," and that test equipment was within the calibration due'date.
The inspector reviewed the completed surveillance test documentation and
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did not note any discrepancies. The inspector found both activities to be well controlled and properly conducted.
No violations or deviations were identified.
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7.
Followup'of Previously-Identified Items (92702)-
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'(Closed)UnresolvedItem(458/8904-01): Malfunction of the Reactor i
Recirculation Flow Control System Which Resulted in Recirculation Flow Oscillations.
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The NRC staff conducted an additional review of the recirculation flow
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control system malfunction which occurred on January 17-18 -1989. The results of the inspection are documented in NRC Inspection i
Report 50-458/89-41. Two-violations of NRC requirements involving maintenance work activities were identified.
Resolution of these i
violations will'be reviewed in a subsequent report.
This unresolved item is closed.
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(Closed) Violation-(458/8940-01):
Failure to_ Provide Adequate Control for Material Access to the Containment.
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The liceme has issued a memorandum requiring radiation protection personnel to notify the shift supervisor of the quantity and location of material being moved into the containment. Materials are now prohibited from being placed on the catwalk directly above the suppression pool 95-foot elevation when the reactor is in Modes 1 or 2.
Signs have been posted outside the containment airlocks and at the -stairways' inside the
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containment to the 95-foot elevation stating these requirements..The-inspectors have conducted several tours of the reactor building and no
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subsequent problems involving material access control have been identified.
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This violation is closed.
(Closed) Open Item (458/8551-05):' Completion of RBS Site Restoration
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Activities.
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The licensee has committed to restore the site area in their Final Environmental Statement, NUREG-1073. This commitment also identified by the licensee's_ commitment tacking system. The NRC staff periodically-
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reviews the licensee's commitment tracking system to ensure identified items are being properly identified and resolved.
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This open item is closed.
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Exit Int"rview An exit interview was conducted with licensee representatives identified in paragraph 1 on April 9, 1990. During this interview, the inspector reviewed the scope and findings of the report. The licensee did not identify as proprietary any information provided to, or reviewed by, the inspectors.
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