IR 05000528/1997017
| ML17313A146 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 12/12/1997 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML17313A145 | List: |
| References | |
| 50-528-97-17, 50-529-97-17, 50-530-97-17, NUDOCS 9712230224 | |
| Download: ML17313A146 (35) | |
Text
U.S. NUCLEAR REGULATORY COMMISSION
REGION IV
Docket Nos.:
License Nos.:
Report No.:
Licensee:
Facility:
Location:
Dates:
Inspectors:
Approved By:
50-528 50-529 50-530 NPF-41 NPF-51 NPF-74 50-528/97-1 7 50-529/97-1 7 50-530/97-1 7 Arizona Public Service Company Palo Verde Nuclear Generating Station, Units 1, 2, and 3 5951 S. Wintersburg Road Tonopah, Arizona October 19 through November 29, 1997 Jim Moorman, Senior Resident Inspector Nancy Salgado, Resident Inspector Dan Carter, Resident Inspector John Russell, Resident Inspector, San Onofre Nuclear Generating Station Dave Corporandy, Project Engineer, Walnut Creek Field Office Dennis F. Kirsch, Chief, Reactor Projects Branch F Attachment:
Supplemental Information 97i2230224 97i2i2 PDR ADOCK 05000528
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-2-Palo Verde Nuclear Generating Station, Units 1, 2, and 3 NRC Inspection Report 50-528/97-17; 50-529/97-17; 50-530/97-17 Operator response to a failed Unit 2 reactor coolant pump lower journal bearing, and the subsequent manual reactor trip, was acceptable (Section 01.1).
The Auxiliary Operators (AOs), during their plant rounds, conducted thorough checks of plant equipment with a good questioning attitude, and took data as required by their controlling procedures.
The AOs performed two clearances methodically and used proper independent verification (Section 01.2).
Control room turnover briefings were conducted thoroughly and professionally.
Minimum shift crew composition consistently conformed to Technical Specification (TS) requirements and operators were knowledgeable of the reasons that certain annunciators were in alarm (Section 01.3).
A noncited violation, resulting from weaknesses in operator attention to detail, was identified as a result of both trains of the Low Pressure Safety Injection (LPSI) and Containment Spray System (CSS) being momentarily inoperable in Mode 1. The licensee's Licensee Event Report (LER) provided a thorough event description and corrective action (Section 08.1),
Maintenance and surveillance activities observed by the inspectors were generally conducted in a safety conscious manner by knowledgeable technicians using current procedures (Section. M1.3).
Licensee electrical maintenance troubleshooting of a reactor trip circuit breaker that spuriously opened, immediately after attempting to close, was acceptable (Section M1.4).
Routine plant tours identified good material conditions; although some housekeeping weaknesses were identified in infrequently accessed areas (Section M2.1).
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Observation of troubleshooting activities and the replacement of a failed differential pressure transmitter inside containment demonstrated good independent verification of critical steps; however, one instance of weak attention to detail was identified when the inspectors informed the instrumentation and control technicians of a loose electrical conduit connection (Section M4.1).
-3-
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engineering evaluation of a failed Unit 2 reactor coolant pump lower journal bearing, and the support of maintenance organization repair efforts, was excellent (Section 2.1).
~
A noncited violation was identified by the licensee as a result of a worker alarming the personnel contamination monitor when exiting a radiologically controlled area and not making a second attempt to pass the monitor or contact a radiation protection (RP) technician.
This event demonstrated inattention to detail by both a radiation worker and RP technicians (Section R4.1).
The inspectors observed good radiation protection practices by the instrumentation and control technicians performing work and by the RP technician covering replacement of a failed differential pressure transmitter (Section M4.1).
I n Unit 1 began the period at 100 percent power.
On October 26, 1997, reactor power was reduced to 60 percent to plug leaking tubes in feedwater Heater 2A. Power was returned to 100 percent on October 28.
On November 12, reactor power was lowered to 95 percent for replacement of condensate Pump C.
On November 16, the unit was returned to 100 percent power and remained there for the duration of the period.
Unit 2 began the period at 100 percent power.
On October 20, the unit was manually tripped from 100 percent power due to high bearing temperature on reactor coolant Pump 2B. The unit returned to 100 percent power on October 30.
On November 1, power was reduced to 80 percent for work on feedwater Heater 1A. Power was returned to 100 percent on November 2 and remained there for the duration of the period.
Unit 3 began the period at 100 percent power.
On November 8, reactor power was lowered to 23 percent for balancing work on a main turbine bearing coupling.
Reactor power was returned to 100 percent on November 9 and remained there for the duration of the period.
Conduct of Operations 01.1 The inspectors reviewed operator actions taken in response to a high temperature condition in RCP 2B lower journal bearing.
b.
rv On October 20, 1997, control room (CR) operators tripped the Unit 2 reactor due to a high,temperature condition in RCP 2B lower journal bearing.
At approximately 10:15 a.m., the temperature of the RCP lower journal bearing exceeded the alarm setpoint of 185'F.
Temperature exceeded the manual trip setpoint (190'F) shortly thereafter.
When the high temperature alarm was received, the operators responded by referencing the appropriate alarm response procedure.
They were directed by the alarm response procedure to use Procedure 40AO-9ZZ04, "Reactor Coolant Pump Emergencies,"
Revision 5. Although Section 3 of Procedure 40AO-9ZZ04 directs the operators to trip the reactor and stop the RCP for the conditions that were occurring at the time, operators had observed faulty bearing temperature indications in the past and chose to not trip the reactor based on that one abnormal temperature indication.
The operators looked at other parameters to verify that an
-2-actual problem existed with the bearing.
There were no other pump parameters in alarm; however, other indications validating the alarm quickly became available to the operators.
A reactor coolant pump engineer, who was on shift at the time, was called to the CR to observe the indications and help validate the cause of the high teperature alarm. At approximately 10:35 a.m., upward trends in other bearing temperatures were indicated, confirming the existence of a problem.
Operators continued to observe and trend these param'eters and at approximately 10:40 a.m.,
pump vibration readings began to increase.
With pump vibrations increasing rapidly, a manual reactor trip was initiated at 10:50 a.m.
The operators correctly implemented Procedure 40EP-9EO01,
"Standard Post Trip Actions," Revision 2, and correctly transitioned to Procedure 40EP-9EO02,
"Reactor Trip Response,"
Revision 1. Once the reactor was verified tripped, the operators stopped RCP 2B.
Procedure 40OP-9ZZ10, "Mode 3 to Mode 5 Operations," Revision 16, was entered to continue the plant cooldown.
C.
Operator response to a failed Unit 2 reactor coolant pump lower journal bearing, and the subsequent manual reactor trip, was acceptable.
01.2 a.
The inspectors accompanied AOs during the performance of Procedure 40DP-9OPA1 "Area 1 Operator Logs, Modes 1-4," Revision 22, and Procedure 40DP-90PA3, "Area 3 Operator Logs, Modes 1-4," Revision 15.
ln addition, the inspectors observed the Area 3 AO perform several clearances.
The AOs were knowledgeable about the performance of structures, systems, and components in their assigned areas of the plant.
The AOs identified and communicated deficiencies to the CR as necessary and took data as required by their respective procedures.
During the monitoring tour in Area 3, the AO was directed by the CR operators to place clearance tags for work packages to inspect/test retorque motor-operated Valve 7A and replace a mechanical seal to eliminate leakage.
The inspectors observed the Area 3 AO methodically position the equipment according to the clearance tag.
No discrepancies were identifie I
-3-c.
The AOs, during their plant rounds, conducted thorough checks of plant equipment with a good questioning attitude, and took data as required by their controlling procedures.
The AOs performed two clearances methodically and used proper independent verification.
01.3 r
v
The inspectors attended several CR operations morning turnover briefings to assess operations communications, and periodically verified that TS requirements for minimum shift crew composition were met.
b.
Shift turnover briefings were conducted thoroughly and professionally.
The turnover environment was adequate for clear communication.
Plant status information was identified, and equipment/operational problems were discussed in enough detail for the oncoming shift to understand the issues. The TS requirements for minimum shift crew composition were verified by the inspectors to be consistently met throughout the reporting period.
During CR observations, the inspectors questioned the operators regarding the reason certain annunciators were in alarmed conditions.
Operators were knowledgeable about all annunciator conditions and the reason the alarm condition existed.
C.
Control room turnover briefings were conducted thoroughly and professionally.
Mini'mum shift crew composition consistently conformed to TS requirements and operators were knowledgeable of the reasons that certain annunciators were in alarm.
Miscellaneous Operations Issues (92901)
08.1 6- -: momentary entry into TS 3.0.3 due to inattention to detail.
This LER describes an instance where both trains of the LPSI and CSS were inoperable while in Mode 1.
In addition, the LER discussed root cause and corrective actions associated with this even Train A of CSS and LPSI had been declared inoperable to support surveillance testing.
During this time, the Train B Essential Chilled Water System (ECWS) was rendered inoperable for approximately 20 seconds to support weekly chemistry sampling.
Plant procedures directed CR personnel to declare the associated ECWS train inoperable while the local disconnect for the train was opened for chemistry sampling.
Additionally, this required that systems supported by the ECWS also be declared inoperable.
Tliis action was not taken because the Control Room Supervisor (CRS) did not recognize, at the time, that opening the ECWS local disconnect switch would make the associated LPSI and CS trains inoperable.
Following a review of plant conditions, and in the process of making a log entry, the CRS realized that both trains of the LPSI and CSS were inoperable for approximately 20 seconds while the disconnect was open.
This licensee-identified and corrected violation of TS 3.0.4 is being treated as a noncited violation consistent with Section VII.B.1 of the NRC Enforcement Policy (50-529/97017-01).
08.2 V'
three examples of operations failing to follow administrative procedures.
The inspectors concluded that the information regarding the reason for the violation, the corrective actions, and the date of full compliance was adequately addressed on the docket in Inspection Report 50-528;529;530/97-006.
M1 Conduct of Maintenance M1.1 a.
In The inspectors observed all or portions of the following work activities:
'I 36ST-9SE01:
32-MT-9ZZ84:
WO 816519:
Excore safety channel log calibration AC motor operational testing Change the oil filter and 0-ring (turbine-driven AFW pump)
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The inspectors found the work performed under these activities to be professional and thorough.
All work observed was performed with the work package present and in active use.
Technicians were experienced and knowledgeable of their assigned task The inspectors observed all or portions of the following surveillance activities:
41 ST-1DG01:
41 OP-1 DG01:
36 ST-9SB02:
Essential Cooling Water Pumps - Inservice Test, Revsion 6 Diesel Generator A Test 4.8.1.1.2:a, Revision 31 Emergency Diesel Generator A Plant Protection System Bistable Trip Units Functional Test, Revision 15 b.
The inspectors found these surveillances were performed with good results and as specified by applicable procedures.
M1.3 Routine maintenance and surveillance activities were generally conducted in a safety e
conscious manner by knowledgeable technicians using current procedures.
M1 4 a.
On November 5, 1997, the inspectors observed portions of the work conducted in accordance with Procedure 32-MT-9SB03, "Maintenance of Westinghouse Type DS-416 Reactor Trip Switchgear," Revision 8.
Electrical maintenance personnel were using this procedure to perform preventive maintenance on a Unit 1, Channel C, RTCB. The inspectors also reviewed records of a root cause evaluation and postmaintenance testing done for a previous failure of Unit 2, Channel C, RTCB (2JSBCC03, serial number 920.421-11).
This breaker was a spare, to be installed if needed.
The inspectors also reviewed Westinghouse Nuclear Service Advisory Letter 94-024, "DS Circuit Breaker Failure to Latch Closed on Demand," Revisions 0 and 1.
Fin i
The preventive maintenance on the Unit 1 RTCB was performed satisfactorily.
RTCB 2JSBCC03 had tripped open while installed in the Unit 2 switchgear, immediately after licensee personnel had attempted to close it. Work Order 00810380, commenced on August 30, 1997, described the cause of failure
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-6-as the shock, from closing springs causing a vibration affecting the trip shaft and tripping the breaker open.
This was the same failure described in the service advisory letter, referenced above.
Based on review of the work order, the inspectors found that the troubleshooting of RTCB 2JSBCCO3 identified an as-found trip shaft adjusting screw position of five turns from the no overlap position.
The as-left position of this screw was four and one-quarter turns from the no overlap position.
The trip shaft adjusting screw changed the overlap of the trip shaft and trip latch.
The service advisory, referenced above, stated that generally maximizing overlap between the trip shaft and the trip latch would minimize vibration from the closing springs affecting the trip shaft.
Adjusting the trip shaft adjusting screw away from the no overlap position increased the amount of overlap.
During the troubleshooting activities the inspectors did not note any other pertinent adjustments made to the breaker.
The breaker was cycled approximately 40 times, in the shop, without failure. The maintenance advisory noted that breakers were more susceptible to this type failure while installed in switchgear, as opposed to when being cycled on a bench.
Revision 1 to the maintenance advisory recommended maximizing the overlap described above while maintaining acceptable gaps between various components in the breaker, and described a method to do this.
Licensee engineers decided not to use this method, although they were aware of the method.
Based on the number of successful breaker cycles, the inspectors found that the problem was intermittent.
Also, the safety function of the breaker was to open, and this did not appear to be impaired by the spurious opening.
C.
Licensee electrical maintenance troubleshooting of a reactor trip circuit breaker that spuriously opened, immediately after attempting to close, was acceptable.
M2 Maintenance and Material Condition of Facilities and Equipment M2.1 v
Routine plant tours identified good material conditions, although some housekeeping weaknesses were identified in infrequently accessed area I
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IVI4 IVlaintenance Staff Knowledge and Performance M4.1 T
I ao On November 14, 1997, the inspectors observed instrumentaion and control (ISC)
technicians troubleshoot and replace the Steam Generator A, reactor coolant system differential pressure Transmitter RCA-PDT-115A. The inspectors reviewed the work package and time response data on the new transmitter, conducted interviews with ISC technicians, and observed the prejob as-low-as-reasonably-achievable briefing.
b.
hl The licensee conducted a good prejob briefing of the work activity. The briefing discussed operations concerns, industrial safety of pe'rsonnel, radiological concerns and stay times, and independent verification of critical procedural steps.
The inspectors accompanied the two ISC technicians arid a RP technician into containment.
Good RP practices were observed; for example, a known low dose rate path was taken to the transmitter area.
The ISC technicians performed their initial troubleshooting activities and determined that the transmitter had to be replaced.
The ISC technicians performed good independent verification of each other when performing valve operations, recording wiring data, and verifying torque wrench settings.
Upon completion of the transmitter replacement, the inspectors performed a final examination of the transmitter for leakage and physical condition and noticed that the connection joining the electrical conduit to the transmitter was loose.
The inspectors informed the l&C technicians of the loose connection and they immediately tightened the connection.
The IS.C team leader stated that the connection should have been tightened.
This demonstrated a weakness in attention to detail by the technicians.
C.
Observation of troubleshooting activities and the replacement of a failed differential pressure transmitter inside containment demonstrated good independent verification of critical steps; however, one instance of weak attention to detail was identified when the inspectors informed the instrumentation and control technicians of a loose
-8-electrical conduit connection.
The inspector observed good RP practices by the instrumentation and control technicians performing work and by the RP technician coveririg replacement of a failed differential pressure transmitter.
M8 Miscellaneous Maintenance Issues (92902}
M8.1 Unit 3 reactor trip following spurious opening of all four reactor trip switchgear breakers.
This event was discussed in NRC Inspection Report 50-528,529,530/97-06.
The issues discussed in the LER were consistent with those discussed in the inspection report.
The LER provided additional information on the cause of the event.
The wrong,lug size contributed to the loosening of the two terminal lugs noted in the inspection report, E2 Engineering Support of Facilities and Equipment E2.1 R
'r On October 20, 1997, the Unit 2 RCP 2B lower journal bearing failed causing a high temperature condition in the bearing oil~ The CR operators tripped the reactor'and secured the pump in accordance with plant procedures.
Inspectors observed engineering activities related to the Unit 2 RCP 2B lower journal bearing repair activities.
System engineers provided specific guidance to maintenance personnel during bearing disassembly to ensure that as-found conditions were recorded for use in the root cause assessment.
The licensee concluded that the most probable cause of the bearing failure was the intrusion of a very small particle of hard material into the area between the lower journal bearing and the shaft protection sleeve.
This particle gouged the face of the bearing material as it rotated, entraining material from the shaft protection sleeve and bearing material.
As the affected area enlarged, friction increased the metal temperature to the point that partial melting of the bearing babbitt material occurred.
The licensee sent the bearing material offsite for analysis.
Maintenance was performed on the Unit 2 RCP 2B thrust bearing assembly (which houses the journal bearing) during the recent Unit 2 refueling outage.
Maintenance was also performed on the RCP 1B thrust bearing assembly.
To address possible
transportability of the problem, work documentation associated with both pumps was reviewed.
Also, oil samples were taken from the 1B bearing assembly and analyzed.
No evidence was found to indicate that the 1B bearing assembly was affected.
C.
Engineering evaluation of a failed Unit 2 reactor coolant pump lower journal bearing, and the support of maintenance organization repair efforts, was excellent.
E8 Miscellaneous Engineering Issues (92700, 92903)
E8. 1 adverse affect of low bench set on Fisher air operated letdown/containment isolation valves.
Revision 1 of this LER was discussed in detail in NRC Inspection Report 50-528;529;530/96-16, which identified concerns with deficiencies in Revision 1.
Revision 1 of the LER concluded that containment isolation could be achieved during a design basis event provided two of three valves were available to close.
Revision 1 did not address leakage in the case where only one valve was available to close, nor did it address the as-found condition of the bench sets.
Subsequently, Revision 2 was issued to address, in part, the concerns identified iri NRC Inspection Report 50-528;529;530/96-16.
The LER related that, for the single valve isolation evaluation, analyses demonstrated that for the lowest as-found bench set, 10 psig, isolation would be accomplished at 1120 psig, which was below the 2485 psig design.
Further evaluation showed that under these conditions, for a postulated letdown line break upstream of the containment isolation valve, the reactor coolant system release to the auxiliary building would result in a 2-hour exclusion area boundary thyroid dose of 22.49 rem.
This was considered an acceptable dose based on Standard Review Plan, Section 15.6.2, which states that the consequences of this event are acceptable if the resulting dose does not exceed a small fraction (10 percent) of 10 CFR Part 100 guidelines (i.e. 10 percent of 300 rem).
LER 50-528/95-007-02 also described the corrective actions taken by the licensee in response to this issue.
The inspectors verified these corrective actions to be thorough and complete.
E8.2 V'
design engineering did not assure that quality standards were applied to penetrations, which provide separation between safety and nonsafety equipment.
The inspectors verified the corrective actions described in the licensee's response letter, dated June 19, 1997, to be acceptable and complete.
No similar problems were identifie E8.3 loss of spent fuel pool level procedure requires manual fuel building essential ventilation actuation.
This event was resolved and discussed in detail in special NRC Inspection Report 50-528,529,530/97-09.
No significant new issues were identified by the LER.
E8.4 Unit 1 reactor trip following RCP load shed from nonclass 13.8 kV Bus 1E. This event was,discussed in NRC Inspection Report 50-528,529,530/97-06.
No new issues were identified by the LER.
V R4 Staff Knowledge and Performance R.4.1 a.
On November 19, 1997, a radiation worker exited a RCA after alarming the personnel contamination monitor (PCM). The worker subsequently left the plant protected area.
v i n in i
On November 19, 1997, a radiation worker exited the RCA in the Unit 2 auxiliary building after alarming the PCM.
Due to a miscommunication, the worker was not informed of the failure to clear the PCM and left the protected area for approximately 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
Subsequently, the worker was notified of the failure to clear the PCM. The worker returned to the PCM and successfully processed out. The PCM alarm was due to high levels of naturally occurring radon daughter products being attracted to clothing by static charge. There was no contamination spread by this event.
Procedure 75DP-9RP01,
"Radiation Exposure and Access Control," Revision 0, Section 3.7, provided guidance for exiting a RCA.
Personnel who alarm a PCM on the first attempt must either make another attempt to clear the PCM or contact a RP technician.
In this instance neither of these actions were taken.
The failure to follow Procedure 75DP-9RP01 constitutes a violation of minor safety significance and is being treated as a noncited violation, consistent with Section IV of the NRC Enforcement Policy (50-529/97017-02).
-11-c.
A noncited violation was identified by the licensee as a result of a worker alarming the PCM when exiting a RCA and not making a second attempt to pass the monitor or contact a RP technician.
This event demonstrated inattention to detail by both a radiation worker.and RP technicians.
V a
X1 Exit Meeting Summary The inspectors presented the inspection results to members of licensee management at the conclusion of the inspection on November 24, 1997.
The licensee acknowledged the findings presented.
The inspectors asked the licensee whether any material examined during the inspection should be considered proprietary.
No proprietary information was identifie I
D T. Bradish, Section Leader, System Engineering D. Carnes, Department Leader, Operations P. Crawley, Director, NFM F. Gowers, Site Representative, El Paso Electric J. Hesser, Director, Design Engineering 5 Projects R. Henry, Site Representative, Salt River Project D. Kanitz, Engineer, Nuclear Regulatory Affairs P. Kirker, Department Leader, Operations A. Krainik, Department Leader, Nuclear Regulatory Affairs D. Leech, Department Leader, Nuclear Assurance J. Levine, Senior Vice President, Nuclear R. Myrick, Manager, Maintenance G. Overbeck, Vice President, Nuclear Production T. Radke, Director, Outages C. Seaman, Director, Emergency Services D. Smith, Director, Operations J. Velotta, Director, Training M. Windsor, Section Leader, Mechanical Maintenance Engineering C, Zell, Department Leader, Operations
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-2-37551 61726 62707 71707 9290.1
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92902 92903 Onsite Engineering Surveillance Observations Maintenance Observations Plant Operations Plant Operations Follow-up Maintenance Follow-up Engineering Follow-up D
50-529/97017-01,NCV failure to declare LPSI and CS systems inoperable when associated essential cooling water was momentarily inoperable 50-529/97017-02 NCV failure of radiation worker to properly clear a personnel contamination monitor QQ'Mi 50-529/9701 7-01 50-529/9701 7-02 50-529/96006-00 NCV failure to declare LPSI and CS systems inoperable when associated essential cooling water was momentarily inoperable NCV failure of radiation worker to properly clear a personnel contamination monitor LER failure to declare LPSI and CS systems inoperable when associated essential cooling water was momentarily inoperable 50-528/97001-00 LER reactor trip following RCP load shed 50-530/97001-00 LER loss of spent fuel pool level procedure requires manual ventiliation
-3-50-530/97002-00 50-528;529;530/
97005-03 50-528;529;530/
97006-01 LER Unit 3 reactor trip following spurious opening of all four reactor trip breakers VIO quality standards were not applied to penetrations LER failure to follow procedures 50-528/95007-01 LER adverse effect of low bench set on valves 50-528/95007-02 l ER adverse effect of low bench set on valves
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AO CR CS ECWS auxiliary operator control room containment spray system essential chilled water system IS.C instrumentation and controls LER LPSI PCM RCA RCP RP RTCB Licensee Event Report low pressure safety injection system personnel contamination monitor radiological controlled area reactor coolant pump radiation protection reactor trip control breaker'S Technical Specifications