IR 05000244/1994026
| ML17263A882 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 12/13/1994 |
| From: | Lazarus W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML17263A881 | List: |
| References | |
| 50-244-94-26, NUDOCS 9412200233 | |
| Download: ML17263A882 (11) | |
Text
U. S.
NUCLEAR REGULATORY CONHISSION
REGION I
DOCKET/REPORT NO.:
LICENSEE:
FACILITY:
DATES:
INSPECTORS:
APPROVED BY:
50-244/94-26 Rochester Gas and Electric Corporation R.
E. 'Ginna Nuclear Power Plant, November 21 to December 2,
1994 J. Stewart, Project Engineer, DRP S. Greenlee, Resident Inspector, BVPS L. Prividy, Senior Reactor Engineer, DRS E. Knutson, Resident Inspector, Ginna i
am J.
ar h ef Reactor Pr 'ec ',3B i~ip.
Date 94i2200233 94i2i3 PDR ADOCK 05000244
TABLE OF CONTENTS
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EXECUTIVE SUMMARY.
TABLE OF CONTENTS
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o ill 1.0 INSPECTION SCOPE AND OBJECTIVES
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2.0 IDENTIFICATION AND RESOLUTION OF DEFICIENT CONDITIONS.
3.0 MANAGEMENT INVOLVEMENT AND OVERSIGHT 4.0 FACILITY INITIATIVES TO PREVENT AND RESOLVE PROBLEMS 5.0 EXIT MEETING
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EXECUTIVE SNMARY R. E. Ginna Nuclear Power Plant November 21 to December 2, 1994 An announced safety inspection at the R.
E. Ginna Nuclear Power Plant included a review of the RG&E programs that ensure the availability and reliability of plant systems that protect the health and safety of the public.
The inspection objective was to evaluate the effectiveness of these programs in the identification, prevention, and resolution of problems that degrade the quality of plant operations or safety.
Overall, RGSE was determined to be effectively implementing programs to resolve plant problems.
However, recent equipment problems that led to disruption in operation of the Ginna facility show weakness in the capability of RGSE to predict and prevent deficient conditions.
Once identified, the scope and depth of attention to individual plant problems was good, and was commensurate with the nature of the failure and its impact on safety.
In assessing pump monitoring programs, the inspectors concluded that the evaluation of data provided by ASIDE Section XI testing was a strength, even though individual component failures were not predicted by the testing.
RGKE has taken action to enhance their equipment failure prediction. by adopting evaluation methods such as vibration signature analysis, thermography, and pump oil analysis.
Licensee root cause analyses and failure assessments were of mixed quality.
The inspectors found the facility review of two feedwater regulating valve failures to be appropriate.
The inspectors reviewed the Ginna overhaul of two
. safety related, component cooling water, motor operated valves and found deficiencies in the reviews of these efforts.
For recent safety injection pump failures, an independently conducted assessment resulted in a comprehensive action plan to assess potential system vulnerabilities and improve overall system reliability.
The inspectors determined the maintenance and oversight of the instrument air system to be good, but not fully commensurate with the risk vulnerability associated with the system.
Management involvement in the analysis and development of corrective actions for recent problems was very good, and was indicative of a strong safety focus.
The involvement of the Ginna safety committees in significant plant operational problems was considered a strength.
Finally, RGSE has instituted a number of programs and initiatives to enhance plant safety and improve equipment reliabilit DETAILS 1.0 INSPECTION SCOPE AND OBJECTIVES An announced safety inspection of R.
E. Ginna Nuclear Power Plant was conducted'rom November 21 to December '2, 1994, using NRC Inspection Procedure 40500.
The scopeof the inspection included a review of the RG&E programs that ensure the availability and reliability of plant systems that protect the health and safety of the public.
The inspection objective was to evaluate the effectiveness of these programs in the identification, prevention, and resolution of problems that degrade the quality of plant operations or safety.
2.0 IDENTIFICATION AND RESOLUTION OF DEFICIENT CONDITIONS Overall, RG&E was determined to be effectively implementing programs to resolve plant problems.
However, recent equipment problems that led to disruption in operation of the Ginna facility show weakness in the capability of RG&E to predict and prevent deficient conditions.
Once identified, the scope and depth of attention to individual plant problems was good, and was commensurate with the nature of the failure and the impact on safety.
The inspectors reviewed recent issues to assess RG&E's ability to identify, prevent, and correct problems.
The specific component problems selected for review included:
repeated failures of the 'B'afety injection (SI) pump including catastrophic failure in April 1994, improper reassembly of the
'B'I pump following the April failure, and its subsequent repair in August; rotor bar cracking in the pump motor in June and a failure of the pump
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recirculation line socket weld in August.
Other pump issues included failure of the 'B'otor driven auxiliary feed water (AFW) pump in August; failure of the 'C'ervice water system (SWS)
pump in Nay; and failure of the 'A'WS pump in August.
The November 1993 and April 1994 failures of the feedwater regulating valves were reviewed as were a recent maintenance overhaul of two component cooling water system motor operated valves.
Additionally, at the system level, a reliability review was conducted of the instrument air system and a January 1994 frazzle ice intrusion of the circulating water intake structure was reviewed.
Overall, in assessing pump monitoring programs, the inspectors concluded that the data provided by ASNE Section XI testing of safety related pumps, such as the safety injection and auxiliary feedwater pumps was a strength, even though the individual component failures were not predicted by the testing.
All of the recent pump problems were preceded by in-service test trends which indicated some degr adation in performance.
The inspectors reviewed the test information to determine if there was a connection between the trends and the pump failures and found that all of the data had been fully evaluated by facility personnel and appropriate, timely action had been taken to correct degrading trends.
The inspectors concurred with facility evaluation that imminent pump failure in the cases reviewed was not indicated by the. test data.
The inspectors considered that the August AFW pump failure could have been prevented if the root cause of an April 1993 failure of the pump recirculation flow control valve had been fully established and corrected.
The facility review indicated that the AFW pump failure in August was due to a low flow
condition caused when the pump recirculation flow control valve failed to open, resulting in the pump running at shutoff head.
The facility further identified the cause of the recirculation valve problem to be intrusion by metal shavings which blocked a nozzle in the valve pneumatic controller.
Netal shaving blockage al.so occurred in April 1993, but facility review of that failure failed to establish the source of the metal filings and adequate corrective action to prevent recurrence was not specified.
RGKE has taken action to enhance equipment failure prediction by adopting evaluation methods such as vibration signature analysis, thermography, and pump oil analysis.
Further, RGLE had taken timely and appropriate action to address industry information on rotor bar cracking but the diagnostic methods adopted by the facility were not fully in place when the SI pump motor failure occurred.
The facility had been informed by Mestinghouse of the potential for rotor bar cracking of pump motors in April of 1994, and had taken diagnostic vibration measurements, but had not fully developed the analytical methods to diagnose the precursor to the rotor bar cracking failure.
Licensee root cause analyses and failure assessments were of mixed quality.
The 'C'WS pump failure was thoroughly reviewed and included a logical method for evaluation of the failure mechanism.
Other reviews, such as of the original 'B'I pump failure, were fairly informal and were limited in technical detail.
Additionally, the process for arriving at the root cause varied for the different failures.
A very detailed materials analysis was performed on the 'C'WS pump following its failure in Nay.
However, some of the SI pump components were discarded (the polyacrylate seal rings and the pump oil) or altered (the pump impellers were heated to remove them from the shaft), prior to analysis of the April failure.
The inspectors also found that the human performance evaluation of the SI pump failure was done several months after the event, which made the accuracy of the assessment questionable.
The inspectors found the facility review of two feedwater regulating valve failures to be appropriate and agreed with the facility assessment that the two failures were independent of each other.
In the November 1993 regulating valve failure, the root cause was identified as a fabrication error when a
feedback arm became detached from the positioner during plant operation.
The April 1994 failure was attributed to an improperly installed set screw in a
'ew model, valve positioner diaphragm assembly installed prior to plant startup.
This fault was also fabrication related and was resolved by replacing the entire positioner assembly with the old model.
The inspectors reviewed the Ginna overhaul of two safety related component cooling water, motor operated valves and found deficiencies in the facility review and documentation of the maintenance.
Component cooling water (CCM)
valves 738A and 738B, are inlet gate valves for CCW supply to the residual heat removal heat exchangers.
The valves are used for decay heat removal during shutdown periods and for long term core heat removal following a loss of coolant accident.
Valve overhauls during the 1994 outage included replacement of a badly worn stem nut in the 'A'alve actuator and similar substantial repairs to the valve internal components.
No root cause evaluation was completed by the facility for these deficient condition Further, the documentation for the 'A'alve overhaul included a work-group assessment that the valve disc and seat were heavily corroded with corrosion products and scale.
The inspectors questioned the nature of the corrosion and were informed that the documentation was in error and that no unusual corrosion had been identified by the work group.
The inspectors determined that both CCW valves are ten inch gate valves, that are throttled during shutdown cooling operation to limit heat removal and maintain plant temperature.
Throttling with gate valves has been known to cause severe degradation of the valve internals as result of cavitation of the flow through the valve.
Cavitation can produce wear and erosion of the valve body, components, and downstream pipe wall.
For CCW valves 738A and 738B, the
, facility had not considered the possibility of wall thinning (described in NRC Information Notice 89-01)
and had not bounded the wall erosion possibility.
The inspectors considered degraded wall thickness to be a possibility because of the use of the gate valve in throttling and considered the valve and pipe wall structural integrity to be unresolved pending facility evaluation.
(UNR 50-244/94-26-01)
The inspectors determined the maintenance and oversight of the instrument air (IA) system to be good, but not fully commensurate with the risk vulnerability associated with the system.
The Ginna probabilistic risk assessment determined the dominant contributor to the calculated core damage frequency from internally initiated events to be loss of instrument air.
In June 1994, a stuck open solenoid valve on one of the redundant instrument air dryers allowed header air pressure to drop to about 95 psig before manual isolation of the leak.
The single valve failure was an example of the type of failure that could result in complete loss of instrument air.
The facility identified and completed corrective actions to address the failure of the IA dryer solenoid valve and further conducted a review in Root Cause Analysis N-94-002.
The evaluation was not able to positively identify the root cause of the failure.
Further, in the corrective maintenance, a
heavily clogged pre-filtet for one of the two air dryer headers was identified.
Corrective actions specified for the failed open solenoid and the clogged pre-filter were comprehensive and appropriate, including establishing routine monitoring of the dryer differential pressure and replacing the solenoids.
However, the inspectors determined that the valve failure and loss of air header pressure was only one in a number of similar functional failures of the system since 1991.
The root cause analysis did not address the commonality of the 1994 occurrence with previous problems nor the failure of prior corrective maintenance efforts in preventing either the valve failure or the existence of a heavily clogged prefilter.
The inspectors further reviewed the RGLE resolution of NRC NUREG-1275, Volume 6, "Solenoid Operated Valve Problems,"
and determined that the facility actions while appropriate, were incomplete in fully resolving the vulnerabilities discussed in the generic communication.
The facility completed a comprehensive review of the instrument air system and its vulnerabilities and established a number of actions to enhance the reliability of the system.
However, the inspectors identified three solenoid-operated valves (SOV), which control safety related air-operated valves (AOV), which
were subjected to air pressure beyond the maximum operating differential air pressure (NOPD).
This condition was one of the bases for the NUREG because it can cause AOV failure if the SOV fails to reposition in a safety application.
The three valves exposed to the condition were the SOV that provides control air to the isolation valve for the instrument air supply to containment, and both steam generator blowdown sample line isolation valves.
The installed SOVs were original installation and had not failed the inservice testing routinely completed for the respective systems.
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The team reviewed the facility corrective actions taken following an intake icing event which occurred -in January 1994 and determined that the actions were very thorough, including appropriate actions by operations, engineering, and maintenance.
Specifically, intake heater bar cleaning in September 1994 and installation of a process computer alarm for low intake temperature would assist in prediction and mitigation of intake icing.
Operations review of the event'and training on rapid down-power maneuvers had been conducted.
3.0 NANAGBlENT INVOLVENENT AND OVERSIGHT Management involvement in the analysis and development of corrective actions for recent problems was very good, and was indicative of a strong safety focus.
To minimize the possibility of bias in the technical assessments, management directed independent oversight and review of the evaluations to be done by plant personnel of the safety injection and auxiliary feedwater pump failures.
For the safety injection failures, management independently conducted an overall re-assessment and established a comprehensive action plan to assess potential system vulnerabilities and improve overall system reliability.
In both cases, the comprehensive action plans included enhancement of equipment monitoring during routine testing, management oversight of test results, and pump overhaul and assessment during the 1995 outage.
The involvement of the Ginna safety committees in significant plant operational problems was considered a strength.
The offsite -safety review committee (Nuclear Safety Audit and Review Board - NSARB) routinely reviews and discusses plant problems in detail.
NSARB directed a special meeting to discuss the root causes and corrective actions associated with pump and motor problems.
Additional corrective actions in the areas of training and the promulgation of lessons learned were specified by the review board and discussions of the pump and motor problems are to continue at the next board meeting.
The on-site safety review committee (Plant Operations Review Committee PORC)
was also involved in the development of the pump and motor assessments and reviewed corrective actions presented to the NSARB.
RG&E management has recognized the need to evaluate their root cause analysis process, and has included this evaluation in their list of corrective actions for recent events.
The inspectors found that the facility had become more sensitive to the need for timely assessment of human performance issues.
A recent low level event involving inadvertent disabling of a radiation monitor was identified for a human performance evaluation.
This current level of sensitivity may have resulted in a more timely analysis of the SI pump reassembly error.0 FACILITY INITIATIVESTO PREVENT AND RESOLVE PROBLENS RGEE has instituted a number of programs and initiatives to enhance plant safety and improve equipment reliability.
The inspectors found that reviews of industry information and operating experience assessments were very good.
Generic communications such as NRC information notices and NUREGs, had received comprehensive review by the facility and action was taken in each case to disseminate relevant information to the technical staff and implement improvements to plant safety and reliability.
The inspectors reviewed a number of facility self-assessments conducted by RGKE quality assurance a'nd found the content of the audits and significance of the findings to be appropriately self-critical and relevant to safety
'mprovement.
Corrective action for the audit findings were appropriate and reasonable time limits were established,to address identified weaknesses.
The inspectors found the RGLE quality assurance involvement in reactive assessments of plant problems to be a strength.
Notable were plant walkdown by quality control personnel of all outage maintenance following self-identification that. a seismic support had not been properly reassembled during a maintenance activity, and a self-assessment of the a self-identified post-accident sample system (PASS) cross contamination event.
RGEE activities to improve reliability of the service water system were also considered a strength.
The Ginna station received a pilot NRC Generic Letter 89-13 inspection and have resolved many of the issues identified by the inspection.
However, the facility has initiated action to complete a followup self-assessment of service water reliability, using industry expertise, with a focus on the vulnerabilities that were identified in the generic letter inspections at other facilities.
RGSE action to integrate the root cause and corrective action determinations for plant deficiencies was also considered a strength.
As discussed in NRC inspection 50-244/94-09, the Ginna station currently has numerous, diverse corrective action programs.
The station has initiated action to integrate the root cause and corrective action processes of five of these programs into a single system, which should provide appropriate coordination and implementation of deficiency correction across different disciplines.
The facility has also initiated action to integrate all corrective action programs into a single point of entry, deficiency reporting system.
The goal of this new process is to provide appropriate management attention to deficiencies and allow trending to identify and resolve issues before significant problems arise.
5.0 EXIT NEETING An exit meeting was conducted on December 2,
1994.
At the meeting, the inspectors reviewed the scope and findings of the inspection, which were acknowledged by the facility management in attendance.
Key persons contacted during the inspection and attendees at the exit meeting are listed below.
None of the information reviewed during the inspection was identified as proprietar ROCHESTER GAS R, Mecredy J.
Widay T. Marlow R. Watts T. White R. Marchionda T. Alexander Q. Wayland G. Wroebel AND ELECTRIC CORPORATION RGLE Vice President, Nuclear Operations Plant Manager Superintendent, Ginna Production Oepartment Manager, Nuclear Assessment Operations Manager Superintendent, Maintenance Manager, Nuclear Assurance Manager, Systems Engineering Manager, Nuclear Safety and Licensing