IR 05000293/1993007
| ML20045D463 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 06/04/1993 |
| From: | Eapen P, Stewart J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20045D454 | List: |
| References | |
| 50-293-93-07, 50-293-93-7, GL-89-04, GL-89-4, NUDOCS 9306290042 | |
| Download: ML20045D463 (11) | |
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U. S. NUCLEAR REGULATORY COMMISSION
REGION I
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REPORT NUMBER:
50-293/93-07
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f DOCKET NUMBER:
50-293
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LICENSE NUMBER:
DPR-35 l
LICENSEE:
Boston Edison Company
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Rocky Hill Road Plymouth, Massachusetts
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FACILITY:
Pilgrim Nuclear Power Station INSPECTION DATES:
May 3 to 7,1993
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INSPECTORS:
T. Frye, Reactor Engineer, DRP R. Paroby, Engineering Co-op LEAD INSPECTOR:
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J. S. Stewart, Reactor Engineer, Systems Date
Section, DRS
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APPROVED BY:
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Dr. P. K. Eapen, Chief I Date Systems Section, Engineering Branch
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Division of Reactor Safety
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I 9306290042 930618 PDR ADOCK 05000293 O
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EXECUTIVE SUMMARY An announced inspection of the Pilgrim Inservice Testing program and its implementation was conducted in accordance with NRC Temporary Instructions 2515/114, " Inspection Requirements for Generic Letter 89-04, Acceptable Inservice Testing Programs," and Temporary Instruction 2515/110, "Parformance of Safety Related Check Valves." This inspection was conducted to review and assess the Pilgrim inservice testing of pumps and valves. The inspection included verification of adherence to the Code of Federal Regulations, conformance to the ASME Code,Section XI requirements, and a general review of the licensee inservice testing program to ensure consisteacy with the provisions of GL 89-04 and the NRC Safety Evaluation Report for the licensee's program, dated April 22,1991.
The alert and action levels for the high pressure safety injection pump were established at levels that are two times higher than specified by the ASME Code,Section XI. The licensee did not take advantage of a number of opportunities to establish more reasonable alert and action vibration levels for this pump.
A number of significant programmatic strengths were identified including program completeness and clarity. Quality assurance audits and surveillance of the inservice testing program were evident and actions taken to correct identified discrepancies were effective.
Finally, the inservice testing program appeared implemented with clearly defined responsibilities and authorities to ensure consistancy in interpretation and administration.
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1.0 INTRODUCTION The NRC Generic Letter (GL) 89-04, issued April 3,1989, addressed several generic inservice testing (IST) program deficiencies and provided specific guidance on meeting the Code of Federal Regulations 10 CFR 50.55a(g) provisions that required adherence to the American Society of Mechanical Engineers (ASME), Boiler and Pressure Vessel Code,Section XI, " Inservice Testing of Pumps and Valves." The NRC Temporary Instructions (TI) 2515/114, " Inspection Requirements for Generic Letter 89-04, Acceptable Inservice Testing Programs," dated haary 15, 1992, and NRC Temporary Instruction 2515/110..
" Performance of Safety Related Check Valves," dated November 19, 1991, were issued to be used by inspectors to assess the effectiveness of licensees in providing assurance that safety related components are both operable and reliable.
This inspection was conducted to review and assess the Pilgrim Nuclear Power Station inservice testing of pumps and valves. The inspection included verification of adherence to the Code of Federal Regulations, conformance of the Pilgrim IST program to the ASME Section XI requirements, and a general review of the licensee IST program to ensure consistency with the provisions of GL-89-04 and the NRC Safety Evaluation Report for the
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licensee's program, dated April 22,1991. On November 25,1992, the licensee submitted to the NRC a revised inservice testing program for the third 10 year interval which began
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December 10, 1992. The third 10 year submittal is required to conform to the 1986 edition of the ASME Code,Section XI and was used to evaluate licensee inservice testing activities.
The inspection was conducted with Pilgrim Nuclear Plant in week 5 of refueling outage, l
RFO-9. The inspectors selected a number of components in the high pressure safety injection, containment isolation, and control rod drive systems for inspection' emphasis. The selection of these systems was based on accident risk as determined using the Pilgrim Individual Plant Examination for Internal Events Report, dated September 1992.
2.0 LICENSEE INSERVICE TESTING PROGRAM The administrative requirements for inservice testing of pumps and valves at Pilgrim Nuclear Power Station are identified in Pilgrim procedure 8.I.1, " Administration of Inservice Pump and Valve Testing." A list of components and testing details are provided in procedure i
8.I.1.1, " Inservice Pump and Valve Testing Program," ' Revision 4, dated November 24,1993. Both prncedures were reviewed during the inspection.
The licensee monitors pump performance using vibration, obtained as displacement amplitude, peak to peak, at the inboard bearing for each pump in the program. Acceptance criteria for these measurements were in accordance with ASME Section XI, Table IWP-3100-2 Vibration velocity (inches per second) is also obtained at the inboard bearing in lieu of bearing temperature as specified by IST program relief request RP-2. The program requires that pumps with velocity amplitude exceeding 0.314 inches per second be evaluated for bearing degradation utilizing velocity spectrum analysis.
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The inspectors observed that all bearings on safety related pumps including those outside the scope of IST monitoring, are vibration velocity tested on a quarterly frequency in the Pilgrim preventative maintenance program. However, the data obtained during preventative maintenance are not evaluated using the criteria specified in ASME,Section XI, IWP-3230, as required for inservice testing. Instead, the vibration measurements are entered into a computer data base for evaluation by individual system engineers and it was not clear what criteria are used to monitor and correct pump degradation.
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The inspectors conducted a review of pump preventative maintenance vibration measurements for High Pressure Safety Injection and Salt Service Water pumps and found no examples
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where identified pump degradation was not properly evaluated by engineering and corrected.
The licensee stated their intention to review the preventative maintenance testing as well as inservice testing, in fulfilling 10 CFR50.65, " Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants," and will consider test optimization by ' combining the programs. The maintenance rule is required to be implemented by July 10, 1996.
Pilgrim Procedure 1.8, " Master Surveillance Tracking Program" was reviewed to assure administrative controls are in place for completion of cold shutdown testing when availability exists. A weekly plan is maintained during cold shutdown periods indicating a surveillance.
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schedule. The inspectors verified that several procedures for cold shutdown testing of valves
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were present in the program. It was concluded that the licensee had appropriate administrative controls for scheduling and completion of cold shutdown testing.
Licensee quality assurance audits of the inservice testing program were reviewed by the inspectors. Although the last audit was performed in 1990, there has been on a regular basis quality assurance surveillance of the inservice testing administrative controls and implementing procedures. Quality assurance audits and surveillance have identified weaknesses in IST program implementation, such as procedure discrepancies and the identified deficiencies were corrected. Licensee quality assurance review of the inservice testing program is considered a strength.
The inspectors reviewed the ranges and calibration of temporary pressure gauges and vibration monitoring equipment used for inservice pump testing. All temporary pressure gauges are calibrated to 0.5% of the applicable full scale. The individual IST procedures specify the size of the gauge to be used in each surveillance, and specify a range three times the nominal pressure or less. The calibration frequency and precision of equipment used to perform the vibration velocity and displacement evaluations were verified by the inspectors.
The inspectors concluded that test equipment used by the licensee complies with ASME code requirement.
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2.1 Check Valve Reliability Program The Pilgrim check valve program, defined by procedure 1.3.113, "PNPS Check Valve Program," includes check valves in those systems important to safety but outside the scope of ASME Section XI testing. In 1991, the program was developed after the licensee conducted a design application review of approximately 150 check valves by evaluating valve type, maintenance history, flow velocity, frequency of use, and similar performance parameters.
Using the reviews, an inspection priority was established and activities such as leak testing,
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exercising, or inspection by disassembly were specified for each valve.
Monitoring of check valves in the program is largely accomplished by disassembly using PNPS procedure 3.M.4-53, " Check Valve Disassembly to Exercise the Disc " The procedure provides instructions for the disassembly, inspection, and restoration of the valves being inspected. The valve disassembly procedure and a number of completed check valve inspection records were reviewed by the inspectors and were found to be acceptable in content and detail.
Non-intrusive testing for check valve performance was used during RFO-9 for RHR-68B, Residual Heat Removal Injection Check Valve." The non-intrusive evaluation included determination of check valve stability by monitoring disc position and motion with the system
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operating. With the valve determined to be stable and no test discrepancies identified, the non-intrusive method was accepted in lieu of valve disassembly. The licensee intended to evaluate and expand the use of non-intrusive check valve testing following RFO-9.
The inspectors reviewed testing of check valves in the normal condensate - feedwater injection flowpath. The condensate pump discharge check valves are exempted from testing based on the design verification review and maintenance history. The feedwater pump discharge check valves, 24-CK-420,421, and 422 are normally open during reactor operation and are required to close when less than three feedwater pumps are supplying the reactor.
The design review identified an upstream disturbance for these valves which may cause flow induced degradation. One of the valves is therefore disassembled every second refueling outage. Additionally, each valve is full stroke exercised on a two year cycle to demonstrate full range of motion.
Finally the inspectors reviewed testing of reactor feedwater isolation valves 6-CK-58A/B (inboard) and 6-CK-62A/B (outboard). These valves are tested for full range of motion in accordance with the inservice testing program and leak tested in accordance with 10 CFR 50, Appendix J. Additionally, the valves are inspected by disassembly in the check valve program one valve each refueling outage. Check valve 6-CK-58A had been scheduled for disassembly during RFO-9, but the disassembly was cancelled when the valve exhibited minimal seat leakage during the Appendix J testing. The decision was based on engineering judgement and was concurred in by the RFO-9 Failure / Analysis team, assembled to review and ensure proper control of testing during the refueling outage. Licensee activities in
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testing the condensate - feedwater injection flowpath check valves were found to be
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commensurate with the safety importance of the system and adequate to monitor and detect valve degradation.
2.2 Containment Isolation Valves The inspectors reviewed the Pilgrim Updated Final Safety Analysis Report, Table 5.2-4, and verified that all Category A containment isolation valves were incorporated in the IST program. Testing of these type A valves includes full stroke exercising and time testing, as specified in ASME Section XI, IWV-3413, and leak rate testing as specified in wh "' CFR 50, Appendix J.
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The inspectors reviewed the results of the stroke time tests for several containment isolation valves. In each case, the surveillance procedure specified the test method and acceptance
criteria. Stroke time data sheets were forwarded to IST engineering where manual plotting for trending of stroke times was completed. When, on occasion, the stroke time was in the alert range, the test frequency was increased to monthly until corrective action was taken to restore the valve stroke time to normal. Neither indications of missed surveillances nor inadequate corrective actions for alert level stroke times were identified by the inspectors.
No stroke times were found in the action range during the inspection.
While all the power operated containment isolation valves are cycled open and shut during
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testing, some valves are stroke timed only in the direction of the valve safety-related function. Although not required by the ASME Code, timing in the non-safety direction could
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identify valve degradation. The licensee agreed to consider stroke time testing during the
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full cycle of operation for containment isolation valves in future testing reviews.
The licensee's IST program for containment isolation valves was determined to be complete and effective. The procedures in use were determined to be adequate for detecting and correcting containment isolation valve degradation.
3.0 IST PROGRAM IMPLEMENTATION
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The inspectors reviewed the Pilgrim IST program implementation by review of testing activities for the Control Rod Drive and High Pressure Coolant Injection systems. These systems were selected based on plant risk as documented in the Pilgrim Individual Plant Examination, dated September 1992.
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3.1 Control Rod Drive System Components
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The inspectors performed a review of the control rod drive (CRD) system and verified that all CRD scram system components were included in the IST program and tested in accordance with ASME code and Generic Letter 89-04, Position 7. Code class components, i
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such as solenoid operated valves which supply air to the scram discharge instrument volume
(SDIV) air operated vent and drain valves, met the IST exemption criteria of IWV-1200(b)
and therefore were not included in the program. The CRD system was walked down to verify the system configuration and to inspect for component degradation. No discrepancies were identified.
Pilgrim inservice test program relief requests RV-9, RV-10, and RV-26, for the control rod drive hydraulic system, were reviewed for technical adequacy. RV-9 and RV-10 documented alternate testing methods for scram system valves in accordance with Generic Letter 89-04, position 7. RV-26 proposed stroke time testing the SDIV air operated vent and drain valves in the closed direction every refueling interval. The inspectors concluded the licensee had adequately justified the relief requests.
Surveillance procedures for CRD system components were also reviewed and the inspectors
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determined that the test methods and frequencies specified in the ASME code were being
implemented. All scram system components reviewed were found to be tested as required.
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The test procedures reviewed were found to be well written with the test objectives and
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acceptance criteria clearly stated. Test results were reviewed by the inspectors and no test
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discrepancies were identified.
3.2 High Pressure Coolant Injection System The inspectors also reviewed the IST program implementation for the High Pressure Coolant Injection (HPCI) system. Plant drawings were used to verify that appropriate HPCI components were included in the IST program and testing was reviewed and found to be in compliance with the ASME code and approved relief requests.
High pressure safety injection component surveillance procedures and results were reviewed and verified to be in accordance with the inservice testing program. The test procedures were well written with reference values, acceptance criteria, alert, and required action range levels clearly identified. The inspectors independently verified that the alert and required action levels for various parameters on the HPCI pumps were calculated in accordance with IWP-3210. The IST program document clearly specified the hydraulic test circuit and test instrumentation used for the quarterly HPCI main and booster pump test. PNPS Procedure
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No. 8.5.4.1, "High Pressure Coolant Injection System Pump and Valve Operability Test,"
incorporated this information into the quarterly test and included the main and booster pump reference values and limits. The inspectors verified that procedure 8.5.4.1 included establishing the Technical Specification required flowrate of 4250 gpm for the HPCI system using the specified hydraulic test circuit, which uses a 10" test line to direct flow from the HPCI pumps back to the condensate storage tank.
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HPCI pump and valve test data from the last operating cycle were reviewed. Testing was performed on HPCI components at the required frequencies and the test data were trended in a format which allowed for easy review and evaluation over several operating cycles.
Trending records were complete and included appropriate alert and required action range levels which aided in the monitoring of components for degradation.
Because the HPCI pump combines the booster and main pumps on one driver, high vibration-during pump operation has been a repeated observation. Reference vibration levels for the r
HPCI pump inboard bearings were last obtained in March 1989, during refueling outage number 7. At that time, reference values were relatively high due to a low frequency vibration that was not observed during subsequent surveillances. The licensee evaluated the relatively high vibration levels and attributed them to pump design. Licensee engineering administratively lowered the reference vibration levels for the main pump, with alert and
required action range levels set accordingly. The recommendations for lowered alert and -
required action range levels were very conservative and appropriate at the time. These levels
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have been in effect for the last two operating cycles up to the current RFO-9 outage.
Inspector review of the vibration trends the HPCI pump during the last two operating cycles revealed that the quarterly horizontal and vertical vibration levels were much less than the new reference values. The limits set by the licensee were not low enough, based on the actual pump data, to be effective in ensuring corrective action for degraded bearing conditions. The licensee stated that new reference values for the HPCI pump would be established after performing HPCI turbine preventative maintenance during the ongoing outage.
3.3 IST Check Valve Program Implementation The testing of check valves in the CRD and HPCI systems was verified to be in accordance with the ASME Code and Generic Letter 8944. Several valves in both systems which were
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full flow tested quarterly were selected for detailed review. The applicable test procedures were verified to establish full flow conditions for each valve and testing was determined to be adequate. In addition, several valves receiving a partial stroke exercise quarterly were reviewed and also found to be adequately tested.
The IST check valve disassembly program is administered by PNPS Procedure No. 8.I.27.
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Those check valves specified for disassembly during RFO 9 were reviewed by the inspectors.
All valves were disassembled and inspected as required. Upon disassembly, HPCI check valve 2301-216 (HPCI turbine steam drain check valve) was found to be stuck in the mid-
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position due to excessive corrosion. The inspectors reviewed the maintenance request and disassembly procedure used for the check valve disassembly / inspection and verified that a thorough restoration and inspection of the repaired valve was accomplished prior to work closecut. The maintenance history for all HPCI check valves in the same group was reviewed and no other in service failures were noted. The two other HPCI check valves in
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the same group as 2301-216 were disassembled / inspected satisfactorily in accordance with the IST program after the 2301-216 failure was identified. Engineering review of the check i
valve failure attributed the cause to materials corrosion and system design which does not ensure that the valve shuts when the system is secured. A 1991 engineering review of the
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valve determined that the valve could be removed from the system because no functional requirement for the check valve could be determined, however work was delayed due to prioritization.
IST program check valve procedure No. 8.I.27 was reviewed by the inspectors and was found to effectively implement the commitments made in IST check valve relief request, RV-27, which stipulates the alternate testing for those valves whose ability to fully open can only
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be verified by disassembly. RV-27 was granted provisional relief for the second interval IST
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Generic Letter 89-04, position 2. The disassembly program was found to be in accordance
with the generic letter, with one exception. As described in the relief request, the licensee -
j has established a sample disassembly program which requires that all valves within a group be disassembled within a maximum of four refueling intervals. Therefore, the maximum time interval can be eight years between disassemblies for the two valve groups that contain
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four valves. Generic Letter 89-04, position 2, states that in order to support extension of-valve disassembly / inspection to longer than once every six years, specific information should be developed by the licensee to support the extension. The licensee had not developed an evaluation to support their interval extension to eight years. Although the check valve program is in accordance with provisionally approved relief request RV-27, the inspectors determined that the four refueling interval schedule currently in place did not meet the intent of position 2 of Generic Letter 89-04. This issue will be reviewed and addressed by the j
NRC during preparation of the safety evaluation report for the third interval IST program submittal.
i 4.0 CONCLUSIONS With the minor exception specified above, the Pilgrim inservice testing program was determined to be in compliance with the requirements of ASME Code,Section XI, and NRC Generic Letter 89-04. Components in the program were adequately tested with exceptions documented in NRC approved relief requests. Test procedures were well organized and thorough, with clear acceptance criteria to identify degraded conditions promptly. Trending was thoroughly and clearly performed and quality assurance review of program implementation was apparent with findings documented and corrected.
A number of areas of NRC concern were identified for licensee consideration. Action and alert levels for the High Pressure Coolant Injection pump appeared to have been established at too high a level and the licensee intends to establish new reference levels during RFO-9.
Pump vibration monitoring appears to be more thoroughly completed in the preventative maintenance program as opposed to the IST program and the licensee intends to review
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implementation of both programs in complying with the maintenance rule,10 CFR 50.65.
Finally, the licensee intends to expand the use of non-intrusive testing as a replacement for
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check valve disassembly following RFO-9.
Overall, the licensee program to monitor safety related pumps and valves was determined to be effective in ensuring continued component operability and readiness.
5.0 EXIT MEETING The inspectors met with the licensee personnel identified in Attachment 1 on May 7,1993, to discuss the inspection findings as detailed in this report. The licensee acknowledged the inspection findings and results.
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ATTACIIMENT 1 -
Persons Contacted
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Pilgrim Nuclear Power Station L. Schmeling Plant Manager
- J. Bellefeuille Deputy Plant Manager (Acting)
- J. Keyes Compliance Division Manager.(Acting)
- F. Famulari Quality Assurance Department Manager
- D. Pierce Lead System Engineer
- P. Manderino Lead System Engineer-
- R. Orkin Senior Program Engineer - Check Valves
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- J. Sabina Senior Test Engineer
- R. Cannon Senior Compliance Engineer W. Rothert General Manager - Technical B. Carroll Test Engineer R. Mattos System Engineer J. McCarthy System Engineer t
U.S. Nuclear Regulatory Commission
- J. Macdonald Senior Resident Inspector D. Kern Resident Inspector
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- Denotes those present at May 7,1993 exit meeting.
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