IR 05000269/1994099
| ML15261A336 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 12/13/1994 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML15261A335 | List: |
| References | |
| 50-269-94-99, 50-270-94-99, 50-287-94-99, NUDOCS 9412280222 | |
| Download: ML15261A336 (6) | |
Text
SYSTEMATIC ASSESSMENT OF LICENSEE PERFORMANCE REPORT OCONEE NUCLEAR STATION 50-269/94-99, 50-270/94-99 AND 50-287/94-99 BACKGROUND The SALP Board convened on November 17, 1994, to assess the nuclear safety performance of Oconee Units 1, 2 and 3 for the period of May 2, 1993, through October 29, 1994. The Board was conducted per Management Directive 8.6, "Systematic Assessment of Licensee Performance."
Board members were A. F. Gibson (Board Chairperson), Director, Division of Reactor Safety; B. A. Boger, Acting Director, Division of Reactor Projects; J. P. Stohr, Director, Division of Radiation Safety and Safeguards; and H. N. Berkow, Director, Project Directorate 11-3, NRC Office of Nuclear Reactor Regulation. This assessment was reviewed and approved by S. D. Ebneter, Regional Administrator, NRC Region I II. PLANT OPERATIONS This functional area addresses the control and execution of activities directly related to operating the plant. It includes activities such as plant startup, power operation, plant shutdown, and response to transients. It also includes initial and requalification training programs for licensed operator During the assessment period, there were nine reactor trips (two of which involved dryout of a steam generator), six unanticipated power reductions (including an automatic runback and taking a unit off line for a day), and four forced outages. Operator performance was considered to be very good in all of the above transients and other off normal conditions, including the startups and shutdowns associated with them and the three refueling outages conducted during this period. An excellent level of performance was apparent in the results of licensed operator examinations. Additionally, midloop operations in support of the Unit 2 steam generator tube leak repair and other steam generator inspection and repair activities throughout the period were well implemented and accomplished without incident. The licensed operator requalification program was adequate to provide for safe plant operations but, some weaknesses were observed in the program and its implementatio Operator performance during routine power and refueling operations was satisfactory. While effective control room operator response and accurate diagnosis prevented, respectively on two separate occasions, a reactor trip and a turbine runback, problems in procedure adherence Enclosure 9412280222 941213 PDR ADOCK 05000269 G
outside of the control room continued from the last two assessment periods; these problems resulted in an inadvertent boron dilution and associated reactor trip, a subcritical reactor protection system actuation, and (in part) a reactor trip from flux to flow imbalanc Performance in safety assessment was also satisfactory. A conservative safety approach was exhibited in the decision to shut down Unit 2 and repair a steam generator tube leak that was well below Technical Specification and administrative limits. Another conservatively addressed issue was the Unit 1 assessment and justification for continued operation that was made with respect to the slow control rod drop times found in Unit 2. On the other hand, examples of a non conservative safety approach included:
delayed resolution of a reactor coolant pump ground, which masked further ground conditions and alarms on all three units for nearly one month'; and a post-trip review which did not adequately assess or explain some anomalous plant response The implementation of a Plant Operations Review Committee in the latter part of the assessment period appeared to have had a positive impact on the thoroughness and outcome of post-trip reviews and other assessments affecting plant safet Corrective actions were not effective in preventing recurrence of the challenges identified in the previous assessment period concerning procedure-related problems (i.e., adequacy and adherence) including wrong unit and other configuration control errors. In addition, the challenges to the plant and operators from equipment-related failures continued throughout the period. The operator challenges and workarounds stemming from procedural inadequacies and equipment-related failures, as well as those resulting from poor fuel pool water clarity and ground detection system limitations, were reflective of Operations'
tolerance of such conditions. Toward the end of the period, licensee efforts were appropriately directed toward addressing operator workaround The Plant Operations area was rated Category II MAINTENANCE This functional area assesses activities associated with diagnostic, predictive, preventive and corrective maintenance of plant structures, systems and components. It also includes all surveillance testing, inservice inspection and other tests associated with equipment and system operabilit Predictive maintenance and equipment monitoring were effective in identifying several potential equipment malfunctions. The licensee effectively utilized thermography, vibration monitoring, acoustic monitoring, and oil analysis programs to identify potential problem Enclosure
There were several instances where the licensee's predictive maintenance program identified incipient failures of critical equipment, thereby averting failures and resultant system challenges, as well as permitting orderly and well-planned repair The licensee took actions to address previously-identified challenge Improvement was noted in developing and implementing integrated system testing, which was identified as a challenge in the last assessment period. The licensee also implemented several initiatives intended to improve maintenance work management. These initiatives appeared to be directed appropriately and, if properly implemented, should effectively address the proble Reliability of equipment continued to be a challenge. A number of equipment-related failures occurred during this period, some due to maintenance errors. Several of these failures resulted in plant transients. Equipment-related failures encountered during this period included:
failures of the Keowee generators due to voltage regulator and field flash breaker failures; a low pressure service water pump motor failure due to insulation breakdown; several failures of inverters due to old, obsolete equipment; significant leaks in letdown coolers; and several failures of main feedwater pumps and supporting equipmen These reliability problems continued even though the licensee maintained an aggressive preventive maintenance program, expending 70 percent of the maintenance resources in the area of preventive maintenanc The licensee's inservice inspection program was effectively implemented. Personnel were knowledgeable and well-trained in their areas of responsibility. The procedures, examination techniques, and documentation of results were generally good. Non-destructive test indications were thoroughly investigated. Licensee personnel who performed steam generator tube inspection activities were adequately trained and performed in a professional manne A number of problems continued to occur relative to not following procedures, making inappropriate changes to procedures, and making errors due to incorrect or inadequate procedures. The licensee's corrective actions were not effective in resolving these problem Conduct of major work activities during outages improved during the period and was considered good overal This was best demonstrated by the effective work planning and execution during the four forced outages. However, maintenance errors did occur as a result of poor work processes, particularly in the area of lifted lead controls. Corrective action had been ineffective in addressing this deficiency. Examples noted during this period included thermocouple leads being crossed when reinstalled on a low pressure injection cooler and inadequate planning for work on main steam stop valve circuitry, resulting in deenergization of the Unit 3 main feeder busse Enclosure
- The licensee's independent self-assessment group was utilized primarily for reactive audits. Although there was no formal program for routine self-assessment audits of the maintenance program, the quality of the audits performed was very goo The Maintenance area was rated Category IV. ENGINEERING Engineering and technical support for plant activities is assessed in this section. Design control as well as support.for operations, maintenance, testing, and licensing activities are include Engineering support to operations and maintenance was satisfactor System engineers maintained good knowledge of the condition of their assigned systems and provided valuable support to operations and maintenance on high-priority emerging issues. However, support in resolving some longer-standing issues was not as effective. Examples included turbine bypass valve logic discrepancies (which led to dryout of a steam generator before being corrected) and ground detection problems. Several of these issues were identified as operator workarounds and were receiving increased attention by Engineering late in the SALP perio In general, the backlog of engineering work was managed satisfactoril The backlog of Problem Investigation Process Reports assigned to Engineering was small and appropriately prioritized. The backlog of drawing changes was reduced substantially from previous years and drawings supporting recent modifications were revised before the modified systems were placed into service. However, the backlog of Work Orders assigned to Engineering was not effectively managed. Many open Work Orders were over two years old. Steps were being taken late in the SALP period to prioritize and schedule resolution of these Work Order Engineering performance in the area of design control was adequat Reviews by system engineers were effective in revealing longstanding design deficiencies, including discrepancies between the as-built plant, the design basis drawings, and procedures. For example, system engineers discovered a failure mode in containment isolation valves that could have caused loss of containment integrity, and piping interactions that could have caused a loss of post accident cooling following a seismic event. The licensee corrected each of these problem Engineering evaluations supporting licensing submittals were satisfactory. However, several engineering evaluations related to service water systems were not thorough. For example, an analysis that predicted two-phase flow in the low pressure service water system failed to assess the effects of piping vibrations caused by this flow. In addition, system design and performance information was not always properly translated into operations and maintenance procedures. For example, the failure to include information on a circuit breaker Enclosure
modification in a maintenance procedure caused an emergency AC power pathway to be inadvertently removed from service and the failure to include a design limit for the differential temperature between steam generator tubes and shell in station procedures resulted in the limit being exceeded. Deficiencies in the documentation and understanding of the Oconee design bases contributed to problems in this are A comprehensive self-assessment conducted late in the assessment period by the site engineering staff provided a candid assessment of engineering performance and the causes for performance deficiencie The Engineering area was rated Category PLANT SUPPORT The Plant Support functional area addresses all activities related to radiological controls, emergency preparedness, plant chemistry, security, fire protection and plant housekeepin Performance in the radiological control area continued to be excellent during this period. The as low as reasonably achievable (ALARA) program was effective in achieving low collective total doses during both normal operation and outage periods. The collective site dose for 1993 was approximately 240 person rem. Although higher than 1993 due to the increased outage work, the collective dose for 1994 was well within the site goal of 592 person rem. ALARA activities that resulted in reduced doses included good outage planning with utilization of mockups, use of remote monitoring techniques, piping replacement, and hot spot remova The internal exposure control program was effective in minimizing intake of radioactive materia An aggressive area contamination control program which placed emphasis on personnel awareness and thorough decontamination methods was effective in maintaining a minimum contaminated area. The environmental monitoring program, supported by a well maintained meteorological system, was effectively implemented during this period. A program enhancement during this period was in the area of groundwater monitoring near the onsite chemical treatment pond Environmental and effluent monitoring program results indicated that control measures were effective such that releases and resultant offsite doses were only a small fraction of established limits. The chemistry control program was adequately implemented, with coolant chemistry levels being maintained well within limits. Self-assessment audits in this area were thorough and effective in identifying problems. However, corrective actions for audit findings were not always adequate or timely, nor were completed actions always documented appropriatel Performance in the emergency preparedness area continued to be a strength. A strong level of management support and involvement in the program was indicated by the level of participation in numerous drills, the well-maintained facilities and equipment, and continuing emergency preparedness program improvements. The emergency response facilities Enclosure
were well-supplied to support a response. Training programs were effective, as demonstrated by the excellent performance during the 1993 and 1994 exercises and walk-through evaluations with control room personne The licensee's self-assessments during exercise critiques and audits were thorough, resulting in the identification of issues for improvement. Corrective actions for items identified in critiques and audits were prompt and effective. An exercise weakness related to internal communications was identified in each of the last two exercises. Appropriate corrective actions were taken by the licensee to correct the identified weaknes With the exception of a failure to adequately protect safeguards information early in the assessment period, the performance of the security program continued at a high level during this perio Appropriate corrective action was taken for this failure and there were no additional findings or problems in this area during the latter portion of the period. Security training was aggressive, with numerous enhancements made during the period such as special training courses, procurement of additional training aids, and additional certification in specialized areas. Audits of the security program were thorough and effective in identifying problem Identified problems were promptly resolved. Equipment testing and maintenance programs were effective in ensuring reliability. Compensatory measures, when necessary, were implemented in a timely and appropriate manner. Assessment aids, alarm stations, and communication equipment performed effectively, and the assessment capability was enhanced during this period by the installation and use of a video capture syste In the fire protection area, there were instances involving lack of control over combustible materials in the Unit 2 electrical penetration room and reactor building. Procedural controls were strengthened and some improvement in the control of combustibles was noted. During the period, there was one small fire (caused by turbine honing oil being spilled onto a steam line) for which an appropriate response was mad Overall, plant housekeeping was good. Post-outage cleanup activities were effective, as evidenced by the appropriate removal of work materials and no remaining debris in containmen The Plant Support area was rated Category Enclosure