05000313/FIN-2013011-08
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Finding | |
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Title | Effectiveness of Shutdown Risk Management Program |
Description | The team reviewed procedure EN-OU-108, Shutdown Safety Management Program, Revision 5, which provided a process to assess the overall impact of plant maintenance on plant risk to satisfy the requirements of 10 CFR 50.65(a)(4) during the cold shutdown and refueling modes of reactor operation. Step 5.4, Conducting the Shutdown Safety Assessment, specified that the Outage Risk Assessment Team be assembled and evaluate the outage schedule, including identification of higher risk evolutions. The team reviewed Condition Report CR-ANO-1-2013-00132, initiated on January 28, 2013, which documented the Outage Risk Assessment Team review of Revision 0 of the Unit 1 Outage schedule. This review identified a table of specific outage items and included an additional comment questioning whether contingency plans were needed for three planned outage activities, including flying the stator on the turbine deck. The resolution of the additional comment identified that the outage management organization determined no contingency plans were necessary for the stator movement. Through interviews with the licensee staff, the team determined that the outage management organization considered the likelihood of a problem with the stator movement to be very low and considered that no practical contingency measures were necessary beyond a temporary modification to provide alternate power to one non-safety intermediate cooling water pump. This determination was based on Unit 1 being scheduled to be in the refueling mode of operation with water level high above the reactor vessel flange. The intermediate cooling water pump normally receives power from non-safety related bus A2, and the system provides cooling water to the spent fuel pool cooling heat exchangers. The temporary modification to supply power to one pump from an alternate offsite source allowed operation of adequate intermediate cooling water system capacity throughout the planned outage of the Green train equipment, including the outage of nonsafety-related bus A2. The temporary modification to provide power to the intermediate cooling water pump was prepared but was not installed prior to beginning the stator lift. For identified higher risk evolutions or conditions, procedure EN-OU-108 specified the use of guidance in procedure Attachment 9.1, Qualitative Risk Evaluation and Risk Mitigation Plan, to assess the impact of higher risk evolutions or conditions on key safety functions. Sheet 4 of 5 in Attachment 9.1 provided a checklist of contingency measures for heavy load lifts. A note contained on the heavy load lift checklist identified that specific compensatory risk management actions were contained in procedure EN-MA-119, Material Handling Program, Revision 16. The checklist included additional contingency measures for heavy load lifts when equipment under the load path is protected. In the plant state at the time of the event (Shutdown Condition 2: reactor vessel head removed, reactor cavity flooded to greater than 23 feet above the reactor vessel flange, fuel in the reactor vessel, and no fuel movement in progress), the Shutdown Operations Protection Plan (Procedure 1015.048, Revision 9) specified that at least one of the offsite power sources be operable. However, all available offsite power sources passed beneath the load path. Furthermore, Technical Specification Limiting Condition for Operation 3.8.2, AC Sources Shutdown, required one offsite source of power be operable in operating modes 5 and 6, and during movement of irradiated fuel assemblies. Therefore, the team determined that at least one offsite power source must be protected in that mode of operation. At the time of the stator movement the nonsafety related bus A2 was removed from service and safety-related buses A3 and A4 were cross-tied and receiving power from the Unit 1 startup transformer offsite source via non-safety bus A1. Therefore, the only operable offsite power source was under the load path for the stator movement. The heavy load handling checklist in Attachment 9.1 to procedure EN-MA-119 included the following possible risk mitigation actions for the protected equipment: Enhance communication to improve awareness of the load lift and its relation to maintenance activities. Revise load path. Add compensatory actions or back-up safety functions to enhance safety function redundancy. Assume safety function is impacted by potential load drop and adjust the key safety function assessment accordingly. Of these actions, the licensee enhanced communication by treating the heavy lift of the stator as an infrequently performed test or evolution (IPTE); and the plant staff prepared a temporary modification to provide an alternate power source to one of the intermediate cooling water pumps if needed. The team evaluated the effectiveness of the implemented measures in managing the effect of a potential heavy load drop on protected electrical equipment. The team reviewed the IPTE briefing materials and the outage schedule to assess how the relationship between the stator movement and other outage activities was controlled. The team found that the briefing materials provided direction related to industrial safety, but the materials did not provide documented restrictions during the heavy load lift related to reactor plant conditions or the availability of equipment for maintenance of key safety functions, such as reactor decay heat removal, reactor makeup water, and electrical power. Interviews with outage management and operating staff personnel indicated that no firm relationships had been established between the stator movement and other refueling outage activities. Through review of the outage schedule, the team identified cases of potentially elevated plant risk during the planned stator movement. For example, the team determined that the planned sequence of stator movements called for positioning the replacement stator in the turbine building at a time when the entire Green train electrical distribution was scheduled to be out of service, including the ability to use one of the two installed safety-related emergency diesel generators and one of two safety-related station batteries. In addition, the outage schedule indicated fuel transfer to the spent fuel pool would be in progress. Based on the absence of administrative controls addressing the relationship between the stator replacement activities and other outage activities related to reactor key safety functions, the team concluded that additional inspection was needed to assess the effectiveness of the plant risk mitigating measures associated with the stator movement activities: Unresolved Item URI 05000313/2013011-08, Effectiveness of Shutdown Risk Management Program. |
Site: | Arkansas Nuclear ![]() |
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Report | IR 05000313/2013011 Section 4OA5 |
Date counted | Jun 30, 2013 (2013Q2) |
Type: | URI: |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | IP 93800 |
Inspectors (proximate) | A Sanchez D Allen D Loveless G Miller J Watkins S Jonesb Lattag Werner J Melfi L Willoughby N Okonkwo |
INPO aspect | |
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Finding - Arkansas Nuclear - IR 05000313/2013011 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Arkansas Nuclear) @ 2013Q2
Self-Identified List (Arkansas Nuclear)
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