ML20147H696
| ML20147H696 | |
| Person / Time | |
|---|---|
| Issue date: | 02/28/1997 |
| From: | Ibarra J, William Jones, Lanik G NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | |
| References | |
| NUREG-1275, NUREG-1275-ERR, NUREG-1275-V12-ERR, NUDOCS 9704040223 | |
| Download: ML20147H696 (5) | |
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March 1997 ERRATA 1
Report Number: NUREG-1275, Vol.12 Report
Title:
Operating Experience Feedback Report, Assessment of Spent Fuel Cooling Prepared by: Office for Analysis and Evaluation of Operational Data ;
i i Date Published: February 1997 f
1 j Instructions: Please replace the pages listed on this errata with the enclosed corrected pages ,
Location Pages i Executive Summary xi/xii O/
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EXECUTIVE
SUMMARY
As directed by the Executive Director for performed model refinements that resulted in Operations, the Office for Analysis and better estimates of near boiling frequency Evaluation of Operational Data (AEOD) (NBF). Although INEL performed no performed an independent assessment of the quantitative estimates of core damage, the likelihood and consequences of an extended loss analysis provided qualitative insights for of spent-fuel-pool (SFP) cooling. The overall identifying improvements to SFPs that may conclusions are that the typical plant may need lessen the risks of events.
improvements in SFP instrumentation, operator procedures and training, and configuration Findings from these assessments are as follows:
csntrol.
From reviewing more than 12 years of The AEOD staff conducted six site visits to gain operating experience, the staff determined an understanding of each licensee's SFP that loss of SFP coolant inventory greater physical configuration, practices, and operating than I foot occurred at a rate of about 1 procedures. During these visits, they found event per 100 reactor years. Loss of SFP great variation among the designs and cooling with a temperature increase greater capabilities of SFPs and systems at the nuclear than 20 F occurred at a rate of plants on these sites. approximately 3 events per 1000 reactor years. The consequences of these actual 1 In November 1992, Mr. Donald Prevatte and events were not severe. However, these Mr. David Lochbaum submitted a defects and events resulted in loss of several feet of SFP noncompliance report on the Susquehanna SFP coolant level, some of the events have lasted to the U.S. Nuclear Regulatory Commission longer than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The primary cause of (NRC). The AEOD staffinterviewed Mr. these events was human error.
Prevatte and Mr. Lochbaum to better understand their concerns. Their report, which has potential
- During review of existing SFP risk generic implications, provided the impetus for assessments, the staff found that after the NRC and the nuclear industry to take a correction for several problems in the closer look at SFPs. analyses, the relative risk produced by loss of spent fuel cooling is low when compared AEOD reviewed the applicable SFP regulations, with the risk of events not involving SFP.
the appIicable acceptance criteria in the NRC The likelihood and consequences of loss of Standard Review Plan, and the applicable SFP cooling events are highly dependent on Regulatory Guides. Because the criteria human performance and individual plant evolved and each reactor was licensed over design features, time, the criteria varies for evaluating these SFP designs.
- The staff determined that utilities' efforts to reduce outage duration have resulted in full The AEOD staff perfonned independent core off-loads occurring earlier in outages.
assessments of the electrical systems, This increased fuel pool heat load reduces instrumentation, heat loads, and radiation from the time available to recover from a loss-of-which they determined the typical SFP SFP-cooling event early in the outage.
configurations and potential problems.
Actions recommended by AEOD based on these Utilizing a previous Susquehanna risk analysis, assessments are as follows:
l Idaho National Engineering Laboratory (INEL) l xi NUREG-1275, Vol.12 l
l A _ _ _ _ _ . _ _
I Executive Summary l l
The need for corrective actions at each plant should be evaluated on a plant-specific I where failures of reactor cavity seal or gate basis. !
seals, or ineffective antisiphon devices ;
could pot 6ntially cause loss' of SFP coolant .
- The need for improved procedures and !
inventory sufficient to uncover the fuel or training for control room operators to i endanger makeup capability, should be respond,to SFP loss-of-inventory and SFP evaluated. loss-of-cooling events, consistent with the i time frames over which events can proceed The need for improvement to configuration and recognizing the heat load and the controls related to the SFP to prevent or possibility of loss of inventory, should be l mitigate SFP loss-of-inventory events and evaluated on a plant-specific basis. j loss-of-cooling events should be evaluated !
on a plant-specific basis. -
The need for improvements to )
instrumentation and power supplies to the i
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The need for plant modifications at some SFP equipment to aid correct operator multiunit sites to account for the potential response to SFP events should be evaluated effects of SFP boiling conditions on safe on a plant-specific basis, shutdown equipment for the operating unit, (
particularly during full core off-loads, l
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