Resolution of Generic Safety Issues: Issue 56: Abnormal Transient Operating Guidelines as Applied to a Steam Generator Overfill Event ( NUREG-0933, Main Report with Supplements 1–34 )
On April 8, 1981, while operating at 100% power, the Arkansas Nuclear One, Unit 1 experienced a moderate feedwater-overfill transient in one of its once-through steam generators. AEOD performed a case study of this event, concluded that the event posed a potential generic safety problem, and issued a preliminary report on April 9, 1982, to document its findings.318 NRR reviewed the report and forwarded comments to AEOD on July 30, 1982.319 The final AEOD report was issued on August 30, 1982. In a memorandum320 to AEOD in October 1982, NRR acknowledged the issues raised by the AEOD report and stated that the two specific recommendations of the AEOD report will be considered in on-going NRR programs. The recommendation that attention should be focused on changes in equipment and procedures to resolve this overfill issue is being considered under USI A-47. The recommendation that the time margins available for operator action should be considered in the human factors control room review is being considered in TMI Action Plan Item I.D.1. In addition, NRR observed that several B&W licensees have committed to actions which may resolve or mitigate the steam generator feedwater-overfill concerns. This position was subsequently reaffirmed in a memorandum321 on November 1, 1982, from the EDO to Commissioner Ahearne which stated:
"...In general, NRR agrees that steam generator overfill is an important concern which needs to be resolved and has on-going programs addressing all of the important aspects of the problem. The USI A-47...is directly addressing the need for automatic action or adequate action times for protection against steam generator overfill...Related activities are under way in the Control Room Design Review (TMI Action Plan Item I.D.1)..."
In addition, the EDO stated321 that:
"The resolution of USI A-47 will establish the requirements and review criteria for steam generator overfill protection...(and) actions by licensees are underway which may resolve or mitigate the overfill concern even before the implmentation of requirements stemming from USI A-47..."
The issue is not a separate issue but rather a sub-task of USI A-47, which is directly addressing the need for automatic action on adequate action times for protection against steam generator overfill, and by the related activities under
TMI Action Plan Item I.D.1 (Control Room Design Review), which is addressing the time margins available for operator action.