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February 18, 1999 The Honorable Shirley Ann JacksonChairman U. S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Dear Chairman Jackson: SUBJECT: LIST OF QUESTIONS TO BE ADDRESSED FOR POSSIBLE RESOLUTION OF KEY ISSUES ASSOCIATED WITH THE PROPOSED REVISION TO 10 CFR 50.59 (CHANGES, TESTS AND EXPERIMENTS) During the February 3, 1999 meeting between the Commission and the Advisory Committee on Reactor Safeguards, the Commission requested that the ACRS provide a list of questions which, if answered, would aid in the resolution of key issues associated with the proposed near-term revision to 10 CFR 50.59. In our discussion of this request during our 459th meeting on February 3-6, 1999, we considered two approaches to the resolution of the issues associated with 10 CFR 50.59 and developed questions for each of these approaches. In Approach 1, we propose a minimal set of questions that, if addressed, would preserve the desirable attributes of the 10 CFR 50.59 process that has been in place for over 30 years. In Approach 2, we propose another set of questions that, if addressed, would result in more profound changes to the 10 CFR 50.59 process. Both of these approaches are intended to address the proposed near-term revision to provide clarity and flexibility in the existing requirements, and not the long-term risk-informed revision to 10 CFR 50.59. APPROACH 1: Reconciliation of the Differences Between 10 CFR 50.59 and NEI 96-07 There is general agreement that the 10 CFR 50.59 process has worked well for over 30 years. Licensee implementation of the current process has been based on the guidance provided by NSAC-125, which the industry has attempted to improve through the development of NEI 96-07. The NRC staff has never formally endorsed the guidance included in these documents, but the staff has acknowledged that the overwhelming majority of the safety evaluations performed by licensees using this guidance have been acceptable. We believe that answering the following questions would provide a near-term revision to 10 CFR 50.59 that could optimize the benefits of past practice and provide regulatory stability.
Observation on Approach 1 Answering the above questions could provide a near-term solution for 10 CFR 50.59 that would maintain a process that has worked successfully and provide regulatory stability by requiring only limited changes to the process currently implemented by licensees and the staff. Such a process would, however, still require safety evaluations for many changes of little or no risk significance. APPROACH 2: Consideration of Margin of Safety and Definition of Change Associated with the Proposed Revision to 10 CFR 50.59 It is possible that, even in the short term, more profound changes to the 10 CFR 50.59 process can be developed by considering the fundamental goal and intent of the 10 CFR 50.59 process. To do this would require resolution of the following questions: Margin of Safety
Definition of Change The definition of "change" is central to the screening step that is implicit in the 10 CFR 50.59 process. The staff needs to define important structures, systems, and components (SSCs) as they relate to the facility, procedures, tests and experiments, malfunctions and accidents. In addressing the definition of change, we have developed the following questions:
Observation on Approach 2 It appears to us that many of the options for changes in the definition of "margin of safety" currently being considered greatly increase the importance of tracking the cumulative effect of such changes. Although the vast majority of changes introduced under the 10 CFR 50.59 process would still involve negligible changes in risk, the new definitions certainly could result in changes that, while acceptable, would not be negligible. This might require more frequent updating of the FSAR and a far more rigorous tracking of the changes. It is not clear to us that this might not result in more regulatory burden than a 10 CFR 50.59 process that is more restrictive on changes. We plan to continue our review of the proposed revision to 10 CFR 50.59 during future meetings. Sincerely, /s/ Dana A. Powers
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