Actions Required from OL Applicants of NSSS Designed By W and CE Resulting from NRC B&O Task Force Review of TMI2 Accident (Generic Letter 80-20)
GL80020 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555 March 10, 1980 TO ALL PENDING OPERATING LICENSE APPLICANTS OF NUCLEAR STEAM SUPPLY SYSTEMS DESIGNED BY WESTINGHOUSE AND COMBUSTION ENGINEERING SUBJECT: ACTION REQUIRED FROM OPERATING LICENSE APPLICANTS OF NUCLEAR STEAM SUPPLY SYSTEMS DESIGNED BY WESTINGHOUSE AND COMBUSTION ENGINEERING RESULTING FROM THE NRC BULLETINS AND ORDERS TASK FORCE REVIEW REGARDING THE THREE MILE ISLAND UNIT 2 ACCIDENT In our letter of September 27, 1979 to all pending operating license applicants concerning followup actions resulting from our reviews regarding the Three Mile Island Unit 2 accident, we indicated that each applicant would receive additional guidance from the NRR Bulletins and Orders Task Force. This guidance would be related to (1) Auxiliary Feedwater (AFW) systems, and (2) analyses for small break loss-of-coolant accidents and inadequate core cooling, including guidelines for emergency operating procedures. The purpose of this letter is to advise you of the information we require related to Auxiliary Feedwater systems. The requirements were identified during the course of the NRR Bulletins and Orders Task Force review of nuclear steam supply systems designed by Westinghouse and Combustion Engineering in light of the Three Mile Island Unit 2 accident. Auxiliary Feedwater (AFW) Systems The Three Mile Island Unit 2 accident and subsequent investigations and studies highlighted the importance of the AFW system in the mitigation of transients and accidents. As part of its assessment of the Three Mile Island Unit 2 accident and related implications for operating plants, the staff evaluated the AFW systems for all operating plants having nuclear steam supply systems designed by Westinghouse and Combustion Engineering. The objectives of the staff's study, related to operation of nuclear steam supply systems designed by Westinghouse, were (a) to identify necessary changes in AFW system design or related operating procedures at operating plants in order to assure continued safe operation of these plants, and (b) to identify other system characteristics in the AFW system design of these plants which on a long-term basis may require system modifications. To accommodate these objectives the staff reviewed plant-specific AFW system designs in light of current requirements, and assessed the relative reliability of the various AFW systems under various loss-of-feedwater transients, one of which was the initiating event at Three Mile Island Unit 2, and other postulated potential failure conditions by determining the potential failure conditions by determining the potential for AFW system failure due to common causes, single point vulnerabilities and human error. . It should be noted that, because of time and personnel limitations, our evaluation of AFW systems was limited to operating reactors at the time these studies were initiated. Our review of these systems resulted in the identification of changes required for current AFW systems. Some of these changes were generic and others were plant specific. A summary of the techniques used in our evaluation is provided in Enclosure 1.* With respect to operating license applications such as yours, we will require that you (a) provide an evaluation which shows how your AFW system meets each requirement in Standard Review Plan 10.4.9 and Branch Technical Position ASB-10-1, (b) perform a reliability evaluation similar in method to that described in Enclosed 1 that was performed for operating plants and submit it for staff review, and (d) respond to Enclosure 2, which requests the information necessary to determine the design basis for your AFW system flow requirements and to verify that your AFW system will meet these requirements. We recognize that operating license applicants for certain facilities, e.d., Salem Unit 2, and North Anna Unit 2, may be essentially identical to plants for which we have identified AFW system modifications. In such instances, information already provided for the operating plants may be directly applicable to plants under review for an operating license. It is acceptable to the staff if you reference such information in your response. However, you must also include a description of any differences between the operating plant and the plant under review for an operating license and provide justification in order for us to determine if the resolution for the operating plant is applicable to your facility. Provide the information discussed above as an amendment to your application. Your schedule for submittal should take into consideration that the current version of the Task Action Plan requires staff review and approval of this information prior to issuance of a full power license. D. F. Ross, Jr., Acting Director Division of Project Management Office of Nuclear Reactor Regulation Enclosures: As Stated cc: Service Lists * Enclosure 1 is Appendix 3 to the staff generic evaluation of Westinghouse designed plants. The techniques described and recommendations are applicable to Combustion Engineering designed plants.
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