NRC Generic Letter 80-33, Actions Req. From OL Applicants of B&W Designed NSSS Resulting From NRC B&O Task Force Review of TMI2 Accident

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GL80033

ENCLOSURE 2

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555

April 24, 1980

TO ALL PENDING OPERATING LICENSE APPLICANTS OF NUCLEAR STEAM SUPPLY SYSTEMS DESIGNED BY BABCOCK AND WILCOX

SUBJECT: ACTIONS REQUIRED FROM OPERATING LICENSE APPLICANTS OF NUCLEAR STEAM SUPPLY SYSTEMS DESIGNED BY BABCOCK AND WILCOX 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 pressurized water reactor nuclear steam supply systems 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. Following the Three Mile Island 2 accident, operating plants having nuclear steam supply systems designed by Babcock and Wilcox were shutdown. During these shutdowns short-term actions were taken to improve the reliability of the AFW system. As part of the long-term requirements of the shutdown of these plants, more systematic reliability analysis of the AFW system has been conducted by the licensees. The staff is currently evaluating these analyses. Also as part of is assessment of the Three Mile Island Unit 2 accident and related implications for operating plants, the staff evaluated the reliability of 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 pressurized water nuclear steam supply system was

(a) to identify necessary chances 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 improve reliability.

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.To accommodate these objectives the staff reviewed plant-specific AFW system designs in light of current requirements, and assessed the relative reliability of which was the initiating event at Three Mile ISland Unit 2, and other AFW system failure due to common causes, single point vulnerabilities and human error.

It should be noted that, because of time personnel limitations, our evaluation of AFW systems was limited to operating reactors at the time these studies were initiated. Our review of these 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 the you

(a) provide an evaluation which show how your AFW system meets each requirement in Standard Review Plan 10.4.9 and Brach Technical Position ASB-10-1,

(b) perform a reliability evaluation similar in method to that described in Enclosure 1 that was performed for operating plants and submit it for staff review,

(c) factor the recommendations of Enclosure 1 into your plant design, 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.

You are required to provide the information discussed above as an amendment to your application. Your schedule for submittal should take into consideration our requirement that both staff approval of your AFW design and actual accomplishment of any necessary modifications be completed prior to issuance of a full power license, as reflected in item II.E.1.1 of the TMI Action Plan (NUREG-0660).

Sincerely,

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 III to the staff generic evaluation of Westinghouse designed plants, NUREG-0611. The techniques described and recommendations are applicable to Combustion Engineering and Babcock and Wilcox designed plants.