NRC Generic Letter 83-31, Safety Evaluation of "Abnormal Transient Operating Guidelines"

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WASHINGTON, D.C. 20555

September 19, 1983

TO ALL OPERATING REACTOR LICENSEES, APPLICANTS FOR AN OPERATING LICENSE AND HOLDERS OF CONSTRUCTION PERMITS FOR BABCOCK & WILCOX PRESSURIZED WATER REACTORS

Gentlemen:

SUBJECT: SAFETY EVALUATION OF "ABNORMAL TRANSIENT OPERATING GUIDELINES" (GENERIC LETTER 83-31)

The NRC staff has reviewed the proposed Oconee Nuclear Station, Unite 3 Abnormal Transient Operating Guidelines (ATOG) as described in Babcock &

Wilcox (B&W) Owners Group letters dated March 31, 1982 and June 15, 1982, and D. Napiors letter from B&W to the Owners Group dated March 14, 1983. As discussed in the enclosed letter to the B&W Owners Group we have concluded that ATOG is acceptable as a basis for implementation of improved plant specific procedures and will provide improved guidance for operator emergency procedures over that which currently exists. Since there is no generic version of ATOG for B&W plants, the utilities who are participating in the Owners Group program are to provide sufficient documentation in the form of plant-specific ATOGs and Transient Information Documents (TIDs) so that the NRC can perform comparisons with the ATOG version evaluated in the enclosed Safety Evaluation Report (SER). We suggest that implementation of the guidelines proceed in 4 steps:

(1) Interim extension of ATOG to better cover ATWS and certain aspects of natural circulation;

(2) Preparation of plant specific procedures which, in general, conform to the ATOG referenced above and implementation of these procedures as required by Generic Letter 82-33, dated December 17, 1982;

(3) Preparation of supplements to the guidelines which cover changes, new equipment, or new knowledge and incorporation of these supplements into the procedures; and

(4) Completion and improvement of the guidelines to meet our long term requirements, followed by incorporation of improvements into plant specific procedures.

Step 1 is to be completed before ATOG is used in the implementation of procedures process. The prompt implementation of Step 2 will allow the benefits of the significant improvements you have achieved to be realized soon. We note however, that the guidelines are written for the procedure writers, not control room operators, and therefore, preparation andSeptember 19, 1983

implementation of procedures will require additional Human Factors input. Step 3 refers to a program for guideline or procedure updates which will be generated as a matter of routine after the implementation. This essentially is a maintenance function. Step 4 refers to a program for addressing those aspects of the guidelines and procedures where additional long term work may be needed in your emergency procedure program.

We have identified in the Safety Evaluation Report (SER) a number of items associated with the guidelines which need further work by the B&W Owners. We require that these items be addressed by either incorporating them into a future guideline revision or otherwise justifying the disposition of the item. The Owners Group letter of May 4, 1983 provided a satisfactory outline of a plan to change the existing ATOG to a more generic document. We share the Owners Group judgement that a B&W generic technical guideline will provide an effective mechanism for future guideline updates, changes and enhancements. Additionally, because the Abnormal Transient Operating Guidelines must be dynamic in that changes must be made to reflect change in equipment or new knowledge, we expect the B&W Owners' Group or a similar coalition of utilities and vendors to accept responsibility for continued maintenance of the guidelines. Therefore, we have requested in the enclosed letter that the B&W Owners' Group provide a plan for addressing the SER items and a description of the program for steps 3 and 4 above.

As discussed in the enclosed SER, the staff finds that ATOG represents a significant improvement over the guidance provided in current emergency operating procedures. ATOG is symptom oriented, considers multiple failures, is tolerant of operator error, addresses plant cooldown following an emergency, and addresses inadequate core cooling. We find the approach used in ATOG to be responsive to the staff's criteria. Further, ATOG contains a significant quantity of valuable information for the guidance of operators under emergency conditions. The guidelines provide sufficient guidance such that they can be translated into acceptable emergency operating procedures using the process identified in NUREG-0899, "Guidelines for the Preparation of Emergency Operating Procedures." The staff therefore concludes that although efforts to improve the guidelines should continue, ATOG will provide a greater assurance of operational safety and are acceptable for implementation.

Sincerely,

Darrell G. Eisenhut, Director Division of Licensing Enclosures:

1. Letter to Mr. Whitney, dated September 19, 1983

2. SER on Guidelines