NRC Generic Letter 81-37, ODYN Code Reanalysis Requirements

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WASHINGTON, D.C.20555

December 29, 1981

ALL BOILING WATER REACTOR LICENSEES (EXCEPT HUMBOLDT BAY AND DRESDEN 1)

SUBJECT: ODYN CODE REANALYSIS REQUIREMENTS (GENERIC LETTER 81-37)

By letter dated November 4, 1980 we informed you of our requirements for use of the ODYN code to calculate pressurization transients. We stated that after January 1982 all operating BWRs with General Electric analyses must have the limiting transients recalculated with the ODYN code, even if no reload submittal has been received.

By letter dated January 29, 1981 we provided you a safety evaluation and a supplemental safety evaluation describing our basis for acceptance of this code, and information required for ODYN application, including a description of two options for application.

For those plants which can be demonstrated to have scram times bounded by the option B scram time distribution, the option B calculations would be expected to be less limiting than REDY. Therefore, delay of OYDN analyses until the next refueling is a reasonable approach. For such plants, the licensees are requested to submit to the NRC before January 1982 their conclusion that option B is applicable to their plant. Those plants which cannot demonstrate scram times bounded by the option B scram time distribution should, by January 1982, submit ODYN analyses in accordance with option A or should propose and support other appropriately conservative operating limitations.

This request for information was approved by OMB under clearance number 3150-0080 which expires December 31, 1982. Comments on burden and duplication may be directed to the Office of Management and Budget, Reports Management Room 3208, New Executive Office Building, Washington, D. C. 20503.

Sincerely,

Darrell G. Eisenhut, Director Division of Licensing Office of Nuclear Reactor Regulation

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