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Bulletin 79-02: Revision 1, (Supplement No. 1), Pipe Support Base Plate Designs Using Concrete Expansion Anchor Bolts
SSINS: 6820 Accession No: 7908150164 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 August 20, 1979 IE Bulletin No. 79-02 Revision No. 1 (Supplement No. 1) PIPE SUPPORT BASE PLATE DESIGNS USING CONCRETE EXPANSION ANCHOR BOLTS Description of Circumstances: The supplement to IE Bulletin No. 79-02 is intended to establish criteria for the evaluation of interim acceptability of plant operation with less than the design factors of safety for piping supports due to as-built problems, under design, base plate flexibility, or anchor bolt deficiencies. In the reviews for system operability of the Duane Arnold and Crystal River facilities, criteria have been developed by the NRC staff that defines pipe support operability. The criteria has been applied in lieu of other analysis or evaluation. Specifically, the licensees identified problems with pipe supports in which the original design factors of safety were not met but some lesser margin was available. The design margins of four or five are intended to be final design and installation objectives but systems may be classed as operable on an interim basis with some lesser margin providing a program of restoration to at least the Bulletin factors of safety has been developed. Facilities which fall outside the operability criteria are considered to probably require a Technical Specification exception and will require review on a case by case basis. Action to be Taken by Licensees: For the following two cases, plant operation may continue or may begin: a. For the support as a unit, the factor of safety compared to ultimate strengths is less than the original design but equal to or greater than two. b. For the anchor bolts the factor of safety is equal to or greater than two and for the support steel the original design factor of safety compared to ultimate strengths is met. The above criteria may be applied provided that the affected systems are upgraded to design margins of safety expeditiously for normally accessible supports and by the next refueling for nonaccessible supports. Accessibility is as defined in Bulletin No. 79-14 where "normally accessible" refers to those areas of plant which can be entered during reactor operation. . IE Bulletin No. 79-02, Revision No. 1 Page 2 of 2 Supplement No. 1 August 20, 1979 1. Any support not satisfying the criteria should be classed as inoperable and the Technical Specification action statement met unless it can be shown that the system can function in a design basis seismic event without the support. 2. Repairs to supports should result in return to the design factor of safety. 3. Operations may be continued while repairs to upgrade the system from a factor of safety equal to or greater than two with respect to design loads are performed. Consideration must be given to the effect of the repair process on support function and system operability. In other words the time the support is not functional should be limited to T.S. action statement times or the support must be determined not to cause the system to be unable to perform its function in a seismic event. The licensee should also exercise care not to take several supports on a given system out of service at the same time or cause both trains of one safeguards system to be made inoperable at the same time. Control over workmen on safety related systems during plant operation requires a high degree of control by the licensee. 4. There are no special reporting requirements for this supplement to the Bulletin; however, the reporting requirements as set forth in the regulations and licenses must be met.
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