ML19323G419

LER 80-018/01T-0:on 800508,during Ongoing Hanger Baseplate Analysis for IE Bulletin 79-02,both Svc Water Headers Inoperable.Caused by Inadequate Hanger Baseplate Supports. Redesign & Mod of Supports Begun.Seven Hangers Completed

ML19323G419
Person / Time
Site:	Millstone
Issue date:	05/22/1980
From:	Criscione J NORTHEAST NUCLEAR ENERGY CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19323G415	List: ML19323G414 ML19323G419
References
IEB-79-02, IEB-79-2, LER-80-018-01T, LER-80-18-1T, NUDOCS 8006020392
Download: ML19323G419 (2)

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EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h O 121 i During the on-coina hancer base-plate analysis for NRC IE Bulletin 79-02. and with I O 12 i i the plant at 100 percent power, both service water headers were declared inocerable l FO TT1 I which resulted in plant operation per Technical Specification 3.0.3 since conditions I

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it ,2, I greater than two. This resulted in plant operation oer Technical Soecification I iii3 1 3.0~.3, and the plant was placed in cold shutdown within 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. Redesign and I iii.i I modification of the service water hanger supports was initiated and is proceeding. I 7 8 9 . 80 STA  % POWER OTHER STATUS IS Y OtSCOVERY OESCRIPTION Ii 15 I lE l@ l1 l 0 l0 l@l NA l l Dl@l Notification From A/E l A TivtTY CO TENT -

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ATTACHMENT LER 80-18/lT-0 Millstone Unit 2 Docket No. 50-336 EVENT DESCRIPTION:

During the on-going hanger base-plate analysis for NRC IE Bulletin 79-02, it was detennined that several service water support hangers did not provide a factor of safety greater than two. Therefo re, both service water headers were declared inoperable which resulted in plant operatinn per Technical Specification 3.0.3 since conditions were in excess of those addressed in the Action Statement of Technical Specification 3.7.4.1. Accordingly, preparations were made to proceed to place the plant in cold shutdown within 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

CAUSE DESCRIPTION AND CORRECTIVE ACTION:

The cause of the inoperable service water headers was a factor of safety of less than 2 on several hanger baseplates. A pipe stress analysis run with the effected hangers removed showed the potential for piping overstress conditions. Work commenced in parallel with the analysis of additional systems identified for further review under Bulletins 79-02 and 79-14 to upgrade all effected hangers to a factor of safety greater than 4. At this time, 7 hangers have been completed on the service water system and additional hanger work is proceeding on the service water headers. Because the piping stress analysis is incomplete, the total number of hangers to be repaired is not known. However, there are hangers identified for analysis by 79-14 on the safety injection system and main steam system. The final results of the hanger modifications will be provided in an update report.

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