ML19291C328

Responds to IE Bulletin 79-14, Seismic Analysis for As- Built Safety-Related Piping. Insp & Measurements of Inaccessible Piping & Supports in Category I Sys Are Complete W/Exception of Welded Pipe Attachments & Valves

ML19291C328
Person / Time
Site:	Millstone
Issue date:	12/14/1979
From:	Counsil W NORTHEAST NUCLEAR ENERGY CO.
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
IEB-79-14, NUDOCS 8001240210
Download: ML19291C328 (2)

Text

- - -1:n IMMM'HI!AST IFFII.ITII!S 1 ZSEEEE.T~ Enfro*nS CONNECTICUT 06101 MM.r; ::""~ m swnn L ' J = 0 L' = C rl December 14, 1979 Docket No. 50-336 Mr. Boyce H. Grier, Director Region I Office of Inspection and Enfcrcement U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406

References:

(1) B. H. Grier letter to W. G. Counsil dated July 2,1979, forwarding I&E Bulletin No. 79-14.

(2) B. H. Grier letter to W. G. Counsil dated August 15, 1979, forwarding I&E Bulletin No. 79-14, Supplement.

(3) W. G. Counsil letter to B. H. Grier dated September 10, 1979.

(4) W. G. Counsil letter to B. H. Grier dated November 7, 1979.

Gentlemen:

Millstone Nuclear Power Station, Unit No. 2 I&E Bulletin No. 79-14 Ref erence (1), as supplemented by Reference (2), requested Northeast Nuclear Energy Company (NNECO) to initiate a program aimed at verifying the accuracy of input information for seismic analysis of safety-related piping.

NNECO submitted the available results of inspections performed on both accessible and inaccessible piping systems, as required by Items 2 and 3 of Reference (1),

in References (3) and (4).

The recent extended outage required to repair feedwater piping indications at Millstone Unit No. 2 afforded the opportunity to perform extensive inspections pursuant to I&E Bulletin No. 79-14, in normally inaccessible areas of the plant.

The inspaction and measurements of all inaccessible piping and supports contained in the seismic Category I systems under investigation have been completed with the exception of certain valves and welded-pipe attachments which are covered by insulation. The insulation must be removed from these valves to verify that the documentation listing the equipment manufacturer is correct.

It was reported in Reference (4) that the inspection and measurements had been completed on all accessible piping and supports in seismic Category I systems pursuant to I&E Bulletin No. 79-14. These inspections and measurements gre 1795 044 800124 0 1IO

complete with the exception of welded-pipe attachments covered by insulation loc.ated in the main steam, feedwater, and chemical s .i volume control system (CVCS) . L e welded-pipe attachments on the main steam and feedwater systems were not verified because of the extreme heat associated with these systems during normal operation. During the outage, inspections of the normally inaccessible piping were determined to be of a higher priority. Heat tracing, which is required to be operational, complicated removal of the insulation on the CVCS; hence, the welded-pipe attachments covered by insulation remain to be verified. NNECO apologizes for any inconvenience which may have resulted from the information contained in Reference (4).

Insulation has been removed and inspections and measurements completed on 85%

of the normally accessible welded-pipe attachments in systems under investigation pursuant to I&E Bulletin No. 79-14. In cddition, all welded-pipe attachments not covered by insulation have been verified. The remaining attachments covered by insulation, representing less than 10% of the total number of hangers identified per I&E Bulletin No. 79-14, will be verified at the next refueling outage. No significant deviations have been discovered in any of the welded-pipe attachments inspected to date. NNECO concludes that a high confidence level exists for the structural integrity of the small number of remaining welded attachments covered by insulation which require inspection / measurement.

This information will not affect the schedule of the ongoing stress review and reanalyses.

The stress review and reanalyses of those deviations discovered to date are continuing as reported in References (3) and (4). At this time, 100 of a total of 250 stress problems have undergone review. These reviews have not identified any deviation which affects the operability or the safe shutdown capability of any system. The reviews are scheduled for completion on or about March 1, 1980. Any reanalysis which may be required as a result of the stress reviews is scheduled to be completed by April 1,1980.

A final report containing the results of the remaining inspections and analyses is scheduled to be submitted upon their completion.

We trust this information is responsive to the NRC Staff's requests.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY

!

• N lOl ~

W. G. Counsil Vice President 1795 045