ML19031B619

04/02/1976 Letter Detailed Analysis and Report on Pressurize Snubber Malfunction

ML19031B619
Person / Time
Site:	Salem
Issue date:	04/02/1976
From:	Schwalje E Public Service Electric & Gas Co
To:	Knuth D NRC/IE
References
Download: ML19031B619 (2)

Text

• PS~G Public Service Electric and Gas Company 80 Park Place Newark, N.J. 07101 Phone 201 /622-7000 April 2, 1976 Dr. Donald F. Knuth, Director U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement 7920 Norfolk Avenue Bethesda, Maryland 20014

Dear Dr. Knuth:

PRESSURIZER SNUBBER MALFUNCTION PRESSURIZER SAFETY AND RELIEF VALVE PIPING NO. 1 UNIT SALEM NUCLEAR GENERATING STATION DOCKET NO. 50-272 On March 4, 1976 a verbal report was made to Region I, Office of Inspection and Enforcement, advising that snubbers installed on the Pressurizer Safety and Relief Valve Piping of No. 1 Unit had malfunctioned. This report was in accordance with provision of 10CFR50.55(e).

The following is a detailed analysis ~nd report on the subject:

During Hot Functional Test SUP 50.0 Hanger Movement Verifica-tion Group reported that snubber units were restricting pipe movement. Ensuing investigations resulted in the removal of twelve units (approximately 28% of the total installed). These units were manufactured by International NuclearSafeguards Corporation (I.N.C.).

Of the 12 units removed from the piping system, 9 were found to be locked up and inoperable during the hot function test and 1 in a similar condition during cool down. The remaining 2 units which were operable during the test were removed for evaluation purposes. The I.N.C. units removed consisted of 2 size No. 1, 8 size No. 2 and 2 size No. 3.

• Initial investigation revealed that shipping and installation locking screws, which had not been removed from 4 units, sheared off during operation. These 4 units are identified as: Size No. 1, S/N 271; Size No. 2, S/N 47 and 118; and Size, No. 3, S/N.002281.

The 12 I.N.C. units were returned to the manufacturer fqr load testing, disassembly and evaluation. The factory tests~ witnessed by a PSE&G QA Engineer revealed the following: Three Size No. 2 Units (S/N 92, 110 and 111) were completely jammed and ~~sassembly The Energy People 95-2001 (400M)

Dr. D. F. Knuth

• 4/2/76 disclosed internal components were heavily corroded. PSE&G Energy Laboratory is now analyzing samples to determine the nature and cause of the corrosion. Five units (Size No *. 1, S/N 271 and 273; Size No. 2, S/N 75 and 118; and Size No. 3, S/N 002281) operated within prescribed load limits and were not disassembled.* The remaining 4 units (Size No. 2, S/N 73, 74 and 78; and Size No. 3, S/N 002281) were operable, but exceeded specified load limits. Disassembly of these 4 units did not reveal evidence of any corrosion.

Additional system testing of installed units will be conducted at the site under th~ direction of the manufacturer and will be evaluated by Engineering Department and witnessed by Site Quality Control personnel.

Preliminary investigation results disclosed that the heavy corrosion of the internal components caused 3 units to jam.

Failure to remove the lock and installation screws* on 4 units caused misop~ration and overloading. Still under investigation is snubber installation alignments which may have affected snubber operability. International NuclearSafeguards Corporation has been requested to revise their snubber installation procedure to include more definitive and precautionary instructions. The vendor has committed to comply by April 15, 1976. Site Quality C-0ntrol will verify implementation during the reinstallations.

PSE&G Engineering Department is currently conducting a study and evaluation on the continued use of these snubbers for the subject application. The action to be taken as a result of those studies will be completed by April 23, 1976.

If you desire additional information on this subject, we will be pleased to discuss it with you.

Very truly yours, 1__

~~~~-~ 1 E. (. S chwaJ;j e Manager of Quality Assurance Engineering & Construction Department cc Mr. J.P. O'Reilly King of Prussia, Pa.