ML18030A034

Part 21 Rept Re Deficiency of Pacific Swing Check Valves, Initially Reported 810119.Hold Tags Placed on Valves. Investigation Initiated.Final Rept Scheduled for May 1981

ML18030A034
Person / Time
Site:	Susquehanna
Issue date:	03/11/1981
From:	Curtis N PENNSYLVANIA POWER & LIGHT CO.
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
REF-PT21-81-381-000 10CFR-50.55E, ERS-100450-1005, PLA-654, PT21-81-381, PT21-81-381-000, NUDOCS 8103231091
Download: ML18030A034 (9)

Text

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PP8,L TWO NORTH NINTH STREET, ALLENTOWN, PA. I 810 I PHONEr (2 I 5) 770-5 I 5 I NORMAN tV. CIIRTtS Vice President-Engineerlny IL Construction-Nuclear 770.5381 March 11, 1981 Mr. Boyce H. Grier Director, Region I U. S. Nuclear Regulatory Commission

.631 Park Avenue King of Prussia, PA 19406 SUSQUEHANNA STEAM ELECTRIC STAT1ON INTERIM REPORT OF A DEFICIENCY RELATING TO PACIFIC SWING CHECK VALVE FAILURES ERs 100450/100508 FILES 840-4/900-10 PLA-654

Dear Mr. Grier:

This letter serves to confirm information provided by A. R. Sabol in a telephone conversation with NRC Region I, Reactor Inspector, Mr. L. Narrow, on January 19, 1981. During that conversation, Mr. Narrow was advised that the subject condition was under evaluation for reportability under the provisions of 10 CFR 50.55(e).

The deficiency involves excessive wear at the hinge arm/disc stud interface of Mark Controls Corporation (MCC)/Pacific Valve Swing Check valves. A description of the problem, its cause, safety implications and the corrective action taken and planned is attached and is submitted as an interim report of the deficiency pursuant to the provisions of 10 CFR 50.55(e) .

Since the details of this report provide information relevant to the reporting requirements of 10 CFR 21, this correspondence is considered to also discharge any formal responsibility PPGL may have for reporting in compliance thereto.

We expect to provide our final report. for this condition in May, 1981.

We trust the Commission will find the information contained herein to be satisfactory.

Very truly yours, N. W. Curtis Vice President-Engineering a Construction-Nuclear PENNSYLVANIA POWER 8 LIGHT COMPANY

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Mr. Boyce H. Grier 2 March 11, 1981 PLW:sab Attachment cc: Mr. Victor Stello (15)

Director-Office of Inspection 6 Enforcement U. S. Nuclear Regulatozy Commission Washington, D.C. 20555 Mr. G. McDonald, Director (1)

Office of Management Information & Program Control U. S. Nuclear Regulatozy Commission Washington, D.C. 20555 Mr. Robert M. Gallo U. S. Nuclear Regulatory Commission P.O. Box 52 Shickshinnyg PA 18655

Attachment to PLA-654 SUBJECT Excessive wear at hinge arm/disc stud interface on MCC/Pacific Swing Check valves.

DESCRIPTION OF PROBLEM Swing check valves manufactured by MCC/Pacific Valves have discs with two stubs, each on either side of the hinge azm, used to prevent the disc from spinning during service (see Figure 1). However, excessive wear at the valve hinge arm/disc stud interface has been noted which allows the disc to have sufficient play for the stubs-to. jam behind the

'inge arm, thus preventing the valve from closing completely. Furthermore, this wear could also render the disc off center, thereby causing a leak path by the seat.

This condition was originally documented on Bechtel NCR-6791 dated 11/3/80. The NCR was based on an inspection of four 10 inch check valves in a Non "Q" system but was written against 94 physically identical valves supplied for use in "Q" systems.

CAUSE OF DEFICIENCY h

MCC/Pacific Valves'ssessment indicates that the Non "Q" valves inspected are subject to abnormally high flow-induced loads which substantially result from dynamic effects which accompany turbulence and/o" vorticity. These loads may have contributed to the check valve failures.

ANALYSIS OF SAFETY IMPLICATION Although a complete safety evaluation of each Pacific Q-listed check valve has not yet been performed, the potential leak path and failure of a check valve to.close completely is considered to be a failure to perform an intended safety function. These valves are used in such "Q" systems as High Pressure Coolant Injection, Reactor Core Isolation Cooling, Emergency Service Water, Residual Heat Removal and Core Spzay Systems. The condition involves significant damage to a component. Extensive repairs may be required to establish the adequacy of the component to perform its intended safety function. Therefore, the condition is considered reportable under 10 CFR 50.55(e).

CORRECTIVE ACTION The immediate corrective action taken involved the placement of hold tags on the 94 valves identified in NCR-6791. A review of Pacific check valves in "Q" installations has been initiated. It is MCC/Pacific Valves'pinion that accelerated wear and premature failure can be minimized by installing check valves at a distance of several pipe diameters of straight pipe downstream of pump discharge> short radius elbows, reducers or expanders.

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Attachment to PLA-654 Bechtel is currently reviewing the layout of the inspected Non "Q" check valves to determine the validity of MCC/Pacific Valves'ssertion.

Bechtel Field Engineering 'will inspect othe" similar "Q" and Non "Q" Pac'fic check valve installations to determ'ne whether a generic. valve design problem exists.

The corrective action for the valves identified as being defective will be documented in our final report which we expect to issue in May, 1981.

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Two lugs integrally cast on the disc on either side of

'he hanger prevent the disc from spinning In service.

This exclusive feature helps extend valve life in difficult services by eliminating disc spinning.

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