ML19031B617

03/31/1976 Letter Failure of CVCS No. 13 Charging Pump Suction Header

ML19031B617
Person / Time
Site:	Salem
Issue date:	03/31/1976
From:	Schwalje E Public Service Electric & Gas Co
To:	Knuth D NRC/IE
References
Download: ML19031B617 (2)

Text

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PS~ e Public Service Electric and Gas Company 80 Park Place Newark, N.J. 07101 Phone 201 /622-7000 March 31, 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:

eves NO. 13 CHARGING PUMP SUCTION HEADER NO. 1 UNIT SALEM NUCLEAR GENERATING STATION DOCKET NO. 50-272 On March 8, 1976 a verbal report was made to Region 1, Office of Inspection and Enforcement, advising that a weld joining the No. 13 CVCS Charging Pump 4-inch suction line to the 8-inch suction header failed. This report was in accordance with provision of 10CFR50.55(e).

The following is a detailed analysis and report on the subject failure:

RCS leakage test SUP 50.5 was being conducted during Hot Functional Testing when a crack developed in the 4" suction line feeding No. 13 Positive Displacement Charging Pump (Model QX-300, Union Pump Company).

The failure was located at the weld of a piping Branch connecting the Charging Pump suction line with the main 8" suction header that supplies all three station Charging Pumps.

Primary system pressure and temperature at the time

• of this occurrence were 2235 psig and 547°F respectively.

No. 13 Charging Pump and No. 14 Reactor Coolant Pump were in service. The Charging Pump was supplying between 40 and 75 gpm to the Reactor Coolant System when the failure was discovered. Plant cooldown was initiated in order for temporary repairs to be effected.

The Energy People 95-2001 (400M)

Dr. Donald F. Knuth

• 3/31/76 The Branch weld crack was caused by transmitted vibration from No. 13 Charging Pump. Corrective action, to take place after Hot Functional Testing, will involve replacing the Branch connection with a forged schedule-40 8 11 x 11 8 x 4" reducing Tee. Additional pipe restraints will be added to minimize transmitted vibration. These measures will provide the added assurance that future failures will be mitigated.

In analyzing the safety implications of this incident, it was noted that the break occurred immediately downsteam of the 8 11 suction header that supplies borated water from the RWST to Nos. 11 and 12 Charging/Safety Injection Pumps for high head safety injection purposes. As there would have been no way to isolate this break from the 8 11 suction header, this event would have had the following consequences if it had occurred during normal plant operations:

1. Impairment of High Head Safety Injection Pump capability, severity dependent upon the size of the break.

2. Subsequent difficulty in performing rapid boration through the Boron Injection Tank or from the Boric Acid Storage System.

Disablement of the High Head Safety Injection subsystem would not have affected our Intermediate or Low Head Safety Injection capabilities.

The replacement reducing tee and pipe restraint work will be completed by April 15, 1976.

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

Very truly yours,

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E. / . Sch~~j e Manager of Quality Assurance Engineering and Construction Department CC Mr. J. P. O'Reilly King of Prussia, Pa.