B11207, Part 21 Rept Re Repeated Failures of RCS Charging Pumps Mfg by Gaulin Corp.Initially Reported on 840522.Caused by Initiation & Propagation of Cracks in Pump Blocks

Part 21 Rept Re Repeated Failures of RCS Charging Pumps Mfg by Gaulin Corp.Initially Reported on 840522.Caused by Initiation & Propagation of Cracks in Pump Blocks

ML20091L710
Person / Time
Site:	Millstone
Issue date:	05/25/1984
From:	Counsil W NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	Deyoung R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
References
REF-PT21-84 B11207, NUDOCS 8406080179
Download: ML20091L710 (3)

Text

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(203) 666-6911 May 25,1984 Docket No. 50-336 B11207 Mr. Richard C. DeYoung, Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Gentlemen:

Millstone Nuclear Power Station, Unit No. 2 Report of Substantial Safety Hazard In conformance with applicable provisions and requirements of 10CFR21, Northeast Nuclear Energy Company hereby provides notification of a Substantial Safety Hazard (SSH) for Millstone Unit 2.

On May 22,1984, Mr. T. C. Elsasser of the NRC Region I office was verbally notified of the repeated failures of the Reactor Coolant System charging pumps used in Millstone Unit No. 2. These pumps are Model NP-18 three-cylinder positive displacement pumps manufactured by the Gaulin Corporation, Everett, Massachusetts. Single pump failures were discovered on or about August 8,1982, February 27,1984, and April 4,1984.

These pumps failed due to the initiation and propagation of cracks in the pump blocks. The cracks were discovered during investigation of Reactor Coolant System leakage from the Chemical and Volume Control System.

The cracks are initiated within the pump blocks and propagate between one or more of the three cylinders and the outside surface. Although the cracks appear as hairline cracks during pump examination, they evidently open up during the pump cycle and permit reactor coolant leakage. In no case did any of the pumps fail to operate while in service.

A failure analysis performed by a NNECO contractor on one failed pump block indicated that most likely the crack resulted from overstressing, with an initiating flaw of a size that was smaller than that detectable by the manufacturing inspection methods used by the manufacturer.

Short-term actions being taken by NNECO personnelinclude ti.e routine Reactor Coolant System leakage monitoring and dye penetrant inspection of the pump blocks during maintenance activities. Long-term actions by NNECO include charging system piping analyses and measurements of charging pump suction conditions to determine if there are any off-normal operating conditions. In 8406080179 840525 gDRADOCK 05000336 PDR

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l c addition, changes in pump design and manufacturing techniques, such as shot peening of cylinder bore surfaces, are being investigated by NNECO with the manufacturer. All of these short-term and long-term actions have been initiated. It cannot be determined at this time how long these actions will take.

Millstone Unit 2 utilizes three (3) of these charging pumps in the Chemical and Volume Control System. Technical Specifications require that two charging

, pumps shall be operable at all times. There is a 48-hour Action Statement in the event two of_ the three pumps become inoperable or unavailable for operation. A charging pump is necessary in mitigating a Main Steam Line Break Accident and a small break Loss of Coolant Accident. Therefore, since (1), charging pump i

operability is required by Technical Specifications, (2), a type of common mode failure has been identified, (3), a clear solution to these failures has not yet been identified and (4), other licensees have experienced failures of the same model

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pumps, NNECO has determined that the failures of the subject pumps (potential major degradation) constitute a Substantial Safety Hazard.

The following information applicable to this SSH determination is provided as

} required by 10CFR21.21(b)(3), i through viii.

(i) Name and Address of Individual Informing the Commission.

William G. Counsil, Senior Vice President, Nuclear Engineering and Operations, Northeast Utilities Service Company, P. O. Box 270, Hartford, Connecticut, 06141-0270.

(ii) Identification of the Basic Component

' Model NP-18 three-cylinder positive displacement Reactor Coolant System charging pumps.

(111) Identification of the Firm Sucolying the Basic Component Gaulin Corporation 44 Garden Street Everett, Massachusetts 02149 (iv) . Nature of the Failure to Comply (See discussion above) 1(v) ' Date on which Information of Such Failure to Comply Was Obtained On or about August 8,1982, February 27, 1984, and April 4,1984 (three failures).

(vi). The Number and Location of All Such Gaulin Charging Pumps' l

l There are three such pumps in service at Millstone' Unit No. 2. No such pumps are used at other nuclear generating units under the responsibility of j

Northeast Utilities.

l i

It is our understanding that this model pump has been in use at various other facilities, including Arkansas Nuclear One and Fort Calhoun, and has been installed at other facilities employing Combustion Engineering Nuclear Steam Supply Systems. We are aware there have been pump failures at certain of the facilities.

(vii) Corrective Action, Organization Responsible, and Time to Complete Action (See discussion above)

-(xiii) Advice Related to the Failure to Comply Being Given to the Licensee.

Not applicable. Refer to supplier.

We trust . this information is complete as required under 10CFR21. Please contact Mr. James R. Himmelwright of my staff if you desire additional information.

Very truly yours, NORTHEWaT NUCLEAR ENERGY COMPANY

. 1 W. d. Counsil Seni2r vice President cc: Dr. Thomas E. Murley, Regional Administrator, Region I 631 Park Avenue King of Prussia, Pennsylvania 19406

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