ML20049J331

Advises That Plant Review & Mgt Safety Review Committees Have Concluded That Continued Operation Is Justified Despite Abnormalities in Makeup Nozzles Found at Crystal River & Oconee.Radiographic & Ultrasonic Exams to Be Performed

ML20049J331
Person / Time
Site:	Rancho Seco
Issue date:	03/09/1982
From:	Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Eisenhut D Office of Nuclear Reactor Regulation
References
NUDOCS 8203150085
Download: ML20049J331 (2)

Text

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e suuo SACRAMENTO MUNICIPAL UTILITY DISTRICT C) 6201 5 Street. Box 15830, Sacramento, California 95813; (916) 452 3211 (O

March 9, 1982

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g RECGygg g.l' fart 5gggyG DIRECTOR OF NUCLEAR REACTOR REGULATION Y

ATTENTION DARRELL G EISENHUT DIRECTOR DIVISION OF LICENSING U S NUCLEAR REGULATORY COMMISSION

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WASHINGTON D C 20555 D0CKET 50-312 RANCHO SEC0 NUCLEAR GENERATING STATION UNIT 1 MAKE-UP N0ZZLE ABNORfMLITIES Yesterday, March 8, 1982, I met with other members of the B&W Owners Regulatory Response Group, you, and your staff concerning the abnormalities which have been discovered in the Crystal River Unit 3, Oconee Unit 3, and v Unit 2 make-up nozzles. As committed to during this meeting, the Sacramento Municipal Utility District held a meeting today of the Plant Review Committee and Management Safety Review Committee. The purpose of this meeting was to discuss and determine if any safety implication existed with the continued operation of Rancho Seco Unit 1 at this time. Both of these committees unani-mously decided that continued operation is justified.

There are several factors which led to the above conclusion.

First, it has been determined that since prior to fuel loading at Rancho Seco, leakage has occurred in the pressurizer level control valve such that flow through the make-up nozzle has only recently been reduced to as low as fifteen gallons per minute during normal plant operation. Even though the bypass valve around the control valve was adjusted initially for a low flow of only one to three gallons per minute, this low a flow has only existed at Rancho Seco Unit 1 during heatup when the leak through of the pressurizer level control valve combined with reactor coolant system expansion exceeds letdown capability. The large number of thermal cycles which contributed to the Crystal River 3 failures, has not existed at Rancho Seco.

Similarly, it is felt that the 2A2 and 3A2 nozzle failures at Oconee may have resulted from starved flow since the 2A1 and 3Al nozzles are sound.

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DARRELL G EISENHUT March 9,1982 A second factor leading to our conclusion is.the fact that the cracking phenomenon which has been discovered at Crystal River 3 and the Oconee units would lead to a leak before a break of the pipe would occur. This is evidenced by the leakage which was discovered and detected at Crystal River Unit 3, which led to the inspection which uncovered the problem. We have also had experience in detecting these magnitudes of leaks at Rancho Seco Unit 1.

This belief in a leak before a break in this situation is agreed to by metallurgists from the Electric Power Research Institute who have indicated to us that this type of cracking would have a slow growth. This conclusion is also supported by our make-up piping configuration which has a pipe support very near the injection nozzle.

A third factor influencing our decision was the fact that all of the Rancho Seco injection lines, including the make-up line, incorporate the proper attenuation i

length between the nozzle and first valve. At Rancho 5eco the make-up nozzle safe end is welded directly to an elbow which is, in turn, welded to a pipe which drops almost two feet before reaching the elevation of the valve.

The Rancho Seco operators will be informed of these recent events and will be instructed to notify their management of any significant increase in primary system leakage even it if remains within technical specification limits. The District also commits at this time to perform both radiographic and ultrasonic examinations of the make-up nozzle during the first outage requiring a cooldown.

We believe this incident has demonstrated the excellent communication which exists between the B&W Owners and the NRC and feel that we can properly revise our decision if necessary as new information becomes available.

If we can provide any additional information for your use at this time, please advise.

Yq John J. Mattimoe l

Assistant General Manager and Chief Engineer I

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