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D. G. Eisenhut, Assistant Director for Systems and Projects, 00R FROM:
Acting Branch. Chief Engineering Branch, D0R
SUBJECT:
RECENT STEAM GENERATOR TUBE LEAK AT TROJAN STATION per your request we have obtained some additional information concerning the steam generator tube leak detected in steam generator B at Trojan during January,1978. The leak was reported in a May 8,1978, letter from B. D. Withers, Trojan Superintendent, to R. H. Engelken, Region V Director. The letter is attached for background information. With assistance for C. Tramell, Trojan project manager, we have learned the following:
1.
This is the first steam generator tube leak to occur at Trojan.
2.
The leak rate at about 1.0 GPD did not increase during the time between its detection in January and the unit shutdown in March.
Other items of particular interest relative to the design and operation of the Trojan steam generators are:
1.
The steam generators are Westinghouse Series 51, similar to Surry Units 1 & 2.
2.
The tubes are full depth expanded within the tubesheet.
The process, performed all prior to wetting, included an initial 3" rolling followed by explosive expansion for the remainder of the tube.
l 3.
A 100% pre-service inspection was performed.
4.
The unit has used an AVT secondary water treatment since the initial start-up.
5.
The unit has always operated with full flow demineralizers.
6.
All steam generator inspections to date have shown no denting nor defects of any kind and minimal sludge levels (approximately 1").
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Based on all available infonnation there seems to be no reason for the Trojan steam generators to be developing leaks.
Primary side stress corrosion cracking near the top of the tubesheet is a possibility. or more likely a leaky weld because of the extremely small leak rate remained constant over a two month period.
We are continuing to monitor the operation of the Trojan steam generators. At this time we do not think it necessary to take any further action.
V. S. Noonan. Acting Branch Chief Engineering Branch Division of Operating Reactors ec:
V. Stello. Jr.
R. Mattson B. Grimes J. P. Knight B. D. Liaw F. Almeter J. Strosnider
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- 3 Based on all available infomation there seems to be no reason for the Trojan steam generators to be developing leaks. Primary side stress corrosion cracking near the top of the tubesheet is a possibility, or more likely a leaky weld because the extremely smtil leak rate remained constant over a two month period.
He are continuing to monitor the operation of the Trojan steam generators. At this time we do not think it necessary to l
take any further action.
Acting Branch Chief Engineering Branch Division of Operating Reactors cc:
B. D. Liaw F. Almeter J. Strosnider R. LaGrange o
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