ML19209A169
| ML19209A169 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 08/28/1979 |
| From: | Broehl D PORTLAND GENERAL ELECTRIC CO. |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| NUDOCS 7910030052 | |
| Download: ML19209A169 (3) | |
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c NY' Q u j pg r \\ O August 28, 1979 Trojan Nuclear Plant Docket 50-344 License NPF-1 Mr. R. H. Engelken, Director U.S. Nuclear Regulatory Commission Region V Suite 202, Walnut Creek Plaza 1990 N. California Boulevard Walnut Creek, CA 94596
Dear Sir:
In accordance with our response of July 19, 1979 to IE Bulletin 79-13, the following report of nondestructive tests of steam generator feedwater piping welds is provided.
Radiographic and ultrasonic examinations of all steam generator nozzle-to-reducer and adjacent reducer-to pipe welds have been performed. The radio-graphy was performed to the 2T penetrameter sensitivity level with the penetrameter on the film side of the weld and with the system dry. All c '
the radiography and ultrasonic examinations were reviewed and concurred with by Mr. Gene Hughes, a Westinghouse consultant who had prior experience with samples removed from plants reporting cracking. Welds examined for steam generators B, C, and D and the reducer-to pipe weld for steam generator A met the requiremente of NC-5000. Only steam generatot A nozzle-to-reducer weld FW145 demonstrated an indication requiring extended evaluatio g A single linear indication was found both radiographically and with ultrasound on the inside surface of the reducer, 1/2-in. from the veld root.
The indication is located at the corner formed by the straight counterbore and the 15' machined transition to reducer ID surface. With the O' position being at the top of the weld and proceeding clockwise with positions established looking at the stean generator from the upstream side of the weld, the indication extends clockwise from 180* to 140*, that is, for 45 in. of the 50-in. circumference (see attached sketch).
The greatest depth of the indication appears to be from the 345* to the 18' position, gradually becoming shallower counterclockwise from 345' to the 180*
position and clockwise from the 18' to 140* position.
'Jhc weld cover was ground flush with the rozzle and reducer at the 345' to 18* area and reradio-graphed for triangulation, using Kodak R film (ultra-fine grain).
Ultrasonic examination to determine location and depth dimensions was also applied. The 7 910 0 3 0 C5 2'.
1984 269 7pg
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s Pcrtland General ElectricCompany Mr. R. H. Engelken, Director August 28, 1979 Page Two indication is on the inside surface of the reducer as described above and has no crack-like characteristics.
The linear indication has the radiographic and ultrasonic appearance of being a machined groove.
A radiograph of a crack found in a steam generator nozzle to pipe weld at the Robinson plant was obtained and compared with radiographs of FW145.
The Robinson plant radiographic image has the appearance of a crack, whereas the FW145 radiographic image appears as a straight line drawn with pencil and ruler.
Radiographs of FW145 made during plant construction also demonstrate the indication, although the image quality is lower because the film used was larger grain (Kodak Type T).
IE Bulletin 79-13 required that evaluation of the examination be performed to ASME Section III NC-5000.
NC-5000 is a fabrication code and does not take into consideration the depth dimension of indications.
While the indication does not meet the acceptance criteria of NC-5000, it does meet the requirements of Table IWD-3514-2, Winter 1975 addendum to Section XI which we believe more closely addresses the pipe, service, material, and thickness in question.
Table IWD-3514-2 will allow a ratio of depth to thickness of 10 percent (a/t) for the FW145 condition.
Radiographic examination yields an a/t value of 10.6 percent; the ultrasonic examination reports the indication as being 8 percent to 9 percent thickness.
Based on the foregoing, the PGE position is to continue plant operation while performing a structural analysis and to develop an ultrasonic procedure pecifically for surveilling rae indication for potential growth during annual plant outages.
Sincerely, D. J. Broehl Attachment c:
Mr. Lynn Frank, Director State of Oregon Department of Energy 1084 270
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