ML19344A637
| ML19344A637 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 08/15/1980 |
| From: | Goodwin C PORTLAND GENERAL ELECTRIC CO. |
| To: | Clark R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8008210381 | |
| Download: ML19344A637 (6) | |
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fC August 15, 1980 Trojan Nuclear Plant Docket 50-344 License NPF-1 Director of Nuclear-Reactor Regulation ATTN:
Mr. Robert A. Clark, Chief Operating Reactors Branch No. 3 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D. C.
20555
Dear Sir:
In accordance with your letter of May 22, 1980, please find attached an interim report describing the results of the destructive examination of U-bends removed from the Trojan steam generator D.
An interim report describing the results of the nondestructive examination of U-bends removed from steam generator D was earlier transmitted to you under a letter dated July 11, 1980.
We will attempt to adhere to the schedule for reporting the final results as requested in your letter, but will inform you of any scheduling prob-lems regarding final report submittal as they become evident. Should you have any questions regarding the attached interim report, please contact us as appropriate.
Sincerely, J
- 8. e/4 C. Goodwin, Jr.
Assistant Vice President Thermal Plant Operation and Maintenance CG/DRS/4sa4A30 Attachment c:
Mr. Lynn Frank, Director g
State of Oregon Department of Energy h\\
\\
Mr. R. H. Engelken Director U. S. Nuclear Regulatory Commission THIS DOCUMENT CONTAINS Region V P00R QUAllTY PAGES 800821038/
STATUS REPORT ON THE DESTRUCTIVE EXAMINATION OF U-BENDS REMOVED FROM TROJAN STEAM GENERATOR D August 1980 INTRODUCTION The last status report on the nondestructive examination of U-bends removed from Trojan steam generator D was dated July 1980. As part of this activity, the measurement of wall thicknesses on selected U-bends was planned using an ultrasonic gage. These readings were not made because reproducible results could not be obtained using water as the coupling fluid which was necessary to avoid contamination.
Three tubes from the same heat were selected for destructive examination at Westinghouse: one leaking U-bend (R1-C6) and two tubes with no indications (R1-C10 and R1-C22).
The general examination procedure to be followed for each U-bend is indicated by the layout on the U-bend in Figure 1.
First, approximately 3-in. long sections containing the straight-to-curved transitions were removed frcs the hot and cold legs of each tube and silastic molds obtained for future dimensional measurements, if required. These sections were then split along the flank positions and wall thickness data obtained. A section like 16A is to be used for chemical analysis. A number of sections will be used for metallography, and for flattening and visual examination to search for cracks.
DESTRUCTIVE EXAMINATION RESULTS 1.
Radiography A print of the double wall radiograph of Rl-C6 is shown in Figure 1.
Included are locations of cuts and identification of samples used in metallography and in bend tests. One of the transitions from straight to curved is smooth and has no well-defined extrados and intrados transitions whereas the opposite transition has defined intrados and extrados transitions.
Single wall x-ray radiograpns were made of these transitions.
No indications were found on the cold leg intrados transition.
An enlarged print of the single wall radiograph of the extrados transition is included in Figure 1.
A segmented crack is present with indicated multiple initiation in the straight section and an extension into the curved section. A wall thickness reduction above the extrados transition is indicated by the lightness of the print in this area.
2.
Metallography Metallography has been completed on Rl-C6 and started on R1-C10 and Rl-C22. No indications have been found on Rl-CIO or Rl-C22.
l On Rl-C6 there are two significant observations:
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cracking at the extrados transir. ion is intergranular and ini-tiates from the ID (see Figure 2); and (b) at a number of locations, there were one grain deep penetrations on the ID of RI-C6.
3.
Visual Examinations Sections of the tubes have been flattened and examined at SX for cracks on the ID.
No cracks have been found.
In Figure 1, the specimens examined for R1-C6 by this technique are underlined. The study on RI-CIO and Rl-C22 is underway.
4 Wall Thickness and Hardnese Measurements Prior double wall X-ray radiography indicated cracks on Rl-C6, Rl-C7 and RI-C26.
Sections similar to E6A (straight leg) were obtained from these three tubes and three other tubes with no indications. Wall thicknesses and hardnesses on these 6 tube sections are compared in Table 1.
The wall thicknesses for the extrados were similar for both groups. Two of the three tubes with cracks had hardnesses higher than the three without indications.
5.
Microanalvtical Results Tight cracks in E6B were examined with energy dispersive X-ray analyses and with the line trace technique employing the electron beam microprobe. A search was made for P, S, Pb, K, Na and As.
Only Si was found to be present in localized areas.
SUMMA 3Y The cracks on RI-C6 are located on the cold-leg extrados predominately just below the curved secton of the bend. These cracks are segmented and intergranular.
Initiation of the cracks is on the ID.
No other crack was found on R1-C6 or on the other two tubes without indications.
Hardnesses were measured on the straight length sections of three tubes with X-ray indications and three without. Two of the tubes with indica-tions had the highest hardnesses. The significance of this observation must be evaluated taking into consideration sample location and possible strain from bending.
No unusual elements were found in the deposits w1 thin the cracks.
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TABLE 1 Comparison of Wall Thickness (mils) and Knoop Hardness (500g) for Three Tubes with X-Ray Indications and Three Without at Various Approximate Angular Positions on a Straight Leg Wall Thickness Hardness (mid wall)
(Ex* r..los )
(Extrados)
Tube / Leg 135*
180*
225*
Average 90*
135*
180*
225*
270*
Averige X-Ray ind"; cation R I-c a.
57 55 54 55.3 219.8 233.9 245.0 234.7 216.7 230.0 Col;*
(Szc. E6A)
RI-C7 57 57 55 56.3 186.7 187.3 178.2 178.0 183.2 182.7 Ilo t **
RI-C26 56 57 56 56.3 199.6 190.4 185.2 201.8 206.3 196.6 Hot **
1 No X-Ray Indication RI-CIO 59 60 57 58.7 179.1 186.4 183.1 180.4 186.1 133.0 Cold 2 RI-Cl3 52 52 54 52.7 187.8 183.1 187.8 186.5 190.8 187.2 Hot **
RI-C22 59 57 55 57.0 181.3 185.2 183.5 176.8 181.3 181.6 Cold *
- Opposite Transition.
- Smooth T6ansition.
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