ML20235A171
| ML20235A171 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Browns Ferry |
| Issue date: | 05/11/1983 |
| From: | Harwell E, Woods T TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML082420107 | List: |
| References | |
| NUDOCS 8709230227 | |
| Download: ML20235A171 (5) | |
Text
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-s M ETALLU RGIC AL REPORT INSPECTION I
O BROWNS FERRY NUCLEAR PLANT UNIT 2 TURBINE EXHAUST PIPING EVALUATION
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e Introduction-An ultrasonio test (UT) examination was performed on the subject carbon steel piping by NCO Inservice Inspection Group, and the data was submitted to the NCO Metallurgy and Codes Section for evaluation. This examination ia_part of our program to monitor suspect areas for wall thinning caused by steam erosion. Failures in these locations may result in forced outages to make necessary repairs, injury to plant personnel, or damage to other plant components.
Discussion-The areas examined are listed below.
1.
Moisture separator room, southeast corner, 1-1/2-inch drain line.
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2.
Moisture separator room, south near wall, 2-1/2-inch header and 6-inch pipe.
3.. Condensate domineralizer valve rooms, 4-inch piping adjacent to drain tank.
4.
Moisture separator room, south, 2-1/2-inch pipe east of header.
The lines examined are designed to carry condensate to the shell side of the main condenser; however, if a pressure drop develops in the lines as the result of a valve malfunctioning, the condensate will flash to saturated steam causing erosion of the. carbon steel line.
UT measurements were taken in the 1-inch by 1-inch squares of the cirouaterential grids inscribed on the piping at the above locations, and the minimum value for each square was recorded.
The evaluation of the data identified one area where the previously established acceptance criteria of 0.080-inch wall loss, the ASME corrosion allowance for piping, was exceeded. This area was in the condensate domineralizer valve room on the 4-inch diameter piping adjacent to the i
drain tank. Wall loss was measured to be 0.097 inch in two aqueres of the grid at this location. Additional wall thinning of 0.077 in6 was also L
detected in other squares of this partibular grid. Wall thinnic.g was the l
most severe in this area; however, significant wall thinning was detected in each of the three remaining areas examined.
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t Conclusion The UT evaluation identified one area where wall loss presently exists in excess of the corrosion allowance and additional areas which are potential problems.
It is recommended that the degraded 4-inch diameter section of piping in the condensate domineralizer valve room be changed out with new carbon steel piping at the earliest available opportunity to preclude throughwall failure. In addition, an investigation should be conducted to
- determine the source of pressure drop in these lines.
The UT monitoring program will be continued in these areas on each unit to preclude unanticipated failures.
TRW:WDA 5/4/83 B1125B.WA i
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PIPI W_4@, THINNING INSPECTION DATA l
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820908 867 Niemorandum TENNESSEE VALLEY AUTHORITY 0
G. T.
enes, Power Plant Superintendent, Browns Ferry Nuclear Plant FROM T. G.
pbe 1, Manager, Nuclear Production,1760 CST 2-C SEP 10198 0
par BROWNS FERRY NUCLEAR PLANT' r 8NEU UNIT 1 ' MOIST.URE SEPARATOR DRAIN PIPE FAILURE Attached for your information is a copy of the metallurgical inspection report pertaining to the subject pipe failure.
T. G. Campbell TFZ:DFG:TRW: SAM Attachment cc (Attachment):
NUC PR ARMS, 1520 CST 2-C
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This was prepared principally by Terry R. Woods.
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