ML20196G463
| ML20196G463 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah, Braidwood, Surry, 05000000 |
| Issue date: | 06/23/1988 |
| From: | Wegner M NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Rosenthal J NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| Shared Package | |
| ML20196G410 | List: |
| References | |
| NUDOCS 8807050528 | |
| Download: ML20196G463 (1) | |
Text
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C JUN 2 31900 MEMORANDUM FOR:
Jack E. Rosenthal, Chief Reactor Operations '..alysis Branch Division of Safety Programs, AE0D THRU:
Matthew Chiramal, Chief l
l Engineering Section Reactor Operations Analysis Branch Division of Safety Programs, AEOD j
FROM:
Mary S. Wegner Engineering Section l
Reactor Operations Analysis Branch Division of Safety Programs, AE00
SUBJECT:
AE0D/T809:
BLOCKED THIMBLE TUBES / STUCK INCORE DETECTOR Enclosed is a technical review report on blocked thimble tubes / stuck detectors.
Thimble tubes through which the incore detector probes are inserted into the reactor in a Westinghouse pressurized water reactor (PWR) may become blocked by hardening of the detector cable lubricant, denting of the thimble tube caused by flow-induced vibration, or by flooding of the tube caused by a leaking thimble tube. Detectors may become stuck when the thimb'e tube is blocked or the withdrawal mechanism is faulty.
Recovery of a stuck detector and cleaning of thimble tubes generally proceed without incident, but several events point out the potential for personnel hazard; including the Sequoyah 1 incident of 1984, and events at Surry 2 and Braidwood 1 in 1988 as well as several foreign events. Causes for the problems include damage to the thimble tubes caused by flow-induced vibration aggravated by damage caused by inserting or withdrawing the detector and a combination of planning and maintenance errors.
W stead by Mary S. Wegner Engineering Section Peactor Operations Analysis Branch Division of Safety Programs, AE0D
Enclosure:
As Stated cc:
W. Beaumont, W Distribution:
L. Gifford, 2 PDR TNovak C. Brinkman, CE ROAB R/F VBenaroya R. Borsum, B&W MWegner CHeltemes MChiramal EJordan MTaylor, ED0 MWilliams JPartlow, OSP KBlack ROAB:D PSE D R0AB:DSP:AE00 R
- DSP:AE0D MWegn P, Chi ramal J osenthal L si / 8
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