ML20081D914
| ML20081D914 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 10/25/1983 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8311010387 | |
| Download: ML20081D914 (2) | |
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TENNESSEE VALLEY AUTHORITY CH ATTANOOGA. TENNFSSEE 37401 400 Chestnut Street Tower II October 25, 1983 BLRD-50-438/82-47 BLRD-50-439/82-42 U.S. Nuclear Regulatory Commission Region II Attn:
Mr. James P. O'Reilly, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303
Dear Mr. O'Reilly:
BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 - EMBEDDED PIPING WITH CRUSHABLE INSULATION - BLRD-50-438/82-47, BLRD-50-439/82 FINAL REPORT The subject deficiency was initially reported to NRC-0IE Inspector J. D. Wilcox on June 29, 1982 in accordance with 10 CFR 50.55(e) as NCR BLN CEB 8209. This was followed by our interim reports dated July 29, 1982 and January 13 and March 29, 1983 Enclosed is our final report.
If you have any questions concerning this matter, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNE 3SEE VALLEY AUTHORITY pS %
L. M. Mills, Manager Nuclear Licensing Enclosure cc:
Mr. Richard C. DeYoung, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Conunission Washington, D.C.
20555 Records Center (Enclosure)
Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 8311010387 8 gDRADOCK05 k
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xi 1983-TVA SOTH ANNIVERSARY
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. An Equal Opportunity. Employer
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.g ENCLOSURE BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 EMBEDDED PIPING WITH CRUSHABLE INSULATION NCR BLN CEB 8209 BLRD-50-438/82-47, BLRD-50-439/82-42 10 CFR 50.55(e)
' FINAL REPORT Description of Deficiency Essential Raw Cooling Water piping analysis problems N4-OKE-P, N4-1KE-F, and N4-2KE-F were analyzed assuming the 36-inch pipe to be embedded in concrete at four locations. Therefore, the analysis assumption was that the pipe was " anchored" at the four locations. Actually, the 36-inch pipe has 3 inches of insulation covering in the area of embedment and, since the insulation may crush, the pipe is not truly " anchored" at the four locations. Therefore, the analysis is unconservative and must be redone assuming only " limited restraint" rather than " anchors" at the four locations.
At the time of occurrence of this deficiency, no policy had been established to model this type of terminal point.
Safety Implications The original analysis had assumed rigidity of the 36-inch pipe and a connecting 24-inch weldolet. Rigidity is necessary to maintain the integrity of the connection (weld) between the weldolet and the pipe.
However, due to the fact that the 36-inch pipe is not actually anchored at the two assumed locations, it may undergo thermal and seismic movements which u:uld overstress the connections between the pipes. This could possibly lead to failure of the ERCW piping system l
which would have adverse effects on the safe operation of the plant.
Corrective Action An independent review was performed of the modeling techniques used on 22 the three piping analysis problems in question. As a result of the review, the final analysis on problem N4-0KE-P was performed using.
limited restraints at the two locations where the pipe. extends into the embedment. During the final analysis of that problem, the need for an additional support was identified. This support will be installed in the field per engineering change notice (ECN) 1562 by November 15, 1983. On problem N4-1KE-F, the original analysis assumptions were found to be satisfactory, and no reanalysis was required. On problem N4-2KE-F, a new model with limited restraint was developed. Subsequent reanalysis with this new model indicated that support loads and stresses were not significantly different than those from the original model.
In order to prevent recurrence, procedures governing the type of model for piping terminal points where insulated pipe, is embedded in concrete have been added to Section 204 of the Bellefonte Rigorous Analysis Handbook as policy number 4, "Modeling of Embedded Piping with Crushable Insulation."
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