ML20009F490
| ML20009F490 | |
| Person / Time | |
|---|---|
| Site: | Phipps Bend  |
| Issue date: | 02/13/1981 |
| 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 8107310231 | |
| Download: ML20009F490 (3) | |
Text
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e M ('op TENNESSEE VALLEY AUTHORl'f{ TE C..
CH ATTANOOG A. TENNESSEE 37401 400 Chestnut Street Tower II
' " n 19 a;.g-PBRD-50-553/81-05 f/-o ov-o3E rebruary 13, 1981
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Mr. James P. O'Reilly, Director 8
Office or Inspection and Enforcement a
U.S. Nuclear Regulatory Commission
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"* %****b Region II - Suite 3100 101 Marietta Street C
Atlanta, Georgia 30303 k
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Dear Mr. O'Reilly:
PHIPPS BEND NUCLEAR PLANT UNIT 1 - BASE METAL CRACK IN DRYWELL VENT STRUCTURE - PBRD-50-553/81-05 The subject deficiency was initially reported to NRC-0IE, Region II, Inspector F. S. Cantrell on January 14, 1981, as NCR PBNP-166.
In ccepliance with paragraph 50.55(e) of 10 CFR 50, we are enclosing the final report on this deficiency.
Very truly yours, TENNESSEE VALLEY AUTHORITY W/P,c p ' / ~,7
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L. M. Mills, Manager Nuclear Regulation and Safety i
Enclosure ~
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Mr. Victor Stello, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 l
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ENCLOSURE PHIPPS BEND NUCLEAR PLANT UNIT 1 BASE METAL CRACK IN DRYWELL VENT STRUCTURE PBRD-50-553/81-05 REPORT NO. 1 (FINAL)
On January 14, 1981, TVA informed NRC-0IE, Region II, Inspector F. S.
Cantrell, of a potentially reportable condition under 10CFR50.55(e) regarding a base metal crack in the drywell vent structure. This is the final report on this deficiency.
Description of Deficiency During installation of the unit 1 drywell vent structure, a crack was discovered in segment DS-17 (plate mark number 12-1-2) which is shown on GE/C. F. Braun drawing S-046.
The crack originated at the weld prep of TVA weld NO. DWVS00037A and propagated into the base metal (see attached sketch). The fracture exhibits no evidence of plastic deformation or thinning of the adjacent base metal.
It is suspected that the fracture resulted from transient stresses in the structure caused by rapid lowering of the ambient temperature. The nat'2re of the fracture is indicative of material with low notch toughness at the prevailing ambient temperatures.
Safety Implications A crack in the drywell vent structure could lead to a degradation of its structural integrity to the point that it might not be capable of performing its intended function. Therefore, this condition could have adversely affected plant safety.
Corrective Action The cracked area will be cut out and replaced with a plate which will I
be welded in accordance with Detsil Weld Procedure SM-U-1B.
All welds will be inspected per original specifications and 211 butt welds will be inspected per AWS D1.1, Section 9 25, requircaents. This repair will be completed by February 28, 1981.
l TVA has erected a temporary enclosure which consists of a plastic sheet draped over the drywell vent structure and has installed heating sources within this enclosure in order to reduce the effects of environmental changes.
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