ML20004D902
| ML20004D902 | |
| Person / Time | |
|---|---|
| Site: | Hartsville  |
| Issue date: | 06/02/1981 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-81-444-000 10CFR-050.55E, 10CFR-50.55E, NCR-HNP-A-108, NCR-HNP-A-109, NCR-HNP-A-115, NCR-HNP-A-87, NCR-SX-19, PT21-81-444, PT21-81-444-000, NUDOCS 8106100287 | |
| Download: ML20004D902 (3) | |
Text
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b 2-Mr. James P. O'Reilly, Director J UN 0 9 193; 5 L-Z Office of Inspection and Enforcement
'84 D =T " D U.S. Nuclear Regulatory Commission O-Region II - Suite 3100 101 Marietta Street Atlanta, Georgia 30303
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Dear Mr. O'Reilly:
HARTSVILLE NUCLEAR PLANT UNITS A1, A2, AND 31 - REPORTABLE DEFICIENCY -
RPV SHIELD WALL WELD DEFICIENCIES (NCR'S HNP-A-087, HNP-A-108, MNP-A-109, HNP-A-115, SX-19)
Initial notification of the subject deficiency was made to R. W. Wright, NRC-0IE, Region II, on February 15, 1980. The first, second, third, and fourth interim reports were submitted on March 13, May 19, September 24, and December 22, 1980, respectively. In compliance with paragraph 50.55(e) of 10 CFR Part 50, this is the final report on the subject deficiency. We consider 10 CFR Part 21 applicable to this nonconformance.
If you have any questions, please call Jim Domer at FTS 857-2014.
Very truly yours, TENNESSEE VALLEY AU"HORITY l
L. M. Mills, Manager Nuclear Regulation and Safety l
Enclosure l
cc:
Mr. Victor Stello, Director (Enclosure)
Office of Inspection and Enforceuent U.S. Nuclear Regulatory Commission Washington, DC 20555 S'!
8106100 N
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HARTSVILLE NUCLEAR PLANT RPV SHIELD WALL - WELD DEFICIENCIES NCR'S HNPA-087, HNPA-108, HNPA-109, HNPA-115, SX-19 10CfR50.55(e) REPORT NO. 5 (FINAL)
On February 15,.1980, TVA informed NRC-0IE, Region II, Inspector, R. W. Wright, of a potentially reportable condition under 10 CFR 50.55(e) regarding welds of questionable quality on the reactor pressure vessel (RPV) shield wall structure supplied by Industrial Engineering Works (IEW), Trenton, New Jersey.
Interim reports were submitted on March 13, May 29, September 24, and December 22,.1980.
This is the final report on this deficiency.
Desc: lotion of Deficiency This deficiency was discovered when TVA was making repairs on the unit Al RPV shield wall structure per NCR HNPA-059 (not significant). NCR HNPA-059 concerns the mismatch of RPV shield wall stiffeners where the stiffeners attach to the skin plate between tier ono and tier two.
There are 48 stiffener-plate-to-skin-plate welds per tier, each approximately 12 feet long. The backing bar was removed from approximately 12 inches in order to properly align the stiffener bars for welding. 'However, when the backing bar was removed, it was observed that a weld between a vertical stiffener and shell plate had an area of lack of penetration, slag, and lack of fusion. TVA removed more backing bars in order to examine other welds. Of the initial 25 welds inspected, 17 were found to be of unacceptable quality. The removal of all backing bars on tier one and tier two disclosed that all weldJ exhibited areas of poor quality.
TVA's further investigation of the condition revealed a similar defect on the unit A2 structure. Inspection of the unit B1 shield wall which had not been shipped to TVA revealed deficient welds also. Additionally, TVA found slugged welds on tier 3 of the unit Al shield wall.
Safety Implications If the faulty welds performed by IEW had not been detected, the structural integrity of the RPV shield wall could have been jeopardized.
This condition could have endangered the safe operation of the plant.
Corrective Action All backing bars between stiffener and shell plates in the unit A1 and A2 structure were removed. A visual inspection of the root of tha weld was performed per the AWS Code. Defects detected by visual inspection have been excavated to the extent that welds are acceptable per AWS visual inspection acceptance criteria. Excavated areas were repaired by welding after inspection. All repaired areas were visually inspected and the entire weld area, both vendor weld and repair weld, were magnetic particle examined.
Arc strikes and gouged areas in the weld area were blended with base
- metal by grinding. Any grinding in excess of 1/16-inch in depth was repaired by welding. All repaired areas were then visually and magnetic particle examined.
1 The above corrective action is limited to vertical stiffeners in accessible areas. Weld areas that would require remaval of other internal stiffener plates for access to the vertical weld was dispositioned by GE to use as-is.
This is true also for welds on horizontal stiffener plates and portions of vertical kelds which occur behind horizontal plates at the intersection of the vertical and horizontal stiffeners.
Areas in which slugged welds were detected were removed.
Insert plates of A441 and SA 516 Grade 70 steel were cut to fit and welded in place by
- using approved welding procedures. All areas of repair for slugged welds were visual and magnetic particle inspected. All full penetration butt welds were also radiographed.
IEW repaired the unit 31 structure to meet applicable requirements. All repairs were acceptable and the structure was released for shipment to the site.
TVA's Quality Engineering Branch has implemented more rigorous and more frequent surveillance and inspections of the remaining structures being fabricated by IEW for other TVA nuclear plants in order to avoid further noncompliance.
All corrective action for the ' unit A1 structure has been completed. The unit A2 structure will be corrected by June 16, 1981.
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