ML20080F619
| ML20080F619 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 08/23/1983 |
| From: | Schuyler J PACIFIC GAS & ELECTRIC CO. |
| To: | Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| Shared Package | |
| ML20080F613 | List: |
| References | |
| NUDOCS 8309190348 | |
| Download: ML20080F619 (3) | |
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PACIFIC GAS AND ELECTR,IC C O M PANY w
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77 BEALE STREET. SAN FRANCISCO, C ALIFORNIA 94106. (415) 7g4211. TWX 9fDhfy6587
- tlly, J.O.SCHUYLER vet Pemotet NJCLE AR P0eER GL4fRAftD4 August 23, 1983 Mr. John B. Martin, Regional khinistrator U. S. Nuclear Regulatory enmmiasion, Region V-1450 Maria Iane, Suite 210 Walnut Creek, CA 945 % -5368 Re: Docket No. 50-275, OL/DPR-76 Diablo Canyon Unit 1 Progress Report on Weld Reinspection
Dear Mr. Martin:
On April 25, 1983, IGandE responded to a Notice of Violation No. 50-275/83-08, issued by the IRC on March 29, 1983. A supplemental response was cubmitted on May 19, 1983. In the supplemental response, FGandE addressed the progress and results of the one hundred percent reinspection of structural steel fillet welds in the Unit 1 Fuel Handling Building (MB). 'Ihis letter is an interim report on the progress of the other reinspections conunitted to in that supplement. Full reinspection of the subject welds in the Unit 1 contairunent structure has been coupleted, and a sanple in excess of 10% of the welds has been completed in the Hot Shop and Unit 2 Fuel Handling Building. 'Ihe reinspection results are reported below.
All structural steel fillet weld reinspections were conducted in accordance with visual inspection criteria specified in H. P. Foley Conpany (Foley) Procedure QCP-5A. 'Ihis procedure is the same procedure used for the initial installation inspection and acceptance of the structural steel welds being reinspected. Specifically, the criteria most pertinent to detemining rework include excessive undercut, undersized welds, and incouplete fusion, which are stenarized below:
e Excessive undercut: Undercut at the edges of finished welds is to be held to a mini==n.
In particular, for structural steel work, undercut shall not exceed 0.01 inch for more than 957. of 8309190348 830913 PDR ALOCK 05000275 G
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Mr. J. B. Martin August 23, 1983 Page Two the welded length and 1/32 inch for the remaining 5% of the welded length when its direction is transverse to the primary tensile stress of the part that is undercut. In other instances, the undercut shall not exceed 1/32 inch.
e Undersized welds: Fillet welds may be 1/16 inch undersized, provided that the undersized portion does not exceed 10% of the total length of weld.
e Inconplete fusion: 'Ihe base metal and weld metal must exhibit thorough fusion. In particular, the sum of' diameters of porosity on the weld surface must tut exceed 3/8 inch in any linear inch of weld, or 3/4 inch in any 12 inch length of weld for fillet welds.
Comparison of the above Foley QCP-5A workmanshia criteria with the American Welding Society workmanship criteria reflects t ut the Foley If ot#',
procedure is significantly more stringent. 'Ihis accounts for the greatest 1
proportion of weld rework done as a result of these reinspections.
'Ihe sample reinspection of the Hot Shop structural steel fillet welds includes 568 welds inspected. One hundred and two (102) welds did not meet criteria and were reworked. 'Ihis indicates a rework rate of IC% for Hot Shop fillet welds.
- Ibe sample reinspection of the Unit 2 Fuel Handling Building structural steel fillet welds was done concurrently with the Hot Shop reinsmction. Of 708 welds inspected, 77 did not meet criteria and were rewor <ed.
'Ihis indicates a rework rate of 11% for the Unit 2 h1 Handling Building fillet welds.
As indicated in our supplemental response, Folay was directed to perform a 100% reinspection of the Unit 2 Fuel Handling Building and Hot Shop. 'Ihis work is currently in progress and is scheduled to be coupleted in early October, 1983.
'Ihe 10% sa:rple reinspection of the Unit 1 containnent annulus and platform structural steel fillet welds was completed in July 1983.
i One hundred fifty-seven (157) welds were inspected on annulus structural steel and 221 on platform structural steel. 'Ihirty-five (35) of the 378 inspected welds did not meet criteria and were reworked. 'Ihis indicates a rework rate of about 9%.
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Mr. J. B. Martin Atsust 23, 1983 Page 3 Based upon the results of the 10% sanple reinspection program, Foley as directed to reinspect 100% of the structural steel fillet welds in Unit 1 contaiment. This reinspection has been completed and all deficiencies corrected. Of 2,674 welds reinspected, 210 welds did not meet criteria and were reworked. ' This is a rework rate of 7.8% for the Unit 1 Containment fillet welds,.which is slightly less than indicaM by the 10% sanple and significantly less than the 18% in the Hot Shop.
The original structural modification work was performed by Foley in the following sequence: 1) Hot Shop, 2) Unit 1 Nel Handling Building, 3)
Unit 2 hel Handling Building, and 4) Unit 1 Contaiment. Our reinspection of this work revealed that the rates of rework, -(i.e., 18%, 14%, 11%, and 7.8%,
respectively) improved significantly with the progression of the original
'Foley work.
-In PGandE's review and investi that some Foley quality control (Q.C.) gation of the causes, it was determined inspectors were not fully qualified in accordance with ANSI N 45.2.6 as required by the Foley quality assurance program. A 10% sample reinspection of fillet welds on electrical supports
. accepted by two of these Q.C. inspectors has been completed. No cases were found where these Foley Q.C. inspector had accepted welds which did not meet requirements. Therefore, their inspections have been accepted "as is," based on this 10% sample inspection. The audits of work previously accepted by other inspectors that were not fully qualified in accordance with ANSI N 45.2.6 will be completed by September, 1983.
In conclusion, our recent reinspections are consistent with IGandE's
.May 19, 1983 letter to the IRC. These reinspections have also shown that the work was improving with time since there was a significant decrease -in the rates of rework for structural steel welds with the progression of the original Foley work. A final report will be submitted by October 14, 1983, to doctanent the results of those inspections currently in progress as well as to sn-arize all issues and causes.
Sincerely, J
cc:
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