ML19290E235
| ML19290E235 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 02/27/1980 |
| From: | Peoples D COMMONWEALTH EDISON CO. |
| To: | |
| References | |
| NUDOCS 8003050515 | |
| Download: ML19290E235 (4) | |
Text
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Commonwealth Edison one First Na'ional Ptaza CNeago 11hreis Address Reply to: Post Cit;ce Box 767 Chicago, lihnois 60690 February 27, 1980 Mr. James G. Keppler, Director Director. ate of Inspection and Enforcement - Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137
Subject:
LaSalle County Station Unit 2 Reactor Containment Structural Steel - 10 CFR 50.55(e) Final Report NRC Docket No. 50-374 Reference (a):
D. L. Peoples letter to J. G Keppler dated November 21, 1979
Dear Mr. Keppler:
As was reported in Reference (a), isolated defects were identified in stub columns for portions of the LaSalle County Unit 2 gallery work.
The assessment of that problem is now complete and rework is nearing completion.
A detailed description of the problem, the inspections performed to identify all discrepant material and future corrective action are contained in Attachment A to this letter.
As is indicated in the attachment, all of the stub columns have been repaired, a single spacer plate found to be of the same discrepant material is on order and will be replaced as soon as it is oelivered to the site.
Because a 100% inspection of the steel on LaSalle County Unit 2 subject to this defect has been made and repairs are either completed or in process, thi s is considered a final report.
In addition, 70% (all plate accessible for inspection) of the steel on Unit 1 of the same chickness as that found defective on Unit 2 has also been inspected with no nonconformities identified.
Therefore, as was indicated in Reference (a) and is addressed in Attachement A, this problem is limited to Unit 2 only.
Es(L/7 30 lll 80 03 o rin f ; 5
Commonwealth Edison Mr. James G. Keppler, Director February 27, 1980 Page 2 If there are any questions in this regard, please direct them to this office.
Very truly yours,
(
7 f q.j,,t.
D. L. Peoples Director of Nuclear Licensing cc:
Director of Inspection and Enforcement
l ATTACHMENT A PLATE MATERIAL PROBLEM IN CONTAINMENT STRUCTURAL STEEL - LaSalle County Unit 2 Description of Problem During the erection of the Unit #2 Containment Structural Steel stub columns for the 740' elevation gallery work, the cap plates of two columns were found to be loose.
These stub columns were shop fabricated by Inland-Ryerson Company.
The attachment weld betwen these two stub columns and the cap plates was found to be cracked.
The loose cap plates were removed and sent to the Commonwealth Edison Operational Analysis Department (OAD) for review.
0AD had the plate material analyzed and found that the 1" thick cap plates were made from a high carbon material resembling SAE 1547 and not the specified material A36.
This high carbon material exhibits a Rockwell hardness range of 40 in the areas where it has been thermal cut.
Insoectinn of Unit #2 Since the high carbon material exhibits a high hardness in an area where thermal cutting has zeeri performed, this fact was used as a basis for inspection of tae Ccntair.inent Structural Steel.
An Equotio Hardness Tester 5udel #JB79-240 was used to inspect all of the la plate in the Unit #2 Containmeat Structural Steel.
Commonweal.th Edison Oper;tional Analysis Department estaolished a hardness acceptance crittria to be used to differentiate between A-36 and the high carbon plate material.
Inland Ryerson Company was able to verify that they have had abrasion resistent carbon steel plata in 1" thickness ir their shop.
The abrasion resistent carbon steel plate is a high carbon material.
Since 1" thick plate was the only size of abrasion resistent steel that Inland Ryerson had, the inspection of the Containment Structural Steel was limited to 1" thick plate.
Nineteen pices of high r:arbon material were found.
Eighteen pieces of the 1" plate were pa:t of ten stub column assemblies on 740' elevation.
The remaining piece of plate was a spacer on elevation 796'.
A review of Inl?ad Ryerson snop records showed that these pieces of structural steel were manufactured in the shop during the same time period.
All of the stub Columns have been repairad.
The spacer plate is on order and will be replaced as soon as it is delivered to the site.
. Insoection of Unit #1 An inspection was made of the Unit #1 Containment Structural Steel.
Approximately 70% of the stub columns containing 1" plate on elevation 740' were inspected.
The remainder of tne stub columns were inaccessible for inspection.
All pieces of plate inspected were found to be acceptable.
The Unit 1 materials were not in the fabricators shop at the time the discrepant materials were fabricated, having already been fabricated before the high carbon material was in use in that shop.
Conclusion The high carbon plate material was inadvertently used in the Inland Ryerson shop.
Based on the number of pieces found, it is assumed that a plate short (a segment of plate) existed in the material rack and was cut up to fabricate part of the stub column plates.
The discrepant pieces of plate aod up to less than 8 square feet of plate.
All plate material in the shop is color coded to differentiate between grades of steel.
The color code for A 36 plate is no color.
The abrasion resistent steel piste has no color coding.
To preclude this from happining in the future, Inland Ryerson has assigned a color code to abrasion resistent steel, i
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