ML17202L286

Forwards Dresden II Upper Vessel Contract Variation Review, La Salle II Upper Vessel Fabrication Summary & Quad-Cities II Upper Vessel Fabrication Summary.

ML17202L286
Person / Time
Site:	Dresden, Quad Cities, LaSalle
Issue date:	07/02/1990
From:	Stols R Commonwealth Edison Co
To:	Murley T NRC Office of Inspection & Enforcement (IE Region III), Office of Nuclear Reactor Regulation, NRC/IRM
Shared Package
ML17202L287	List: ML17202L286 ML17202L288
References
NUDOCS 9007090040
Download: ML17202L286 (3)

Text

Commonwa.. Edison 1400 Opus Plll-

. Downers Grove, Illinois 60515 July 2, 1990

\

Dr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission 799 Roosevelt Road, Region III Glen Ellyn, IL 60137 ATTN: Document Control Desk

Subject:

Quad Cities Nuclear Station Unit 2

.Dresden Nuclear Station Unit 2 LaSalle County Nuclear Station Unit 2 Reactor Vessel Fabrication History Summary NRC Docket No. 50-265. 50-237 and 50-374

Reference:

R. Stols to T.E. Murley Jetter dated May 4, 1990.

Dr. Murley:

On April 19, 1990 members of the Nuclear Reactor Regulation's <NRR) and Commonwealth Edison Company's staffs conducted a technical meeting to discuss the cracks identified in_the Quad Cities Unit 2 Reactor Vessel Head.

During that meeting, Commonwealth Edison indicated that we believed the cracks were related to the fabrication processes of the vessel head. Therefore, Commonwealth Edison committed to research the fabrication history of its Boiling Water Reactor <BWR) vessels. The referenced letter provided the schedule for submitting the summary of the fabrication history for .the six (6)

BWR vessels.

The fabrication records research conducted on the Quad Cities Unit 2 and LaSalle Unit 2 vessels revealed that the critical information, which is required for the development of the inspection plan and evaluation of the respective vessels, can be found in the Contract Variations. An exhaustive review of all fabrication records did not provide any additional related information of interest beyond that contained in the Contract Variations for the respective vessel. The Contract Variations provide the required information to identify major mismatches, repairs and fabrication anomalies.

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Dr. T. E. Murley _. 2 - July 2, 1990 Enclosed are the fabrication history summaries for the Quad Cities Unit 2 and the LaSalle Unit 2 heads and upper vessels which were developed through the search of fabrication records:* Due to the*~arge quantity of records generated during fabrication, a summary of the fabrication history for the Dresden Unit 2 head upper vessel, based on the review of fabrication records, could not be completed prior to this submittal. Commonwealth Edison.

however, has enclosed a summary of the Dresden Unit 2 Contract Variations which provides the information of interest. Attached is a brief summary of the head and upper vessel fabrication history for the three vessels.

Finally, due to the learning experience associated with the information contained in the Contracts Variations, Commonwealth Edison has decided to suspend the resource intensive fabrication records review and devote the required resources to the development of Contract Variance and General Electric Quality Control Checklist summaries. We have determihed that this information will provide us and the NRC Staff the necessary information to assure target areas are properly inspected. These summaries will be

_:provided. to th.e. NRC Staff in accordance with the schedule provided in referenced letter.

If there are any questions or comments, please direct them to me at 708/515-7283.

Very truly yours, R. Stol s Nuclear Licensing Administrator cc: A.B. Davis, Regional Administrator - Riii L.N. Olshan, Project Manager - NRR B. Elliot, Technical Staff - NRR T. Taylor. Senior Resident Inspector - Riii

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ATTACHMENT OVERVIEW OF FABRICATION SUMMARIES Fabrication history ~ummaries have been developed-for*the-Dresden 2, the Quad Cities 2 and LaSalle 2 reactor pressure vessels. Each summary describes the fabrication history for the upper head, the vessel shell-to-flange and uppermost shell-to-shell welds.

LaSalle Unit 2 The LaSalle 2 vessel was fabricated solely by Chicago Bridge and Iron. The records revealed that some repairs of base metal, butt welds and cladding occurred; however, no mismatches were identified. Both the head-to-flange and shell-to-flange subassemblies were clad continuously by the subarc welding <SAW) process (i.e. back cladding was not applied). The uppermost shell-to-shell weld was back clad by gas metal arc welding <GMAW>.

Sketches from the summary report of the head and upper vessel which illustrate the findings of the record search are attached.

Dresden 2 and Quad Cities 2 The Dresden 2 and Quad Cities 2 reactor vessel fabrication reviews reveal a number of variations related to base material repairs, machining errors, lack of dimensional control for formed sections, mismatches at butt welds, and various process control violations. These variations were properly reviewed and dispositioned. The record review did not provide any additional information to identify specific target areas for inspection other than the major mismatches that occurred between the sections to be joined. These mismatches were identified at the Dresden 2 head-to-flange and shell-to-flange welds and at the Quad Cities 2 top head dollar-to-torus and torus-to-flange welds and the shell-to-flange weld which were manually back clad by shielded metal arc <SMAW). Sketches from the summary reports of the head and upper vessel which illustrate the findings are attached.