ML20077K151
| ML20077K151 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/02/1991 |
| From: | Broughton T GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| C311-91-2086, IEB-89-001, IEB-89-1, NUDOCS 9108070027 | |
| Download: ML20077K151 (2) | |
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6, GPU Nuclear Corporation Nuclear
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Middletown, Pennsylvania 170$7 0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:
(717) 948-8005 Augast 2, 1991 C311-91-2086 U. S. Nuclear Regulatory Commission Attn:
Document Control Desk Washington, D.C.
20555 Gentlemen:
Subject:
Three Mile Island Nuclear Station, Unit I (THI-1)
Operating License No. DPR-50 Docket No. 50-289 Response to NRC Bulletin 89-01 Supplement 2 failure of Westinghouse Steam Generator Tube Mechanical Plugs GPUN has reviewed NRC Bulletin 89-01 Supplement 2.
In its response to IEB 89-01, GPUN stated that no Westinghouse mechanical plugs from the subject heats are installed in the TMl-1 steam generators.
Therefco 5. the action requested in item I is not directly applicable to TMI-1.
The.TMI Unit I does, however, have approximately 1000 Westinghouse rolled plugs of heat NX-2387 installed in both steam generators.
Although the heat treatment and machining processes of both plug types are similar, the design configuration of the Westinghouse rolled plug is different than that of the mechanical plug.
The Westinghouse rolled plug design is considered less susceptible to Stress Corrosion Cracking than their mechanical ribbed plug design.
GPUN evaluated the information provided in Table 2 of WCAP-12244-R3, Addendum 2, Page 5 which listed alloy 600 mechanical plugs of heat NX-2387 installed in Arkansas Nuclear One, Unit I during the same period that the TMI-l rolled plugs were installed.
GPUN was able to determine that the hot leg plugs are acceptable for use until 1998 and the cold leg plugs through the end of plant-life.
As a result of the information provided above, action 2, items a, c, and e are not applicable to TMI-1.
In response to the remaining items; the remaining lifetime estimates have been determined for the Westinghouse rolled plugs i
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Document Control Desk C311-91-2086 Page 2 of 2 installed in the THl-1 steam generaters, future installation of Westinghouse mechanical plugs fabricated from 'nconel 600 will not be permitted, and appropriate ALARA consideration will be effected to minimize dose when evaluating future plug repair and replacement methods.
Sincerely, f%sW T.G.Brouhkton Vice President & Director, TMI-l WGil cc: Administrator, Region 1 Senior Project Manager-TMI Senior Resident inspector I
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