ML19305B471
| ML19305B471 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 03/10/1980 |
| From: | Janecek R COMMONWEALTH EDISON CO. |
| To: | Ziemann D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8003190711 | |
| Download: ML19305B471 (1) | |
Text
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Commonwealth Edison one First National Plaza. Chicago. lilinois Address Reply to: Post Office Box 767 Chicago, Ilhnois 60690 March 10, 1980 Dennis L. Ziemann, Chief Operating Reactors Branch #2 Division of Operating Reactors U.S. Nuclear Regulatory Commission Washington D.C.
20555
Subject:
Comments on SEP Topic III-8.C Irradiation Damage, Use of Sensitized Stainless Steel and Fatigue Resistance Dresden Unit 1 Docket 50-10
Dear Mr. Ziemann:
In response to your January 17, 1980 letter requesting our review of the draft evaluation of Systematic Evaluation Program Topic III-8.C we do not believe the evaluation establishes that the vessel internals are sensitized.
The draft also goes beyond the safety objective of reviewing reactor internals by including external piping.
The inclusion of the external piping may be pertinent, however, if the pipe cracking experience is used as a demonstration that IGSCC could occur if the reactor internal are sensitized and the residual stress from welding is high.
The incidents described in the evaluation include one case of stress corrosion in a material / condition which was satisfactorily replaced and has not been used for twenty years.
Another incident involved cracking due to a mechanism other than stress corrosion.
Since this problem occurred nineteen years ago and was unrelated to stress corrosion and did not involve sensitized stainless steel, the relevance of this incident is highly questionable.
A third incident involved cracking during fabrication, and is unrelated to stress corrosion.
The fourth incident occurred in piping, not reactor internals and was outside the scope of this survey.
The conclusion from these incidents that the integrity of reactor internals components is degraded by the use of sensitized stainless steel is surprising as no evidence of any incidents which would suggest this conclusion has been presented.
No incident involving the use of sensitized stainless steel in reactor internals was cited.
Please refer any questions concerning this matter to this office.
One (1) signed original and thirty nine (39) copies are attached for your use.
Very truly yours, c
Robert F.
Janecek Nuclear Liscensing Administrator Boiling Water Reactors NPS/sb 8 0031gg gg ;
2168A