ML20137D763

Forwards Safety Evaluation Supporting Use of Mechanical Stress Improvement Process in Primary Sys Stainless Steel Piping to Modify Residual Stress Pattern at Piping Butt Welds & Reduce Probability of IGSCC

ML20137D763
Person / Time
Site:	LaSalle
Issue date:	11/18/1985
From:	Butler W Office of Nuclear Reactor Regulation
To:	Farrar D COMMONWEALTH EDISON CO.
Shared Package
ML20137D767	List: ML20137D763 ML20137D808
References
NUDOCS 8511270143
Download: ML20137D763 (3)

Text

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NOV 't 8 1985 Docket No. 50-373 Mr. Dennis L. Farrar

Director of Licensing Ccmonwealth Edison Company P.O. Box 767 Chicago, Illinois 60690

SUBJECT:

SAFETY EVALUATION OF MECHANICAL STRESS IMPROVEMENT PROCESS LA SALLE COUNTY STATION, UNIT 1 By letter dated July 19, 1985, Ccmonwealth Edison submitted its application for utilizing the Mechanical Stress Improvement Process (MSIP). In your letter, you stated that you proposed to apply MSIP to the primary system stainless steel piping in the La Salle Unit 1 plant to modify the residual stress pattern at piping buttwelds. Enclosed is our Safety Evaluation to your submittal. *

' Based on the available information, the staff concludes that the MSIP can be used on stainless steel piping to reduce the probability of intergranular 1 stress corrosion =(IGSCC) and that its effect is expected to be comparable to that afforded induction heating stress improvement treated welds if and when the action items listed below are satisfactorily completed:

(1) Pipe sanples containing MSIP treated weldments should be included in the ongoing EPRI. test program; (2) independent clasto-plastic analyses should be perfomed to confirm those-already done by O'Donnell & Associates; and (3) through-the-wall experimental residual stress analyses should be performed to' confirm the theoretical analysis results.

Furthermore, the staff also concludes that the long range benefits of MSIP can only be proven out by long term pipe tests and actual service experience.

Therefore, augmented inspections to confirm the performance of MSIP treated

' welds are considered necessary.

If there are questions concerning these matters, please contact A. Bournia, theProjectManager(301-492-8535).

Sincerely, pgj!270143 esists OD UfYdN."Nier, Chief Licensing Branch No. 2 Division of Licensing

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%*****/ NOV 181985 Docket No. 50-373 Mr. Dennis L. Farrar Director of Licensing Comonwealth Edison Company P.O. Box 767 Chicago, Illinois 60690

SUBJECT:

SAFETY EVALUATION OF MECHANICAL STRESS IMPROVEMENT PROCESS LA SALLE COUNTY STATION, UNIT 1 By letter dated July 19, 1985, Ccmonwealth Edison submitted its application for utilizing the Mechanical Stress Improvement Process (MSIP). In your letter, you stated that you proposed to apply MSIP to the primary system stainless steel piping in the La Salle Unit 1 plant to modify the residual stress pattern at piping buttwelds. Enclosed is our Safety Evaluation to i your submittal .

Based on the available information, the staff concludes that the MSIP can be used on stainless steel piping to reduce the probability of intergranular stress corrosion (IGSCC) and that its effect is expected to be comparable to that afforded induction heating stress improvement treated welds if and when the action items listed below are satisfactorily ccmpleted:

(1) Pipe samples containing MSIP treated weldments should be included in the ongoing EPRI test program; (2) independent elasto-plastic analyses should be performed to confirm those already done by O'Donnell & Associates; and (3) through-the-wall experimental residual stress analyses should be performed to confirm the theoretical analysis results.

Furthermore, the staff also concludes that the long range benefits of MSIP can only be proven out by long term pipe tests and actual service experience.

Therefore, augmented inspections to confirm the performance of MSIP treated welds are considered necessary.

If there are questions concerning these matters, please contact A. Bournia, theProjectManager(301-492-8535). ,

Sincerely,

(./ t 4_

Walter R. Butler, Chief Licensing Branch No. 2 Division of Licensing

Enclosure:

As stated

- __MESQQ mnG fDG

Mr. Dennis L. Farrar La Salle County Nucler.r Power Station Commonwealth Edison Corrpany Units 1 & 2 cc:

Philip P. Steptoe, Esquire John W. McCaffrey Suite 4200 Chief, Public Utilities Division One First National Plaza 160 North La Salle Street, Room 900 Chicago, Illinois 60603 Chicago, Illinois 60601 Assistant Attorney General 188 West Randolph Street Suite 2315 Chicago, Illinois 60601 Resident Inspector /LaSalle, NPS U.S. Nuclear Regulatory Comission Rural Route No. 1 Post 0Ffice Box 224 Marseilles, Illinois 61341 Chairman La Salle County Board of Supervisors La Salle County Courthcuse .

Ottawa, Illinois 61350 Attorney General 500 South 2nd Street Springfield, Illinois 62701 Chairman Illinois Comerce Ccmission Leland Building 527 East Capitol Avenue Springfield, Illinois 62706 Mr. Gary N. Wright,11anager Nuclear Facility Safety Illinois Department of Nuclear Safety 1035 Outer Park Drive, 5th Floor Springfield, Illinois 62704 Regional Administrator, Region III U. S. Nucir.ir Regulatory Comission 799 Rossevcit Road Glen Ellyn, Illinois 60137