ML20058J109

Safety Evaluation Accepting Licensee 921228 Submittal of Suppl Response to GL 88-01, NRC Position on Intergranular Stress Corrosion Cracking (IGSCC) in BWR Austenitic Stainless Steel Piping

ML20058J109
Person / Time
Site:	Browns Ferry
Issue date:	12/03/1993
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20058J108	List: ML20058J105 ML20058J109
References
GL-88-01, GL-88-1, NUDOCS 9312130397
Download: ML20058J109 (3)

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NUCLEAR REGULATORY COMMISSION W ASHINGTON, D.C. N0001 ENCLOSURE

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPLEMENTAL RESPONSE TO GENERIC LETTER 88-01 FROM THE TENNESSEE VALLEY AUTHORITY BROWNS FERRY UNIT 3 -

DOCKET NUMBER 50-296

1.0 INTRODUCTION

By letter dated Decsmber 28, 1992, the Tennessee Valley Authority (the licensee) submitted its supplemental response to Generic Letter (GL) 88-01, "NRC Position on Intergranular Stress Corrosion Cracking (IGSCC) in BWR Austenitic Stainless Steel Piping", for the Browns Ferry Nuclear Plant (BFN)

Unit 3. GL 88-01 requested licensees to provide their plans for replacement, inspection, repair, and leakage detection of piping susceptible to IGSCC, and state whether they intend to follow the staff positions or propose alternatives. The :ansee's submittal of December 28, 1992 supplemented its August 1, 1988 respoase to GL 88-01 to describe its efforts to mitigate IGSCC at BFN Unit 3. In the earlier letter, the licensee stated that it had not made final decisions on measures to mitigate IGSCC for BFN Unit 3, and that it would submit a schedule of planned activities later. Recently the licensee performed non-destructive examinations, repairs, stress improvement and pipe replacement with corrosion resistant materials on BFN Unit 3. The NRC staff's evaluation of the licensee's program to mitigate IGSCC at BFN Unit 3 is presented below.

2.0 EVALUATION For BFN Unit 3, the licensee has taken the following measures for the long-term mitigation of IGSCC:

Inspection with state-of-the-art nondestructive examination equipment, qualified examiners, and qualified techniques has been performed.

IGSCC susceptible welds have been inspected, or have been removed and replaced, except for the residual heat removal penetrations.

The licensee plans to inspect inaccessible welds as described in its letter of November 25, 1992.

IGSCC indications are being repaired with full structural weld overlays, or the piping is being replaced. The material for the overlays and replacement piping is resistant to IGSCC.

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d Where practical, stress improvements of susceptible piping and replacement piping has been performed. Methods used are the mechanical stress improvement process and induction heating.

The number of welds in replacement piping has been reduced with integral bends and branches.

The licensee stated that future inspections of piping in the scope of GL 88-01 will conform to the NRC staff positions on methods, personnel, schedules, and expansion plans. To meet the requirements for inspection schedules and '

expansion plans, the susceptible welds have been categorized according to NUREG-0313, Revision 2.

Under GL 88-01, the technical specifications should state that the inservice 4 inspection program covered by GL 88-01 will conform to the staff positions.

In a letter of November 25, 1992, the licensee requested approval of alternative methods for inservice inspections for the residual heat removal system. The staff found the alternative methods acceptable and approved them in its letter of February 18, 1993.

On December 15. 1986, the licensee proposed changes to the BFN technical specifications to comply with the leak detection requirements in Generic Letter 84-11. NRC approved the changes in a letter dated August 26, 1987.

The changes made to the dFN Unit 3 technical specifications at that time satisfy the intent of Ge:1eric Letter 88-01.

After performing the work to mitigate IGSCC, the licensee will report any new flaws found, or changes found in the condition of existing flaws. The licensee will report the flaw evaluation, strategy, and technical '

justification for repair or continued operation.

3.0 CONCLUSION

The staff finds the licensee's submittal acceptable. The plans for replacement, inspection, repair of piping susceptible to intergranular stress corrosion cracking for BFN Unit 3 conform to the guidance of GL 88-01.

Principal Contributor: M. Banic Dated: December 3, 1993 i

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Tennessee Valley Authority BROWNS FERRY NUCLEAR PLANT ATIN: Dr. Mark 0. Medford cc:

Mr. Craven Crowell, Cha'rman TVA Representative Tennessee Valley Authority Tennessee Valley Authority ET 12A 11921 Rockville Pike, Suite 402 400 West Summit Hill Drive Rockville, MD 20852 Knoxville, TN 37902 General Counsel Mr. W. H. Kennoy, Director Tennessee Valley Authority Tennessee Valley Authority ET llH ET 12A 400 West Summit Hill Drive 400 West Summit Hill Drive Knoxville, TN 37902 Knoxville, TN 37902 Chairman Mr. Johnny H. Hayes, Director Limestone County Commission Tennessee Valley Authority P.O. Box 188 ET 12A Athens, AL 35611 400 West Summit Hill Drive Knoxville, TN 37902 State Health Officer Alabama Department of Public Health Mr. R. M. Eytchison, Vice President 434 Monroe Street Nuclear Operations Montgomery, AL 36130-1701 Tennessee Valley Authority 3B Lookout Place Regional Administrator 1101 Market Street U.S. Nuclear Regulatory Commission Chattanooga, TN 37402-2801 Region II 101 Marietta Street, NW., Suite 2900 Mr. Pedro Salas Atlanta, GA 30323 Site Licensing Manager Browns Ferry Nuclear Plant Mr. Charles Patterson Tennessee Valley Authority Senior Resident Inspector P.O. Box 2000 Browns Ferry Nuclear Plant Decatur, AL 35602 U.S. Nuclear Regulatory Commission Route 12, Box 637 Mr. O. J. Zeringue, Vice President Athens, AL 35611 Browns Ferry Nuclear Plant Tennessee Valley Authority Mr. T. D. Shriver P.O. Box 2000 Site Quality Manager Decatur, AL 35602 Browns Ferry Nuclear Plant Tennessee Valley Authority Mr. B. S. Schofield, Manager P.O. Box 2000 Nuclear Licensing and Regulatory Affairs Decatur, AL 35602 Tennessee Valley Authority 4G Blue Ridge Mr. D. E. Nunn, Vice President 1101 Market Street Tennessee Val' j Authority Chattanooga, TN 37402-2801 3B Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 1