ML20116F079

Application for Amends to Licenses NPF-37,NPF-66,NPF-72 & NPF-77,eliminating Corrosion Testing Requirement for SG Tube Sleeving

ML20116F079
Person / Time
Site:	Byron, Braidwood
Issue date:	08/02/1996
From:	Hosmer J COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20116F081	List: ML20116F079 ML20116F093
References
NUDOCS 9608060231
Download: ML20116F079 (7)

Text

I Commonwealth rAlison Company l 400 Opua Place Downers Gros e. IL 60515-5701 August 2,1996 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001

Subject:

Application for Amendment to Facility Operating Licenses:

Byron Nuclear Power Station, Units 1 and 2 NPF-37 and NPF-66: NRC Docket Nos. 50-454 and 50-455 Braidwood Nuclear Power Station, Un ts 1 and 2 NPF-72 and NPF-77: NRC Docket Nos. 50-456 and 50-457 l

" Elimination of the Corrosion Testing Requirement for Steam Generator Tube Sleeving" l

Reference:

R. Assa(NRC) letter to D. Farrar (Comed) dated January 6,1995, transmitting the Safety Evaluation Report (SER) approving the incorporation of the sleeving j

l conditions into the Byron and Braidwood Operating Licenses and Technical l

Specifications l

Pursuant to Title 10, Code of Federal Regulations, Part 50, Section 90 (10 CFR 50.90)

Commonwealth Edison Company (Comed) proposes to amend the Facility Operating Licenses NPF-37, NPF-66, NPF-72, and NPF-77.

l The proposed amendment would eliminate Facility Operating License NPF-37 Condition 2.C.16, l

Facility Operating License NPF-66 Condition 2.C.5, Facility Operating License NPF-72 Condition 2.C.6, and Facility Operating License NPF-77 Condition 2.C.5:

i "The licensee shall conduct additional corrosion testing to establish the design lift for the laser welded sleeved tubes in the presence of a crevice. The corrosion testing shall l

demonstrate the corrosion resistance for the laser welded joints in tubes that bound the material parameters in the steam generators. The corrosion testing results shall be reviewed and accepted by the Nuclear Regulatory Commission prior to the Beginning-of-Cycle 7 (Beginning-of-Cycle 9 for Byron 1 and Cycle 8 for Byron 2). If conformance with the requirements of the plant Technical Specifications for tube structural integrity is not confirmed, the tubes containing the sleeves in question shall be removed from service."

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U.S. Nuclear Regulatory Comraission August 2,1996 The amendment package consists of the following:

Attachment A: Description and Safety Analysis of Proposed Changes Attachment B: Proposed Changes to Facility Operating Licenses l

Attachment C: Evaluation of Significant Hazards Considerations Attachment D: Environmental Assessment for Proposed Changes The proposed amendment has been reviewed and approved by the On-site and Off-site Review Committees in accordance with Comed procedures. Comed has reviewed this proposed amendment in accordance with 10 CFR 50.92(c) and has determined that no significant hazards consideration exists.

Comed is notifying the State ofIllinois of our application for this proposed amendment by I

transmitting a copy of this letter and the associated attachments to the designated state official.'

i Comed requests that NRC review and approval of this proposed amendment be completed by December 31,1996. This license' amendment request is considered to be a cost beneficial licensing action (CBLA) in accordance with the NRC guidance.

To the best of my knowledge and belief, the statements contained in this document are true and correct.

Please address any comments or questions regarding this proposed amendment to Denise Saccomando, Senior PWR Licensing Administrator at (708) 663-7283.

Sincerely, Fl; OFFICIAL SEAL[;

MARY JO YACK 8/

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{";,m co***SS*".f".7*01'.'*-Ib John B. Hosmer

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Engineering Vice President NNe cur 7M-c4, f 4 74 Attachments

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A. B. Beech, Regional Administrator - RIII G. F. Dick Jr., Byron Project Manager - NRR R. R. Assa, Braidwood Project Manager - NRR S. Burgess, Senior Resident Inspector - Byron C. Phillips, Senior Resident Inspector - Braidwood Office of Nuclear Facility Safety - IDNS k nla bytod atmgens hvicorrtduc.2 2

I ATTACHMENT A DESCRIPTION AND SAFETY ANALYSIS OF l

PROPOSED CHANGES TO FACILITY OPERATING LICENSES NPF-37, NPF-66, NPF-72, AND NPF-77 A.

DESCRIPTION OF THE PROPOSED CIIANGE Commonwealth Edison (Comed) proposes to amend Facility Operating Licenses NPF-37, NPF-66, NPF-72 and NPF-77 to delete the requirement to perform additional corraion testing to establish the design life for the laser welded sleeved tubes in the presence o' crevice. This license condition was added at the request of the Nuclear Regulatory Commission (NRC) as a requirement for conducting laser welded sleeving that was approved in Amendments 58 (Byron) and 46 (Braidwood)

This change is described in detail in Section E of this Attachment. Copies of the affected license pages showing the ac:aal proposed change are included in Attachment B of this license amendment request.

B.

DESCRIPTION OF THE CURRENT REQUIREMENT License conditions 16 (NPF-37, Byron Unit 1), 5 (NPF-66, Byron Unit 2 and NPF-77, Braidwood Unit 2), and 6 (NPF-72, Braidwood Unit 1) require laboratory corrosion testing to be conducted to establish the design life oflaser welded sleeves in the presence of a crevice. The purpose of the testing is to determine the effects that material microstructure, chemistry, and joint crevices will have on primary water stress corrosion cracking (PWSCC) initiation and growth.

The testing is to bound the material condition that exists in Byron and Braidwood steam generators, and include the associated stress intensity values. The testing results are to be reviewed and accepted by the NRC prior to the beginning of Byron Unit 1 Cycle 9, Byron Unit 2 Cycle 8 and Braidwood Cycle 7 for Units 1 and 2.

Until this testing is satisfactorily completed, Comed also committed to perform an inservice inspection of a random sample of a minimum of 20% of the installed sleeves at the end of each cycle, with provisions for sample expansion ifimperfections of 40% or greater depth are detected l

(TS 4.4.5.2). This requirement was incorporated with the Byron and Braidwood Amendments 67 and 57, respectively. Following completion of the corrosion testing, sleeve inspections would i

resume at the 3% sample level. This requirement was subsequently revised in Amendments 83 e.~m

,(Byron) and 76 (Braidwood) which approved the ABB-CE Tungsten Inert Gas (TIG) welded sleeving. process. The current Technical Specification requires Comed to perform an inservice inspection of a random sample of a minimum of 20% of the installed sleeves, regardless of type.

C.

BASES FOR THE CURRENT REQUIREMENT The following references form the bases for the current requirement to perform corrosion testing:

Teleconference of February 18,1994, between Comed and the NRC concerning a proposed amendment to permit kinetically and laser welded sleeve installation at Byron and Braidwood.~

i R. Assa (NRC) letter to D. Farrar (Comed) dated February 22,1994, identifying certain conditions necessary for NRC approval of the proposed sleeving amendment.

D. Saccomando (Comed) letter to T.E. Murley (NRC) dated February 24,1994, committing Comed to the conditions requested by the NRC relative to the proposed sleeving amendment.

D. Saccomando (Comed) letter to W. T. Russell (NRC) dated June 3,1994, requesting an amendment to incorporate the required conditions relative to kinetically and laser welded sleeving processes.

R. Assa(NRC) letter to D. Farrar (Comed) dated January 6,1995, transmitting the Safety Evaluation Report (SER) approving the incorporation of the sleev' g conditions into the m

Byron and Braidwood Operating Licenses and Technical Specifications (Amendments 67 and 57, respectively).

H. D. Pontious, Jr. (Comed) letter to USNRC dated May 17,1995, (and associated supplements) requesting an amendment to permit installation of ABB-CE TIG welded sleeves and deleting the provisions allowing installation of kinetically welded sleeves.

During the NRC's review of the Comed amendment request to permit the installation of kinetically and laser welded sleeves into the Byron and Braidwood steam generators, the NRC

- identified several conditions that would be required for the approval of this amendment. These conditions included a reduction of the primary-to-secondary leakage limit to 150 gallons per day (gpd) in any one steam generator, performance of additional corrosion testing to establish the design life of the kinetically welded and laser welded sleeves, performance ofinservice inspection on a higher percentage ofinstalled sleeves until corrosion testing was completed, and performance of post-weld heat treatment at specified temperatures and holding times on kinetically and laser welded sleeves until additional supporting data became available.

Comed incorporated the first three conditions into License Amendments 67 (Byron) and 57 (Braidwood) and incorporated the fourth condition into the sleeving installation processes.

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NEED FOR REVISION OF THE REQUIREMENT l

Comed believes that corrosion test results will not provide any meaningful information for predicting sleeve life. Therefore, Comed believes that the benefit of the corrosion testing with respect to ensuring health and safety of the public is not commensurate with the expense required to perform the testing. The cost of the corrosion testing is estimated to be $125,000 for the Model D-4 configuration. Testing of the Model D-5 tubing would result in significant additional costs.

The belief that additional testing will not provide any meaningful data is further supported in recent NRC approvals of the ABB-CE TIG welded sleeving methodology, in which statements have been made as to the reliability of sleeve service life assessment on the basis of corrosion testing. In particular, in the December 14,1995, ABB-CE sleeve Safety Evaluation Report for Waterford Steam Electric Station, Unit 3, the NRC stated in Section 3.2, "The staff has concluded that accelerated corrosion tests should provide a good qualitative assessment of relative service life for variem sleeving processes. However, quantitative estimates of service life do not have a high degree of reliability. Periodic inspection as discussed in Section 2.3 and primary-to-secondary leakage monitoring will identify any premature degradation that may occur in the sleeved joints."

A similar statement was made in the SER for Amendments 83 (Byron) and 76 (Braidwood) which approved the use of the ABB-CE sleeve for Comed's Byron and Braidwood Stations (Letter from G. Dick (NRC) to D. Farrar (Comed) dated April 12, 1996). The NRC stated in Section 4.4, "The staff has concluded that accelerated corrosion tests should provide a good qualitative assessment of relative service life for various sleeving processes. However, quantitative estimates of service life do not have a high degree of reliability. For this reason, the staff does not accept deterministic life prediction calculations for tube material."

E.

DESCRIPTION OF THE REVISED REQUIREMENT Comed proposes to delete license condition 2.C.16 for NPF-37 (Byron Unit 1), license condition 2.C.5 for NPF-66 (Byron Unit 2) and NPF-77 (Braidwood Unit 2) and license condition 2.C.6 for NPF-72 (Braidwood Unit 1). There are no changes required to the Technical Specifications or Bases pages.

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' BASES FOR THE REVISED REQUIREMENT F

l l-Deletion of the requirement to perform the added corrosion testing isjustified because the I

corrosion test results will not provide any meaningful information. Comed has taken measures that allow for early detection of a sleeve flaw: sleevejoint inservice inspections, the primary-to-secondary leakage limits and the primary-to-secondary leakage monitoring program.

The sleeve joint inservice inspection requirements consist of a 20% random sample of all sleeved tubes with expansion criteria should sleevejoint degradation be detected. During Byron Unit l's seventh refuel outage (B1R07),100% of the sleeves installed during the mid-cycle outage (BlP02) were inspected by EPRI Appendix H qualified eddy current inspection techniques with no degradation detected. _ All future inservice inspections will also be conducted using EPRI Appendix H qualified techniques. The sample sizes and expansion requirements selected are consistent with the EPRI PWR Steam Generator Tube Examination Guideline. Tubes with sleeve joints that have degraded beyond the Technical Specific tia on limit will be plugged.

As noted previously, Comed has adopted the reduced Technical Specification primary-to-secondary leakage limit of 150 gpd in any one steam generator for Byron and Braidwood Stations (Amendments 67 and 57, respectively). Administrative requirements are also applied which l

require plant shutdown in response to a step increase in primary-to-secondary leakage. These administrative requirements are consistent with, or more conservative than, the EPRI PWR Primary-to-Secondary Leak Guidelines and are described in the September 1,1995,3.0 volt Interim Plugging Criteria Technical Specification Amendment Application Supplement.. The primary-to-secondary leakage monitoring program includes periodic sampling of steam generators for leakage detection, and monitoring the response of plant radiation monitors. The leakage limits and the monitoring program enable Byron and Braidwood to detect premature degradation of sleevejoints and to take appropriate actions to place the plant in a safe condition in the event of tube leakage. Operator training and simulator training programs have been updated to include various tube rupture, tube leak, and main steam line break scenarios, which include varying radiation monitor responses.

Currently, only Byron Unit I has laser welded sleeves installed (2046 sleeves installed during BlP02 in the Fall of 1995). The Byron Unit 1 Steam Generator replacement is currently scheduled for the Spring of 1998. The Braidwood Unit I steam generators are scheduled for replacement in the Fall of 1998.

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1MPACT OF THE PROPOSED CHANGE Adequate controls are in place to detect leakage resulting from premature degradation of sleeved tubes and to provide appropriate operator response to such events. Additionally, the inspection sample size of 20% of all sleeved tubes ensures that sleevejoint degradation is detected during steam generator inspections.

l Implementation of this proposed change will not result in any new equipment being installed or

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any existing equipment being modified. No new operating modes or procedures will be created.

Therefore, these proposed changes will have no significant negative impact on any operating mode, equipment or procedure.

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SCHEDULE REQUIREMENTS The Braidwood Unit I sixth refuel outage (AlR06) begins in March of 1997. Approval of this change is requested by December 31,1996 to support the current outage schedule.

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