ML13262A035

Requests for Additional Information for the Review of the Byron Nuclear Station, Units 1 and 2, and Braidwood Nuclear Station, Units 1 and 2, License Renewal Application -Aging Management, Set 1

ML13262A035
Person / Time
Site:	Byron, Braidwood
Issue date:	10/07/2013
From:	Daily J Division of License Renewal
To:	Gallagher M Exelon Generation Co
John Daily 301-415-3873
References
TAC MF1879, TAC MF1880, TAC MF1881, TAC MF1882
Download: ML13262A035 (7)

Text

Mr. Michael P. Gallagher UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 October 7, 2013 Vice President, License Renewal Projects Exelon Generation Company, LLC 200 Exelon Way Kennett Square, PA 19348

SUBJECT:

REQUESTS FOR ADDITIONAL INFORMATION FOR THE REVIEW OF THE BYRON NUCLEAR STATION, UNITS 1 AND 2, AND BRAIDWOOD NUCLEAR STATION, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION -AGING MANAGEMENT, SET 1 (TAC NOS. MF1879, MF1880, MF1881, AND MF1882)

Dear Mr. Gallagher:

By letter dated May 29, 2013, Exelon Generation Company, LLC, submitted an application pursuant to Title 10 of the Code of Federal Regulations Part 54, to renew operating licenses NPF-37, NPF-66, NPF-72, and NPF-77 for Byron Nuclear Station, Units 1 and 2, and Braidwood Nuclear Station, Units 1 and 2, respectively, for review by the U.S. Nuclear Regulatory Commission staff. The staff is reviewing the information contained in the license renewal application and has identified, in the enclosure, areas where additional information is needed to complete the review.

These requests for additional information were discussed with John Hufnagel, and a mutually agreeable date for the response is within 30 days from the date of this letter. If you have any questions, please contact me at 301-415-3873 or by e-mail at john.daily@nrc.gov.

Sincerely, J:d:. ~~ager Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-454, 50-455, 50-456, and 50-457

Enclosure:

As stated cc: Listserv

ML13262A035 OFFICE LA: DLR/RPB2 PM: DLR/RPB1 BC: DLR/RPB1 PM: DLR/RPB1 NAME I King JDaily YDiaz-Sanabria JDaily (JUribe for)

DATE 9/26/13 10/2/13 10/4/13 10/7/13

Letter toM. P. Gallagher from John W. Daily dated October 7, 2013

SUBJECT:

REQUESTS FOR ADDITIONAL INFORMATION FOR THE REVIEW OF THE BYRON STATION, UNITS 1 AND 2, AND BRAIDWOOD STATION, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION -AGING MANGEMENT, SET 1 (TAC NOS. MF1879, MF1880, MF1881, AND MF1882)

DISTRIBUTION:

E-MAIL:

PUBLIC RidsNrrDir Resource RidsNrrDirRpb1 Resource RidsNrrDirRpb2 Resource RidsNrrDraApla Resource RidsOgcMaiiCenter JDaily LRobinson DMclntyre, OPA JWiebe, DORL EDuncan, Rill JBenjamin, Rill AGarmoe, Rill SRI, Byron Station, Rill JRobbins, Rill VMitlyng, Rill PChandrathil, Rill

BYRON NUCLEAR STATION, UNITS 1 AND 2 AND BRAIDWOOD NUCLEAR STATION, UNITS 1 AND 2 REQUEST FOR ADDITIONAL INFORMATION AGING MANAGEMENT, SET 1 (TAC NOS. MF1879, MF1880, MF1881, AND MF1882)

RAI 2.1.5.2-1, 1 CB006 and similar SSCs Applicability:

Byron Nuclear Station (Byron) and Braidwood Nuclear Station (Braidwood), all units

Background:

License renewal application (LRA) Section 2.1.5.2, "Nonsafety-Related Affecting Safety Related-10 CFR 54.4(a)(2)" (pg. 2.1-24), states, in part:

However, there is the potential for communications between nonsafety-related [Systems, Structures, and Components] SSCs located in the turbine building and safety-related SSCs located in the adjacent Auxiliary Building due to ventilation openings in the wall that separates these two structures. Therefore, water, oil, or steam filled SSCs located within the vicinity of these ventilation openings are included within the scope of license renewal due to potential for spatial separation.

During the on-site scoping and screening methodology audit, the staff performed a walkdown of the emergency diesel generators (EDGs}, portions of the main steam and feedwater lines, and the gland steam condenser lines located near the EDG ventilation openings and between the auxiliary and turbine buildings. During the walkdown, the staff identified components and later performed a review to determine if these components were included within the scope of license renewal in accordance with LRA Section 2.1.5.2.

Issue:

As a result of this review, the staff identified that valve 1 CB006 and the associated condensate piping were not included in the scope for license renewal. Additionally, the licensee did not identify this valve in any of the license renewal drawings.

Request:

Please provide a justification for not including valve 1 CB006 and associated piping within the scope of license renewal in accordance with the requirements of LRA Section 2.1.5.2. The staff also requests that the applicant perform an extent of condition review and indicate whether the review identifies additional components that were not included in the scope of license renewal.

Provide a list of these components, if applicable.

RAI 2.1.5.2-2, Unidentified safety-related SSCs in Turbine Building Applicability:

Byron and Braidwood Stations, all units ENCLOSURE

Background:

LRA Section 2.1.5.2, "Nonsafety-Related Affecting Safety-Related-10 eFR 54.4(a)(2)" (pg.

2.1-24), states in part:

Issue:

The [Byron Station and Braidwood Station] BBS turbine building contains a limited number of sses that are classified as safety-related. The components located in the turbine building that perform a safety-related function are either fail-safe or anticipatory and, therefore, are not targets for potential spatial interaction.

The staff needs further information regarding the components referenced above.

Request:

Please provide the following information related to the safety-related sses located in the Byron and Braidwood turbine buildings:

1. Name of the SSe

2. Function of the SSe

3. Basis for concluding the SSe is either fail-safe or anticipatory

4. General location of the SSe RAI 8.2.1.3-1, Byron Closure stud OE not included in LRA Applicability:

Byron, Units 1 and 2

Background:

During the audit of the "operating experience" program element for Byron, Units 1 and 2, the staff found that operating experience provided by the applicant in the LRA was incomplete.

Specifically, the applicant's onsite database contained information related to a stuck reactor vessel closure stud for Byron, Unit 2. Based on the information provided by the applicant during the audit, Stud No. 11 became stuck in the 2010 outage and did not have enough thread engagement to be tensioned. The applicant decided to leave the stuck stud in place after cutting approximately 5 inches from the top end of the stuck stud. Since 2010, Byron, Unit 2, has only 53 of 54 studs operable.

Issue:

The LRA does not provide any information regarding the significant plant-specific operating experience relative to Stud No. 11 for Byron, Unit 2. In addition, no information was provided in the LRA or during the audit on the root cause of the failure. Without a root cause, the staff is concerned that similar failures could reoccur and further challenge the integrity of the reactor vessel head.

Request:

1. Perform a complete plant-specific search of reactor vessel closure studs operating experience for Byron, Units 1 and 2. In addition to Stud No. 11, provide search results that include all instances of stuck studs, missing threads, damaged threads, or any form of degradation in reactor pressure vessel studs, washers, vessel flange threads, and nuts.

2. Provide a detailed chronology of the events related to Byron, Unit 2, Stud No. 11.

3. Provide a root cause analysis related to the failure of Stud No. 11. Include corrective actions, inspection results, engineering changes, repair replacement activities related to Stud No. 11 and its respective flange hole.

4. For Byron, Unit 2, explain in detail the current configuration of Stud No. 11 and the flange hole.

RAI 8.2.1.3-2, BBS Closure Stud OE may not be bounded by GALL Report OE Applicability:

Byron and Braidwood Stations, all units

Background:

LRA Section AMP B2.1.3 "Reactor Head Closure Stud Bolting" states that the aging management program (AMP) will be consistent with the ten elements of AMP XI.M3, "Reactor Head Closure Stud Bolting," specified in NUREG-1801, "Generic Aging Lessons Learned (GALL) Report," with an exception and an enhancement to the "preventive measures" program element.

The Abstract in Chapter XI of the GALL Report states, "if an applicant takes credit for a program in the GALL Report, it is incumbent on the applicant to ensure that the conditions and operating experience at the plant are bounded by the conditions and operating experience for which the GALL Report program was evaluated. If these bounding conditions are not met, it is incumbent on the applicant to address the additional effects of aging and augment the GALL Report aging management program(s) as appropriate." The staff performed a search of operating experience and noted that Byron, Unit 2 (with the exception of Braidwood, Unit 2), is the only pressurized-water reactor plant that is operating with an inoperable (un-tensioned) closure stud and the only one that has a stud left in place and inoperable.

Issue:

The applicant's discussion of plant-specific operating experience regarding its closure stud does not fully address how the applicant's plant-specific operating experience is bounded by industry operating experience as considered in AMP XI.M3 of the GALL Report. The staff noted that LRA AMP B2.1.3, "Reactor Head Closure Stud Bolting," may not be applicable, and a plant-specific AMP may be necessary in light of the plant-specific operating experience.

Request:

Justify how the plant-specific operating experience is bounded by the industry operating experience as considered in AMP XI.M3 of the GALL Report. As alternatives, either provide revisions to your AMP with associated reasoning, or provide a plant-specific AMP to manage aging effects of the reactor vessel head closure studs during the period of extended operation.

RAI 8.2.1.3-3, Byron Unit 2 Rx Closure stud 11, flange hole, and boric acid Applicability:

Byron, Unit 2

Background:

During the audit when discussing the stuck Stud No. 11, the staff noted that the threads are not leak-tight and borated water may enter into the flange hole bottom space during refueling outages. The staff also noted that the boric acid concentration may continually increase following each refueling outage and subsequent plant heat-up.

Issue:

Due to the stuck Stud No. 11 being stuck and left in place, the conditions at the location for the flange hole and the stuck stud are unknown. As a result, accelerated boric acid corrosion could occur and may go undetected.

Request:

Discuss the condition of Stud No. 11 and the flange hole. Explain how the AMP will detect and monitor boric acid corrosion for the stud and flange-hole.