RS-15-035, Update to Report the Completion of Commitment 47, Related to the Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, License Renewal Application

Update to Report the Completion of Commitment 47, Related to the Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, License Renewal Application

ML15023A382
Person / Time
Site:	Byron, Braidwood
Issue date:	01/23/2015
From:	Gallagher M Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-15-035
Download: ML15023A382 (7)

Text

Michael P. Gallagher Vice President. License Renewal Exelon Generation Exelon Nuclear 200 Exelon Way Kennett Square. PA 19348 610 765 5958 Office 610 765 5956 Fax www.exeloncorp.com michaelp.gallagher@exeloncorp.com 10 CFR 50 10 CFR 51 10 CFR 54 RS-15-035 January 23, 2015 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455

Subject:

Update to Report the Completion of Commitment 47, Related to the Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, License Renewal Application

References:

1. Letter from Michael P. Gallagher, Exelon Generation Company LLC (Exelon) to NRC Document Control Desk, dated May 29, 2013, "Application for Renewed Operating Licenses"

2. Letter from Michael P. Gallagher, Exelon, to NRC Document Control Desk, dated December 19, 2013, "Updated Responses to two NRC Requests for Additional Information from Set 1, dated October 7, 2013, related to the Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2 License Renewal Application" In Reference 1, Exelon Generation Company, LLC (Exelon) submitted the License Renewal Application (LRA) for the Byron Station, Units 1 and 2, and Braidwood Station, Units 1 and 2 (BBS) . In Reference 2, Exelon provided information related to the Byron Unit 2 reactor head closure stud 11, including a commitment.

During the Byron Unit 2 refueling outage in the fall of 2014, Exelon removed the previously stuck reactor head closure stud 11 and installed a new stud at this location, thereby completing license renewal commitment 47. Upon removal of stud 11, only minor surface corrosion of the removed stud and its associated reactor vessel head flange stud hole was found . Debris and

January 23, 2015 U.S. Nuclear Regulatory Commission Page 2 dirt were found within the stud hole and were removed via vacuuming and steam cleaning.

There were no signs of thread damage to either the removed stud or the stud hole. The stud hole was evaluated and determined acceptable for re-use, with minor clean-up performed, prior to placing the new stud in service at this location. These findings are consistent with the stuck-stud cause evaluation provided within the response to Request 3 associated with RAI B.2.1.3-1, contained in Exelon letter RS-13-247.

Enclosure A contains an update to the affected portion of LRA Appendix B, Section B.2.1.3, Reactor Head Closure Stud Bolting.

Enclosure B contains an update to the affected portion of LRA Appendix A, Section A.5, License Renewal Commitment List, updating the implementation status of this commitment. In addition, the Commitment List update corrects an editorial error associated with both Commitments 47 and 48, as further described in Enclosure B.

There are no new regulatory commitments contained in this letter.

If you have any questions, please contact Mr. Al Fulvio, Manager, Exelon License Renewal, at 610-765-5936.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on /- ~ J ""' 2 ()/ S-Respectfully, Michael P. Gallagher Vice President - License Renewal Projects Exelon Generation Company, LLC

Enclosures:

A: Byron and Braidwood Stations (BBS), Units 1 and 2, License Renewal Application (LRA) Update B: Byron and Braidwood Stations (BBS), Units 1 and 2, License Renewal Commitment List Update cc: Regional Administrator- NRC Region Ill NRC Project Manager (Safety Review), NRR-DLR NRC Project Manager (Environmental Review), NRR-DLR NRC Senior Resident Inspector, Braidwood Station NRC Senior Resident Inspector, Byron Station NRC Project Manager, NRR-DORL-Braidwood and Byron Stations Illinois Emergency Management Agency - Division of Nuclear Safety

RS-15-035 Enclosure A Page 1 of 3 Enclosure A Byron and Braidwood Stations (BBS), Units 1 and 2, License Renewal Application (LRA) Update This Enclosure provides an update to the Byron and Braidwood Stations (BBS), Units 1 and 2, LRA Appendix B, Reactor Head Closure Stud Bolting Program Description sub-section of Section B.2.1.3, as previously revised by Exelon submittal RS-13-285.

Revisions are indicated with bolded italics for inserted text and strikethroughs for deleted text.

B.2.1.3 Reactor Head Closure Stud Bolting Program Description The Reactor Head Closure Stud Bolting aging management program is an existing preventive and condition monitoring program which credits ASME Code,Section XI inspections of reactor head closure studs and associated RPV head flange threads, nuts, and washers for cracking and loss of material. The Reactor Head Closure Stud Bolting aging management program manages aging effects of an air with borated water leakage environment. The program is based on the examination and inspection requirements specified in the ASME Section XI Code, Subsection IWB, Table IWB-2500-1, and preventive measures described in NRC NUREG-1339, "Resolution of Generic Safety Issue 29: Bolting Degradation or Failure of Nuclear Power Plants"; and NRC Regulatory Guide 1.65, Materials and Inspection for Reactor Vessel Closure Studs.

The current Byron and Braidwood ISI program plans for the third ten-year inspection interval are based on the 2001 Edition of the ASME Code,Section XI, through the 2003 addenda. The future 120-month inspection intervals will incorporate the requirements specified in the version of the ASME Code incorporated into 10 CFR 50.55a, 12 months before the start of the inspection interval. The Reactor Head Closure Stud Bolting aging management program implements ASME Code,Section XI inspection requirements through the ISI program plan. The inspections monitor for cracking, loss of material, and reactor coolant leakage. The program uses visual and volumetric examinations in accordance with the requirements of Section XI, Subsection IWA-2000. The Reactor Head Closure Stud Bolting aging management program was developed in accordance with the requirements detailed in the ASME Code,Section XI, Division 1, Subsection IWB, Table IWB-2500-1.

ASME Code,Section XI allows for a number of examination methods to be used for volumetric and visual inspections. The RPV head flange threads and studs receive a volumetric examination and the surfaces of nuts and washers are inspected using a VT-1 examination. All pressure-retaining boundary

RS-15-035 Enclosure A Page 2 of 3 components in Examination Category B-P receive a visual VT-2 examination during the system leakage test and the system hydrostatic test. The extent and schedule for examining and testing the reactor head closure studs and associated RPV head flange threads, nuts, and washers is specified in Table IWB-2500-1 for Examination Category B-G-1 components, Pressure Retaining Bolting Greater than 2 Inches in Diameter.

Indications and relevant degraded conditions detected during examinations are evaluated in accordance with ASME Code,Section XI Subsection IWB-3100 for Class 1 components by comparing ISI results with the acceptance standards of IWB-3400 and IWB-3500. Specifically, flaw indications or relevant degraded conditions are evaluated in accordance with IWB-3515 or IWB-3517 as indicated in Table IWB-2500-1 and Table 3410-1 of ASME Code,Section XI. These monitoring methods are effective in detecting cracking and loss of materials and the frequency of monitoring is adequate to prevent significant age-related degradation.

The reactor head closure studs are constructed of ASME Code, SA540, Class 3, Grade B23 material, which has a maximum tensile strength of less than 170 ksi, which complied with Reg Guide 1.65, Revision 0 that was in effect during plant construction. The Reactor Head Closure Stud Bolting aging management program utilizes preventive measures to mitigate cracking described in Reg Guide 1.65, which includes the use of approved corrosion inhibitors and lubricants. The reactor head closure studs, nuts, and washers are fabricated with an acceptable phosphate coating to inhibit corrosion. In addition, a stable lubricant that does not contain molybdenum disulfide is applied to the threads prior to reactor vessel head re-installation.

Currently, Byron Unit 2 stud 11 and Braidwood Unit 2 stud 35 are is not in-service because they are it is not tensioned during operation. The configuration of the reactor vessel in-service studs, nuts, and washers is designed to allow them to be completely removed during each refueling outage and placed in storage racks on the containment operating deck. Therefore, in-service studs, nuts, and washers are not exposed to the borated refueling cavity water.

Also, in-service reactor vessel flange stud holes are sealed with plugs before the reactor cavity is flooded with borated water. After the reactor cavity is drained, borated water is removed from the areas above the plugs, the plugs are removed, and the reactor vessel flange holes are inspected. If any borated water has leaked past the plugs, the borated water is removed and the holes are cleaned. The out-of-service Braidwood Unit 2 reactor vessel flange stud hole 35, which is not plugged, is cleaned and inspected prior to reactor vessel flood-up. In addition, Braidwood Unit 2 reactor vessel flange stud hole 35 is cleaned, inspected, and borated water is removed after the reactor cavity is drained.

Therefore, exposure of accessible reactor vessel flange holes to borated water is minimized.

As shown in Appendix A, Table A.5, License Renewal Commitment List, items 47 and 48, commitments were made to repair Byron Unit 2 reactor head closure

RS-15-035 Enclosure A Page 3 of 3 stud location 11 and Braidwood Unit 2 reactor head closure stud location 35 will be repaired so that all 54 reactor head closure studs will be in-service and managed as described above during the period of extended operation.

Commitment item 47 was satisfied in October 2014 when the Byron Unit 2 stud 11 location was repaired.

RS-15-035 Enclosure B Page 1 of 2 Enclosure B Byron and Braidwood Stations (BBS), Units 1 and 2, License Renewal Commitment List Update This Enclosure provides an update to the Byron and Braidwood Stations (BBS), Units 1 and 2, LRA Appendix A, Table A.5 License Renewal Commitment List, documenting that Commitment 47 has been satisfied. In addition, the superscripted note in the Program or Topic column, associated with both Commitments 47 and 48, was inadvertently changed from Note 3 to Note 2 in Exelon letter RS-14-216. This is corrected, consistent with Exelon submittal RS 285.

Notes:

To facilitate understanding, portions of the original License Renewal Commitment List have been repeated in this Enclosure, with revisions indicated.

Existing LRA text, as modified by subsequent Exelon correspondence, is shown in normal font. Additions are highlighted with bolded italics; deletions are shown using strikethroughs.

RS-15-035 Enclosure B Page 2 of 2 As a result of the completion of activities at Byron Station, Unit 2, an update is being made to the implementation status of Commitment 47, as shown below. In addition, the superscripted note in the Program or Topic column, associated with both Commitments 47 and 48, was inadvertently changed from Note 3 to Note 2 in Exelon letter RS-14-216. This is corrected, consistent with Exelon submittal RS-13-285. Existing text from the LRA, as modified by subsequent submittals, is shown in normal font. Text inserted as a result of this update is shown in bolded italics; deleted text is shown with strikethroughs.

A.5 LICENSE RENEWAL COMMITMENT LIST NO. PROGRAM OR IMPLEMENTATION COMMITMENT SOURCE TOPIC SCHEDULE*

47 Byron Unit 2 Reactor Head Byron Unit 2 reactor head closure stud location 11 will be No later than six months prior to the Exelon letter Closure Stud Configuration repaired so that all 54 reactor head closure studs are period of extended operation. RS-13-285 (Byron only)Note 23 tensioned during the period of extended operation. Complete. 12-19-2013 RAI B.2.1.3-2 updated response Exelon letter RS-14-216 12/15/2014 Exelon letter RS-15-035 01/23/2015 48 Braidwood Unit 2 Reactor Braidwood Unit 2 reactor head closure stud location 35 will be No later than six months prior to the Exelon letter Head Closure Stud repaired so that all 54 reactor head closure studs are period of extended operation. RS-13-285 Configuration tensioned during the period of extended operation. 12/19/2013 (Braidwood only)Note 23 RAI B.2.1.3-2 updated response Exelon letter RS-14-216 12/15/2014 Exelon letter RS-15-035 01/23/2015