RS-14-041, Stations, Units 1 and 2 - Response to NRC Requests for Additional Information, Set 9, Dated January 22, 2014, Related to the License Renewal Application

Stations, Units 1 and 2 - Response to NRC Requests for Additional Information, Set 9, Dated January 22, 2014, Related to the License Renewal Application

ML14051A154
Person / Time
Site:	Byron, Braidwood
Issue date:	02/19/2014
From:	Gallagher M Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-14-041
Download: ML14051A154 (20)

Text

10 CFR 50 10 CFR 51 10 CFR 54 RS-14-041 February 19, 2014 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:

Response to NRC Requests for Additional Information, Set 9, dated January 22, 2014, 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 Lindsay R. Robinson, US NRC to Michael P. Gallagher, Exelon, dated January 22,2014, "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, Set 9 (TAC NOS. MF1879, MF1880, MF1881, AND MF1882)

In the Reference 1 letter, 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 the Reference 2 letter, the NRC requested additional information to support the staffs' review of the LRA.

Enclosure A contains the responses to these requests for additional information.

Enclosure B contains updates to sections of the LRA (except for the License Renewal Commitment List) affected by the responses.

February 19, 2014 U.S. Nuclear Regulatory Commission Page 2 Enclosure C provides an update to the License Renewal Commitment List (LRA Appendix A, Section A.5). There are no other new or revised regulatory commitments contained in this letter.

If you have any questions, please contact Mr. AI 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-/1- 20/1 Respectfully,

~£Jtt----

Michael P. Gallagher Vice President - License Renewal Projects Exelon Generation Company, LLC

Enclosures:

A: Responses to Requests for Additional Information B: Updates to affected LRA sections C: License Renewal Commitment List Changes cc: Regional Administrator - NRC Region III 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-14-041 Enclosure A Page 1 of 14 Enclosure A Byron and Braidwood Stations (BBS), Units 1 and 2 License Renewal Application Responses to Requests for Additional Information RAI B.2.1.39-1 RAI B.2.1.39-2 RAI B.2.1.39-3 RAI B.2.1.39-4

RS-14-041 Enclosure A Page 2 of 14 RAI B.2.1.39-1 Applicability:

Byron Station (Byron) and Braidwood Station (Braidwood)

Background:

The applicant states that license renewal application (LRA) aging management program (AMP) B.2.1.39, Inaccessible Power Cables Not Subject To 10 CFR 50.49 Environmental Qualification Requirements, is a new program that is consistent with the Generic Aging Lessons Learned (GALL) Report AMP XI.E3, Inaccessible Power Cables Not Subject To 10 CFR 50.49 Environmental Qualification Requirements.

The GALL Report AMP XI.E3, program element preventive actions states that if water is found during inspections (i.e., cable exposed to significant moisture) corrective actions are taken to keep the cable dry and assess cable degradation. However, the preventive actions program element of LRA AMP B.2.1.39 only states if water is found during inspection, water is drained and other corrective actions are taken, as appropriate.

Issue:

The applicants program is not consistent with the GALL Report AMP XI.E3 in that it does not specifically include an assessment of cable degradation (e.g., tests to assess cable condition) when inaccessible power cables are exposed to significant moisture.

Request:

Identify testing and inspection techniques used to assess the condition of inaccessible cables when cables are exposed to significant moisture.

Exelon Response:

The Byron and Braidwood LRA AMP B.2.1.39, Inaccessible Power Cables Not Subject To 10 CFR 50.49 Environmental Qualification Requirements, will include an assessment of cable degradation when inaccessible power cables are exposed to significant moisture.

The assessment of cable degradation includes direct visual inspection inside the cable vault and an evaluation of cable test results. The testing techniques used to assess the condition of inaccessible cables when the cables are exposed to significant moisture are one or more of the following techniques: Dielectric Loss (Dissipation Factor/Power Factor), AC Voltage Withstand, Partial Discharge, Step Voltage, Time Domain Reflectometry, Insulation Resistance and Polarization Index, Line Resonance Analysis, or other testing that is state-of-the-art at the time the tests are performed. One or more tests may be used to assess the condition of the cables so they will continue to meet their intended function during the period of extended operation. Direct visual inspections inside cable vaults are also used to assess the condition of inaccessible cables when the cables are exposed to significant moisture. The inspection frequency for water collection is established and adjusted based on plant specific operating experience with cable wetting or submergence, including water accumulation over time and event driven

RS-14-041 Enclosure A Page 3 of 14 occurrences such as heavy rain or flooding. The cable vault inspections occur at least annually.

The preventive actions program element of the AMP Basis Document for LRA AMP B.2.1.39, Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements is revised to clarify that the preventive actions program element is consistent with the GALL Report. The preventive actions program element of the AMP Basis Document now states:

a) This condition monitoring aging management program takes periodic actions to prevent cables from being exposed to significant moisture. This program inspects manholes and associated accessible conduit ends for the non-EQ, in scope, inaccessible cables (greater than or equal to 400 volts), for water collection so that draining or other corrective actions can be taken.

b) The objective of the inspections, as a preventive action, is to prevent inaccessible cables from being exposed to significant moisture. Therefore, the inspection frequency for water collection is established and adjusted based on plant specific operating experience with cable wetting or submergence, including water accumulation over time and event driven occurrences such as heavy rain or flooding. The inspections occur at least annually. The inspection includes direct observation to assure cables are not wetted or submerged, cables and connections are intact without observable surface damage, cable support structures are intact, and drainage systems or dewatering devices, if installed, and associated alarms are operating properly. Manhole dewatering devices, if installed, are either (1) equipped with alarms signifying less than adequate functioning of dewatering devices, or (2) inspected as part of procedural controlled activities for a potential significant weather event. If water is found during inspection, corrective actions are taken to keep the cable dry and to assess cable degradation. The first inspections for license renewal will be completed prior to period of extended operation.

The preventive actions program element of the LRA AMP B.2.1.39, Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements, is consistent with the GALL Report AMP XI.E3.

RS-14-041 Enclosure A Page 4 of 14 RAI B.2.1.39-2 Applicability:

Byron and Braidwood

Background:

The applicant states that LRA AMP B.2.1.39, Inaccessible Power Cable Not Subject To 10 CFR 50.49 Environmental Qualification Requirements, is a new program that is consistent with GALL Report AMP XI.E3, Inaccessible Power Cables Not Subject To 10 CFR 50.49 Environmental Qualification Requirements.

The detection of aging effects program element of LRA AMP B.2.1.39 states that the condition of cable insulation is assessed with reasonable confidence using one of the following techniques: Dielectric Loss (Dissipation Factor or Power Factor), AC Voltage Withstand, Partial Discharge, Step Voltage, Time Domain Reflectometry, Insulation Resistance and Polarization Index, Line Resonance Analysis, or other testing that is state-of the art at the time the tests are performed. However, the GALL Report AMP XI.E3 states that the applicant can assess the condition of the cable insulation with reasonable confidence using one or more tests.

Issue:

Limiting the number of tests performed to one test may result in inadequate detection of cable insulation degradation. For example, Electric Power Research Institute (EPRI) has stated that three practical tests are currently available for shielded extruded polymer medium-voltage cable: partial discharge, tan , and power frequency or very low frequency (VLF) withstand. Depending on the nature of the cable design and the cable or accessory (termination or splice), more than one test may be needed to assess cable insulation degradation.

Request:

Explain why limiting LRA AMP B.2.1.39 to a single test to detect cable insulation degradation is consistent with GALL Report AMP XI.E3.

Exelon Response:

The Byron and Braidwood LRA AMP B.2.1.39, Inaccessible Power Cables Not Subject To 10 CFR 50.49 Environmental Qualification Requirements, assesses the condition of the cable insulation with reasonable confidence using one or more tests. LRA Section A.2.1.39 states, in part, One or more tests may be used to determine the condition of the cables so they will continue to meet their intended function during the period of extended operation. Limiting LRA AMP B.2.1.39 to a single test to detect cable insulation degradation is not consistent with GALL Report AMP XI.E3.

The detection of aging effects program element of the AMP Basis Document for LRA AMP B.2.1.39, Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification

RS-14-041 Enclosure A Page 5 of 14 Requirements is revised to clarify that the detection of aging effects program element assesses the condition of the cable insulation with reasonable confidence using one or more tests. The detection of aging effects program element of the AMP Basis Document now states:

a) The BBS non-EQ, in scope, inaccessible power cables, which are exposed to significant moisture, are tested at a frequency of at least every 6 years. The first tests will be performed prior to period of extended operation. The 6-year interval provides multiple data points which can be used to characterize the rate of degradation, if occurring. This is an adequate period to monitor performance of the cables and take appropriate corrective actions since experience has shown that aging degradation is a slow process. More frequent testing may occur based on test results and operating experience. The first tests for license renewal are to be completed prior to period of extended operation.

b) The condition of cable insulation is assessed with reasonable confidence using one or more of the following techniques: Dielectric Loss (Dissipation Factor or Power Factor), AC Voltage Withstand, Partial Discharge, Step Voltage, Time Domain Reflectometry, Insulation Resistance and Polarization Index, Line Resonance Analysis, or other testing that is state-of-the-art at the time the tests are performed.

Tests assure that cables will continue to perform their intended functions during the period of extended operation.

The detection of aging effects program element of the LRA AMP B.2.1.39, Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements, is consistent with the GALL Report AMP XI.E3.

Consistent with this response, LRA Section B.2.1.39 is revised as shown in Enclosure B.

Consistent with this response, the Byron and Braidwood LRA Table A.5 Commitment List, Item 39 is revised as shown in Enclosure C.

RS-14-041 Enclosure A Page 6 of 14 RAI B.2.1.39-3 Applicability:

Byron and Braidwood

Background:

The applicant states that LRA AMP B.2.1.39, Inaccessible Power Cable Not Subject To 10 CFR 50.49 Environmental Qualification Requirements, is a new program that is consistent with GALL Report AMP XI.E3, Inaccessible Power Cables Not Subject To 10 CFR 50.49 Environmental Qualification Requirements.

The monitoring and trending program element of the LRA AMP states that test results that have an ability to trend are trended to provide additional information on the rate of cable degradation. The GALL Report AMP XI.E3 states that trending actions are included as part of this AMP, although the ability to trend results is dependent on the specific type of tests or inspections chosen. Trended results provide additional information on the rate of cable insulation degradation.

Issue:

Trending actions should be considered for testing as well as inspection. The LRA AMP B.2.1.39 only includes trending of test results.

Request:

Explain why trending of inspection results is not included or considered for LRA AMP B.2.1.39.

Exelon Response:

Consistent with current operating term practice, LRA AMP B.2.1.39 will include trending the inspection results in addition to trending the testing results. The monitoring and trending program element of the AMP Basis Document for LRA AMP B.2.1.39, Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements is revised to clarify that the monitoring and trending program element includes trending of the inspection results that are trendable. The monitoring and trending program element of the AMP Basis Document now states:

Test or inspection results that are trendable are trended to provide additional information on the rate of cable degradation.

The monitoring and trending program element of the LRA AMP B.2.1.39, Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements, is consistent with the GALL Report AMP XI.E3.

RS-14-041 Enclosure A Page 7 of 14 RAI B.2.1.39-4 Applicability:

Byron and Braidwood

Background:

The applicant states that the LRA AMP B.2.1.39, Inaccessible Power Cable Not Subject To 10 CFR 50.49 Environmental Qualification Requirements, is a new program that is consistent with GALL Report AMP XI.E3, Inaccessible Power Cables Not Subject To 10 CFR 50.49 Environmental Qualification Requirements.

The GALL Report AMP XI.E3 states that periodic actions are taken to prevent inaccessible cables from being exposed to significant moisture. Examples of periodic actions are inspecting for water collection in manholes and conduits and then draining water as needed. The inspection should include direct observation that cables are not wetted or submerged, cables/spices and cable support structures are intact, and that dewatering/drainage systems (sump pumps) and associated alarms operate properly.

Applicable operating experience (OE) examples noted during the Byron and Braidwood Station audits are described below:

1. During review of the applicants OE, which included work orders and action requests (ARs), the staff identified unresolved cases of water intrusion into manholes and cable vaults which could potentially expose in-scope power cables to significant moisture and/or cable submergence.

2. In 2011, the applicant found the water level to be approximately 5 feet deep when manhole 0B2 (Byron Station) was opened for yearly inspection. Most of the cables in the manhole were submerged. The applicants corrective action was to revise the preventive maintenance (PM) inspection from 1 year to 3 months. In their evaluation of this AR, the applicant stated that the short term submergence of these cables will not affect cable function and that these cables are suitable for installation in either wet or dry locations and were tested for long-term submergence.

3. PM inspections performed on Aug 15, 2013 noted no water in manhole 0B2.

A follow-up PM inspection was performed on Aug 26, 2013 as a result of heavy rainfall of 2.5 inches in the local area. During the Byron AMP audit, the applicant noted that water was found approximately 4 feet deep in manhole 0B2. The applicant also stated that based on cable condition trending from 2007, this was the second time cables were submerged in manhole 0B2. The applicant initiated an AR and concluded in its evaluation that these cable were tested by the manufacturer for submergence.

The staff noted that the manufacturer stated that based on actual experience with installed cables over many years, insulators which have the capability of withstanding total water immersion at 90 degrees Celsius should be capable of a life in excess of a generating stations design life in an environment of 100% humidity.

RS-14-041 Enclosure A Page 8 of 14 The staff also noted that during its audit of Byron and Braidwood OE, Braidwood has also experienced manhole and cable vault degradation including cable support structure degradation, water intrusion, and cable submergence.

Issue:

When a power cable is exposed to wet or submerged conditions for which it is not designed, an aging effect of reduced insulation resistance may result, causing a decrease in the dielectric strength of the conductor insulation. This insulation degradation caused by wetting or submergence can potentially lead to failure of the cables insulation system.

The staff is concerned that the applicants manhole inspections and corrective actions may not be adequate to prevent in-scope inaccessible power cables from being subjected to significant moisture. The staff could not determine, based on Byron and Braidwood OE, whether the applicants LRA AMP B.2.1.39 would ensure that in-scope inaccessible power cables will continue to perform their intended function during the period of extended operation.

Request:

1. Describe the corrective actions (e.g., inspection, preventive maintenance) taken to ensure the reliable operation of cable manhole/vault sump pumps to prevent exposure of inaccessible power cables to significant moisture.

2. For inaccessible power cables subjected to submergence (significant moisture), describe the inspections and testing performed and acceptance criteria used to establish the condition and operability of these cables as part of the corrective action to ensure that these cables remain capable of performing their intended function consistent with the current licensing basis. Include in the discussion how the interval to inspect for water intrusion of vault manholes, vault manhole structures, and cable supports is established and adjusted for plant specific and industry operating experience.

3. Include a discussion of the implementation schedule for corrective actions, including those items already completed for both Byron and Braidwood.

Exelon Response:

1. The following describes the corrective actions (e.g., inspection, preventive maintenance) taken to ensure the reliable operation of cable manhole/vault sump pumps to prevent exposure of inaccessible power cables to significant moisture.

RS-14-041 Enclosure A Page 9 of 14 Byron There are no permanent sump pumps installed in the in-scope cable vaults at Byron. Byron utilizes direct visual inspections in conjunction with manual pumping actions (as appropriate) to prevent exposure of inaccessible power cables to significant moisture.

As noted by the staff in the Background section, Byron cable vault 0B2 has recently experienced an adverse trend with regard to water intrusion after a significant rainfall. This operating experience and associated corrective actions are discussed later in item 3 of this response.

Braidwood There is only one in-scope power cable at Braidwood. Operating experience at Braidwood has demonstrated that the in-scope cable in the cable vaults is not exposed to significant moisture when the cable vault sumps are in service. The cable vault sump pump controllers are equipped with local trouble alarms and high water level alarms. When an alarm condition is discovered, the condition is entered into the corrective action program and the condition is resolved in accordance with the corrective action program. In addition, Braidwood utilizes periodic direct visual inspections of the in-scope cable vaults. The direct visual inspections are presently performed monthly. The cable vault inspection interval will not exceed one year.

When problems are discovered, the condition is entered into the corrective action program and is resolved using the work management process at Braidwood. Preventive maintenance activities are planned for every 36 months on the cable vault sump pumps in accordance with the pump manufacturers recommendation to ensure continued good operating service. Since the installation of the sump pumps and the implementation of the direct visual inspection activities at Braidwood, operating experience and trending has demonstrated that the in-scope power cable in the cable vaults are not exposed to significant moisture.

Specific operating experience for Braidwood and associated corrective actions are discussed later in item 3 of this response.

2. The following describes the inspections and testing performed and acceptance criteria used to establish the condition and operability for inaccessible power cables subjected to submergence (significant moisture) to ensure that these cables remain capable of performing their intended function consistent with the current licensing basis.

Byron and Braidwood - Cable Vault Inspections and Acceptance Criteria Industry and actual plant operating experience is considered for determining the interval for cable vault direct visual inspections. The intervals for direct visual inspections of the in-scope cable vaults do not exceed one year based on current industry best practices and the GALL Report AMP XI.E3. In addition, based on actual cable vault inspection trending, direct visual inspections of the cable vaults may also be made in response to anticipated or actual adverse weather conditions that may cause water intrusion into the cable vaults. The as-found conditions during cable vault inspections are documented and trended for long term evaluation in accordance with the corrective action program. The actual plant cable vault inspection trending data is used to determine the individual cable vault inspection intervals. Cable vault

RS-14-041 Enclosure A Page 10 of 14 inspection intervals are adjusted (not to exceed one year) based on the conditions found during the direct visual inspection in accordance with the corrective action program.

The acceptance criteria for these direct visual inspections are: 1) cables are not wetted or submerged, 2) cables and connections are intact without observable surface damage, 3) cable support structures are intact, and 4) drainage systems or dewatering devices, if installed, and associated alarms are operating properly. If the cable vault structures or cable support inspection results do not meet an acceptance criterion, the condition is entered and evaluated in the corrective action program. If water is unexpectedly found in a cable vault during a visual inspection or the cables are found submerged, the condition is entered into the corrective action program, the water is manually pumped out as appropriate, the cable condition is evaluated in the corrective action program, and the inspection interval is evaluated based on trend results.

Corrective actions are established and implemented to resolve the water intrusion issue so that the cables remain capable of performing their intended function consistent with the current licensing basis through the period of extended operation.

Byron and Braidwood - Cable Testing and Acceptance Criteria Inaccessible power cables subject to significant moisture are assessed by periodic tests at least every six years based on current industry best practices and the GALL Report AMP XI.E3. The cable test results are documented and trended for long term evaluation in accordance with the corrective action program.

The in-scope inaccessible power cables subject to significant moisture are unshielded cables.

The acceptance criterion for the insulation resistance test on unshielded power cable is (Rated Voltage____ KV +1)* 1000/_____Length in feet = _____ Meg-ohms.

If a cable test result does not meet an acceptance criterion, the condition is entered into the corrective action program, the cable condition is assessed, and the condition is documented in the corrective action program. Current plant operating experience shows that there have been no in-scope inaccessible power cable testing failures at Byron or Braidwood.

3. Actions will be taken during the current operating term to establish the conditions necessary to implement LRA AMP B.2.1.39 at Byron and Braidwood prior to the period of extended operation in accordance with license renewal commitment Item 39. The following is a discussion of the implementation plan which includes the current material condition of the in-scope power cables and cable vaults, completed corrective actions, and currently planned corrective actions. The completed and planned actions to support the current and near term material condition of the in-scope power cables are discussed in the Current Operating Term Activities section under Cable Testing. The completed and planned actions to support the current and near term material condition of the in-scope cable vaults are discussed in the Current Operating Term Activities section under Cable Vault Inspection. Byron is discussed first, Braidwood is discussed second. The planned actions to support the implementation of the LRA AMP B.2.1.39 for both Byron and Braidwood are discussed under Byron and Braidwood LRA AMP B.2.1.39 Implementation Plan section.

RS-14-041 Enclosure A Page 11 of 14 Byron - Current Operating Term Activities Cable Testing Operating experience shows that there have been no in-scope inaccessible power cable failures at Byron. The in-scope power cables are tested during normally scheduled bus outages or equipment maintenance work windows. Nineteen of the 23 in-scope power cables have been tested (insulation resistance) since 2012. Three (3) of the remaining four (4) in-scope power cables are planned to be tested in 2014. The last cable is planned to be tested during its associated transformer outage during refueling outage B1R22 in 2018. All cable test results to date have met all acceptance criteria. It has been determined that the in-scope power cable insulation is in good condition. Testing will continue to be conducted periodically to trend and characterize the power cable insulation condition. The current plan is to test the in-scope power cables every six years. The cable test frequency may be adjusted (not to exceed six years) based on actual plant operating experience and data trending in accordance with the corrective action program.

Cable Vault Inspection Annual visual inspections of Byron's outdoor safety-related cable vaults started in 2003 in response to the industry operating experience discussed in Information Notice 2002-12, Submerged Safety-Related Electrical Cables. The scope of the annual visual inspections expanded to Byron's indoor safety-related cable vaults in 2007 in response to actual plant operating experience.

Annual visual inspections of the nonsafety-related cable vaults at Byron were started in 2010 in response to industry operating experience that expanded the concern of power cables exposed to significant moisture to nonsafety-related medium and low voltage power cables.

The initial inspections of the cable vaults found varying degrees of water inside the cable vaults.

The as-found conditions were entered into the corrective action program to initiate appropriate corrective actions and for trending. The cable vaults were emptied, if required, and assessed in order to systematically refurbish cable vaults and cable support structures. The refurbishment of cable vaults started in 2011. Thirteen out of 16 cable vaults in the scope of this AMP have been refurbished. The remaining three cable vaults are planned to be refurbished in 2014.

Ground water intrusion into the in-scope cable vaults is limited at Byron because of the relatively low water table at Byron. In addition, operational experience and trending has shown that any water found in the cable vaults has been from significant rain events. Cable vault water level trending at Byron since 2010 has shown that in-scope power cables are normally not submerged in water. This is because of an effective cable vault inspection and manual pumping plan.

As noted by the staff in the Background section, Byron cable vault 0B2 has recently experienced an adverse trend with regard to water intrusion after a significant rainfall. This operating experience and associated corrective actions are discussed below.

On August 26, 2013, the power cables in cable vault 0B2 were unexpectedly found submerged in water. The condition was entered into the corrective action program. The

RS-14-041 Enclosure A Page 12 of 14 water was removed from the cable vault, the cable condition was assessed, and the evaluation was documented in the corrective action program. Cable vault 0B2 was inspected again on 9/3/13 after a rain fall several days prior. No water was found in the cable vault. Cable vault 0B2 was inspected on 9/19/13 during a rain fall and again after the rain fall stopped on 9/25/13. Only two (2) inches of water was found in the cable vault. No cables were submerged in water. Cable vault 0B2 was inspected again on 10/05/13 after a significant rain fall a few days prior. The cables were found to be submerged in water. The condition was entered into the corrective action program. The water was removed from the cable vault, the cable condition was assessed, and the evaluation was documented in the corrective action program. Additional cable vault inspections were completed on 11/03/13, 11/07/13, 11/11/13, and 12/03/13 after limited rain fall a few days prior. In each case, no water was found in the cable vault.

Based on the investigation to date, the primary source of rain water intrusion into cable vault 0B2 is via cable ducts from an outside handhole. A work order is planned to change the surface grading around the handhole to divert rain water away from the handhole cover, and seal the handhole cover to resist rain water intrusion.

Direct visual inspections of cable vault 0B2 now occur at an increased frequency (once per month) and after any significant rain fall. If water is found in the cable vault during a visual inspection or the cables are found submerged, the condition is entered into the corrective action program, the water is manually pumped out as appropriate, and the cable condition is evaluated in the corrective action program.

This description demonstrates how plant operating experience is incorporated into corrective actions to minimize the exposure of in-scope power cables to significant moisture at Byron.

In conclusion, the in-scope power cables in 15 out of 16 cable vaults at Byron have not been found submerged since the implementation of the cable vault direct inspection and manual pumping plan in 2010.

Braidwood - Current Operating Term Activities Cable Testing There is only one in-scope inaccessible power cable at Braidwood. The in-scope power cable has been tested (insulation resistance) three times since 2003. All cable tests results to date have met all acceptance criteria and it has been determined that the in-scope power cable insulation is in good condition. Testing will continue to be performed to trend and characterize the power cable insulation condition. The current plan is to test the in-scope power cable at least every six years. The cable test frequency may be adjusted based on data trending in accordance with the corrective action program.

Cable Vault Inspection There are no safety-related cable vaults at Braidwood. Visual inspections of the nonsafety-related cable vaults at Braidwood were started in 2008 in response to industry operating experience that expanded the concern of power cables exposed to significant moisture to nonsafety-related power cables. The initial inspections of the cable vaults found varying

RS-14-041 Enclosure A Page 13 of 14 degrees of water inside the cable vaults. The as-found conditions were entered into the corrective action program to initiate appropriate corrective actions and for trending. The cable vaults were emptied, if required, and assessed in order to systematically refurbish the cable vault and the cable support structures.

Seven (7) out of eight (8) in-scope cable vaults were found to be in adequate condition. The concrete on the north wall of cable vault 1E has significant cracks, and loose concrete pieces have fallen away from the wall. The concrete that is separating from the wall is fill concrete around the conduits and is not structural concrete for the vault. The degradation was assessed and determined to be the result of cracks formed from thermal expansion and contraction, moisture intrusion, and the subsequent water freeze-thaw cycles that exacerbate the cracking such that pieces of the concrete fall away from the wall. Wooden shoring has been installed to prevent concrete pieces from dropping on to the cables. Permanent repairs are planned for 2014.

Operational experience and trending determined that the ground water levels at Braidwood are such that ground water intrusion into some of the underground cable ducts and vaults occurs at a rapid rate (less than one week). The trending analysis determined that the in-scope motor driven fire pump power cable could not be kept dry in many of the cable vaults by manual pumping. As a result, the cable vaults that have significant ground water intrusion rates were equipped with automatic dewatering pumps and high water level alarms.

The in-scope cable vaults were refurbished in 2012 and 2013. Since 2012, the in-scope power cable in the cable vaults at Braidwood, have not been found submerged in water. This is because of an effective cable vault automatic pumping system supplemented by a consistently executed visual inspection plan.

Occasionally, a cable vault visual inspection reveals a problem with the sump pump or the discharge line. For example, on August 7, 2013 the sump pump discharge line in cable vault 1F was found to be broken. As a result, the water in the bottom of the cable vault was being re-circulated within the vault. However, the cables were not submerged in water. The condition was entered into the corrective action program. A visual inspection of the cable vault was performed frequently (almost daily) until the discharge pipe was repaired to ensure that that the in-scope power cable did not become submerged in water. The discharge pipe was repaired on August 26, 2013 prior to any significant water level increase in the cable vault.

This description demonstrates how plant operating experience is incorporated into corrective actions to minimize the exposure of the in-scope power cable to significant moisture at Braidwood.

In conclusion, the operating experience at Braidwood demonstrates that the in-scope power cable in the cable vaults has not been submerged in water since the installation of the cable vault automatic pumping system and implementation of the supplementary direct visual inspection plan.

Bryon and Braidwood - LRA AMP B.2.1.39 Implementation Plan The current operating term activities and lessons learned will provide input for the implementation of the LRA AMP B.2.1.39, Inaccessible Power Cables Not Subject to 10 CFR

RS-14-041 Enclosure A Page 14 of 14 50.49 Environmental Qualification Requirements at Byron and Braidwood prior to the period of extended operation. Specifically, additional cable tests will be performed prior to the period of extended operation, and the frequency of the cable test may be adjusted based on data trending, with the maximum interval between tests not exceeding six years, which meets the recommended frequency in GALL Report AMP XI.E3. Also, additional cable vault inspections will be performed prior to the period of extended operation and the frequency of inspections for accumulated water may be adjusted based on inspection results to ensure that the in-scope power cables are not exposed to significant moisture. The cable vault inspection interval will be no longer than one year, which meets the recommended frequency in GALL Report AMP XI.E3.

RS-14-041 Enclosure B Page 1 of 2 Enclosure B Byron and Braidwood Stations, Units 1 and 2 License Renewal Application (LRA) updates resulting from the responses to the following RAI:

RAI B.2.1.39-2 Note: To facilitate understanding, the original LRA pages have been repeated in this Enclosure, with revisions indicated. Existing LRA text is shown in normal font. Changes are highlighted with bold italics for inserted text and strikethroughs for deleted text.

RS-14-041 Enclosure B Page 2 of 2 As a result of the response to RAI B.2.1.39-2 provided in Enclosure A of this letter, LRA Appendix B, Section B.2.1.39, page B-260, second paragraph of the Program Description is revised as shown below. Additions are indicated with bolded italics and strikethroughs for deleted text.

B.2.1.39 Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements Program Description The Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements program is a new condition monitoring program that manages non-EQ, in scope, inaccessible or underground (e.g. in conduit, duct bank, or direct buried) power cables that are exposed to significant moisture. For this program, power is defined as greater than or equal to 400 V. Significant moisture is defined as periodic exposure to moisture that lasts more than a few days (e.g., cable wetting or submergence in water). Periodic exposures that last less than a few days (e.g., normal rain and drain) are not significant. Power cable exposure to significant moisture may cause reduced insulation resistance that can potentially lead to failure of the cable's insulation system.

The cables in the scope of this aging management program will be tested using a one or more proven tests for detecting reduced insulation resistance of the cables insulation system due to wetting or submergence, such as Dielectric Loss (Dissipation Factor or Power Factor), AC Voltage Withstand, Partial Discharge, Step Voltage, Time Domain Reflectometry, Insulation Resistance and Polarization Index, Line Resonance Analysis, or other testing that is state-of-the-art at the time the test is performed. Corrective actions such as more frequent testing or replacement of the affected cable are taken and a determination is made as to whether the same condition or situation is applicable to other accessible or inaccessible, in-scope power cables when test results do not meet acceptance criteria or operating experience suggests more frequent testing is necessary. The cables will be tested at least once every 6 years. The first tests will be completed prior to the period of extended operation.

RS-14-041 Enclosure C Page 1 of 2 Enclosure C Byron and Braidwood Stations (BBS) Units 1 and 2 License Renewal Commitment List Changes This Enclosure identifies commitments made in this document and is an update to the Byron and Braidwood Station (BBS) LRA Appendix A, Table A.5 License Renewal Commitment List.

Any other actions discussed in the submittal represent intended or planned actions and are described to the NRC for the NRCs information and are not regulatory commitments. Changes to the BBS LRA Appendix A, Table A.5 License Renewal Commitment List are as a result of the Exelon response to the following RAI:

RAI B.2.1.39-2 Notes:

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

• Existing LRA text is shown in normal font. Changes are highlighted with bold italics for inserted text and strikethroughs for deleted text.

RS-14-041 Enclosure C Page 2 of 2 As a result of the response to RAI B.2.1.39-2, Item 39 on page A-91 of the License Renewal Commitment List is revised as shown below. The RAI that led to this commitment modification are listed in the SOURCE column. Any other actions described in this submittal represent intended or planned actions. They are described for the NRCs information and are not regulatory commitments.

A.5 License Renewal Commitment List NO. PROGRAM OR COMMITMENT IMPLEMENTATION SOURCE TOPIC SCHEDULE 39 Inaccessible Power Cables Inaccessible Power Cables Not Subject to 10 CFR 50.49 Program to be implemented Section A.2.1.39 Not Subject to Environmental Qualification Requirements is a new program that will prior to the period of extended 10 CFR 50.49 be used to manage the aging effects and mechanisms of non-EQ, in operation.

Environmental Qualification scope, inaccessible power cables.

Requirements First cable tests and manhole Cables will be tested using a one or more proven tests for detecting inspections to be performed reduced insulation resistance of the cables insulation system. The prior to the period of extended Exelon letter cables will be tested at least once every 6 years. More frequent operation. RS-14-041 testing may occur based on test results and operating experience. 2/19/2014 Periodic actions will be taken to prevent inaccessible cables from RAI B.2.1.39-2 being exposed to significant moisture. Manholes associated with the cables included in this program will be inspected for water collection with subsequent corrective actions (e.g., water removal), as necessary. Prior to the period of extended operation, the frequency of inspections for accumulated water will be established and adjusted based on plant specific operating experience with cable wetting or submergence, including water accumulation over time and event driven occurrences such as heavy rain or flooding. Operation of dewatering devices, if installed, will be verified prior to any known or predicted heavy rain or flooding event. During the period of extended operation, the inspections will occur at least annually.