RS-15-021, Fourth Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)

Fourth Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)

ML15058A261
Person / Time
Site:	Limerick
Issue date:	02/27/2015
From:	Jim Barstow Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
EA-12-049, RS-15-021
Download: ML15058A261 (18)

Text

RS-15-021 February 27, 2015 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Limerick Generating Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-39 and NPF-85 NRC Docket Nos. 50-352 and 50-353 Order No. EA-12-049

Subject:

Fourth Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)

References:

1. NRC Order Number EA-12-049, "Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," dated March 12, 2012

2. NRC Interim Staff Guidance JLD-ISG-2012-01, "Compliance with Order EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," Revision 0, dated August 29, 2012

3. NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide,"

Revision 0, dated August 2012

4. Exelon Generation Company, LLC's Initial Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049), dated October 25, 2012

5. Exelon Generation Company, LLC Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049), dated February 28, 2013 (RS-13-022)

6. Exelon Generation Company, LLC First Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA 049), dated August 28, 2013 (RS-13-123)

7. Exelon Generation Company, LLC Second Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA 049), dated February 28, 2014 (RS-14-012)

U.S. Nuclear Regulatory Commission Integrated Plan Report to EA-12-049 February 27, 2015 Page2

8. Exelon Generation Company, LLC Third Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA 049), dated August 28, 2014 (RS-14-210)

9. NRC letter to Exelon Generation Company, LLC, Limerick Generating Station, Units 1 and 2 - Interim Staff Evaluation Relating to Overall Integrated Plan in Response to Order EA-12-049 (Mitigation Strategies) (TAC Nos. MF0847 and MF0848), dated January 10, 2014 On March 12, 2012, the Nuclear Regulatory Commission ("NRC" or "Commission") issued an order (Reference 1) to Exelon Generation Company, LLC (EGC). Reference 1 was immediately effective and directs EGC to develop, implement, and maintain guidance and strategies to maintain or restore core cooling, containment, and spent fuel pool cooling capabilities in the event of a beyond-design-basis external event. Specific requirements are outlined in of Reference 1.

Reference 1 required submission of an initial status report 60 days following issuance of the final interim staff guidance (Reference 2) and an overall integrated plan pursuant to Section IV, Condition C. Reference 2 endorses industry guidance document NEI 12-06, Revision O (Reference 3) with clarifications and exceptions identified in Reference 2. Reference 4 provided the EGC initial status report regarding mitigation strategies. Reference 5 provided the Limerick Generating Station, Units 1 and 2 overall integrated plan.

Reference 1 requires submission of a status report at six-month intervals following submittal of the overall integrated plan. Reference 3 provides direction regarding the content of the status reports. References 6, 7, and 8 provided the first, second, and third six-month status reports, respectively, pursuant to Section IV, Condition C.2, of Reference 1 for Limerick Generating Station. The purpose of this letter is to provide the fourth six-month status report pursuant to Section IV, Condition C.2, of Reference 1, that delineates progress made in implementing the requirements of Reference 1. The enclosed report provides an update of milestone accomplishments since the last status report, including any changes to the compliance method, schedule, or need for relief and the basis, if any. The enclosed report also addresses the NRC Interim Staff Evaluation Open and Confirmatory Items contained in Reference 9.

This letter contains no new regulatory commitments. If you have any questions regarding this report, please contact David P. Helker at 610-765-5525.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 2th day of February 2015.

Respectfully submitted, James Barstow Director - Licensing & Regulatory Affairs Exelon Generation Company, LLC

U.S. Nuclear Regulatory Commission Integrated Plan Report to EA-12-049 February 27, 2015 Page 3

Enclosure:

1. Limerick Generating Station, Units 1 and 2 Fourth Six-Month Status Report for the Implementation of Order EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events cc:

Director, Office of Nuclear Reactor Regulation NRC Regional Administrator - Region I NRC Senior Resident Inspector-Limerick Generating Station, Units 1 and 2 NRC Project Manager, NRA Limerick Generating Station, Units 1 and 2 Ms. Jessica A. Kratchman, NRR/JLD/PMB, NRC Mr. Jack R. Davis, NRR/DPR/MSD, NRC Mr. Eric E. Bowman, NRR/DPR/MSD, NRC Mr. Jeremy S. Bowen, NRR/DPR/MSD/MSPB, NRC Mr. Robert L. Dennig, NRR/DSS/SCVB, NRC Mr. John D. Hughey, NRR/JLD/JOMB, NRC Director, Bureau of Radiation Protection - Pennsylvania Department of Environmental Resources R. R. Janati, Chief, Division of Nuclear Safety, Pennsylvania Department of Environmental Protection, Bureau of Radiation Protection

Enclosure Limerick Generating Station, Units 1 and 2 Fourth Six-Month Status Report for the Implementation of Order EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (14 pages)

Limerick Generating Station. Units I and 2 Fourth Six Month Status Report for the Implementation of FLEX February 27. 2015 Enclosure Limerick Generating Station, Units 1 and 2 Fourth Six Month Status Report for the Implementation of Order EA-12-049, Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events l

Introduction Limerick Generating Station. Units 1 and 2 developed an Overall Integrated Plan (Reference I in Section 8). documenting the diverse and flexible strategies (FLEX), in response to NRC Order EA-12-049 (Reference 2). This enclosure provides an update of milestone accomplishments since submittal of the last status report, including any changes to the compliance method. schedule. or need for relief/relaxation and the basis, if any.

2 Milestone Accomplishments The following mitestone(s) have been completed since the August 28. 2014 status report (Reference 10) and are current as of January 31, 2015.

All Unit 2 Engineering change packages for plant modifications have been approved and issued.

The first FLEX generator has been received.

3 Milestone Schedule Status The following provides an update to Attachment 2 of the Overall Integrated Plan (Reference I). It provides the activity status of each item. and whether the expected completion elate has changed. The dates are planning dates subject to change as design and implementation details are developed.

The need for relief/relaxation on site implementation of Order EA-12-049 is provided in Section 5 of this enclosure.

Milestone Schedule Site: Limerick Generating Station Target Revised Target Activity Completion Activity Status Completion Date Date Submit 60 Day Status Report October 2012 Complete Submit Overall Integrated Plan February 2013 Complete Contract with RRC October 2012 Complete Submit 6 Month Updates:

Update 1 August 2013 Complete Update 2 February 2014 Complete Page 1 of 14

Limerick Generating Station. Units I and 2 Fourth Six Month Status Report for the Implementation of FLEX February 2015 Target Revised Target Activity Completion Activity Status Completion Date Date Update 3 August 2014 Complete Update 4 February 2015 Complete with this submittal Update 5 August 2015 Not Started Update 6 February 2016 Not Started Update 7 August 2016 Not Started Submit Completion Report April 2016 Not Started April 2018 See Section 5 Modification Development &

Implementation:

Target date Unit I Modification Development (All change for June 2015 Started Engineering will FLEX Phases) not impact implementation dates Unit I Modification Implementation (All April 2016 Statted FLEX Phases)

Unit 2 Modification Development (All November 2014 Complete FLEX Phases)

Unit 2 Modification Implementation (All April 2015 Started FLEX Phases)

Procedures:

Create Site-Specific Procedures April 2015 Statted Validate Procedures (NEI I 2-06. Sect.

February 2015 Statted March 2015 11.4.3)

Create Maintenance Procedures April 2015 Not Stmted Perform Staffing Analysis November 2014 Complete Storage Plan and Construction April 2015 Statted FLEX Equipment Acquisition April 2015 Started Training Completion April 2015 Started Regional Response Center Operational December 2014 Complete Page 2 of 14

Limerick Generating Station. Units I and 2 Fourth Six Month Status Report for the Implementation of FLEX Fehruary 2015 Target Revised Target Activity Completion Activity Status Completion Date Date I Unit 1 FLEX Implementation April 2016 Started April 2018 See Section 5 Unit 2 FLEX Implementation April 2015 Stm1ed April 2017 See Section 5 I Full Site FLEX Implementation April 2016 Sta11ed April 2018 See Section 5 I

4 Changes to Compliance Method There are no changes to the FLEX strategies identified at this time.

5 Need for Relief/Relaxation and Basis for the Relief/Relaxation This section provides a summary of needed relief/relaxation only.

Limerick Generating Station will he in compliance with the of the Reference l Unit I and Unit 2 Mitigation that do not rely upon a Hardened Containment Vent System unless otherwise descrihed.

Limerick Generating Station submitted the request for relaxation to the NRC by letter dated February 26.

2014 (Reference 8). The NRC approved the Limerick relaxation request for full compliance of NRC Order EA-12-049 by letter dated April 15. 2014 (Reference 9).

6 Open Items from Overall Integrated Plan and Draft Safety Evaluation The following tables provide a summary of the open items documented in the Overall Integrated Plan or the Draft Safety Evaluation (SE) and the status of each item.

0 IP Section Reference Overall Integrated Plan Open Item Status Sequence of Events (p. 8)

The times to complete aetions in the Events Started Timeline are based on operating judgment, conceptual designs. and cunent supporting analyses. The final timeline will be time validated once detailed designs are completed and procedures developed.

Page 3 of 14

Limerick Generating Station. Units I and 2 Fourth Six Month Status Report for the Implementation of FLEX February 27. 2015 Sequence of Events (p. 7)

Installed Phase I Equipment (p.37)

Sequence of Events (p. 7)

Identify how strategies will be deployed in all modes (p. 11)

Identify how the programmatic controls will be met (p. 12)

Initial evaluations were used to determine the fuel pool timelines. Formal calculations will he performed to validate this information during development of the spent fuel pool cooling strategy detailed design.

Analysis of deviations between Exelon's engineering analyses and the analyses contained in BWROG Document NEDC-33771 P. "GEH Evaluation of FLEX Implementation Guidelines" and documentation of results was not completed and submitted with the Overall Integrated Plan (Reference I).

Transportation routes will be developed from the equipment storage area to the FLEX staging areas. An administrative program will be developed to ensure pathways remain clear or compensatory actions will be implemented to ensure all strategies can be deployed during all modes of operation.

Identification of storage areas and creation of the administrative program are open items.

An administrative program for FLEX to establish responsibilities, and testing &

maintenance requirements will be i mplernented.

Page 4 of 14 Complete (Reference 10)

Complete (Reference 4)

Started Storage Building locations for equipment have been identified and travel routes to point of use determined.

A change is being made in 1

1 the site yard storage approval procedure (MA-LG-716-026-100 l) to review and approve yard laydown requests. This procedure change is being tracked to completion.

The haul path evaluation is in progress and will be documented in Technical Evaluation 1550669-08.

Started A corporate fleet-wide program (CC-AA-118) has been approved and the site specific portion of the program (CC-LG-118) is under development.

Limerick Generating Station, Units l and 2 Fourth Six Month Status Rep011 for the Implementation of FLEX February 27. 2015 Sequence of Events (p. 9)

Additional work will be performed dming detailed design development to ensure A review of the BWROG Suppression Pool temperature will suppo11 RCIC paper has been RCIC operation, in accordance with approved completed to confirm that BWROG analysis. throughout the event.

elevated suppression pool temperatures will support RCIC operation during a BDBEE. One open item remains a review of pipe stresses at elevated temperatures, and is being tracked to completion.

Portable Equip Phase 2 Complete an evaluation of the spent fuel pool Complete with this (p. 50) area for steam and condensation.

submittal.

Calculation LM-0710 has been prepared to evaluate spent fuel area heat up rates (posted to ePortal).

Installed Equip Phase l Evaluate the habitability conditions for the Started (p.47)

Main Control Room and develop a strategy to Habitability conditions maintain habitability.

within the MCR and other Portable Equip Phase 2 areas of the plant will be (p. 49) maintained with a tool box approach limiting the impact of high temperatures with methods such as supplemental cooling, personnel rotation and/or availability of fluids.

Technical Evaluation 1550669-04 (posted on ePortal) concludes that actions to ventilate the main control room will not be required until after at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> post event.

Guidance for establishing ventilation has been included in site procedure T-362 that has been drafted.

Page 5of14

Limerick Generating Station. Units I and 2 Fourth Six Month Status Report for the Implementation of FLEX Installed Equip Phase 1 (pA7)

Portable Equip Phase 2 (p. 50)

Item Number Open Item 3. I. 1. 2. A Open Item 3.1.1.3.A Open Item 3.1.2.2.A Open Item 3.2.3.A February 2015 Develop a procedure to prop open battery room doors upon the battery chargers to prevent a buildup of hydrogen in the battery rooms.

Interim Staff Evaluation (ISE)

Open Items I Confirmatory Actions NEI 12-06 states that if power is required to move or deploy the equipment to open the door from a storage location). then power supplies should be provided as part of the deployment. The Integrated Plan did not address whether or not power would be required to move or deploy equipment and thus this evaluation must be completed satisfactorily.

The licensee did not address actions to be taken if key instruments were lost due to a seismic event. as specified in NEI 12-06, section 5.3.3. Verify that this activity is completed satisfactorily.

Further review is required regarding how the licensee will address NEI 12-06 Section 6.2.3.2 deployment considerations 2, 4, 5, and 8 with respect to transient floods. This review shall include an applicable procedure review.

With regard to maintaining containment. the implementation of Boiling Water Reactor Owners Group (BWROG) Emergency Procedure Guideline (EPG)/Severe Accident Guideline (SAG), Revision 3, including any associated plant-specific evaluations. must be completed in accordance with the provisions of NRC letter dated January 9, 2014.

Page 6 of 14 Started Technical Evaluation 1550669-05 (posted on ePortal) documents that ventilation is not required until 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the event. Guidance for establishing ventilation has been included in site procedure T-361 that has been drafted.

Status Complete (Reference lO )

Started Procedure T-370 has been drafted providing guidance for monitoring plant parameters using alternate instrumentation.

Complete (Reference 7)

Complete Note I

Open Item 3.2.4.2.C Open Item 3.4.A Limerick Generating Station. Units 1 and 2 Fourth Six Month Status Repott for the Implementation of FLEX February 27. 2015 With regard to elevated temperatures in Complete (Reference I 0) general. the licensee should provide an evaluation of the impact of elevated temperatures. as a result of loss of ventilation and/or cooling. on electrical equipment being credited as part of the ELAP strategies (e.g.,

electrical equipment in the RCIC pump rooms).

The licensee should provide details that Complete with this demonstrate the minimum capabilities for submittal.

offsite resources will be met. per NEI 12-06 All licensees, including Section I Exelon Generation Company. relying on SAFER and the National SAFER Response Centers (NSRC), have executed contractual agreements with Pooled Equipment Inventory Company (PEI Co) which allows for the capabilities (considerations) in Section 12.2 of NEI 12-06. The NRC audit results concluded that the NSRCs and the SAFER plans and procedures conform to the guidance described by the 10 capabilities (considerations) of NEI 12-06, Section 12.2.

By letter dated September

26. 2014 the NRC endorsed the SAFER program as meeting the requirements of Order EA-12-049 (ML14265A107). The details of the SAFER program are outlined in a letter from NEI to the NRC dated September 1 1, 2014 (ML14259A222 and an NEI white paper, ML l 4259A223).

Page 7 of 14 I

Confirmatory Item 3.1.1.4.A Confirmatory Item J.1.5.2.A Confirmatory Item 3.2.1.1.A Confirmatory Item 3.2.1.1.8 Confirmatory Item 3.2. l. l.C Confirmatory Item J.2.1.1.D Confirmatory Item 3.2.1.3.A Limerick Generating Station. Units I and 2 Fourth Six Month Status Report for the Implementation of FLEX February 27. 2015 With regard to offsite resources, confirm that Complete the licensee develops a plan that will address Note I the logistics for equipment transportation.

area set up. and other needs for ensuring the equipment and commodities to sustain the site's coping strategies.

The licensee stated that the design of the Complete with this storage facilities will include provisions to submittal.

ensure the equipment storage facilities are not CBI design specification impacted by high temperatures. Confirm that 151871-DC-C-OOOO I shows this is evaluated appropriately.

the design requirements for the robust buildings (posted on ePortal).

Benchmarks must be identified and discussed Complete (Reference I 0) which demonstrate that Modular Accident Analysis Program (MAAP) is an appropriate code for the simulation of an ELAP event at LGS. consistent with the NRC endorsement of the industry position paper on MAAP.

Confirm that the collapsed reactor pressure Complete (Reference I 0) vessel level remains above Top of Active Fuel and the reactor coolant system cool down rate is within technical specifications limits.

Confirm that MAAP is used in accordance Complete (Reference I 0) with Sections 4.1. 4.2. 4.3. 4.4. and 4.5 of the June 2013 position paper.

Confirm that, in using MAAP. the licensee Complete (Reference I 0) identifies and justifies the subset of key modeling parameters cited from Tables 4-1 through 4-6 of the "MAAP Application Guidance, Desktop Reference for Using MAAP Software, Revision 2" (Electric Power Research Institute Report I 020236).

The licensee stated that the "times to complete Sta1ted actions in the events timeline are based on...

current supporting analyses." Confirm that the final timeline is validated once detailed designs are completed and procedures are developed.

Page 8 of 14 I I i

Confirmatory Item 3.2.1.4.A Confirmatory Item 3.2.1.4.B Confirmatory Item 3.2.1.4.C Confirmatory Item 3.2.1.7.A Limerick Generating Station. Units 1 and 2 Fourth Six Month Status Repo11 for the Implementation of FLEX February 27. 2015 The licensee stated that the detailed design will determine containment heat-up rate and the subsequent impacts on RCIC operation and the need for any modifications. Confirm that this evaluation is completed satisfactorily.

The licensee identified two RCIC room switch set points that were above the predicted maximum temperature but pointed out that the "RCIC Equipment Room Delta Temperature High" setpoint was below that temperature at 109 °F. It is not clear whether or not any of the setpoints would have an adverse impact on the planned use of the RCIC as a mitigation strategy. Thus, further clarification is needed for this issue.

Because the Integrated Plan makes reference to use of the Phase 3 equipment as backup, the Integrated Plan should address the guidance of NEI 12-06 regarding site procedures for Phase 3 implementation. The licensee addressed this concern during the audit response and stated that LGS would ensure connection capabilities of the Phase 3 off site equipment to site systems and would develop any procedural guidance required for those connections. Confirm that the connections for the Phase 3 equipment have been properly determined. once the details are finalized.

The licensee stated that LGS plans to abide by the generic resolution for refueling and cold shutdown conditions. The licensee stated that a review is in progress to develop a plan to address potential plant specific issues associated with implementing the generic approach. Confirm that this evaluation is completed satisfactorily.

Page 9 of 14 Started A review of the BWROG RCIC paper has been completed to confirm that elevated suppression pool temperatures will support RCIC operation during a BDBEE. One open item remains a review of pipe stresses at elevated temperatures. and is being tracked to completion.

Complete (Reference Complete (Reference I 0)

Complete Note I

Confirmatory Item 3.2.1.8.A Confirmatory Item 1.8.B Confirmatory Item 3.2.2.A Confirmatory Item 3.2.4.2.A Confirmatory Item 3.2.4.2.B Limerick Generating Station. Units 1 and 2 Fourth Six Month Status Report for the Implementation of FLEX February 27. 2015 The licensee stated that the final design of the Complete FLEX pump suction will determine if additional screens are required. Confirm that the potential for entrained debris as a result of extreme external hazards (e.g., suspended solids especially during flood conditions. or from high wind debris) in the cooling water from the spray pond is addressed.

Insufficient technical information is presented Complete (Reference I or referenced in the Integrated Plan to confirm the ability of the portable FLEX pumps to deliver the required flow through the system of FLEX hoses, couplings, valves. elevation changes, etc. for the configurations described.

Confirm that these evaluations are completed and documented.

The licensee stated that formal calculations Complete (Reference I 0) will be performed to validate the timing required for supplying cooling water to the spent fuel pool. Confirm that these calculations are performed. with acceptable results.

It was not clear from the information Complete with this presented in the Integrated Plan what analysis submittal.

or technical basis was used to conclude that Technical Evaluation the battery room temperature rise is 1550669-05 (posted on inconsequential. Also, no discussion was ePortal) documents the presented to address possible low temperature battery impacts from effects. Confirm the adequacy of the battery elevated or lowered room ventilation to protect the batteries from temperature.

the effects of elevated or lowered temperatures.

The licensee stated that battery room Started ventilation will be addressed through Based on the computations procedure changes and that the proposed noted above. proceduralized methods of ventilation, open doors and fans, actions are being developed will be confirmed during the detailed design to address battery room process. Confirm that this is completed ventilation. Draft satisfactorily.

procedure T-361 for battery room ventilation has been written.

Page 10 of 14 I

Limerick Generating Station. Units l and 2 Fourth Six Month Status Report for the Implementation of FLEX February 2015 Confirmatory Item Confirm that the proposed communications Started 3.2.4.4.A upgrades in the licensee's communications Communications upgrade assessment are completed as planned.

conceptual design is complete.

For the I st - 2nd refuel outage. (Li2R 13). the site will have 3 portable Iridium Satellite phones available for the SM/SEO in the MCR area.

Additional handheld radios for use on talk-around with spare batteries will be staged in the robust FLEX building. Bull horns for help with notifications are staged in the MCR.

In addition. for the 2nd -

2nd refuel outage, (Li IR16), the site will complete the NARS Upgrade satellite communications system along with additional satellite handsets installed in the MCR.

Confirmatory Item The licensee stated that keys for access to the Complete with this 3.2.4.5.A plant are available to security, the shift submittal.

manager and to the radiation protection group.

The key analysis has been The licensee further stated that plant areas completed and additional requiring access as part of the FLEX security keys have been response, will be evaluated to determine if placed in the Shift Manager sufficient keys are available or if additional key locker. This will keys will be required. Confirm that this ensure all field operators evaluation is completed.

will be issued vital area keys to allow movement in and out of required vital areas without delay.

Page 11 of 14

Confirmatory Item 3.2.4.6.A Confirmatory Item 3.2.4.6.B Confirmatory Item 3.2.4.8.A Confirmatory Item 3.2.4.10.B Limerick Generating Station. Units I and 2 Fourth Six Month Status Report for the Implementation of FLEX February 2015 According to the licen habitability conditions will be evaluated and a strategy will be developed for the main control room.

Confirm that the and associated suppo1t analyses are completed.

With regard to the fuel building habitability.

the licensee acknowledged that the evaluation of the spent fuel pool area for steam and condensation has not yet been performed.

Confirm that this evaluation is completed. and its resulting conclusions satisfactorily addressed.

The Integrated Plan did not provide information regarding the technical basis for the selection and size of the FLEX generators to be used in support of the coping strategies.

Confirm that this evaluation is satisfactorily completed.

The licensee stated minimum limit for the de bus voltage is 105 volts. More information is needed to understand if this minimum voltage provides for sufficient operating voltages at the device terminals to ensure proper operation in support of the strategies.

Page 12 of 14 Started Technical Evaluation 1550669-04 (posted on ePortal) concludes that actions in the main control room will not be required until after at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> post event. Guidance for establishing ventilation has been included in a new site procedure (T-362).

Habitability conditions within the MCR and other areas of the plant will be maintained with a tool box approach limiting the impact of high temperatures with methods such as supplemental cooling, personnel rotation and/or availability of fluids.

Started Calculation LM-0710 has been prepared to evaluate spent fuel area heat up rates. (posted on ePortal)

T-346 has been drafted to direct these setup activities early enough following the event and before the conditions become unfavorable for hose setup.

Complete (Reference I 0)

Complete (Reference 7)

Limerick Generating Station. Units I and 2 Fourth Six Month Status Report for the Implementation of FLEX February 2015 Confirmatory Item Although the licensee addressed the potential Complete 3.2.4.10.C adverse impact from load shedding on main Note 1 generator hydrogen control. the licensee needs to address any other potential adverse impacts to mitigation strategies resulting from the load shed plan.

Note 1: The information with respect to these ISE Open and Confirmatory items was presented to the NRC FLEX Audit Team during their onsite visit the week of October 12. 2014. Work is either in-progress or completed for each of the items. The "status of the item (OPEN or CLOSED) is determined by the NRC through the audit process. Preliminary classification from the Audit Team, pending review and approval through the NRC audit report generation and approval process, is that all of these items are to be statused as closed. The status of all of these items will be updated in a future 6-Month Update pending receipt of the NRC FLEX Audit Repott.

7 Potential Draft Safety Evaluation Impacts There are no potential impacts to the Draft Safety Evaluation identified at this time.

8 References The following references support the updates to the Overall Integrated Plan described in this enclosure.

1.

Exelon Generation Company. LLC, Overall Integrated Plan in Response to March 12. 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049). dated February 28. 2013 (RS-13-022)

2.

NRC Order Number EA-12-049. "Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events." dated March

12. 2012

3.

NRC Order EA-13-109, "Issuance of Order to Modify Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions," dated June 6. 2013

4.

Exelon Generation Company, LLC, First Six-Month Status Report in Response to March 12.

2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigating Strategies for Beyond-Design Basis External Events (Order Number EA-12-049), dated August

28. 2013 (RIS13-123)

5.

NRC Letter to Exelon Generation Company. LLC. Limerick Generating Station Units 1 and 2.

Interim Staff Evaluation Relating to Overall Integrated Plan in Response to Order EA-12-049 (Mitigating Strategies) dated January 10, 2014

6.

NEl 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide." Revision 0, dated August 2012

7.

Exelon Generation Company, LLC. Second Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigating Strategies for Beyond-Design Basis External Events (Order Number EA-12-049), dated February 28, 2014 (RIS 14-012)

Page 13 of 14

Limerick Generating Station. Units I and 2 Fourth Six Month Status Report for the Implementation of FLEX February 2015

8.

Exelon Generation Company. LLC. Limerick Generating Station Units I and 2. "Request for Relaxation from NRC Order EA-12-049, "Order Modifying Licenses With Regard To Requirements For Mitigation Strategies For Beyond-Design-Basis External Events." Dated February 26. 20 I 4 (RS-14-044)

9.

NRC Letter to Exelon Generation Company. LLC, Limerick Generating Station. Units I and 2 -

Relaxation of Certain Schedular Requirements for Order EA-12-049 "Issuance of Order to Modify Licenses with regard to Requirements for Mitigation for Beyond Design Basis External Events." Dated April 15. 2014

10. Exelon Generation Company. LLC. Third Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigating Strategies for Beyond-Design Basis External Events (Order Number EA-12-049), dated August 28, 2014 (RS-14-210) 9 Attachments

1.

None Page 14 of 14