RS-18-012, Tenth 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)

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Tenth 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)
ML18059A219
Person / Time
Site: Limerick Constellation icon.png
Issue date: 02/28/2018
From: Jim Barstow
Exelon Generation Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
EA-12-049, RS-18-012
Download: ML18059A219 (18)
v • d • e


Text

Exelon Generation .

Order No. EA-12-049 RS-18-012 February 28, 2018 U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, DC 20555-0001 Limerick Generating Station, Unit 1 Renewed Facility Operating License No. NPF-39 NRC Docket No. 50-352

Subject:

Tenth 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 O, 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 28, 2018 Page 2

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. Exelon Generation Company, LLC 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 049), dated February 27, 2015 (RS-15-021) 1O. Exelon Generation Company, LLC Fifth 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, 2015 (RS-15-212)
11. Exelon Generation Company, LLC Sixth 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 26, 2016 (RS-16-024)
12. Exelon Generation Company, LLC Seventh 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 26, 2016 (RS-16-147)
13. Exelon Generation Company, LLC Eighth 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, 2017 (RS-17-020)
14. Exelon Generation Company, LLC Ninth 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, 2017 (RS-17-095)
15. NRG 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
16. NRG letter to Exelon Generation Company, LLC, Limerick Generating Station, Units 1 and 2 - Report for the Audit Regarding Implementation of Mitigating Strategies and Reliable Spent Fuel Pool Instrumentation Related to Orders EA-12-049 and EA-12-051 (TAC Nos. MF0847, MF0848, MF0854, and MF0855), dated March 17, 2015
17. Exelon Generation Company, LLC, Report of Full Compliance with 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 July 20, 2017 (RS-17-062)

On March 12, 2012, the Nuclear Regulatory Commission ("NRG" or "Commission") issued an order (Reference 1) to Exelon Generation Company, LLC (EGG). Reference 1 was immediately effective and directs EGG 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 Attachment 2 of Reference 1.

U.S. Nuclear Regulatory Commission Integrated Plan Report to EA-12-049 February 28, 2018 Page 3 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, 8, 9, 1O, 11, 12, 13, and 14 provided the first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth 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 tenth 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 15, and any NRC Audit Report open items contained in Reference 16.

The Limerick Generating Station, Unit 2 HCVS Phase 1 installation was complete at the end of the Li2R14 refuel outage in May 2017. Limerick Generating Station, Unit 2 is now in full compliance with NRC Order EA-12-049 as described in Reference 17.

This letter contains no new regulatory commitments. If you have any questions regarding this report, please contact David J. Distel at 610-765-5517.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 281h day of February 2018.

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

Enclosure:

Limerick Generating Station, Unit 1 Tenth 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

U.S. Nuclear Regulatory Commission Integrated Plan Report to EA-12-049 February 28, 2018 Page 4 cc: NRC Regional Administrator - Region I NRC Senior Resident Inspector - Limerick Generating Station NRC Project Manager, NRA - Limerick Generating Station Mr. Jason C. Paige, 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, Unit 1 Tenth 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 (13 pages)

Limerick Generating Station, Unit I Tenth Six Month Status Report for the Implementation of FLEX February 28, 2018 Enclosure Limerick Generating Station, Unit 1 Tenth 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 1 Introduction Limerick Generating Station, Units I 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.

With the report of Unit 2 full compliance (Reference 21) on July 20, 2017, this six-month update provides the status of Limerick Generating Station, Unit I mitigating strategies implementation.

2 Milestone Accomplishments The following milestone(s) have been completed since the August 28, 2017 status report (Reference 22) and are current as of February 15, 2018.

  • None 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 date 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 I August 2013 Complete Page I of 13

Limerick Generating Station, Unit I Tenth Six Month Status Report for the Implementation of FLEX February 28, 2018 Target Revised Target Activity Completion Activity Status Completion Date Date Update 2 February 2014 Complete Update 3 August 2014 Complete Update 4 February 2015 Complete Update 5 August 2015 Complete Update 6 February 20 16 Complete Update 7 August 2016 Complete Update 8 February 2017 Complete Update 9 August 2017 Complete Complete with Update IO February 2018 this submittal Date change aligns with Submit Completion Report June 2018 Not Started completion of Refuel Outage (Li I RI 7)

Modification Development &

Implementation:

Unit I Modification Development (All September 2015 Complete FLEX Phases)

Unit I Modification Implementation (All April 2016 Complete FLEX Phases)

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

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

Procedures:

Create Site-Specific Procedures April 2015 Complete Validate Procedures (NEI 12-06, Sect.

March 2015 Complete 11.4.3)

Create Maintenance Procedures April 2015 Complete Perform Staffing Analysis November 2014 Complete Storage Plan and Construction October 2015 Complete Page 2 of 13

Limerick Generating Station, Unit I Tenth Six Month Status Report for the Implementation of FLEX February 28, 2018 Target Revised Target Activity Completion Activity Status Completion Date Date FLEX Equipment Acquisition April 2015 Complete Training Completion April 2015 Complete Regional Response Center Operational December 2014 Complete Unit 1 FLEX Implementation April 2018 Started See Section 5 Unit 2 FLEX Implementation May 2017 Complete See Section 5 Full Site FLEX Implementation April 2018 Started See Section 5 4 Changes to Compliance Method None 5 Need for Relief/Relaxation and Basis for the Relief/Relaxation This section provides a -,urnmary of needed relief/relaxation only.

Limerick Generating Station is in compliance with the a-,pects of the Reference I, Unit I and Unit 2 Mitigation Strategie~ that do not rely upon a Hardened Containment Vent Sy<>tem. Limerick Generating Station submitted the reque-;t 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).

The Limerick Generating Station, Unit 2 HCYS Order Phase I installation was complete at the end of the Li2R 14 refuel outage in May 2017. Limerick Generating Station, Unit 2 is now in full compliance with NRC Order EA-12-049 a~ de~cribed in Reference 21.

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.

Page 3 of 13

Limerick Generating Station, Unit 1 Tenth Six Month Status Report for the Implementation of FLEX February 28, 2018 Section Reference Overall Integrated Plan Open Item Status Sequence of Events (p. 8) The times to complete actions in the Events Complete (Reference 17)

Timeline are based on operating judgment, conceptual designs, and current supporting analyses. The final timeline will be time validated once detailed designs are completed and procedures developed.

Sequence of Events (p. 7) Initial evaluations were used to determine Complete (Reference 10)

Installed Phase 1 the fuel pool timelines. Formal calculations Equipment (p.37) will be performed to validate this information during development of the spent fuel pool cooling strategy detailed design.

Sequence of Events (p. 7) Analysis of deviations between Exelon's Complete (Reference 4) engineering analyses and the analyses contained in BWROG Document NEDC-33771P, "GEH Evaluation of FLEX Implementation Guidelines" and documentation of results was not completed and submitted with the Overall Integrated Plan (Reference 1).

Identify how strategies Transportation routes will be developed Complete (Reference 17) will be deployed in all from the equipment storage area to the modes FLEX staging areas . An administrative (p. 11) 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 .

Identify how the An administrative program for FLEX to Complete (Reference 17) programmatic controls establish responsibilities, and testing &

will be met (p. 12) maintenance requirements will be implemented.

Page 4 of 13

Limerick Generating Station, Unit l Tenth Six Month Status Report for the Implementation of FLEX February 28, 2018 Section Refere nee Overall Integrated Plan Open Item Status Sequence of Events (p. 9) Additional work will be performed during Complete (Reference 17) detailed design development to ensure Suppression Pool temperature will support RCIC operation, in accordance with approved BWROG analysis, throughout the event.

Portable Equip Phase 2 Complete an evaluation of the spent fuel Complete (Reference 11)

(p. 50) pool area for steam and condensation.

Installed Equip Phase l Evaluate the habitability conditions for the Complete (Reference 17)

(p.47) Main Control Room and develop a strategy to maintain habitability .

Portable Equip Phase 2 (p. 49)

Installed Equip Phase I Develop a procedure to prop open battery Complete (Reference 17)

(p.47) room doors upon energizing the battery chargers to prevent a buildup of hydrogen in Portable Equip Phase 2 the battery rooms.

(p. 50)

Item Number Interim Staff Evaluation (ISE)

Status Open Items I Confirmatory Actions Open Item 3.1.1.2.A NEI 12-06 states that if power is required to Complete (Reference I 0) move or deploy the equipment (e.g., 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 satisfactori Iy.

Open Item 3. l. l.3 .A The licensee did not address actions to be Complete (Reference 17) 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.

Page 5 of 13

Limerick Generating Station, Unit I Tenth Six Month Status Report for the Implementation of FLEX February 28, 2018 Item Number Interim Staff Evaluation (ISE)

Status Open Items I Confirmatory Actions Open Item 3.1.2.2.A Further review is required regarding how the Complete (Reference 7) licensee will address NEI 12-06 Section Complete (Reference 17)

NRC Audit Open Item 6.2.3.2 deployment considerations 2, 4, 5, and 8 with respect to transient floods. This review shall include an applicable procedure review.

Open Item 3.2.3.A With regard to maintaining containment, the Complete (Reference 17) 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.

Open Item 3.2.4.2.C 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 room~) .

Open Item 3.4.A The licensee should provide details that Complete (Reference 11) demonstrate the minimum capabilities for offsite resources will be met, per NEI 12-06 Section 12.2.

Confirmatory Item With regard to offsite resources, confirm that Complete (Reference 17) 3.1.1.4.A the licensee develops a plan that will address the logistics for equipment transportation, area set up, and other needs for ensuring the equipment and commodities to sustain the site's coping strategies.

Confirmatory Item The licensee stated that the design of the Complete (Reference 11)

3. 1.5.2.A storage facilities will include provisions to ensure the equipment storage facilities are not impacted by high temperatures. Confirm that this is evaluated appropriately.

Page 6 of 13

Limerick Generating Station, Unit I Tenth Six Month Status Report for the Implementation of FLEX February 28, 20 I 8 Item Number Interim Staff Evaluation (ISE)

Status Open Items I Confirmatory Actions Confirmatory Item Benchmarks must be identified and Complete (Reference I 0) 3.2.1.1.A discussed 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.

Confirmatory Item Confirm that the collapsed reactor pressure Complete (Reference I 0) 3.2.1.1.8 vessel level remains above Top of Active Fuel and the reactor coolant system cool down rate is within technical specifications limits.

Confirmatory Item Confirm that MAAP is used in accordance Complete (Reference 10) 3.2.1.1.C with Sections 4. I, 4.2, 4.3, 4.4, and 4.5 of the June 20 I 3 position paper.

Confirmatory Item Confirm that, in using MAAP, the licensee Complete (Reference I 0) 3.2.1.1.D identifies and justifies the subset of key modeling parameters cited from Tables 4- I through 4-6 of the "MAAP Application Guidance, Desktop Reference for Using MAAP Software, Revision 2" (Electric Power Research Institute Report I 020236).

Confirmatory Item The licensee stated that the "times to Complete (Reference I 7) 3.2. 1.3.A complete actions in the events timeline are based on ... current supporting analyses."

NRC Audit Open Item Confirm that the final timeline is validated once detailed designs are completed and procedures are developed.

Confirmatory Item The licensee stated that the detailed design Complete (Reference 17) 3.2.1.4.A 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 satisfactori 1y.

Page 7 of 13

Limerick Generating Station, Unit 1 Tenth Six Month Status Report for the Implementation of FLEX February 28, 2018 Item Number Interim Staff Evaluation (ISE)

Status Open Items I Confirmatory Actions Confirmatory Item The licensee identified two RCIC room Complete (Reference 7) 3.2.1.4.B 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.

Confirmatory Item Because the Integrated Plan makes reference Complete (Reference 10) 3.2.1.4.C 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 offsite 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.

Confirmatory Item The licensee stated that LGS plans to abide Complete (Reference 12) 3.2.1.7.A by the generic resolution for refueling and Complete (Reference 17) 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.

Confirmatory Item The licensee stated that the final design of Complete (Reference 10) 3.2.1.8.A the 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.

Page 8of13

Limerick Generating Station, Unit I Tenth Six Month Status Report for the Implementation of FLEX February 28, 20 I 8 Item Number Interim Staff Evaluation (ISE)

Status Open Items I Confirmatory Actions Confirmatory Item Insufficient technical information is Complete (Reference I 0) 3.2.1.8.B presented 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.

Confirmatory Item The licensee stated that formal calculations Complete (Reference I 0) 3.2.2.A 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.

Confirmatory Item It was not clear from the information Complete (Reference I 1) 3.2.4.2.A presented in the Integrated Plan what analysis or technical basis was used to NRC Audit Open Item conclude that the battery room temperature rise is inconsequential. Also, no discussion was presented to address possible low temperature effects. Confirm the adequacy of the battery room ventilation to protect the batteries from the effects of elevated or lowered temperatures .

Confirmatory Item The licensee stated that battery room Complete (Reference 17) 3.2.4.2.B ventilation will be addressed through procedure changes and that the proposed methods of ventilation, open doors and fans, will be confirmed during the detailed design process. Confirm that this is completed satisfactori Iy.

Confirmatory Item Confirm that the proposed communications Complete (Reference 19) 3.2.4.4.A upgrades in the licensee's communications assessment are completed as planned.

NRC Audit Open Item Page 9 of 13

Limerick Generating Station, Unit 1 Tenth Six Month Status Report for the Implementation of FLEX February 28, 2018 Item Number Interim Staff Evaluation (ISE)

Status Open Items I Confirmatory Actions Confirmatory Item The licensee stated that keys for access to Complete (Reference 11) 3.2.4.5.A the plant are available to security, the shift manager and to the radiation protection group. The licensee further stated that plant areas requiring access as part of the FLEX response, will be evaluated to determine if sufficient keys are available or if additional keys will be required. Confirm that this evaluation is completed.

Confirmatory Item According to the licensee, habitability Complete (Reference 17) 3.2.4.6.A conditions will be evaluated and a strategy will be developed for the main control room.

Confirm that the strategy and associated support analyses are completed .

Confirmatory Item With regard to the fuel building habitability, Complete (Reference 17) 3.2.4.6.B the licensee acknowledged that the evaluation of the spent fuel pool area for NRC Audit Open Item steam and condensation has not yet been performed. Confirm that this evaluation is completed, and its resulting conclusions satisfactorily addressed.

Confirmatory Item The Integrated Plan did not pro vide Complete (Refere nee 10) 3.2.4.8.A 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.

Confirmatory Item The licensee stated minimum limit for the de Complete (Reference 7) 3.2.4.10.B 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.

Confirmatory Item Although the licensee addressed the potential Complete (Reference 12) 3.2.4.10.C adverse impact from load shedding on main generator hydrogen control, the licensee needs to address any other potential adverse impacts to mitigation strategies resulting from the load shed plan.

Page IO of 13

Limerick Generating Station, Unit 1 Tenth Six Month Status Report for the Implementation of FLEX February 28, 2018 Item Number NRC Audit Open Items Status (Reference 12)

AQ-22 049-RAI- Limerick-22: Support Systems Complete (Reference 17)

Ventilation - Battery Room. Provide a discussion of battery room ventilation to prevent hydrogen accumulation while recharging the batteries in phase 2 or 3. In your response, include a description of the exhaust path if it is different than the design basis. Also provide information on the adequacy of the ventilation provided in the battery room to protect the batteries from the effects of extreme high and low temperatures.

OIP-4 Identify how strategies will be deployed in Complete (Reference 17) all modes (OIP p. 11)

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.

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.

I. 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 Page 11 of 13

Limerick Generating Station, Unit 1 Tenth Six Month Status Report for the Implementation of FLEX February 28, 2018

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 IO, 2014
6. NEI 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)
8. Exelon Generation Company, LLC, Limerick Generating Station Units l 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, 2014 (RS-14-044)
9. NRC Letter to Exelon Generation Company, LLC, Limerick Generating Station, Units 1 and 2 -

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

11. Exelon Generation Company, LLC, Fourth 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 27, 2015 (RS-15-021)
12. NRC Letter to Exelon Generation Company, LLC, Limerick Generating Station, Units l and 2 -

Report for the Audit Regarding Implementation of Mitigating Strategies and Reliable Spent Fuel Pool Instrumentation Related to Orders EA-12-049 and EA-12-051, dated March 17, 2015

13. Exelon Generation Company, LLC letter to USNRC, Request for Schedule Relaxation from NRC Order EA-12-049, "Order Modifying Licenses With Regard To Requirements For Mitigation Strategies For Beyond-Design-Basis External Events" dated April 2, 2015 (RS IO 1)
14. NRC Letter to Exelon Generation Company, LLC, Limerick Generating Station, Unit 2, Relaxation of Certain Schedule Requirements for Order EA-12-049, "Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond Design Basis External Events," dated April 29, 2015
15. Exelon Generation Company, LLC letter to USNRC, Request for Second Schedule Relaxation from NRC Order EA-12-049, "Order Modifying Licenses With Regard To Requirements For Mitigation Strategies For Beyond-Design-Basis External Events" dated July 9, 2015 (RS-15-183)
16. NRC Letter to Exelon Generation Company, LLC, Limerick Generating Station, Unit 2- 180 day Relaxation of Certain Schedule Requirements for Order EA-12-049, "Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond Design Basis External Events," dated July 20, 2015 Page 12 of 13

Limerick Generating Station, Unit I Tenth Six Month Status Report for the Implementation of FLEX February 28, 2018

17. Exelon Generation Company, LLC, Fifth 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, 2015 (RS-15-212)
18. Exelon Generation Company, LLC, Sixth 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 26, 2016 (RS-16-024)
19. Exelon Generation Company, LLC, Seventh 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 26, 2016 (RS-16-147)
20. Exelon Generation Company, LLC, Eight 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, 2017 (RS-17-020)
21. Exelon Generation Company, LLC, Report of Full Compliance with 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), July 20, 2017 (RS-17-062)
22. Exelon Generation Company, LLC, Ninth 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, 2017 (RS-17-095) 9 Attachments
1. None Page 13 of 13
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