RS-17-066, Sixth Six-Month Status Report for Phases 1 and 2 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe..

Sixth Six-Month Status Report for Phases 1 and 2 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe..

ML17181A031
Person / Time
Site:	Limerick
Issue date:	06/30/2017
From:	Jim Barstow Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
EA-13-109, RS-17-066, TAC MF4418, TAC MF4419
Download: ML17181A031 (22)

Text

Exelon Generation Order No. EA-13-109 RS-17-066 June 30, 2017 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

Subject:

Sixth Six-Month Status Report For Phases 1 and 2 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109)

References:

1. NRC Order Number 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

2. NRC Interim Staff Guidance JLD-ISG-2013-02, "Compliance with Order EA-13-109, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation under Severe Accident Conditions", Revision 0, dated November 14, 2013

3. NRC Interim Staff Guidance JLD-ISG-2015-01, "Compliance with Phase 2 Order EA-13-109, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation under Severe Accident Conditions", Revision 0, dated April 2015

4. NEI 13-02, "Industry Guidance for Compliance With Order EA-13-109, BWR Mark I & II Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions", Revision 1, dated April 2015

5. Exelon Generation Company, LLC's Answer to June 6, 2013, Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109), dated June 26, 2013

6. Exelon Generation Company, LLC Phase 1 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109), dated June 30, 2014 (RS-14-060)

7. Exelon Generation Company, LLC First Six-Month Status Report Phase 1 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109), dated December 17, 2014 (RS-14-304)

8. Exelon Generation Company, LLC Second Six-Month Status Report Phase 1 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109), dated June 30, 2015 (RS-15-150)

U.S. Nuclear Regulatory Commission Integrated Plan Report to EA-13-109 June 30, 2017 Page 2

9. Exelon Generation Company, LLC Phase 1 (Updated) and Phase 2 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109), dated December 15, 2015 (RS-15-301)

10. Exelon Generation Company, LLC Fourth Six-Month Status Report For Phases 1 and 2 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109), dated June 30, 2016 (RS-16-108)

11. Exelon Generation Company, LLC Fifth Six-Month Status Report For Phases 1 and 2 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109), dated December 15, 2016 (RS-16-234)

12. 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 Phase 1 of Order EA-13-109 (Severe Accident Capable Hardened Vents) (TAC Nos. MF4418 and MF4419), dated April 1, 2015

13. 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 Phase 2 of Order EA-13-109 (Severe Accident Capable Hardened Vents) (TAC Nos. MF4418 and MF4419), dated August 2, 2016 On June 6, 2013, 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 require their BWRs with Mark I and Mark II containments to take certain actions to ensure that these facilities have a hardened containment vent system (HCVS) to remove decay heat from the containment, and maintain control of containment pressure within acceptable limits following events that result in loss of active containment heat removal capability while maintaining the capability to operate under severe accident (SA) conditions resulting from an Extended Loss of AC Power (ELAP). Specific requirements are outlined in Attachment 2 of Reference 1.

Reference 1 required submission of an Overall Integrated Plan (OIP) by June 30, 2014 for Phase 1 of the Order, and an OIP by December 31, 2015 for Phase 2 of the Order. The interim staff guidance (References 2 and 3) provide direction regarding the content of the OIP for Phase 1 and Phase 2. Reference 3 endorses industry guidance document NEI 13-02, Revision 1 (Reference 4) with clarifications and exceptions identified in References 2 and 3. Reference 5 provided the EGC initial response regarding reliable hardened containment vents capable of operation under severe accident conditions. Reference 6 provided the Limerick Generating Station, Units 1 and 2, Phase 1 OIP pursuant to Section IV, Condition D.1 of Reference 1.

References 7 and 8 provided the first and second six-month status reports pursuant to Section IV, Condition 0.3 of Reference 1 for Limerick Generating Station. Reference 9 provided the Limerick Generating Station, Units 1 and 2, Phase 1 updated and Phase 2 OIP pursuant to Section IV, Conditions D.2 and D.3 of Reference 1. References 1O and 11 provided the fourth and fifth six-month status reports pursuant to Section IV, Condition D.3 of Reference 1 for Limerick Generating Station.

U.S. Nuclear Regulatory Commission Integrated Plan Report to EA-13-109 June 30, 2017 Page 3 The purpose of this letter is to provide the sixth six-month update report for Phases 1 and 2, pursuant to Section IV, Condition D.3 of Reference 1, that delineates progress made in implementing the requirements of Reference 1 for Limerick Generating Station, Units 1 and 2.

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 items contained in References 12 and 13.

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 301h day of June 2017.

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

Enclosure:

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for Phases 1 and 2 Implementation of Order EA-13-109, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions cc: Director, Office of Nuclear Reactor Regulation NRC Regional Administrator - Region I NRC Senior Resident Inspector - Limerick Generating Station NRC Project Manager, NRA - Limerick Generating Station Mr. Raj Auluck, NRR/JLDfTSD/JCBB, NRC Mr. Brian E. Lee, NRR/JLD/JCBB, 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 Sixth Six-Month Status Report for Phases 1 and 2 Implementation of Order EA-13-109, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (18 pages)

Enclosure Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for Phases 1 and 2 Implementation of Order EA-13-109, "Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions" 1 Introduction Limerick Generating Station (LGS) developed an Overall Integrated Plan (Reference 1),

documenting the installation of a Hardened Containment Vent System (HCVS) that provides a reliable hardened venting capability for pre-core damage and under severe accident conditions, including those involving a breach of the reactor vessel by molten core debris, in response to Reference 2. Updates of milestone accomplishments will be based on the combined Phases 1 and 2 Overall Integrated Plan dated December 15, 2015.

LGS developed an updated and combined Phases 1 and 2 Overall Integrated Plan (Reference 1), documenting:

1. The installation of a Hardened Containment Vent System (HCVS) that provides a reliable hardened venting capability for pre-core damage and under severe accident conditions, including those involving a breach of the reactor vessel by molten core debris, in response to Reference 2.

2. An alternative venting strategy that makes it unlikely that a drywall vent is needed to protect the containment from overpressure related failure under severe accident conditions, including those that involve a breach of the reactor vessel by molten core debris, in response to Reference 2.

This enclosure provides an update of milestone accomplishments since submittal of the combined Phases 1 and 2 Overall Integrated Plan, including any changes to the compliance method, schedule, or need for relief/relaxation and the basis, if any.

2 Milestone Accomplishments The following milestone(s) have been completed since the November 1, 2016 status report (Reference 14) and are current as of June 1, 2017.

Sixth 6 Month Update Completed with this Submittal Phase 1 Specific Milestones:

Unit 2 Modifications Evaluation Unit 2 Design Engineering On-site/Complete Unit 2 Walk Through Demonstration/Functional Test Unit 2 Implementation Outage Unit 2 Operations Procedure Changes Developed Unit 2 Site Specific Maintenance Procedures Developed Unit 2 Procedure Changes Active Unit 2 Training Complete Unit 2 HCVS Implementation Page 1of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017 3 Milestone Schedule Status The following provides an update to Attachment 2 of the combined Phases 1 and 2 Overall Integrated Plan. 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.

Comments Target Milestone Completion Activity Status {Include date Date changes in this column}

Phases 1 and 2 HCVS Milestone Table Submit Overall Integrated Plan Jun 2014 Complete Reference 7 Submit 6 Month Updates Update 1 Dec 2014 Complete Reference 8 Update 2 Jun 2015 Complete Reference 9 Update 3 [Simultaneous with Phase 2 Reference 1 Dec 2015 Complete OIP]

Update 4 Jun 2016 Complete Reference 12 Update 5 Dec 2016 Complete Reference 14 Jun 2017 Complete with Update 6 this submittal Update 7 Dec 2017 Not Started Update 8 Jun 2018 Not Started Update 9 Dec 2018 Not Started June 2019 Added to Align Update 10 Not Started with Schedule Phase 1 Specific Milestones Phase 1 Modifications Hold preliminary/conceptual design Jun 2014 Complete meeting Updated to align Unit 1 Modifications Evaluation Feb 2018 Started with schedule and does not Page 2of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017 Comments Target Milestone Completion Activity Status {Include date Date changes in this column}

Phases 1 and 2 HCVS Milestone Table affect compliance date Added line as Units 1 and 2 have different Unit 2 Modifications Evaluation Mar 2017 Complete schedules and compliance dates Updated to align with schedule Unit 1 Design Engineering On-Feb 2018 Started and does not site/Complete affect compliance date Unit 1 Implementation Outage Apr2018 Not Started Unit 1 Walk Through Apr2018 Not Started Demonstration/Functional Test Unit 2 Design Engineering On-May 2017 Complete site/Complete Unit 2 Walk Through May 2017 Complete Demonstration/Functional Test Unit 2 Implementation Outage May 2017 Complete Phase 1 Procedure Changes Active Unit 1 Operations Procedure Changes Feb 2018 Not Started Developed Unit 1 Site Specific Maintenance Feb 2018 Not Started Procedure Developed Unit 1 Procedure Changes Active Apr2018 Not Started Unit 2 Operations Procedure Changes Feb 2017 Complete Developed Page 3of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017 Comments Target Milestone Completion Activity Status {Include date Date changes in this column}

Phases 1 and 2 HCVS Milestone Table Tracking mechanisms for maintenance Unit 2 Site Specific Maintenance procedures are Feb 2017 Complete Procedure Developed created and procedures will be issued prior to being required.

Unit 2 Procedure Changes Active May 2017 Complete Phase 1 Training Unit 1 Training Complete Feb 2018 Not Started Unit 2 Training Complete Feb 2017 Complete Phase 1 Completion Unit 1 HCVS Implementation Apr2018 Not Started Unit 2 HCVS Implementation May 2017 Complete Phase 2 Specific Milestones Phase 2 Modifications Hold preliminary/conceptual design Jun 2016 Complete meeting Modifications Evaluation Feb 2019 Started Unit 1 Design Engineering On-Oct 2017 Started site/Complete Unit 1 Implementation Outage Apr2018 Not Started Unit 1 Walk Through Apr2018 Not Started Demonstration/Functional Test Unit 2 Design Engineering On-Mar2018 Not Started site/Complete Page 4of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017 Comments Target Milestone Completion Activity Status {Include date Date changes in this column}

Phases 1 and 2 HCVS Milestone Table Unit 2 Walk Through Apr2019 Not Started Demonstration/Functional Test Unit 2 Implementation Outage May 2019 Not Started Phase 2 Procedure Changes Active Unit 1 Operations Procedure Changes Feb 2018 Not Started Developed Unit 1 Site Specific Maintenance Feb 2018 Not Started Procedure Developed Unit 1 Procedure Changes Active Apr2018 Not Started Unit 2 Operations Procedure Changes Feb 2019 Not Started Developed Unit 2 Site Specific Maintenance Feb 2019 Not Started Procedure Developed Unit 2 Procedure Changes Active May 2019 Not Started Phase 2 Training Unit 1 Training Complete Feb 2018 Not Started Unit 2 Training Complete Feb 2019 Not Started Phase 2 Completion Unit 1 HCVS Implementation Apr2018 Not Started Unit 2 HCVS Implementation May 2019 Not Started Full Site HCVS Implementation May 2019 Not Started Submit Unit 1, Phase 1 & Phase 2, Completion Report [60 days after Unit Jun 2018 Not Started 1 compliance]

Submit Unit 2, Phase 1 & Phase 2, Completion Report [60 days after Unit Jul2019 Not Started 2 compliance]

Page 5of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017 4 Changes to Compliance Method LGS has completed site specific MAAP evaluations to determine the number of vent cycles required during initial 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> into the event. Based on the MAAP evaluation, less than 3 cycles are required. Based on MAAP evaluation input, LGS has designed and installed a volume of gases used for purge and PCIV motive force that are sized for a minimum of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of operation. The purge gas volume is sufficient for 4 purge cycles and the PCIV motive force (air) volume is sufficient for 8 open cycles. This is in compliance with NEI 13-02 Rev. 1, NRC endorsed HCVS-WP-02 guidance for determining number of vent cycles.

The PCPL value of 60 psig is in Calculation MEL-0138. The design temperature for supports and piping components shall be at least 350'F to satisfy the recommendations of NEI 13-

02. One exception is applied for the maximum operating temperature in relation to the piping and supports HBD-842-H003, H004 and HOOS. Instead of 350'F, 308'F is used as it corresponds to saturated steam at the PCPL pressure of 60 psig. This meets the design intent of the NEI guidance and provides design analysis margin. (Reference 422831, Section 3.5.2.1) 5 Need for Relief/Relaxation and Basis for the Relief/Relaxation LGS expects to comply with the order implementation date and no relief/relaxation is required at this time.

6 Open Items from Combined Phases 1 and 2 Overall Integrated Plan and Interim Staff Evaluations The following tables provide a summary of the open items documented in the combined Phases 1 and 2 Overall Integrated Plan or the Interim Staff Evaluation (ISE) and the status of each item.

Combined Phase 1 and Phase 2 OIP Open Items Status Phase 1 Open Items 01-1 Determine how Motive Power and/or HCVS Battery Power Closed to /SE -I will be disabled during normal operation.

01-2 Confirm that the Remote Operating Station (ROS) will be in Closed to ISE-3 an accessible area following a Severe Accident (SA).

01-3 Determine wetwell line size to meet I% venting criteria. Closed to /SE- 4 01-4 Confirm suppression pool heat capacity. Closed to ISE-4 01-5 Determine the approach for combustible gases. Closed to ISE-9 and /SE-JO 01-6 Provide procedures f or HCVS Operation. Closed to /SE-I 3 Page 6of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017 Combined Phase 1 and Phase 2 OIP Open Items Status Phase 1 Open Items 01-7 Verify the external piping consists solely of large bore Complete (Reference EC piping and its supports have less than 300 square feet of 423331, Attachment 8 (formally cross section. known as ECR 16-000// )). EC 423331 is available in ePortal.

01-8 Evaluate d1ywell pressure indication for environmental Unit 1 - Complete. Unit I qualifications to ensure this instrument can survive for 7 Pressure indicator will not days after an event. survive the environmental conditions for 7 days after the event. This has been added to the scope for Unit 1 Phase 1 activities to replace the pressure indicator.

Unit 2 Complete (Reference EC 617568, Section 3.2). EC 617568 is available in ePortal.

01-9 Determine Pe1formance Criteria for Motive gas Cylinders, Unit 1 - Started Argon Cylinders, FLEX Diesel Generator, and FLEX Unit 2 - Complete The (SA WA) pump pressure at 500 gpm. peiformance criteria for the Motive gas Cylinders, Argon Cylinder has been defined and the system will meet the requirements of the order.

(Reference EC 423333, Sections 3.5 and 3.33 and EC 423281, Section 3.19). EC 423333 and EC 423281 are available in ePortal.

See ISEP2-6for FLEX SAWA response 01-/0 Pe1form radiological evaluation for Phase 1 vent line Units 1 and 2 - Complete impact on ERO response actions. The peak dose rates and 7-day integrated doses at operating stations, equipment locations, and along transit pathways required for sustained operation of the HCVS have been calculated. The peak dose rates along potential operator transit pathways external to the Reactor Building are bounded by the peak dose rate outside the FLEX storage building. (Reference Calculation LM-0721 ).

Calculation LM-0721 is available in ePortal.

Page 7of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017 Combined Phase 1 and Phase 2 OIP Open Items IStatus Phase 1 Open Items Phase 2 Open Items I None I

Phase 1 Interim Staff Evaluation Open Items Status

/SE-I Make available for NRC staff audit documentation of a Unit I - Started method to disable HCVS during normal operation to Unit 2 Complete provide assurances against inadvertent operation that The system is designed to also minimizes actions to enable HCVS operation prevent inadvertent operation.

following an ELAP. The new control switch HS-057V-283 installed in the MCR panel 20-C689 is a key-lock switch. The switch is kept locked in "OFF" position (with key removed) to prevent inadvertent powering of the HCVS components from 125 Vdc HCVS battery source.

Additionally, locked valves are used with the gas bottles to prevent inadvertent operation.

(Reference EC 423333, Section 3.19). EC 423333 is available in ePortal.

ISE-2 Make available for NRC staff audit the final sizing Unit I - Started evaluation for HCVS batteries/battery charger including Unit 2 - Complete. The HCVS incorporation into FLEX DG loading calculation. batteries have been sized to meet the requirements of the HCVS system and function for the initial 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> into the event. (Reference Calculation LE-0128)

The FLEX diesel generator loading is acceptable and rated loading of the FLEX diesel generator will not be exceeded due to the additional HCVS loading. (Reference EC 423333, Section 3.35). LE-0128 and EC 423333 are available in ePortal.

Page 8of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017 Phase 1 Interim Staff Evaluation Open Items Status ISE-3 Make available for NRC staff audit an evaluation of Unit I - Started temperature and radiological conditions to ensure that Unit 2 - Complete.

operating personnel can safely access and operate The primary operating station controls and support equipment. for HCVS operation is located in the Main Control Room. A remote operating station (ROS) is located in the EDG Corridor, El. 217' (Room 317). The ROS location and travel path to ROS location was evaluated for habitability and accessibility during a severe accident. (Reference EC 423281, Section 3.19). EC 423281 is available in ePortal.

/SE-4 Make available for NRC staff audit analyses Unit 1 - Started demonstrating that HCVS has the capacity to vent the Unit 2 - Complete steam/energy equivalent of one percent of licensed/rated The required one percent thermal power (unless a lower value is justified), and capacity at the lower of that the suppression pool and the HCVS together are Prima1y Containment Pressure able to absorb and reject decay heat, such that following Limit or containment design a reactor shutdown from full power containment pressure will be verified using pressure is restored and then maintained below the Reactor Excursion and leak prima1y containment design pressure and the primary Analysis Program (RELAP). Jn containment pressure limit. addition, Modular Accident Analysis Program (MAAP) analyses will be credited to verify that venting can be delayed for at least three hours and that anticipatory venting can be credited to maintain Reactor Core Isolation Cooling (RCIC) functional (Reference EC 423281, Section 3.33 and LM-709). EC 423281 is available in ePortal.

ISE-5 Make available for NRC staff audit the seismic and Complete tornado missile final design criteria for the HCVS stack. (Reference EC 423331, Sections 3.2, 3.5, 3.9, and 3.38 (formally known as 16-00011) and EC 423332, Section 3.38 (formally known as 16-00012),

and EC 422831,Section 3.24 (formally known as13-264))

describe seismic and tornado missile design criteria for HCVS stack.. EC pkRs 423331, Page 9of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017 Phase 1 Interim Staff Evaluation Open Items Status 423332, and 422831 are available in ePortal for review.

JSE-6 Make available for NRC staff audit the descriptions of Unit /-started local conditions (temperature, radiation and humidity) Unit 2-Complete anticipated during ELAP and severe accident for the HCVS is designed to minimize components (valves, instrumentation, sensors, the impact of elevated transmitters, indicators, electronics, control devices, temperatures, due to the etc.) required for HCVS venting including confirmation potential loss of ventilatio12, that the components are capable of pe1forming their radiation and humidity impact functions during ELAP and severe accident conditions. on the ability of operators to initiate and maintain the functionality of the HCVS. The locations of system equipment that require operator action and the travel paths to reach the controls and indications are in mild environments. The loss of all general area lighting, coincident with the ELAP, does not pose a threat to the operators' ability to access and operate HCVS, since self-contained emergency lights illuminate the travel paths and handheld or portable lighting is available to manipulate HCVS equipment. (Reference EC 423281, Section 3.19 and 3.24)

EC 423281 is available in ePorta/for review.

ISE-7 Make available for NRC staff audit documentation of the Unit I-Started HCVS nitrogen pneumatic system design including sizing Unit 2 Complete and location. HCVS is designed to operate forfirst 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with installed independent pneumatic air supply, thereby eliminating the reliance on portable equipment. HCVS is also designed for multiple ve12ting and purge cycles during the first 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period without the need to recharge pneumatic air supplies. The pneumatic air supply is located in the emerJ!,ency diesel corridor.

Page 10of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017 Phase 1 Interim Staff Evaluation Open Items Status (Reference EC 423333, Section

3. 19 and Calculation LM-0723 ). EC 423333 and Calculation LM-0723 are available in ePortal for review.

lSE-8 Make available for NRC staff audit documentation that Complete demonstrates adequate communication between the This communication method is remote HCVS operation locations and HCVS decision the same as accepted in Order makers during El.AP and severe accident conditions. EA-12-049. These items will be powered and remain powered using the same methods as evaluated under EA-12-049 for the period of sustained operation, which may be longer than identified for EA-12-049.

Communication will be via the plant radio system if available.

If the radios system is not available the Plant page system can be used. The page system was modifiedfor FLEX to include a UPS that can be manually aligned to repower the system. (Reference AR 2492527-42). AR 2492527-42 is available in ePortal for review.

lSE-9 Provide a description of the final design of the HCVS to Unit 1-Sta rted address hydrogen detonation and deflagration. Unit 2-Complete HCVS has been designed to ensure the flammability limits of gases passing through the system are not reached. The vent piping is routed with a continuously upward slope. A purge gas (argon) supply system has been provided to displace potentially flammable/detonatable mixtures of gases that may be present in the vent after system actuation. The purge gas supply system is designed for four purge cycles during the first 24-hour period without the need to recharge.

Page 11of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017 Phase 1 Interim Staff Evaluation Open Items Status (Reference EC 423333, Section 3.19) EC 423333 is available in ePortal f or review.

ISE-10 Provide a description of the strategies for hydrogen Unit I - Complete control that minimizes the potential for hydrogen gas As discussed in the December migration and ingress into the reactor building or other 2015 OJP, the Limerick buildings. wetwell vent Line for each unit has a dedicated HCVS flowpathfrom the wetwell penetration to the outside with no interconnected system. The discharge point meets the guidance of "HCVS Release Point", HCVS-FAQ-04 (Reference 11).

Unit 2 - Complete. (Reference EC 423281 and Calculation LM-0709 are available in ePortal for review).

/SE-II Make available for NRC staff audit documentation of a Unit I-Not Started seismic qualification evaluation of HCVS components. Unit 2 Complete Seismic documentation has been provided in Reference EC 423331, Sections 3.4 and 3.38, 423333, Sections 3.4, 3.38 and Attachment 45, and EC 617568, Section 3.2. ECs 423331, 423333, 617568 are available in ePortal f or review.

JSE-12 Make available for NRC staff audit descriptions of all Unit /-Started instrumentation and controls (existing and planned) Unit 2 Complete necessary to implement this order including qualification EC 423333 installed and methods. qualified the following components in the MCR and in the plant:

valve position indicating lights, power key-locked switch, temperature indicator displays, radiation monitoring system consisting of an element local to the HCVS vent pipe, and a monitor.

(Reference EC 423333, Section 3.19 and 3.36)

Existing pressure instrument P/-042-270-1 will be used to monitor containment pressure Page 12of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017 Phase 1 Interim Staff Evaluation Open Items Status in the drywell. See EC 617568, Section 3.2 for qualification of the component.

ECs 423333 and 617568 are available in ePortal for review.

ISE-13 Make available for NRC staff audit the procedures for Unit 1-Not Started HCVS operation. Unit 2 - Complete Reference the following procedures.

SAMP-1Sht1 -7: RPV and Primary Containment Flooding Control SAMP-2 Sht 1- 3:

Containment and Radioactivity Release Control T-101: RPV Control T-102 : Prima1y Containment Control SPIT, SP/L, PCIP, DWIT, PC/H T-111: RPV Level Restoration/ Steam Cooling T-116: RPV Flooding T-117 : Level/Power Control T-334 : Flex Generator Connection for Repowering DIV 2 Batte1y Charger T-341 : Prima1y Containment Venting Via Hardened Containment Vent System RT-6-000-914-0: Inspection of FLEX Pump Storage Building Equipment RT-6-000-915-0: Inspection of Flex Generator Storage Building Equipment RT-6-000-916-0: Routine inspection of Spare HCVS Argon and Air Bottles RT-6-057V-400-2 : HCVS PCIV Valve Exercise Test GP-19: Operator Activities ST-6-092-116-2 D22: Diesel Generator 4KV SFGD Loss of Power LSF-SAA and Outage Testing RT-6-092-452-2 : Procedure for Deenergizing and Page 13of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017 Phase 1 Interim Staff Evaluation Open Items Status Reenergizing the D22 Safeguard Bus During a Refuel Outage ST-6-092-118-2: D24 Diesel Generator 4KV SFGD Loss of Power LSF-SAA and Outage Testing RT-6-092-452-2: Procedure for Deenergizing and Reenergizing the D22 Safeguard BUS during a Refueling outage ST-6-060-460-2 : Primary Containment Isolation Capability Check OP-LG-108-/03-1102:

Limerick Generating Station Unit 2 Locked Valve List RT-6-000-360-2 : Unit 2 Accessible Locked Valve Walkdown 2S57V. 1.A : Equipment Alignment of the Hardened Containment Vent System for Normal Operation SE-10-1: Breaker Reset Following LOCA RT-6-057V-901-2: HCVS Batte!)' Monthly Check RT-6-057V-902-2 HCVS Battery Quarterly Check F-R-714: South Stack Instrument Room 714 F-D-317: Unit 2 Diesel Generator Access Corridor and Condensate Pump Rooms Rooms 317 and 318 (El 217')

F-FPSB-001 : Pre-Fire Plan Strategy for Flex Pump Storage Building 2S92. l.N: Equipment Alignment for 2A Diesel Generator Operator S57V.8.A : Startup of the HCVS Batte1y Charger S57V.8.B: Shutdown of the HCVS Batte1y Char~er Page 14of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report tor the Implementation of HCVS Phases 1 and 2 June 30, 2017 Phase 1 Interim Staff Evaluation Open Items Status ST-6-076-360-2 : RX ENCL SEC CNTMT Integrity Verification These procedures are in ePorta[for review.

Phase 2 Interim Staff Evaluation Open Items Status ISEP2-l Licensee to demonstrate that the HCVS components Complete meeting reasonable protection from tornado missiles is Per Drawing HBD-842-01, at least 30 feet above the highest grade within 300 yards. HCVS pipe leaves the protected structure more than 120 feet above grade elevation, which is 217 feet MSL, as indicated on site topographical drawi11g C-0062 that shows grade elevatio11 referenced to MSL within 300 yards of the HCVS components evaluated.

ISEP2-2 Licensee to confirm through analysis the temperature Started a11d radiological co11ditio11s to ensure that operating personnel can safely access and operate controls and support equipment.

/SEP2-3 Licensee to evaluate the SA WA equipment and controls, Started as well as the ingress and egress paths for the expected severe accident conditio11s (temperature, humidity, radiation) for the sustained operatinf? period.

/SEP2-4 Licensee to demonstrate that containment failure as a Complete result of overpressure can be prevented without a The wetwell vent has been drywell vent during severe accident conditions. designed and installed to meet NE! 13-02 Rev 1 guidance, which will ensure that it is adequately sized to prevent containment overpressure under severe accident conditions.

The SA WM strategy will ensure that the wenvell vent remains functional for the period of sustained operation.

LGS will follow the guidance (jlow rate and timing) for SA WA/SA WM described in BWROG-TP-15-008 and BWROG-TP-15-011.These Page 15of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report tor the Implementation of HCVS Phases 1 and 2 June 30, 2017 Phase 2 Interim Staff Evaluation Open Items Status documents have been posted to the ePortal for NRC staff review. The wetwell vent will be opened prior to exceeding the PCPL value of 60 PSIG.

Therefore, containment over pressurization is prevented without the need for a d1ywell vent.

ISEP2-5 Licensee shall demonstrate how the plant is bounded by Complete the reference plant analysis that shows the SA WM Using Figure 2.1.Cfrom the strategy is successful in making it unlikely that a d1ywell combined Phases 1and2 OJP, vent is needed. compare the reference plant parameters to the plant specific parameters.

Reference LGS Plant Torus Suppression free board Pool volume is free board 525,0001 volume is gallons 147,670ft3 (1,104,572 Rallons)

SA WA.flow SA WA.flow is is500GPM 500 GPM at at 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> followed by followed by lOOGPM JOOGPM from 12 from 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to hours to 168 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> hours The above parameters for LGS compared to the reference plant that determine success of the SA WM strategy demonstrate that the reference plant values are bounding.

Therefore, the SA WM strategy implemented at LGS makes it unlikely that a DW vent is needed to prevent containment overpressure related failure.

1 Peach Bottom available freeboard volume in gallons is estimatedfrom nominal water Page 16of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017 Phase 2 Interim Staff Evaluation Open Items Status level of I 4. 7 feet to 2 I feet. 2 I feet is the upper range of the wide range torus level instrument and the assumed loss of wetwell vent function . The Peach Bottom torus is 3 I feet in diameter.

!SEP2-6 Licensee to demonstrate that there is adequate Complete communication between the MCR and the operator at the This communication method is FLEX pump during severe accident conditions. the same as accepted in Order EA-12-049. These items will be powered and remain powered using the same methods as evaluated under EA-12-049 for the period of sustained operation, which may be longer than identified for EA-12-049.

Communication will be via the plant radio system if available.

If the radios system is not available the Plant page system can be used. The page system was modified for FLEX to include a UPS that can be manually aligned to repower the system. (Reference AR 2492527-42)

/SEP2 -7 Licensee to demonstrate the SA WM flow instrumentation Unit I - Started qualification for the expected environmental conditions Unit 2 - Not Started 7 Interim Staff Evaluation Impacts There are no potential impacts to the Interim Staff Evaluation(s) identified at this time.

8 References The following references support the updates to the combined Phases 1 and 2 Overall Integrated Plan described in this attachment.

1. Limerick Generating Station, Units 1 and 2, Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109)," dated December 15, 2015

2. NRG Order Number EA-13-109, "Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions" dated June 6, 2013 Page 17of18

Limerick Generating Station, Units 1 and 2 Sixth Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 June 30, 2017

3. NEI 13-02, "Industry Guidance for Compliance with NRC Order EA-13-109, 'To Modify Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions," Revision 1, dated April 2015

4. NRC Interim Staff Guidance JLD-ISG-2013-02, "Compliance with Order EA-13-109, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions," Revision 0, dated November 2013 (Accession No. ML133048836)

5. NRC Endorsement of Industry "Hardened Containment Venting System (HCVS) Phase 1 Overall Integrated Plan Template (EA-13-109) Rev O" (Accession No. ML14128A219)

6. NRC Interim Staff Guidance JLD-ISG-2015-01, "Compliance with Phase 2 of Order EA-13-109, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions," Revision O, dated April 2015 (Accession No. ML15104A118)

7. Exelon Generation Company, LLC, Phase 1 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109), dated June 30, 2014

8. Exelon Generation Company, LLC, First Six-Month Status Report for Phase 1 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109), dated December 17, 2014

9. Exelon Generation Company, LLC, Second Six-Month Status Report for Phase 1 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109), dated June 30, 2015

10. Missile Evaluation for HCVS Components 30 feet Above Grade, HCVS-WP-04, Revision O (ML15244A923), August 8, 2015

11. HCVS Release Point, HCVS-FAQ-04, Revision 1, (ML14120A289), April 14, 2014

12. Fourth Six-Month Status Report For Phases 1 and 2 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109) dated June 30, 2016

13. Limerick Generating Station Units 1 And 2 - Interim Staff Evaluation Relating To Overall Integrated Plan In Response To Phase 2 of Order EA-13-109 (Severe Accident Capable Hardened Vents) (CAC NOS. MF4418 and MF4419)

14. Fifth Six-Month Status Report For Phases 1 and 2 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109) dated December 15, 2016 Page 18of18