RS-17-153, Seventh 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 ...

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Seventh 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 ...
ML17349A035
Person / Time
Site: Limerick  Constellation icon.png
Issue date: 12/15/2017
From: Jim Barstow
Exelon Generation Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
EA-13-109, RS-17-153
Download: ML17349A035 (23)
v • d • e


Text

Exelon Generation .,

Order No. EA-13-109 RS-17-153 December 15, 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:

Seventh 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 O, 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 December 15, 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. Exelon Generation Company, LLC 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), dated June 30, 2017 (RS-17-066}
13. 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 Phase 1 of Order EA-13-109 (Severe Accident Capable Hardened Vents) (TAC Nos. MF4418 and MF4419}, dated April 1, 2015
14. 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 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 D.3 of Reference 1 for Limerick Generating Station. Reference 9 provided the Limerick

U.S. Nuclear Regulatory Commission Integrated Plan Report to EA-13-109 December 15, 2017 Page 3 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, 11, and 12 provided the fourth, fifth, and sixth six-month status reports pursuant to Section IV, Condition D.3 of Reference 1 for Limerick Generating Station.

The purpose of this letter is to provide the seventh 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 13 and 14.

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 15th day of December 2017.

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

Enclosure:

Limerick Generating Station, Units 1 and 2 Seventh 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/JLD/TSD/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 Seventh 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 (19 pages)

Enclosure Limerick Generating Station, Units 1 and 2 Seventh 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 7) 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 drywell 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 June 30, 2017 status report (Reference 15) and are current as of December 1, 2017.

Seventh 6-Month Update Completed with this Submittal 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.

Page 1of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 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 Update 6 Jun 2017 Complete Reference 15 Dec 2017 Complete with Update 7 this submittal 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 with schedule Unit 1 Modifications Evaluation Feb 2018 Started and does not affect compliance date Added line as Unit 2 Modifications Evaluation Mar 2017 Complete Unit 1 and Unit 2 have different schedules and Page 2of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 Comments Target Milestone Completion Activity Status {Include date Date changes in this column}

Phases 1 and 2 HCVS Milestone Table 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 Apr 2018 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 Started Developed Unit 1 Site Specific Maintenance Feb 2018 Started Procedure Developed Unit 1 Procedure Changes Active Apr2018 Started Unit 2 Operations Procedure Changes Feb 2017 Complete Developed Tracking mechanisms for Unit 2 Site Specific Maintenance maintenance Feb 2017 Complete Procedure Developed procedures are created and procedures will Page 3of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 Comments Target Milestone Completion Activity Status {Include date Date changes in this column}

Phases 1 and 2 HCVS Milestone Table 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 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 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-Mar 2018 Started site/Complete Unit 2 Walk Through Apr2019 Not Started Demonstration/Functional Test Unit 2 Implementation Outage May 2019 Not Started Page 4of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 Comments Target Milestone Completion Activity Status {Include date Date changes in this column}

Phases 1 and 2 HCVS Milestone Table Phase 2 Procedure Changes Active Unit 1 Operations Procedure Changes Feb 2018 Started Developed Unit 1 Site Specific Maintenance Feb 2018 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 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 5of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 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, NRG 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 EC 422831 section 3.5.2.1) This exception applies to Unit 2 compliance.

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 Closed to /SE -I Power will be disabled during normal operation.

01-2 Confirm that the Remote Operating Station (ROS) will be Closed to /SE-3 in 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 ISE-10 01-6 Provide procedures for HCVS Operation. Closed to ISE-13 Page 6of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 Combined Phase 1 and Phase 2 OIP Open Items Status Phase 1 Open Items 01-7 Verify the external pipi11g consists solely of large bore Complete (Reference EC pipi11g and its supports have less than 300 square feet of 423331, Attachment 8 (formally cross section. k11ow11 as ECR 16-00011 )). EC 423331 is available in ePortal.

01-8 Evaluate drywell pressure indication for e11viro11mental Unit 1 - Complete. Unit 1 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.

U11it 2 Complete (Reference EC 617568 section 3.2).EC 617568 is available in ePortal.

01-9 Determi11e 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. performance criteria for the Motive gas Cylinders, Argon Cylinder has been defined and the system will meet the requireme11ts of the order.

(Reference EC 423333 sectio11s 3.5 and 3.33 and EC 423281 Section 3.19). EC 423333 and EC 423281 are available in ePortal.

See JSEP2-6for FLEX SAWA response.

01-10 Peiform radiological evaluation for Phase 1 vent line U11its 1 and 2 - Complete.

impact on ERO response actions. The peak dose rates and 7-day integrated doses at operating stations, equipment locations, and alo11g transit pathways required for sustained operation of the HCVS have been calculated. The peak dose rates along pote11tial 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.

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Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 Combined Phase 1 and Phase 2 OIP Open Items IStatus Phase 1 Open Items Phase 2 Open Items INone 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 1 - Started evaluation for HCVS batteries/battery charger Unit 2 - Complete. The HCVS including incorporation into FLEX DG loading batteries have been sized to calculation. 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 8of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 Phase 1 Interim Staff Evaluation Open Items Status ISE-3 Make available for NRC staff audit an evaluation of Unit 1 - 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 423281section3. 19). EC 423281 is available in ePortal.

ISE-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 The required one percent licensed/rated thermal power (unless a lower value is capacity at the lower of justified), and that the suppression pool and the HCVS Primary Containment together are able to absorb and reject decay heat, such Pressure Limit or containment that following a reactor shutdown from full power design pressure will be containment pressure is restored and then maintained verified using Reactor below the primary containment design pressure and the Excursion and Leak Analysis primary containment pressure limit. Program (REI.AP). Jn addition, Modular Accident Analysis Program (MMP) analyses will be credited to verify that venting can be delayed for at least three hours and that anticipat01y venting can be credited to maintain Reactor Core Isolation Cooling (RC/C) 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 (Reference EC 423331 section stack. 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 Page 9of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 Phase 1 Interim Staff Evaluation Open Items Status missile design criteria for HCVS stack. EC pkgs 423331, 423332, and 422831 are available in ePortal for review.

ISE-6 Make available for NRC staff audit the descriptions of Unit I-Started local conditions (temperature, radiation and humidity) Unit 2-Complete anticipated during El.AP 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 ventilation, that the components are capable of pe1forming their radiation and humidity impact functions during El.AP 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 El.AP, 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 423281section3.19 and 3.24) EC 423281 is available in ePortal for review.

ISE-7 Make available for NRC staff audit documentation of Unit I-Started the HCVS nitrogen pneumatic system design including Unit 2 Complete sizing and location. HCVS is designed to operate for first 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 venting and purge cycles during the fl rst 24-hour period without the need to rechart?e Page 10of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 Phase 1 Interim Staff Evaluation Open Items Status pneumatic air supplies. The pneumatic air supply is located in the emergency diesel corridor. (Reference EC 423333 section 3. 19 and Calculation LM-0723). EC 423333 and Calculation LM-0723 are available in ePortal for review.

ISE-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 EI.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 radio 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). AR 2492527-42 is available in ePortal for review.

ISE-9 Provide a description of the final design of the HCVS to Unit ]-Started 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/denotable mixtures of gases that may be present in the vent after system actuation. The purRe Ras Page 11of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 Phase 1 Interim Staff Evaluation Open Items Status supply system is desig11ed for four purge cycles duri11g the first 24-hour period without the need to recharge.

(Reference EC 423333 section 3.19) EC 42333 is available in ePortal for review.

/SE-JO 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 buildi11g or 2015 O/P, the limerick other buildings. wetwell ve11t li11e for each unit has a dedicated HCVS flow path from the wetwell penetration to the outside with no interconnected system. The discharge point meets the guidance of "HCVS Release Point", HCVS-FAQ-04 (Reference I I).

Unit 2 - Complete. (Reference EC 423281 a11d Calculation LM-0709)

/SE-I I Make available for NRC staff audit documentatio11 of a U11it I- Started seismic qualification evaluation of HCVS components. U11it 2 Complete Seismic documentatio11 has been provided in Reference EC 423331section3.4 and 3.38, 423333 section 3.4, 3.38 a11d attachment 45, and 617568 section 3.2. EC 423331, 423333, 617568 are available in ePortal for review.

ISE-12 Make available for NRC staff audit descriptions of all U11it I-Started instrumentatio11 and controls (existing and planned) Unit 2 Complete 11ecessary to implement this order including EC 423333 installed and qualification methods. qualified the following components in the MCR and in the plant:

valve position indicati11g lights, power key-locked switch, temperature indicator displays, radiatio11 111011itori11g system consisti11g of an element local to the HCVS vent pipe, and a mo11itor.

Page 12of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 Phase 1 Interim Staff Evaluation Open Items Status (Reference EC 423333 section 3.19 and 3.36)

Existing pressure instrument Pl-042-270-1 will be used to monitor containment pressure in the d1ywell. See EC 617568 section 3.2 for qualification of the component.

EC 423333 and 617568 are available in ePortal for review.

ISE-13 Make available for NRC staff audit the procedures for Unit 1 - Started HCVS operation. Unit 2 - Complete Reference the following procedures.

SAMP-1Slit1 -7: RPV and Primary Containment Flooding Control SAMP-2 Sht 1- 3:

Containment and Radioactivity Release Control T-101: RPV Control T-102: Primary Containment Control SPIT, SPIL, PC/P, DW/T, 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: Primwy 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 Page 13of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 Phase 1 Interim Staff Evaluation Open Items Status ST-6-092-I I6-2 D22: Diesel Generator 4KV SFGD Loss of Power LSF-SM and Outage Testing RT-6-092-452-2: Procedure for Deenergizing and Reenergizing the D22 Safeguard Bus During a Refuel Outage ST-6-092-I I8-2: D24 Diesel Generator 4KV SFGD Loss of Power LSF-SM 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-108-103-I I02:

Limerick Generating Station Unit 2 Locked Valve List RT-6-000-360-2: Unit 2 Accessible Locked Valve Walkdown 2S57V.I.A: Equipment Alignment of the Hardened Containment Vent System for Normal Operation SE-JO-I: Breaker Reset Following LOCA RT-6-057V-90I-2: HCVS Battery Monthly Check RT-6-057V-902-2 HCVS Battery Quarterly Check F-R-7I4: South Stack Instrument Room 7I 4 F-D-3I7: Unit 2 Diesel Generator Access Coordinate and Condensate Pump Rooms 3I7 and 3I8 (El 217')

F-FPSB-OOI: Pre-Fire Plan Strategy for Flex Pump Stora/le BuildinR Page 14of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 Phase 1 Interim Staff Evaluation Open Items Status 2S92. 1.N: Equipment Alignment for 2A Diesel Generator Operator S57V.8.A: Startup of the HCVS Batte1y Charger S57V.8.B: Shutdown of the HCVS Battery Charger ST-6-076-360-2: RX ENCL SEC CNTMT Integrity Verification These procedures are in ePortalfor 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 HCVS pipe leaves the yards. protected structure more than 120 feet above grade elevation, which is 217 feet MSL, as indicated on site topographical drawing C-0062 that shows grade elevation referenced to MSL within 300 yards of the HCVS components evaluated.

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

ISEP2-3 Licensee to evaluate the SAWA equipment and Started controls, as well as the ingress and egress paths for the expected severe accident conditions (temperature, humidity, radiation) for the sustained overatinJ! oeriod.

ISEP2-4 Licensee to demonstrate that containment failure as a Complete result of overpressure can be prevented without a The wetwell vent has been d1ywell 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.

Page 15of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 Phase 2 Interim Staff Evaluation Open Items Status The SA WM strategy will ensure that the wetwell vent remains functional for the period of sustained operation.

LGS will follow the guidance (flow rate and timing) for SA WA/SA WM described in BWROG-TP-15-008 and BWROG-TP-15-011.These documents have been posted to the ePortal for NRC staff review. The wetwell vent will be opened prior to exceeding the PCPL value of60 PS/G.

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

ISEP2-5 Licensee shall demonstrate how the plant is bounded Complete by the reference plant analysis that shows the SA WM Using Figure 2.1.Cfrom the strategy is successful in making it unlikely that a combined Phases 1 and 2 OlP, drywell vent is needed. compare the reference plant parameters to the plant specific parameters.

Reference LGS Plant Torus Suppression free board Pool volume is freeboard 525,000 volume is gallons 147,670ft3 (1,104,572 Rallons)

SAWAflow SAWAflow is is 500GPM 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 Page 16of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017 Phase 2 Interim Staff Evaluation Open Items Status plant values are bounding.

Therefore, the SA WM strategy implemented at LGS 111akes it unlikely that a DW vent is needed to prevent containment overpressure related failure.

ISEP2-6 licensee to demonstrate that there is adequate Complete communication between the MCR and the operator at This communication method is the 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 radio 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 afif?ned to repower the system. (Reference AR 2492527-42)

JSEP2-7 licensee to demonstrate the SA WM flow Unit 1 - Started instrumentation qualification for the expected Unit 2 - Started environmental conditions 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 Page 17of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017

2. NRC 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
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 0, 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), dated August 2, 2016 Page 18of19

Limerick Generating Station, Units 1 and 2 Seventh Six-Month Status Report for the Implementation of HCVS Phases 1 and 2 December 15, 2017

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
15. 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) dated June 30, 2017 Page 19of19
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