RS-16-021, 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-12-049)

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-12-049)

ML16057A209
Person / Time
Site:	Byron
Issue date:	02/26/2016
From:	Kaegi G Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
EA-12-049, RS-16-021, TAC MF0872, TAC MF0873, TAC MF0893, TAC MF0894
Download: ML16057A209 (28)

Text

Adnow AMEMW Anwo- ExeLon Generation.

Order No. EA-12-049 RS-16-021 February 26, 2016 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Unit 2 Renewed Facility Operating License No. NPF-66 NRC Docket No. STN 50-455

Subject:

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-12-049)

References:

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

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

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

Revision 0, dated August 2012

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

5. Exelon Generation Company, LLC Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049), dated February 28, 2013 (RS-13-018)

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-13-115)

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-14-008)

U.S. Nuclear Regulatory Commission Integrated Plan Report to EA-12-049 February 26, 2016 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-14-206)

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-15-017) 10.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-15-209) 11.NRC letter to Exelon Generation Company, LLC, Byron Station, Units 1 and 2 Interim Staff Evaluation Relating to Overall Integrated Plan in Response to Order EA-12-049 (Mitigation Strategies) (TAC Nos. MF0893 and MF0894), dated December 17, 2013 12.NRC letter Exelon Generation Company, LLC, Byron 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. MF0893, MF0894, MF0872 and MF0873), dated December 17, 2014 On March 12, 2012, the Nuclear Regulatory Commission ("NRC" or "Commission") issued an order (Reference 1) to Exelon Generation Company, LLC (EGC). Reference 1 was immediately effective and directs EGC to develop, implement, and maintain guidance and strategies to maintain or restore core cooling, containment, and spent fuel pool cooling capabilities in the event of a beyond-design-basis external event. Specific requirements are outlined in of Reference 1.

Reference 1 required submission of an initial status report 60 days following issuance of the final interim staff guidance (Reference 2) and an overall integrated plan pursuant to Section IV, Condition C. Reference 2 endorses industry guidance document NEI 12-06, Revision 0 (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 Byron Station, Unit 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, and 10 provided the first, second, third, fourth, and fifth six-month status reports, respectively, pursuant to Section IV, Condition C.2, of Reference 1 for Byron Station, Unit 2. The purpose of this letter is to provide the sixth 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 11, and the NRC audit open items contained in Reference 12.

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

U.S. Nuclear Regulatory Commission Integrated Plan Report to EA-12-049 February 26, 2016 Page 3 I declare under penalty of perjury that the foregoing is true and correct. Executed on the 26th day of February 2016.

Respectfully submitted,

_JJtl~ ~

Glen T. Kaegi Director - Licensing & Regulatory Affairs Exelon Generation Company, LLC

Enclosure:

1. Byron Station, Unit 2 Sixth Six-Month Status Report for the Implementation of Order EA 049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events cc: NRC Regional Administrator - Region III NRC Senior Resident Inspector - Byron Station NRC Project Manager, NRR - Byron Station Mr. John D. Hughey, NRR/JLD/JOMB, NRC Illinois Emergency Management Agency - Division of Nuclear Safety

Enclosure Byron Station, Unit 2 Sixth Six-Month Status Report for the Implementation of Order EA-12-449, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (23 pages)

Enclosure Byron Station, Unit 2 Sixth 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 (23 pages)

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX Byron Station, Unit 2 Sixth 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 1 Introduction Byron Station developed an Overall Integrated Plan (Reference 1 in Section 8), documenting the diverse and flexible strategies (FLEX), in response to 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.

Reference 41 provided the Byron Station, Unit 1 report of full compliance with NRC Order EA-12-049.

2 Milestone Accomplishments The following milestone(s) have been completed since August 28, 2015 and are current as of January 26, 2016.

• Unit 1 is FLEX Compliant

• Modification Development, Phase 1 modifications, Unit 1

• Modification Implementation, Phase 1 modifications, Unit 1

• Modification Implementation, Phase 2 modifications, Unit 1

• Procedure Development for Unit 1 o Strategy procedures o Validate procedures (NEI 12-06, Sect. 11.4.3)

• Training completion NOTE: The "Status" indicated in this document is as of January 26, 2016. This date was chosen to support the development, review, approval and submittal of this report by the required February 26, 2016 due date.

3 Milestone Schedule Status The following provides an update to Attachment 2 of the 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 1 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX Site: Byron Original Target Activity Status Revised Target Completion Completion Date Date Submit 60 Day Status Report Complete Submit Overall Integrated Complete Implementation Plan Contract with Strategic Complete Alliance for FLEX Emergency Response National SAFER Response Center Submit Six (6) month Updates Aug 2013 Update 1 Complete Feb 2014 Update 2 Complete Aug 2014 Update 3 Complete Feb 2015 Update 4 Complete Aug 2015 Update 5 Complete Feb 2016 Update 6 Complete with this submittal Unit 1 Unit 2 Modification Development Unit 1 Unit 2 Unit 1 Unit 2 Aug Dec

• Phase 1 modifications Complete Complete Complete 2014 2013 Aug Dec

• Phase 2 modifications Complete Complete Complete May 2014 2013 2016 Aug Dec

• Phase 3 modifications Complete 2014 2013 Unit 1 Unit 2 Modification Implementation Sept Oct

• Phase 1 modifications Complete Complete May 2015 2014 2016 Sept Oct

• Phase 2 modifications Complete Complete May 2015 2014 2016 Sept Oct

• Phase 3 modifications Complete 2015 2014 Procedure Development Unit 1 Unit 2 Oct 2014 Strategy procedures Complete plete Complete May Tcom Page 2 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX 2016

• Validate Procedures Complete Complete Complete Apr 2014 (NEI 12-06, Sect.

11.4.3 Oct 2014

• Maintenance Complete Complete procedures Jun 2014 Staffing analysis Complete Oct 2014 Storage Plan and Complete construction Oct 2014 FLEX equipment acquisition Complete Oct 2014 Training completion Complete Aug 2014 National SAFER Response Complete Center Operational Sept 2015 Unit 1 Implementation date Complete Oct 2014 Unit 2 Implementation date Started May 2016 4 Changes to Compliance Method Change 1 Section: General Integrated Plan Elements PWR Key site assumptions to implement NEI 12-06 strategies.

Reason for Change: Site FLEX response strategies have been updated to reflect installation of the Westinghouse Generation III Safe Shutdown Seals (SDS).

Change:

Note: Byron Station has installed the Westinghouse reactor coolant pump (RCP) SHIELD Passive Thermal Shutdown Seals (SDS) (Generation III). The SHIELD SDSs are installed in all 4 RCPs on Unit 1 and will be installed on Unit 2 in the spring of 2016. The NRC has concluded that the use of the Westinghouse SHIELD Passive Thermal SDS is acceptable for use in ELAP evaluation for Order EA-12-049 as documented in ADAMS Accession No. ML14132A128, Ref 33.

Installation of the SHIELD seals has changed the Units' response in a BDBEE described in NEI 12-06. As a result, the site has performed additional calculations to ensure the site Fukushima strategy remains viable. The additional calculations were completed for B1 R20 (Fall 2015). The results of these calculations have been communicated with the post outage compliance letter for Unit 1, Reference 41.

Change 2 Section: General Integrated Plan Elements PWR Key site assumptions to implement NEI 12-06 strategies.

Page 3 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX Reason for Change: Site FLEX response strategies have been updated. Westinghouse performed the following five (5) new calculations to evaluate the FLEX Strategies:

CN-LIS-1 5-034, Byron and Braidwood Stations Reactor Coolant System ELAP Inventory Control Analysis, Ref 31, CN-LIS-1 5-039, Byron and Braidwood Stations Reactor Coolant System ELAP Long-Term Subcriticality Analysis, Ref 32, CN-LIS-15-040, Byron and Braidwood Stations Delayed AFW FLEX Studies, Ref 30, CN-LIS-1 5-038, Calculation of Asymmetric Natural Circulation Cooldown Rate Limits for the Byron and Braidwood Units in Support of the FLEX Program, Ref 38, CN-LIS-1 5-048, Byron and Braidwood Condensate Consumption / Auxiliary Feedwater Usage Evaluation, Ref 39.

LTR-LIS-1 5-336, ELAP Summary Report, Ref 40 Change: With the New SDS installation:

RCS Inventory and Boration The inventory and shutdown margin calculations require boration of 6000 gallons of RWST borated water to commence before 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />. The inventory portion is not required prior to the bounding time of 58 hours6.712963e-4 days <br />0.0161 hours <br />9.589947e-5 weeks <br />2.2069e-5 months <br /> to prevent an end of single phase natural circulation and 186 hours0.00215 days <br />0.0517 hours <br />3.075397e-4 weeks <br />7.0773e-5 months <br /> until core uncovery occurs.

Auxiliary Feedwater Delay provided the bounding time of 45.03 minutes to SG dryout for Ul and 62.95 minutes to SG dryout on Unit 2.

Asymmetrical Cooldown, Byron Station intends to perform a symmetric cooldown as prescribed in the shutdown margin calculation by 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> starting at the 4-6 hour point time and resources permitting. The cooldown rate will be at a target value of 50°F/hr. Due to the reduced decay heat at the 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> time Westinghouse provided the following recommended maximum cooldown rates for the first cooldown evolution, in an asymmetric SG alignment:

Byron Unit 1 / Braidwood Unit 1 (BWI replacement steam generators): 11 OF/hr Byron Unit 2 / Braidwood Unit 2 (Model D5 original steam generators): 250F/hr The second RCS cooldown will further reduce Tavg to the cold shutdown temperature following the isolation of the accumulators. The recommended maximum cooldown rates for the second cooldown evolution, in an asymmetric SG alignment are:

Byron Unit 1 / Braidwood Unit 1 (BWI replacement steam generators): 80F/hr Byron Unit 2 / Braidwood Unit 2 (Model D5 original steam generators): 20°F/hr Auxiliary Feedwater Make Up Usage provided the quantity of SX water that would be required to support the FLEX strategy to complete both cooldowns out to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after the event onset.

With the FLEX strategy Byron Station will initiate SX Makeup from a deep well at the 6-9 hour point which will provide all the additional SG feedwater that would be required.

Change 3 Section: Attachment 1 A Sequence of Events Timeline Reason for Change: Site FLEX response strategies have been updated. Westinghouse performed the following five (5) new calculations to evaluate the FLEX Strategies:

Page 4 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX CN-LIS-15-034, Byron and Braidwood Stations Reactor Coolant System ELAP Inventory Control Analysis, Ref 31, CN-LIS-15-039, Byron and Braidwood Stations Reactor Coolant System ELAP Long-Term Subcriticality Analysis, Ref 32, CN-LIS-1 5-040, Byron and Braidwood Stations Delayed AFW FLEX Studies, Ref 30, CN-LIS-1 5-038, Calculation of Asymmetric Natural Circulation Cooldown Rate Limits for the Byron and Braidwood Units in Support of the FLEX Program, Ref 38, CN-LIS-1 5-048, Byron and Braidwood Condensate Consumption / Auxiliary Feedwater Usage Evaluation, Ref 39.

LTR-LIS-1 5-336, ELAP Summary Report, Ref 40 Change:

1. Action Item 3, updated reference with new Westinghouse Calculation CN-LIS-1 5-40, Byron and Braidwood Stations Delayed AFW FLEX Studies.

2. Action Item 4, Changed time to 5-30 minutes to match the validation performed after the Westinghouse Calculation CN-LIS-15-40, Byron and Braidwood Stations Delayed AFW FLEX Studies provided a bounding dryout time of 45 minutes.

3. Action Item 8, Changed time of the SX short cycle cooling realignment to align with the earlier start of 30 minutes. Also changed step order to align times.

4. Action Item 9, Changed order to align times.

5. Action Item 10, Changed order to align times.

6. Action Item 11, Changed order to align times based on Westinghouse Calculation CN-LIS-15-39, Byron and Braidwood Stations Reactor Coolant System ELAP Long-Term Subcriticality Analysis with Low-Leakage Reactor Coolant Pump Seal Packages.

Bounding time was to commence cooldown within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, time and resources permitting. The recommended cooldown rate of 50°F/hr is bounded by the ERD Setpoint of <100°F/hr.

7. Action Item 12, Changed order to align times.

8. Action Item 13, Changed order to align times.

9. Action Item 14, Changed order to align times from Action Item 11.

10.Action Item 15, Changed order to align times.

11. Action Item 16, Changed order to align times.

5 Need for Relief/Relaxation and Basis for the Relief/Relaxation Byron Station, Unit 2 has received an 18-month extension of the Order due to Westinghouse methodology review for the RCP Seal Leakoff, and is scheduled to be in compliance May 2016 in accordance with NRC letter (ADAMS Accession No. ML14260A294) stating: "Accordingly, based upon the authority granted to the Director, Office of Nuclear Reactor Regulation, the requirement of the order for full order implementation for Byron Unit 2 is relaxed until the completion of the Spring 2016 refueling outage to allow the licensee sufficient time to complete the engineering analysis and procedure changes associated with the final, NRC endorsed RCP Seal leakage analytical basis."

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 5 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX Section Reference Overall Integrated Plan Open Item Status Key Site assumptions (p.4) Primary and secondary storage Complete (Ref-29) locations have not been selected yet; once locations are finalized implementation strategies and routes will be assessed for hazard impact.

Sequence of events (p.5) The final timeline will be time Complete The timeline from validated once detailed designs are the current design has been completed and procedures are validated.

developed.

Identify how strategies will Identification of storage area and Complete (Ref-29) be deployed (p.7) creation of the administrative program.

Programmatic controls (p.8) Develop an administrative program Complete (Ref-37) for FLEX responsibilities, and testing

& maintenance.

National SAFER Response Development of Byron Station's Complete (Ref-29)

Center plan (p.9) response plan.

Key Reactor Parameters Identify additional parameters that Complete (Ref-29) are needed in order to support key (p. multiple) actions identified in the plant procedures/guidance or to indicate imminent or actual core damage.

Deployment Conceptual Develop the storage structure Complete (Ref-29)

Design (p. multiple) conceptual design.

Maintain RCS Inventory A calculation will be required for the Complete The Control, Phase 2 (p.23) timing of the boration and quantity Westinghouse Calculation required. CN-LIS-15-034, Byron and Braidwood Stations Reactor Coolant System FLAP Inventory Control Analysis with SHIELD Reactor Coolant Pump Seal Packages, is complete and provides a minimum time of 58 hours6.712963e-4 days <br />0.0161 hours <br />9.589947e-5 weeks <br />2.2069e-5 months <br /> to the end of single-phase natural circulation and 186 hours0.00215 days <br />0.0517 hours <br />3.075397e-4 weeks <br />7.0773e-5 months <br /> until Core Uncovery occurs.

The Westinghouse Calculation CN-LIS-15-039, Page 6 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX Byron and Braidwood Stations Reactor Coolant System FLAP Long-Term Subcriticality Analysis with Low-Leakage Reactor Coolant Pump Seal Packages, provides for a bounding calculation that boration would start by 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> into the FLAP with a minimum of 6000 gallons of 2300ppm borated water injected.

Maintain Containment, Additional calculations will be Complete (Ref-29)

Phase 1 (p.31) performed to evaluate containment Installation of the response.

Westinghouse reactor coolant pump (RCP) SHIELD Passive Thermal Shutdown Seals (SDS) (Generation 111) will reduce the amount of leakage into containment assumed in calculation BYR13-235 (Ref. 12),

resulting in additional margin to reaching design basis temperature and pressure.

Maintain Spent Fuel Pool Procedure development for Initial Complete (Ref-29)

Cooling, Phase 1 (p.39) Spent fuel pool make-up with gravity drain from the RWST.

Maintain Spent Fuel Pool Initial calculations were used to Complete (Ref-29)

Cooling, Phase 1 (p.39) determine the fuel pool timelines.

Formal calculations will be performed to validate this information during development of the spent fuel pool cooling strategy detailed design.

Maintain Spent Fuel Pool Evaluation of the spent fuel pool area Complete (Ref-29)

Cooling, Phase 1, (p.39 for steam and condensation will be and p.42) performed and used to determine if vent path strategy is needed.

Safety Functions Support, Habitability conditions will be Complete (Ref-29)

Phase 2 (p.51) evaluated and a strategy will be developed to maintain Main Control Page 7 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX Room.

Safety Functions Support, Critical ventilation assets may be Complete (Ref-29)

Phase 2 (p.51) required to support DDAF pumps, station battery rooms, miscellaneous electric equipment rooms, and fuel handling building personnel habitability and/or component survivability. Specific analyses of these rooms will be performed.

Interim Safety Evaluation Open Item Status Byron Station's ISE Response Line Item Description Answer Number Number 1 Open Item Core Subcriticality- The NRC staff Complete 3.2.1.8.A has not endorsed the industry-The Westinghouse Calculation proposed position paper regarding CN-LIS-15-039, Byron and boron mixing. The licensee has Braidwood Stations Reactor indicated that Byron is planning on Coolant System ELAP Long-Term following this methodology. Thus, Subcriticality Analysis with Low-further resolution of this issue will be Leakage Reactor Coolant Pump necessary in the next phase of the Seal Packages, provides for a audit process.

bounding calculation that boration would start by 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> into the ELAP with a minimum of 6000 gallons of 2300ppm borated water injected.

Confirmatory Items 51111 N 2 3.1.1.1.A Storage & Protection of FLEX Complete (Ref-29) equipment - Confirm final design of FLEX storage structure conforms to N E 112-06, Sections 5.3.1, 7.3.1, and 8.3.1 for storage considerations for the hazards applicable to Byron.

3 3.1.1.3.A Procedural Interface Considerations Complete (Ref-29)

(Seismic) Confirm procedure for measuring key instruments at containment penetrations using Page 8 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX portable instrument.

4 3.1.1.4.A Off-Site Resources Confirm Complete (Ref-28)

National SAFER Response Center local staging area and method of transportation to the site in future 6-month update 5 3.1.5.1.A Protection of Equipment (High Complete (Ref-29)

Temperature) - Confirm FLEX storage structure will maintain FLEX equipment at a temperature range to ensure its likely function when called upon.

6 3.1.5.3.A Deployment of Equipment (High Complete (Ref-29)

Temperature) - Confirm that the effects of high temperature on FLEX equipment have been evaluated in the locations they are intended to operate.

7 3.2.1.A RCS cooling & RCS inventory Complete (Ref-29) control - Specify which analysis performed in WCAP-1 7601 is being applied to Byron. Additionally, justify the use of that analysis by identifying and evaluating the important parameters and assumptions demonstrating that they are representative of Byron and appropriate for simulating the FLAP transient.

8 3.2.1.1.A NOTRUMP - Confirm that the use of Complete (Ref-29)

NOTRUMP in the ELAP analysis is limited to the flow conditions before reflux condensation initiates. This includes specifying an acceptable definition for reflux condensation cooling.

9 3.2.1.1.B FLAP Analysis - Confirm Complete (Ref-29) calculations to verify no nitrogen injection into RCS during depressurization.

10 3.2.1.1.0 Confirm analysis for secondary side Complete (Ref-29)

SG fouling due to the use of Page 9 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX abnormal water sources (RWST, well water, SX water) 11 3.2.1.1.D Complete analysis for length of time Complete (Ref-29) prior to depletion of the RWST and determine whether additional boration equipment is needed for Phase 3 coping strategy.

12 3.2.1.2.13 Reactor Coolant Pump (RCP) Seal Complete - Byron Station has Leakage - In some plant designs, installed the Westinghouse the cold legs could experience reactor coolant pump (RCP) temperatures as high as 580 OF SHIELD Passive Thermal before cooldown commences. This Shutdown Seals (SDS) is beyond the qualification (Generation 111) on Unit 1 and will temperature (550°F) of the 0-rings install the SDS on Unit 2, May used in the RCP seals. For those 2016. Byron Station has Westinghouse designs, a discussion Westinghouse RCP Model should be provided to justify that (1) 93A. Credit for the SHIELD seals the integrity of the associated 0- has been endorsed for rings will be maintained at the Westinghouse Model 93A RCPs temperature conditions experienced as documented in ADAMS during the FLAP event, and (2) the Accession No.

seal leakage rate of 21 gpm/seal MI-1 4132A1 28. The RCP seal used in the FLAP is adequate and leakage assumed in CN-LIS-1 5-acceptable. 34, Exelon Byron and Braidwood Stations Reactor Coolant System FLAP Inventory Control Analysis SHIELD Reactor Coolant Pump Seal Packages, is consistent with ADAMS Accession No.

MI-14132A128 limitations and conditions number 4.

The qualification testing of the shutdown seal was performed at conditions based on a cold leg temperature of 571OF. The maximum shutdown seal temperature remains below the shutdown seal temperatures experienced during qualification testing.

Following a loss of AC power, it is possible for the RCS cold leg temperature to exceed 571OF for short periods of time without the Page 10 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX shutdown seal heating up beyond the temperatures experienced during qualification testing. This is due to the significant thermal inertia of the massive reactor coolant pump internals and pressure boundary. The evaluation documented in calculation CN-LIS-15-40 (Ref-30) concludes that even if the cold leg temperature is 581 IF for the first 3000 seconds (50 minutes) following ELAP initiation, the maximum fluid temperature at the reactor coolant pump seal inlet remains below the temperatures experienced during shutdown seal qualification testing. Auxiliary Feedwater flow to the steam generators will be initiated at approximately 30 minutes into the ELAP event. Following the restoration of Auxiliary Feedwater flow to the steam generators and prior to initiating plant cooldown, cold leg temperature will be dictated by the Main Steam Safety Valves. Cold leg temperature will remain less than 571 OF during this period based on the lowest Main Steam Safety Valve setting of 1175 psig adjusted for setting tolerance and lift setpoint testing uncertainty.

Westinghouse LTR-RES-13-153, Documentation of 7228C Compound O-Rings at ELAP Conditions, concludes, with a high level of confidence, that the integrity of the RCS 0-rings will be maintained at the temperature conditions experienced during the ELAP event.

Page 11 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX 13 3.2.1.2.E RCP Seal Leakage Rates - The Complete (Ref-28) licensee is requested to provide the manufacturer and model number of the RCP seals and discuss whether or not the RCP and seal combination complies with a seal leakage model described in WCAP-17601.

14 3.2.1.3.A Decay Heat- Verify that the Complete - (Ref-37)

Integrated Plan update provides the details of the WCAP 17601 -P methodology to include the values of certain key parameters used to determine the decay heat levels.

Address the adequacy of the values used.

15 3.2.1.4.A Initial Values for Key Plant Complete - (Ref-37)

Parameters and Assumptions-Confirm WCAP- 17601 -P analyses are bounding for Byron for strategy response or verify plant-specific analyses if more restrictive limits are used due to more restrictive plant specific limits.

16 3.2.1.4.13 Initial Values for Key Plant Complete (Ref-29)

Parameters and Assumptions-Confirm calculations to validate 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> run time limit on DDAF pump batteries and DDAF room temp for pump operation and human occupancy. Also, confirm site phase 2 staffing study confirms the required time can be met for refilling diesel day tank.

17 3.2.1.5.A Monitoring Instruments and Control- Complete (Ref-28)

Confirm additional parameters evaluated for use in plant procedures/guidance or to indicate imminent or actual core damage.

18 3.2.1.6.A Sequence of Events - Confirm that Complete the final timeline has been time There was one change based on validated after detailed designs are the calculation CN-LIS-15-40, completed and procedures are Byron and Braidwood Stations Page 12 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX developed. The results may be Delayed AFW FLEX Studies, provided in a future 6-month update. which allowed less time to dry out. The steps to isolate the SG PORVs and to start the B AF Pump were shortened. Byron Station updated BCA 0.0, Loss of All AC, steps and the BFSG-2, Alternate AFW/EFW Suction Source steps and direction. This change was revalidated and updated in the Time Sensitive Actions Procedure.

The timeline was updated using the times documented in the Westinghouse calculations.

The new Timeline, Attachment A in the updates, has been already validated and the changes required do not impact the time or margins that have been documented.

19 3.2.1.6.13 Sequence of Events - Confirm Complete (Ref-29) analysis to validate Phase 2 pump capacities.

20 3.2.1.9.A Use of portable pumps - Confirm Complete (Ref-29) final design of strategies meets "use of portable pumps" guideline in NEI 12-06 Section 3.2.2 Guideline 13.

21 3.2.2.A SFP cooling -Verify procedure for Complete (Ref-29)

SFP makeup via gravity drain; confirm verification of timeline for performing the strategy; and confirm evaluation of SFP area for steam and condensation affects.

22 3.2.3.A Containment - Confirm containment Complete (Ref-37) reanalysis supports no Phase 1, 2, and 3 mitigation strategies are required because containment pressure and temperature are I Page 13 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX maintained within acceptable limits.

23 3.2.3.13 Containment - Confirm evaluation Complete (Ref-29) performed for the need to monitor containment temperature.

24 3.2.4.1 A Equipment cooling - Confirm Complete (Ref-29) modification has been performed to prevent DDAF pump from overheating due to cooling water recirculation flow paths within the SX system cycling and overheating the pump within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

25 3.2.4.2.A Ventilation - Equipment Cooling - Complete (Ref-29)

Review licensee's evaluation of loss of ventilation effects on equipment in various rooms (DDAF pump room, battery rooms, control room, miscellaneous electrical equipment rooms) 26 3.2.4.2.B A discussion is needed on the Complete (Ref-29) extreme high/low temperatures effects of the battery's capability to perform its function for the duration of the ELAP event and hydrogen gas ventilation during recharging batteries during Phase 2 and 3.

27 3.2.4.3.A Heat Tracing - Confirm that potential Complete (Ref-29) adverse impacts from a loss of heat tracing and normal heating on any equipment credited for ELAP mitigation are adequately addressed. In particular, ensure an RCS inventory and source of borated water is available for a BIDBEE associated with extreme cold, ice, and snow.

28 3.2.4.4.A Communications - Confirm that Complete upgrades to the site's Byron Station has completed the communications systems have been NARS Upgrade satellite completed.

communications system per RFI 9.3.

Byron Station has 3 Iridium Satellite phones available for the SM/SED in Page 14 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX the MCR area. Additional handheld radios for use on talk-around with batteries are staged in the robust FLEX building. The Site has Sound Powered phones and cords in lockers in the plant with cables as well as Bull Horns for help with notifications.

29 3.2.4.6.A Personnel Habitability - Review Complete (Ref-28) licensee's evaluation of loss of ventilation effects on personnel habitability and accessibility.

30 3.2.4.7.A Water Sources - Justify the time at Complete - Westinghouse which SG dryout will occur. Calculation CN-LIS-15-40, Byron and Braidwood Stations Delayed AFW FLEX Studies provided bounding information that the shortest time to dry out would be 2702 seconds, or 45.03 minutes on U2 and 3777 seconds, or 62.95 minutes on U1.

31 3.2.4.8.A Electrical Power Sources / Isolation Complete (Ref-29) and interactions- confirm class 1 E equipment is protected from faults in portable/FLEX equipment and multiple sources do not attempt to power electrical buses.

32 3.2.4.9.A Portable Equipment Fuel - Confirm Complete (Ref-29) that complete analysis of fuel usage requirements has been developed after the specific FLEX equipment is identified and the fuel usage is determined. A discussion is needed on maintaining the quality of fuel stored in the tanks for extended periods of time 33 3.2.4.10.A Load reduction to conserve DC Complete (Ref-29) power- Confirm sizing calculations for FLEX generators and details of load shedding.

Additional Questions Page 15 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX from Audit 1 AQ-27 Ventilation: Provide a discussion on Complete, (Ref 37) the impact of elevated temperatures, as a result of loss of ventilation and/or cooling, on support equipment being credited as part of the ELAP strategies (e.g., support equipment in the turbine driven auxiliary feedwater pump rooms). In your response specify whether the initial temperature condition assumed the worst-case outside temperature with the plant operating at full power. Provide the list of support components that are located in the pump rooms that are necessary to ensure successful operation of required pumps. Also provide the qualification level for temperature and pressure for these support components for the duration that the pumps are assumed to perform its mitigating strategies function.

2 SE #10 Transition from Phase 2 to 3. Complete (Ref 37) 3 SE #12 The NRC staff understands that Complete Westinghouse has recently Byron Station has installed the recalculated seal leakoff line Westinghouse reactor coolant pressures under loss of seal cooling pump (RCP) SHIELD Passive events based on a revised seal Thermal Shutdown Seals (SDS) leakage model and additional (Generation III) in all 4 RCPs on design-specific information for Unit 1 and will install on Unit 2 in certain plants. Please clarify the spring of 2016. The NRC has whether the piping in your seal concluded that the use of the leakoff line is capable of Westinghouse SHIELD Passive withstanding the pressure predicted Thermal SDS is acceptable for use during an ELAP event according to in ELAP evaluation for Order EA-the revised seal leakage model. If 12-049 as documented in ADAMS not, please discuss any planned Accession No. ML14132A128.

modifications to the seal leakoff (Ref 33) piping design and the associated completion timeline. Alternately, Page 16 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX please clarify that the seal leakage rate would remain in an acceptable range if the affected seal leakoff piping were to rupture.

4 SE #13 Accuracy of the NOTRUMP Complete (Ref 37)

Computer Code:

Westinghouse used the NOTRUMP computer code to develop certain timelines for operator actions in an FLAP event (see WCAP-1 7601 -P for example). NRC simulations using the TRACE code indicate some differences, which may be significant enough to affect the timeline for operator actions. The PWROG is working with the NRC on a resolution, which may be applicable to all PWRs.

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

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

1. Byron Station, Units 1 and 2, "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-13-017).

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

3. NEI 12-06, Rev. 0, Diverse and Flexible Coping Strategies (FLEX) Implementation Guide, dated August 2012.

4. Byron Station's First Six Month Status Report for the Implementation of FLEX, dated August 28, 2013.

5. Byron Station's Second Six Month Status Report for the Implementation of FLEX, dated February 28, 2014.

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Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX

6. Byron Station, Units 1 and 2 Interim Staff Evaluation Relating to Overall Integrated Plan in Response to Order EA-12-049 (Mitigating Strategies) (TAC NOS. MF0895 AND MF0896), dated December 17, 2013.

7. BYR99-010/BRW-99-0017-1, Rev. 2, Documentation of the Basis of the Emergency Operating Procedures (EOP) Setpoints, dated June 2014.

8. BYR1 4-060/BRW-1 4-0080-E, Rev. 0, Unit 1(2) 125 VDC Battery FLEX Coping Calculation Common Calc Beyond Design Basis, dated May 2014.

9. BYR1 3-240/BRW-1 3-0222-M, Rev. 0, Spent Fuel Pool Boil Off Analysis during an ELAP Event, dated March 2014.

10.BYR1 3-239/BRW-1 3-0221 -M, Rev. 0, RCS Boration Analysis during an ELAP Event, dated June 2014.

11.Exelon Structural Drawing S-183, Rev. AF, Roadway Plan Plant and Construction Laydown Area, dated 5/2014.

12.BYR1 3-235/BRW-1 3-0217-M, Rev. 0, Containment Pressure and Temperature Response during an ELAP Event, dated June 2014.

13. BYR1 3-234/BRW-1 3-0216-M, Rev. 0, Auxiliary FW Pump Room Temperature Analysis during and ELAP Event, dated March 2014.

14.BYR13-237/BRW-13-0219-M, Rev. 0, MEER and Battery Room Conditions Following ELAP, dated June 2014.

15.BYR1 3-236/BRW-1 3-0218-M, Rev. 0, Control Room and Auxiliary Electric Equipment Room heat up and Ventilation during an ELAP, dated June 2014.

16.BYR1 3-026/BRW-1 3-0031 -M, Rev. 0, Transient Analysis of SX System Following Loss of A-C Power, dated August 2014.

17.BYR14-046/BRW-14-0058-M, Rev. 0, Containment Environment Following an Extended Loss of AC Power During Shutdown, dated June 2014.

18. WCAP 17601 -P, Rev. 1, Reactor Coolant System Response to the Extended Loss of AC Power Event for Westinghouse, Combustion Engineering and Babcock & Wilcox NSSS Designs, dated January 2013.

19.BYR1 3-238/BRW-1 3-220-E, Rev. 0, DDAF Pump Battery Duty Cycle and Sizing for a BDBEE, dated January 2014.

20. BYR1 3-144/BRW-1 3-0160-M, Rev. 0, FLEX Pump Sizing and Hydraulic Analysis, dated April 2014.

21. Letter to Mr. Jack Stringfellow, "Boron Mixing Endorsement Letter in Regards to Mitigation Strategies Order EA-12-049," January 8, 2014. (Agency wide Documents Access and Management System (ADAMS) Accession Number MI-1 3276A1 83)

22. Westinghouse Correspondence LTR-FSE-14-43, Revision O-A, "Exelon Generation Company, LLC Mitigation Strategies Order (EA-12-049) Design ELAP Simulation Parameters," July 16, 2014.

Page 18 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX

23. BYR1 4-119 UHS, Rev 0, Volume Analysis during an ELAP Event, dated July 2014.

24. Letter to David Flahive of Westinghouse, "Exelon Generation Company, LLC Mitigation Strategies Order (EA-12-049) Open and Confirmatory Item Responses," Letter LTR-FSE-1 4-61 Rev.0-A, dated July 17, 2014.

25. BYR1 4-130/BRW-1 4-0211 -M, Rev. 0, Evaluation of Tank and Hose Freezing during an ELAP, dated August 2014.

26. BYR1 4-150, Byron Units 1 &2 FLEX Steam Generator Degraded Heat Transfer Analysis Through 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, dated Nov 2014.

27. BYR1 4-129 / BRW-1 4-0212-M, RWST Usage During FLEX Scenarios, dated October 2014.

28. Byron Station's Third Six Month Status Report for the Implementation of FLEX, dated August 28, 2014.

29. Byron Station's Fourth Six Month Status Report for the Implementation of FLEX, dated February 27, 2015.

30. CN-LIS-15-40, Exelon Byron and Braidwood Stations Delayed AFW FLEX Studies.

31. CN-LIS-15-34, Exelon Byron and Braidwood Stations Reactor Coolant System ELAP Inventory Control Analysis with SHIELD Reactor Coolant Pump Seal Packages.

32. CN-LIS-15-39, Exelon Byron and Braidwood Stations Reactor Coolant System ELAP Long-Term Subcriticality Analysis with Low-Leakage Reactor Coolant Pump Seal Packages.

33. Letter to Mr. James A. Gresham, "Use of Westinghouse SHIELD Passive Shutdown Seal for FLEX Strategies," May 28, 2014. (Agency wide Documents Access and Management System (ADAMS) Accession Number ML14132A128)

34. PWROG-14027-P, Rev 3, No.1 Seal Flow Rate for Westinghouse Reactor Coolant Pumps Following Loss of All AC Power. Task3: Evaluation of Revised Seal Flow Rate on Time to Enter Ref lux Cooling and Time at which the Core Uncovers.

35. PWROG-1 4064-P, Rev 0, Application of NOTRUMP Code Results for Westinghouse Designed PWRs in Extended Loss of AC Power Circumstances.

36. Letter to Mr. Jack Stringfellow, "Application of NOTRUMP Code Results for Westinghouse Designed PWRs in Extended Loss of AC Power Circumstances" (Agency wide Documents Access and Management System (ADAMS) Accession Number ML15061A442), dated June 16, 2015.

37. Byron Station's Fifth Six Month Status Report for the Implementation of FLEX, dated August 28, 2015

38. CN-LIS-15-38, Calculation of Asymmetric Natural Circulation Cooldown Rate Limits for the Byron and Braidwood Units in Support of the FLEX Program.

39. CN-LIS-1 5-48, AFW Makeup Usage.

40. LTR-LIS-15-336, ELAP Summary Report, dated October 13, 2015.

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Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX

41. Exelon letter to the NRC, Byron Station, Unit 1 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 049), RS-15-267, dated November 30, 2015.

Page 20 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX Attachment 1A Sequence of Events Timeline Time Action Remarks /

Elapsed Time Action Constraint item Applicability Y/N Event Starts, BDBEE occurs, Unit I and Unit 2 reactors 1 0 automatically trip and all rods are inserted. NA Unit I and Unit 2 Loss of off-site power (LOOP) affecting both units occurs. @100% power.

2 0-1 min Emergency Operating Procedures, (EOPs) and Station Black NA BCA 0.0, Loss of Out, (SBO), Procedures are entered. All AC Power, action.

3 3-5 mins MCR closes C & D S/G PORVs to conserve inventory. Y 5 BCA 0.0, Loss of minutes All AC Power, action. CN-LIS 40, Reference 30 4 5-30 mins Verify DDAF Pp is operating properly. Y-45 BCA 0.0, Loss of minutes All AC Power, action. CN-LIS 40, Reference 30 5 10-30 mins Attempt starting Emergency D/G's. NA BCA 0.0, Loss of All AC Power, action.

6 30 mins ELAP condition recognized and ELAP Procedures are entered. NA BCA 0.0, Loss of All AC Power, attachment B for ELAP.

Reference BRW 7 30 mins to 6 hrs Connect FLEX 480V AC generators to ESF bus 32X and verify Y 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 0080-E, Rev 0, Unit they are supplying power to Div 2 - 125V DC battery chargers. 1(2) 125 VDC Battery FLEX Coping Calculation Common Calc Beyond Design Basis, dated May 2014.

BCA 0.0, Loss of 8 30 mins to 90 mins SX Short Cycle Cooling EC is aligned to cool the B AF Pp Y - 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> All AC Power, within 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> after pump start. action. BYR13-026 Ref 16.

' Instructions: Provide justification if No or NA is selected in the remarks column If yes, include technical basis discussion as required by NEI 12-06, Section 3.2.1.7 Page 21 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX Time Action Remarks /

Elapsed Time Action Constraint item Applicability Y/N 1 Reference BRW 9 35 mins to 65 mins Operators dispatched to perform DC Bus Load Shed. Y - 65 0080-E, Rev 0, Unit minutes 1(2) 125 VDC Battery FLEX Coping Calculation Common Calc Beyond Design Basis, dated May 2014.

10 3 5 hrs Set up and establish ventilation in AEER and MCR. Y 5.15 Directed from hours OBFSG-51Alternate MCR Ventilation Reference calculation BYR13-236/BRW-13-0218-M, Control Room and Auxiliary Electric Equipment Room heat up and Ventilation during an ELAP.

11 4-6 hrs Start depressurization of S/Gs to 260 psig at approximately Y - 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> _BCA 0.0, Loss of 50°F/hr cooldown with SG PORV local/manual operation. SG All AC Power, feed is controlled with Local/Manual operation of AFW flow action. CN-LIS control valves. 39, Reference 32.

12 6 9 hrs Deploy FLEX DG to SX tower switchgear room and establish Y 17 Reference calculation power to one of the ESF Busses 131ZJ132Z for power to a Well hours BYR14-119 UHS Water, (WW), Pump and establish make up flow to the UHS. Volume Analysis during an ELAP Event.

13 6 - 10 hrs Deploy all hoses and connections in FHB for alternate SFP Fill Y - 10.94 Directed from strategy before FHB becomes uninhabitable from SFP Boiling. hours OBFSG-5 and OFSG-

11. Reference BRW-13-0222-M, Rev 0, Spent Fuel Pool Boil Off Analysis during an ELAP Event, dated April 2014.

14 7-10 hrs SI Accumulator borated water begins to inject into the RCS NA Operator Judgment.

15 7-16 hrs Isolate SI Accumulators. NA 1/2BFSG -10 action.

16 11-16 hrs Maintain SG pressure 260 psig and RCS temperature between NA CN-LIS-15-39, 420F 410F with SG PORV operation. Reference 32.

Maintain SG level.

17 11-14 hrs Stage and connect Phase 2 high pressure FLEX Pumps and Y- 16 CN-LIS-15-39, ensure they are available to supply borated make-up to the RCS. hours Reference 32.

18 16 - 20 hrs Stage and connect Phase 2 med head FLEX Pumps and ensure NA 1/2BFSG-5action.

they are available to supply make-up to the SG's.

19 24 hrs Initiate SFP Make up via OA FC Purification pump as required NA OBFSG-11 action.

Reference BRW Page 22 of 23

Byron Station, Unit 2- Sixth Six Month Status Report for the Implementation of FLEX Time Action Remarks /

Elapsed Time Action Constraint item Applicability YjN 1 for level and temperature control. 0222-M, Rev 0, Spent Fuel Pool Boil Off Analysis during an ELAP Event, dated April 2014.

20 24 hrs National SAFER Response Center resources begin arriving on NA National SAFER site. Response Center Guide.

21 24 - 72 hrs Continue to maintain critical functions of Core Cooling (via NA End of analytical DDAF), RCS Inventory Control (via FLEX pump injection to simulation.

RCS) and SFP Cooling (via FLEX pump injection to SFP). Utilize initial National SAFER Response Center equipment and resources.

Page 23 of 23