RS-15-209, 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-12-049)

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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-12-049)
ML15240A304
Person / Time
Site: Byron  Constellation icon.png
Issue date: 08/28/2015
From: Kaegi G
Exelon Generation Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
EA-12-049, RS-15-209
Download: ML15240A304 (31)
v • d • e


Text

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Exeton Generationc, Order No. EA-12-049 RS-15-209 August 28, 2015 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455

Subject:

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-12-049)

References:

1. NRC Order Number EA-1 2-049, "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. NEt 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-1 2-049), 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-1 2-049), 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-1 2-049), dated February 28, 2014 (RS-14-008)

U.S. Nuclear Regulatory Commission Integrated Plan Report to EA-1 2-049 August 28, 2015 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-1 2-049), 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-1 2-049), dated February 27, 2015 (RS-15-017) 10.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 11.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-1 2-049 and EA-1 2-051 (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, Units 1 and 2 overall integrated plan.

Reference 1 requires submission of a status report at six-month intervals following submittal of the overall integrated plan. Reference 3 provides direction regarding the content of the status reports. References 6, 7, 8, and 9 provided the first, second, third, and fourth six-month status reports, respectively, pursuant to Section IV, Condition C.2, of Reference 1 for Byron Station.

The purpose of this letter is to provide the fifth 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 10, and the NRC audit open items contained in Reference 11.

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

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 28th day of August 2015.

U.S. Nuclear Regulatory Commission Integrated Plan Report to EA-1 2-049 August 28, 2015 Page 3 Respectfully submitted, A&~

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

Enclosure:

1. Byron Station, Units 1 and 2 Fifth Six-Month Status Report for the Implementation of Order EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events cc: Director, Office of Nuclear Reactor Regulation NRC Regional Administrator Region III NRC Senior Resident Inspector Byron Station, Units 1 and 2 NRC Project Manager, NRR Byron Station, Units 1 and 2 Ms. Jessica A. Kratchman, NRR/JLD/PMB, NRC Mr. Jack R. Davis, NRR/DPR/MSD, NRC Mr. Eric E. Bowman, NRR/DPR/MSD, NRC Mr. Jeremy S. Bowen, NRR/DPR/MSD/MSPB, NRC Mr. Robert L. Dennig, NRR/DSS/SCVB, NRC Mr. John D. Hughey, NRR/JLD/JOMB, NRC Illinois Emergency Management Agency Division of Nuclear Safety

Enclosure Byron Station, Units 1 and 2 Fifth 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 (27 pages)

Byron Station, Units 1 and 2 Fifth Six-Month Status Report for the Implementation of Order EA-1 2-049, 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.

2 Milestone Accomplishments The following milestone(s) have been completed since February 28, 2015 and are current as of July 27, 2015.

. None 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.

Site: Byron Original Target Activity Status Revised Target Completion Date Completion Date Submit 60 Day Status Report Complete Submit Overall Integrated Complete Implementation Plan Contract with Strategic Alliance Complete 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 Page 1 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 Feb 2015 Update 4 Complete Aug 2015 Update 5 Complete with this submittal Feb 2016 Update 6 Not Started Unit 1 Unit 2 Modification Development Unit 1 Unit 2 Unit 1 Unit 2 Aug Dec

  • Phase 1 modifications Started Complete Sept 2014 2013 2015 Aug Dec
  • Phase 2 modifications Started Complete Sept May 2014 2013 2015 2016 Aug Dec
  • Phase 3 modifications Complete 2014 2013 Unit 1 Unit 2 Modification Implementation Sept Oct
  • Phase 1 modifications Started Complete May 2015 2014 2016 Sept Oct
  • Phase 2 modifications Started Complete May 2015 2014 2016 Sept Oct
  • Phase 3 modifications Complete 2015 2014 Procedure Development Unit 1 Unit 2 Oct 2014
  • Strategy procedures Started Complete Sept May 2015 2016
  • Validate Procedures Started Complete Sept Apr 2014 (NEI 12-06, Sect. 2015 11.4.3)

Oct 2014

  • Maintenance Started Sept 2015 procedures Jun 2014 Staffing analysis Complete Oct 2014 Storage Plan and construction Complete 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 Started Oct 2014 Unit 2 Implementation date Started May 2016 Page 2 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 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, and PWROG-1 4027-P Rev. 3 issued.

Change:

Note: Byron Station has committed to install the Westinghouse reactor coolant pump (RCP)

SHIELD Passive Thermal Shutdown Seals (SDS) (Generation Ill). The SHIELD SDSs will be installed in all 4 RCPs on Unit 1 in the fall of 2015 and 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 will change the Unit's response in a BDBEE described in NEI 12-06. As a result, the site is in the process of performing additional calculations to confirm the site Fukushima strategy. The additional calculations will be completed prior to the completion of Bi R20, in the fall of 2015. The results of these calculations will be communicated with the post outage compliance letter for Unit 1.

Change 2 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.

Change: With the New SDS installation there are changes that are being impacted in the existing calculations. Westinghouse is performing updated calculations now and the results will be provided in the compliance letter for Unit 1 and in the next 6-month update for Unit 2.

Change 3 Section: In the 6-month updates Section 6 Open Items from Overall Integrated Plan and Draft Safety Evaluation Reason for Change: With the new SDS installation the calculations utilized for leakage and the reduced inventory loss are impacting completed items as well as the open items pertaining to the RCP Seals.

Change: Some of the completed items have been reset to Started and some of the in-progress items have been updated with the new Westinghouse RCP seal status.

  • Maintain RCS Inventory Control, Phase 2 (p.23) In Progress With the New SDS installation there are changes that are being impacted in the existing calculations.

Westinghouse is performing updated calculations now and the results will be provided in Page 3 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 the compliance letter for Unit 1 and in the next 6-month update for Unit 2. (Ref- 30, 31, 32)

  • Maintain Containment, Phase 1 (p.31) Started The new Westinghouse calculations will feed into the existing Containment calculations which will require an update.
  • From ISE Response Open Item 3.2.1.8.A With the New SIDS installation there are changes that are being impacted in the existing calculations. Westinghouse is performing updated calculations currently and the results will be provided in the compliance letter for Unit 1 and in the next 6-month update for Unit 2. (Ref- 30, 31, 32)
  • Confirmatory Items 3.2.1.A Started With the New SIDS installation there are changes that are being impacted in the existing calculations. Westinghouse is performing updated calculations currently and the results will be provided in the compliance letter for Unit 1 and in the next 6-month update for Unit 2. (Ref- 30, 31, 32)
  • Confirmatory Items 3.2.1.13 Started With the New SIDS installations there are changes that are being impacted in the existing calculations. Westinghouse is performing updated calculations currently and the results will be provided in the compliance letter for Unit 1 and in the next 6-month update for Unit 2. (Ref- 30, 31, 32)
  • Confirmatory Items 3.2.1.6.A Started The final time line will be validated as the time sensitive actions, listed in Attachment 1 A, go through the validation process. Results will be provided in the compliance letter for Unit 1 and in the next 6-month update for Unit 2.
  • Confirmatory Items 3.2.4.4.A Started Updated information of the new Satellite Communication installation.
  • Confirmatory Items 3.2.4.7.A Reopening with new Westinghouse calculations. (Ref 30)

Started With the New SIDS installation there are changes that are being impacted in the existing calculations. Westinghouse is performing updated calculations currently and the results will be provided in the compliance letter for Unit 1 and in the next 6-month update for Unit 2. (Ref- 30, 31, 32)

Change 4 Section: Attachment 1 A Sequence of Events Timeline Reason for Change: With the new SIDS installation the calculations utilized for leakage and the reduced inventory loss are impacting the order and timing of required actions pertaining to the RCP Seals.

Change:

1. Item #2 was changed to enter BCA 0.0 within 1 min of event onset, and has been validated.
2. Item #3 was changed to reflect actual validated time with updated procedure BCA 0.0.
3. Item #4 was changed to reflect actual validated time with updated procedure BCA 0.0.
4. Item #9 was changed to reflect same duration with an earlier start time from B AF Pump start time.
5. Item #15 was changed to update the timeline for setting up the high pressure FLEX pump and hoses at 11 to 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> ensuring RCS makeup will be available prior to ref lux boiling based on PWROG- 1 4027-P Rev. 2, No.1 Seal Flow Rate for Westinghouse Reactor Coolant Pumps Following Loss of ALL AC Power.

Page 4 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 Change 5 Section: Maintain Core Cooling & Heat Removal PWR Installed Equipment Phase 1 and Maintain RCS Inventory Control PWR Installed Equipment Phase 1.

Reason for Change: Align wording to site strategy Change: Change last paragraph to the following:

Deploying and implementing portable FLEX pumps to supply injection flow must commence immediately from the time direction is provided in site emergency procedures. This should be plausible because more personnel are on site during outages to provide the necessary resources. Strategies for makeup water include deploying a FLEX pump to take suction from the RWST and /or UHS as described in the Phase 2 Core Cooling section. Guidance will be provided to ensure that sufficient area is available for deployment and that haul paths remain accessible without interference from outage equipment during refueling outages.

Change 6 Section: General Integrated Plan Elements PWR Extent to which the guidance, JLD-ISG-2012-01 and NEI 12-06, are being followed. Identify any deviations to JLD-ISG-2012-01 and NEI 12-06.

Reason for Change: Byron is taking an alternate approach to NEI 12-06, Sections 3.2 and 3.2.1.3. The alternate approach is for the method of protecting the permanently installed power operated relief valve (PORV) manual hand pumps from all design basis external events. The PORV operators are within robust structures with a non-robust access door. The PORV hand pumps are relied upon for symmetric cool down following a beyond design basis external event (BDBEE).

Basis for alternate approach:

NEI 12-06, Rev. 0, Section 3.2 states, "Installed equipment that is designed to be robust with respect to design basis external events is assumed to be fully available. Installed equipment that is not robust is assumed to be unavailable." Also, Section 3.2.1.3 states, "Permanent plant equipment that is contained in structures with designs that are robust with respect to seismic events, floods, and high winds, and associated missiles, are available." Robust is defined in Appendix A as, "the design of an SSC either meets the current plant design basis for the applicable external hazards or has been shown by analysis or test to meet or exceed the current design basis."

Byron's PORV hand pumps do not meet all of the plant robust requirements for all design basis external events, due to the location behind a non-robust door. Specifically, the door is designed for high winds, but not tornado winds or wind driven missiles.

The PORV operators are within the Category I, robust main steam safety valve (MSSV) room concrete structures at grade elevation, surrounding the containment building. The rooms are protected from tornado missiles and wind by robust concrete labyrinth vestibules with entry via steel Category II doors. The non-safety related PORV manual operators are seismically-mounted within the labyrinth vestibules, but the components are subject to tornado winds and wind generated missiles through the non-robust door.

Page 5 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 Per Byron UFSAR Section 2.3.1.2.2, the predominant tornado path is southwest to northeast. These doors are located on the west side of the site.

The Unit 1 and Unit 2 ND MSSV rooms are located back, closer to the turbine building, and protected by the turbine building structure and transformer yard firewalls. These structures provide reasonable assurance tornado winds or wind driven missiles will not strike or damage the outer door and prevent access or disable the PORV manual controllers.

The Unit 1 and Unit 2 B/C MSSV rooms are exposed to the environment facing west.

Large concrete blocks will be placed in front of the two (2) B/C MSSV room doors to protect the PORV operators from design basis horizontal missiles. The blocks also limit the amount of possible large debris build-up in front of the doors, since the blocks are placed approximately four (4) feet from the entrance.

This configuration ensures all four sets of permanently installed PORV hand pumps have "reasonable protection" and will survive all BDBEEs.

Change: The site is crediting the availability of the SG PORV manual controllers to provide the operators with a method to symmetrically cool down the RCS following a BDBEE.

Change 7 Section: General Integrated Plan Elements PWR Extent to which the guidance, JLD-ISG-201 2-01 and NEI 12-06, are being followed. Identify any deviations to JLD-ISG-2012-01 and NEI 12-06.

Reason for Change: An alternate approach is being proposed to the N+1 requirement applicable to hoses and cables as stated in Section 3.2.2 of NEI 12-06.

Basis for the alternate approach:

NEI 12-06, Section 3.2.2 specifically states that a site will have FLEX equipment to meet the needs of each unit on a site plus one additional spare. This is commonly known as N+1 where N is the number of units at a given site. The relevant text from NEI 12-06 is as follows:

NEI 12-06, Section 3.2.2 states: "In order to assure reliability and availability of the FLEX equipment required to meet these capabilities, the site should have sufficient equipment to address all functions at all units on-site, plus one additional spare, i.e., an N+1 capability, where "N" is the number of units on-site. Thus, a two-unit site would nominally have at least three portable pumps, three sets of portable ac/dc power supplies, three sets of hoses & cables, etc."

NEI 12-06, Section 11.3.3 states: "FLEX mitigation equipment should be stored in a location or locations informed by evaluations performed per Sections 5 through 9 such that no one external event can reasonably fail the site FLEX capability (N)."

Typically the hoses utilized to implement a FLEX strategy are not a single continuous hose but are composed of individual sections of a smaller length joined together to form a sufficient length. In the case of cables, multiple individual lengths are used to construct a circuit such as in the case of 3-phase power.

Page 6 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 Proposed Alternative:

NEt 12-06 currently requires N+1 sets of hoses and cables. As an alternative, the spare quantity of hose and cable is adequate if it meets either of the two methods described below:

Method 1: Provide additional hose or cable equivalent to 10% of the total length of each type/size of hose or cable necessary for the "N" capability. For each type/size of hose or cable needed for the "N" capability, at least 1 spare of the longest single section/length must be provided.

Example 1-1: An installation requiring 5,000 ft. of 5 in. diameter fire hose consisting of 100 50 ft. sections would require 500 ft. of 5 in. diameter spare fire hose (i.e., ten 50 ft. sections).

Example 1-2: A pump requires a single 20 ft. suction hose of 4 in. diameter, its discharge is connected to a flanged hard pipe connection. One spare 4 in.

diameter 20 ft. suction hose would be required.

Example 1-3: An electrical strategy requires 350 ft. cable runs of 4/0 cable to support 480 volt loads. The cable runs are made up of 50 ft. sections coupled together. Eight cable runs (2 cables runs per phase and 2 cable runs for the neutral) totaling 2800 ft. of cable (56 sections) are required. A minimum of 280 ft. spare cable would be required or 6 spare 50 ft. sections.

Example 1-4: An electrical strategy requires 100 ft. of 4/0 cable (4 cables, 100 ft. each) to support one set of 4 kv loads and 50 ft. of 4/0 (4 cables, 50 ft. each) to support another section of 4 kv loads. The total length of 4/0 cable is 600 ft.

(100 ft. x4 plus 50 ft. x4). One spare 100'4/0 cable would be required representing the longest single section/length.

Method 2: Provide spare cabling and hose of sufficient length and sizing to replace the single longest run needed to support any single FLEX strategy.

Example 2-1 A FLEX strategy for a two unit site requires 8 runs each of 500 ft. of 5 in. diameter hose (4000 ft. per unit). The total length of 5 in. diameter hose required for the site is 8000 ft. with the longest run of 500 ft. Using this method, 500 ft. of 5 in. diameter spare hose would be required.

For either alternative method, both the N sets of hoses or cables and the spare set of hoses or cables would all be kept in a location that meets the reasonable protection requirements for the site.

The NRC has endorsed (ML15125A442) the NEt position paper (ML15126A135) for the above stated alternate approach. If using Method 2, per the endorsement letter, Exelon will ensure that the FLEX pumps and portable generators are confirmed to have sufficient capability to meet flow and electrical requirements when a longer spare hose/cable is substituted for a shorter length. Exelon acknowledges that the NRC staff has not reviewed and is not endorsing the specific examples included in the NEt endorsement request dated May 1, 2015. If necessary, Exelon will provide additional justification regarding the acceptability of various cable and hose lengths with respect to Page 7 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 voltage drops, and fluid flow resistance, rather than merely relying on the additional, longest length cable/hose as implied by Example 1-4 in the subject letter.

Hoses and cables are passive devices unlikely to fail provided they are appropriately inspected and maintained. The most likely cause of failure is mechanical damage during handling provided that the hoses and cables are stored in areas with suitable environmental conditions (e.g., cables stored in a dry condition and not subject to chemical or petroleum products). The hoses and cables for the FLEX strategies will be stored and maintained in accordance with manufacturers' recommendations including any shelf life requirements. Initial inspections and periodic inspections or testing will be incorporated into the site's maintenance and testing program implemented in accordance with Section 11.5 of NEI 12-06.

Therefore, the probability of a failure occurring during storage is minimal, resulting in the only likely failure occurring during implementation. Mechanical damage will likely occur in a single section versus a complete set of hose or cable. Therefore, the N+1 alternative addresses the longest individual section/length of hose or cable.

Providing either a spare cable or hose of a length of 10% of the total length necessary for the "N" capability or alternatively providing spare cabling or hose of sufficient length and sizing to replace the single longest run needed to support any single FLEX strategy is sufficient to ensure that a strategy can be implemented. Mechanical damage during implementation can be compensated for by having enough spares to replace any damaged sections with margin. It is reasonable to expect that an entire set of hoses or cables would not be damaged provided they have been reasonably protected.

Change: The spare quantity of hose and cable is adequate if it meets either of the two methods described below:

Method 1: Provide additional hose or cable equivalent to 10% of the total length of each type/size of hose or cable necessary for the "N" capability. For each type/size of hose or cable needed for the "N" capability, at least 1 spare of the longest single section/length must be provided.

Method 2: Provide spare cabling and hose of sufficient length and sizing to replace the single longest run needed to support any single FLEX strategy.

For either alternative method, both the N sets of hoses or cables and the spare set of hoses or cables would all be kept in a location that meets the reasonable protection requirements for the site.

Change 8 Section: 6 Open Items from Overall Integrated Plan and Draft Safety Evaluation Reason for Change: Addition of Additional Questions from Audit Change: Added:

  • AQ-27 Status Complete with information provided
  • SE #10 - Status Complete with information provided Page 8 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015

  • SE #12 Status Complete with information provided
  • SE #13 - Complete with this update 5 Need for Relief/Relaxation and Basis for the Relief/Relaxation Byron Station, Unit 1 expects to comply with the order implementation date of September 2015.

Byron 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 by May 2016. NRC letter ADAMS Accession No. ML14260A294, 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.

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 The corporate and for FLEX responsibilities, and testing the Site program documents

& maintenance. CC-AA -118 and CC-BY-1 18 are in place.

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 Page 9 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 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 Started With the New SDS Control, Phase 2 (p.23) timing of the boration and quantity installation there are required. changes that are being impacted in the existing calculations. Westinghouse is performing updated calculations currently and the results will be provided in the compliance letter for Unit 1 and in the next 6-month update for Unit 2. (Ref- 30, 31,32)

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 Ill) will reduce the amount of leakage into containment assumed in calculation BYR1 3-235/BRW-1 3-0217-M (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.

Page 10 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 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 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's ISE Response Line Item Description Answer Number Number 1 Open Item Core Subcriticality- The NRC staff Complete (Ref-29) 3.2.1.8.A has not endorsed the industry-With the New SIDS installation there proposed position paper regarding are changes that are being boron mixing. The licensee has impacted in the existing indicated that Byron is planning on calculations. The boron mixing following this methodology. Thus, issue is factored into the new further resolution of this issue will be calculations that Westinghouse is necessary in the next phase of the performing, the results will be audit process.

provided in the compliance letter for Unit 1 and in the next 6-month update for Unit 2. (Ref- 30, 31, 32)

Confirmatory Items 3.1.1.1.A Storage & Protection of FLEX Complete (Ref-29) equipment Confirm final design of FLEX storage structure conforms to NE! 12-06, 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 portable instrument.

Page 11 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 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 ELAP 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 ref lux condensation initiates. This includes specifying an acceptable definition for ref lux condensation cooling.

9 3.2.1.1.13 ELAP 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 abnormal water sources (RWST, well water, SX water)

Page 12 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 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 Started -

Leakage In some plant designs The new, lower leakage rates are the cold legs could experience being utilized in calculation temperatures as high as 580 OF revisions for Containment before cooldown commences. This Pressure, Containment is beyond the qualification Temperature, and Boration.

temperature (550°F) of the 0-rings used in the RCP seals. For those With the New SDS installation there Westinghouse designs, a discussion are changes that are being should be provided to justify that (1) impacted in the existing the integrity of the associated 0- calculations. Westinghouse is rings will be maintained at the performing updated calculations temperature conditions experienced currently and the results will be during the ELAP event, and (2) the provided in the compliance letter for seal leakage rate of 21 gpm/seal Unit 1 and in the next 6-month used in the ELAP is adequate and update for Unit 2. (Ref- 30, 31, 32) acceptable.

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 The Westinghouse Integrated Plan update provides the nuclear steam supply system details of the WCAP 17601-P (NSSS) calculations documented in methodology to include the values of WCAP1 7601-P using the certain key parameters used to NOTRUMP code were performed determine the decay heat levels, with the ANS 5.1 1979 + 2 sigma Address the adequacy of the values decay heat model and assumed the used. reactor is initially operating at 100%

power (NOTRUMP reference case core power is 3723 MWt).

Implementation of this model includes fission product decay heat resulting from the fission of U-235, U-238, and Pu-239 and actinide Page 13 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 decay heat from U-239 and Np-239. The power fractions are typical values expected for each of the three fissile isotopes through a three region burn-up with an enrichment based on typical fuel cycle feeds that approach 5%. With that, a conversion ratio of 0.65 was used to derive the decay power of the two actinides U-239 and Np-239. Fission product neutron capture is treated per the ANS standard. The decay heat calculation utilizes a power history of three 540-day cycles separated by two 20-day outages that bounds initial condition 3.2.1.2 (1) of the Nuclear Energy Institute (NEI) document NEI 12-06, Section 3.2.1.2 (with a minimum assumption from NEI 12-06 that the reactor has been operated at 100%

power for at least 100 days prior to event initiation). Therefore, the decay heat curve assumed in the Westinghouse calculations in WCAP 17601-P is representative of Byron Units 1 and 2. The primary-side transient profile assumed in the reactor coolant system (RCS) inventory control and long-term sub-criticality calculations for Modes 1 through 4 with steam generators available is based on the Westinghouse reference coping case of WCAP-17601 -P and plant specific parameters such as reactor coolant system nominal temperature(s), pressures(s), and volumes, and accumulator cover gas pressures. These calculations do not, however, include any decay heat model and rely on the case runs cited from WCAP-1 7601-P regarding decay heat related Page 14 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 phenomenon.

15 3.2.1.4.A Initial Values for Key Plant Complete The primary system Parameters and Assumptions- conditions considered are based on Confirm WCAP-1 7601 -P analyses the Westinghouse reference coping are bounding for Byron for strategy cases described in Section 5.2.1 of response or verify plant-specific WCAP-1 7601 -P (Ref. 18). The analyses if more restrictive limits are extended loss of alternating current used due to more restrictive plant (AC) power (ELAP) simulation specific limits, parameters matrix provided in Westinghouse Correspondence LTR-FSE-1 4-43 (Ref. 22) outlines the comparison of items for Byron Station.

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

- Started The final time line will be the final timeline has been time validated as the time sensitive validated after detailed designs are actions, listed in Attachment 1A, go completed and procedures are through the validation process.

developed. The results may be Results will be provided in the provided in a future 6-month update. compliance letter for Unit 1 and in the next 6-month update for Unit 2.

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.

Page 15 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 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-29) and the reanalysis supports no Phase 1, 2, installation of the Westinghouse and 3 mitigation strategies are reactor coolant pump (RCP) required because containment SHIELD Passive Thermal pressure and temperature are Shutdown Seals (SOS) (Generation maintained within acceptable limits. Ill) will reduce the amount of leakage into containment assumed in calculation BYR13-235/BRW-13-0217-M (Ref. 12), resulting in additional margin to reaching design basis temperature and pressure.

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 3.2.4.2.13 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 Page 16 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 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 BDBEE associated with extreme cold, ice, and snow.

28 3.2.4.4.A Communications Confirm that

- Started Communications upgrade upgrades to the sites conceptual design is complete.

communications systems have been For the 1 st 2nd refuel outage, completed.

(B2R18), the Site will have 3 Iridium Satellite phones available for the SM/S ED in the MCR area.

Additional handheld radios for use on talk-around with batteries will be staged in the robust FLEX building.

The Site will have Sound Powered phones and cords in lockers in the plant with cables as well as Bull Horns for help with notifications.

In addition, for the 2nd -22'ndRefuel outage, (Bi R20), the site will complete the NARS Upgrade satellite communications system.

The design of the NARS Communication upgrade for Byron is one (1) installed dish, permanently mounted, that will provide primary satellite communication for the MCR. As backup emergency communication in BDBEE, two trailer mounted satellite communications systems are staged in the robust FLEX building. One of the trailer satellite systems is designated for MCR backup use and the other for TSC

& OSC. Each trailer has its own small Yanmar portable diesel Page 17 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 generator unit for emergency power. The trailers are compact and can be deployed via any small vehicle with a trailer hitch. The trailers have automatically deploying dish, satellite communications terminal box, remote satellite terminals as well as necessary cable and miscellaneous items to establish communications from a remote satellite deployment location.

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

- Reopening with new Westinghouse which SG dryout will occur. calculations. (Ref 30)

Started With the New SIDS installation, there are changes that are being impacted in the existing calculations. Westinghouse is performing updated calculations currently and the results will be provided in the compliance letter for Unit 1 and in the next 6-month update for Unit 2. (Ref- 30, 31, 32) 31 3.2.4.8.A Electrical Power Sources I 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 Page 18 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 33 3.2.4.1 0.A Load reduction to conserve DC Complete (Ref-29) power- Confirm sizing calculations for FLEX generators load shedding.

Additional Questions from Audit AQ-27 Ventilation: Provide a discussion on Complete, with information the impact of elevated temperatures, provided.

as a result of loss of ventilation Calculation BYR1 3-236/BRW-1 3-and/or cooling, on support 0218-M, Control Room and equipment being credited as part of Auxiliary Electric Equipment Room the ELAP strategies (e.g., support heat up and Ventilation during an equipment in the turbine driven ELAP (Ref. 15) shows the Unit 2 auxiliary feedwater pump rooms). In Auxiliary Electric Equipment Room your response specify whether the portion of the MCR boundary initial temperature condition reaching temperature limits first assumed the worst-case outside within approximately 5.15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br />.

temperature with the plant operating OBFSG-51, Alternate Control Room at full power. Provide the list of Ventilation, provides operators with support components that are located the necessary guidance to in the pump rooms that are establish alternate ventilation.

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 Byron Station is a FLEX Phase 2 coping strategy. The NSRC Equipment that is coming for Phase 3 support is only a backup to the station's N+1 equipment that is stored and protected In the robust FLEX Storage building. In case any FLEX Equipment from the NSRC is required the transition is provided in the _BFSG-1 3, TRANSISTION FROM FLEX EQUIPMENT, Attachment L TRANSISTION TO Page 19 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 NSRC EQUIPMENT.

3 SE #12 The NRC staff understands that Complete Westinghouse has recently Byron Station has committed to recalculated seal leakoff line install the Westinghouse reactor pressures under loss of seal cooling coolant pump (RCP) SHIELD events based on a revised seal Passive Thermal Shutdown Seals leakage model and additional (SDS) (Generation Ill). The design-specific information for SHIELD SDSs will be installed in all certain plants. Please clarify 4 RCPs on Unit 1 in the fall of 2015 whether the piping in your seal and on Unit 2 in the spring of 2016.

leakoff line is capable of The NRC has concluded that the withstanding the pressure predicted use of the Westinghouse SHIELD during an ELAP event according to Passive Thermal SDS is the revised seal leakage model. If acceptable for use in ELAP not, please discuss any planned evaluation for Order EA-12-049 as modifications to the seal leakoff documented in ADAMS Accession piping design and the associated No. ML14132A128. (Ref 33) completion timeline. Alternately, please clarify that the seal leakage With the New SDS installation there rate would remain in an acceptable are changes that are being range if the affected seal leakoff impacted in the existing piping were to rupture. calculations. Westinghouse is performing updated calculations currently and the results will be provided in the compliance letter for Unit 1 and in the next 6-month update for Unit 2. (Ref- 30, 31, 32) 4 SE #13 Accuracy of the NOTRUMP Complete Computer Code: Westinghouse submitted Westinghouse used the NOTRUMP NOTRUMP to the NRC for review computer code to develop certain and acceptance. The NRC timelines for operator actions in an reviewed and accepted the ELAP event (see WCAP-1 7601-P NOTRUMP, see Jack Stringfellow for example). NRC simulations using letter dated June 16, 2015 ADAMS the TRACE code indicate some ML15061A442, Ref 36. The NRC differences, which may be credited NOTRUMP and significant enough to affect the referenced the PWROG-14064-P, timeline for operator actions. The Ref 35 and the PWROG-14027-P PWROG is working with the NRC on Rev 3, Ref 34. The NRC went on to a resolution, which may be say in their acceptance that they applicable to all PWR5. had some exceptions as noted. The review of the Westinghouse and PWROG documents show that with the installation of the new SHIELD Passive Thermal Shutdown Seals Page 20 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 (SDS) (Generation HI), the reduced leakage provides significant margin to show that there will be no adverse impact on the timeline for operator actions as presented in the timeline of Byron's FLEX Strategies.

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. NEt 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.
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 M170896), 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. BYR14-060/BRW-14-0080-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.

Page 21 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015

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.BYR1 3-237/BRW-1 3-0219-M, Rev. 0, MEER and Battery Room Conditions Flowing 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. BYR13-144/BRW-13-0160-M, Rev. 0, FLEX Pump Sizing and Hydraulic Analysis, dated April 2014.
21. Letter to Mr. Jack Stringfellow titled "Boron Mixing Endorsement Letter in Regards to Mitigation Strategies Order EA-1 2-049," January 8, 2014 (Agency wide Documents Access and Management System (ADAMS) Accession Number ML13276A183).
22. Westinghouse Correspondence LTR-FSE-14-43, Revision 0-A, "Exelon Generation Company, LLC Mitigation Strategies Order (EA-12-049) Design ELAP Simulation Parameters," dated July 16, 2014.
23. BYR14-1 19 UHS, Rev 0, Volume Analysis during an ELAP Event, dated July 2014
24. Letter to David Flahive, of Westinghouse, titled "Exelon Generation Company, LLC Mitigation Strategies Order (EA-12-049) Open and Confirmatory Item Responses,"

Letter LTR-FSE-14-61, Rev.0-A, dated July 17, 2014.

25. BYR1 4-1 30/BRW-1 4-0211 -M, Rev. 0, Evaluation of Tank and Hose Freezing during an ELAP, dated Aug 2014.
26. BYR14-1 50 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. BYR14-129 / BRW-14-0212-M, RWST Usage During FLEX Scenarios, dated October 2014.

Page 22 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015

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-1 5-40, Exelon Byron and Braidwood Stations Delayed AFW FLEX Studies, Draft.
31. CN-LIS-1 5-34, Exelon Byron and Braidwood Stations Reactor Coolant System ELAP Inventory Control Analysis with SHIELD Reactor Coolant Pump Seal Packages, Draft.
32. CN-LlS-1 5-39, Exelon Byron and Braidwood Stations Reactor Coolant System ELAP Long-Term Subcriticality Analysis with Low-Leakage Reactor Coolant Pump Seal Packages, Draft.
33. Letter to Mr. James A. Gresham titled "Use of Westinghouse SHIELD Passive Shutdown Seal for FLEX Strategies," dated 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-14064-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 titled "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.

Page 23 of 27

Byron Station, Units 1 and 2- Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 Attachment 1A Sequence of Events Timeline Time Action Remarks /

Elapsed Time Action Constraint Item Applicability V/N Event Starts, BDBEE occurs, Unit 1 and Unit 2 reactors 1 0 automatically trip and all rods are inserted. NA Unit 1 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. Reference WCAP 17601-P and operator judgment.

4 5-25 mins Verify DDAF Pp is operating properly. Y-36 _BCA 0.0, Loss of minutes All AC Power, action. Reference WCAP 17601-P reference. New Westinghouse analysis Reference.

5 10-30 mins Attempt starting Emergency DIG's. NA _BCA 0.0, Loss of All AC Power, Instructions: Provide justification if No or NA is selected in the remark column If yes include technical basis discussion as requires by NEI 12-06, Section 3.2.1.7 Page 24 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 Time Action Remarks /

Elapsed Time Action Constraint item Applicability YIN 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.

Reference BRW 8 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.

9 35 mins to 70 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 />

_BCA 0.0, Loss of 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. All AC Power, action. Reference BRW-1 3-0031 -M Rev. 0, Transient Analysis of SX System Following Loss of A-C Power.

10 1.5 hrs Start depressurization of S/Os to 260 psig at approximately Y 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />

_BCA 0.0, Loss of 75°F/hr cooldown with SO PORV local/manual operation. SO All AC Power, Page 25 of 27

Byron Station, Units 1 and 2 Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 Time Action Remarks /

Elapsed Time Action Constraint item Applicability V/N 1 feed is controlled with Local/Manual operation of AFW flow action. Reference control valves. BRW-13-0221-M Rev 0, RCS Boration Analysis during an ELAP Event, dated June 2014.

11 2.25 hrs SI Accumulator borated water begins to inject into the RCS. NA Operator Judgment.

12 3.5 hrs Maintain SG pressure 260 psig and RCS temperature between NA Reference BRW 420F 410F with SO PORV operation.

- 0221-M Rev 0, RCS Boration Analysis Maintain SO level, during an ELAP Event, dated June 2014.

13 3-5 hrs Set up and establish ventilation in AEER and MCR. Y 5.15 Directed from hours OBFSG-5 lAlternate MCR Ventilation Reference calculation BYR1 3-2361BRW-13-0218-M, Control Room and Auxiliary Electric Equipment Room heat up and Ventilation during an ELAP.

Page 26 of 27

Byron Station, Units 1 and 2 - Fifth Six Month Status Report for the Implementation of FLEX August 28, 2015 14 5 7 hrs Isolate SI Accumulators. NA 1/2BFSG -10 action.

15 6-9 hrs Deploy FLEX DO to SX tower switchgear room and establish Y-17 Reference calculation power to one of the ESF Busses 131Z1132Z for power to a Well hours BYR14119 UHS Water, (WW), Pump and establish make up flow to the UHS. Volume Analysis during an ELAP Event 16 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 0BFSG5 and 0FSG-

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

17 11-14 hrs Stage and connect Phase 2 high pressure FLEX Pumps and Y 17 PWROG44027P ensure they are available to supply borated make-up to the RCS. hours Rev. 3.

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 SO's.

19 24 hrs Initiate SFP Make up via OA FC Purification pump as required NA OBFSG-1 laction.

for level and temperature control. Reference BRW 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 27 of 27

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