NL-16-1897, Fifth Six-Month Status Report of the Implementation of the Commission Order with Regard to Requirements for Reliable Hardened Containment Vents (EA-13-109)

Fifth Six-Month Status Report of the Implementation of the Commission Order with Regard to Requirements for Reliable Hardened Containment Vents (EA-13-109)

ML16349A160
Person / Time
Site:	Hatch
Issue date:	12/14/2016
From:	Pierce C Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
EA-13-109, NL-16-1897
Download: ML16349A160 (16)

Text

~~ Southern Nuclear DEC 1 4 2016 Docket Nos.: 50-321 50-366 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Charles R. Pierce Regulatory Affairs Director Edwin I. Hatch Nuclear Plant-Units 1 and 2 40 Inverness Center Parkway Post Office Box 1295 Birmingham, AL 35242 205 992 7872 tel 205 992 7601 fax crpierce@southemco.com NL-16-1897 Fifth Six-Month Status Report of the Implementation of the Commission Order with Regard to Requirements for Reliable Hardened Containment Vents (EA-13-1 09)

References:

1. NRC Order Number EA-13-109, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions, dated June 6, 2013.

2. SNC Letter, Edwin I. Hatch Nuclear Plant-Units 1 and 2 Phase 1 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (EA-13-109), dated June 27, 2014.

3. SNC Letter, Edwin I. Hatch Nuclear Plant-Units 1 and 2 Third Six-Month Status Report of the Implementation of Commission Order with Regard to Requirements for Reliable Hardened Containment Vents (EA-13-109), dated December 23, 2015.

Ladies and Gentlemen:

On June 6, 2013, the Nuclear Regulatory Commission (NRC) issued an Order (Reference 1) to Southern Nuclear Operating Company (SNC). Reference 1 was immediately effective and directs the Edwin I. Hatch Nuclear Plant - Units 1 and 2 (HNP) to install a reliable hardened venting capability for pre-core damage and under severe accident conditions, including those involving a breach of the reactor vessel by molten core debris. Specific requirements are outlined in of Reference 1.

In addition, Reference 1 also required submission of a Phase 1 overall integrated plan pursuant to Section IV, Condition D, and status reports at six-month intervals thereafter. SNC submitted the Phase 1 overall integrated plan (OIP) by letter dated June 27, 2014 (Reference 2). The third six-month update for Phase 1 of the Order included the required HCVS Phase 2 OIP submittal, and was submitted on December 23, 2015 (Reference 3). The consolidated HCVS Phase 1 and 2 OIP document (Reference 3) provided a list of the Phase 1 OIP open items, and addressed the NRC Interim Staff Evaluation open items for Phase 1. This letter is being submitted to satisfy the requirements for providing the six-month updates for Phase 1 and 2 of the Order in accordance with Section IV, Condition D.3, of Reference 1.

U.S. Nuclear Regulatory Commission NL-16-1897 Page 2 This letter contains no new NRC commitments. If you have any questions, please contact John Giddens at 205.992.7924.

Mr. C. R. Pierce states he is the Regulatory Affairs Director for Southern Nuclear Operating Company, is authorized to execute this oath on behalf of Southern Nuclear Operating Company and, to the best of his knowledge and belief, the facts set forth in this letter are true.

Resc.n~su~

11 C. R. Pierce Regulatory Affairs Director CRP/JMG/GLS d before me this J.j_ day of~

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Notary Public My commission expires: /0 -D -)6/-'1

Enclosure:

Fifth Six-Month Status Report Regarding Requirements for Reliable Hardened Containment Vents (EA-13-109) cc:

Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bast, Executive Vice President & Chief Nuclear Officer Mr. D. R. Vineyard, Vice President-Hatch Mr. M. D. Meier, Vice President-Regulatory Affairs Mr. D. R. Madison, Vice President-Fleet Operations Mr. B. J. Adams, Vice President-Engineering Mr. G. L. Johnson, Regulatory Affairs Manager-Hatch RType: CHA02.004 U.S. Nuclear Regulatory Commission Ms. C. Haney, Regional Administrator Mr. M. D. Orenak, NRR Project Manager-Hatch Mr. D. H. Hardage, Senior Resident Inspector-Hatch State of Georgia Mr. R.E. Dunn, Director-Environmental Protection Division

Edwin I. Hatch Nuclear Plant-Units 1 and 2 Fifth Six-Month Status Report of the Implementation of the Commission Order with Regard to Requirements for Reliable Hardened Containment Vents (EA-13-1 09)

Enclosure Fifth Six-Month Status Report Regarding Requirement for Reliable Hardened Containment Vents (EA-13-1 09)

Enclosure to N L 1897 Fifth Six-Month Status Report for Vent Order Implementation Edwin I. Hatch Nuclear Plant-Units 1 and 2 Fifth Six Month Status Report for the Implementation of Order EA-13-1 09 1 Introduction Southern Nuclear Operating Company developed an Overall Integrated Plan (References 1 and 8) for the Edwin I. Hatch Nuclear Plant-Units 1 and 2 (HNP) documenting the installation of a Hardened Containment Vent System (HCVS). Updates of milestone accomplishments are based on the combined Phase 1 and 2 Overall Integrated Plan dated December 23, 2015.

HNP developed an updated and combined Phase 1 and 2 Overall Integrated Plan (Reference 8), documenting:

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

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

HNP has elected to upgrade the existing HCVS to comply with the requirements of EA-13-109 for Phase 1 and 2 under Revision 1 of NEI 13-02. Revision 1 of NEI13-02 addresses methodology to implement Phase 2 requirements of order EA-13-109 and additional clarifications and guidance for implementation of Phase 1.

This enclosure provides an update of milestone accomplishments since submittal of the combined Phase 1 and 2 Overall Integrated Plan (Reference 8), including any changes to the compliance method, schedule, or need for relief/relaxation and the basis, if any.

2 Milestone Accomplishments The following milestone(s) have been completed since the development of the combined Phase 1 and 2 Overall Integrated Plan (Reference 8), and are current as of October 31, 2016.

Unit 2 Design Engineering On-site/Complete 3

Milestone Schedule Status The following provides an update to Attachment 2 of the combined Phase 1 and 2 Overall Integrated Plan. It provides the activity status of each item, and whether the expected completion date has changed. The dates are planning dates subject to change as design and implementation details are developed.

The revised milestone target completion dates do not impact the order implementation date.

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Enclosure to NL-16-1897 Fifth Six-Month Status Report for Vent Order Implementation Phase 1 and 2 HCVS Milestone Table Milestone Target Activity Comments Completion Status Date Submit Overall Integrated Plan Jun.2014 Complete Submit 6 Month Updates:

Update 1 Dec.2014 Complete Update 2 Jun.2015 Complete Update 3 Dec.2015 Complete Simultaneous with Phase 2 OIP Update 4 Jun.2016 Complete Update 5 Dec.2016 Complete with this submittal Update 6 Jun.2017 Not Started Update 7 Dec.2017 Not Started Phase 1 Specific Milestones Phase 1 Modifications:

Hold preliminary/conceptual Jun. 2014 Complete design meeting Unit 1 Design Engineering On-Feb.2017 Started Current Projection site/Complete Nov. 2016 Unit 1 Implementation Outage Mar. 2018 Not Started Unit 1 Walk Through Mar. 2018 Not Started Demonstration/Functional Test Unit 2 Design Engineering On-May 2016 Complete site/Complete Unit 2 Walk Through Feb.2017 Not Started Demonstration/Functional Test Unit 2 Implementation Outage Feb.2017 Not Started Phase 1 Procedure Changes Operations Procedure Changes Dec.2017 In Progress Current Projection Developed Jan. 2017 Site Specific Maintenance Jan.2017 Not Started Procedure Developed Procedure Changes Active Feb.2017 Not Started E-2

Enclosure to NL-16-1897 Fifth Six-Month Status Report for Vent Order Implementation Milestone Target Activity Comments Completion Status Date Phase 1 Training:

Training Complete Dec.2016 Not Started Current Projection Mar. 2018 Phase 1 Completion Unit 2 HCVS Implementation Mar. 2017 Started Current Projection Feb.2017 Unit 1 HCVS Implementation Mar. 2018 Current Projection Started Feb. 2018 Full Site HCVS Implementation Mar. 2018 Started Current Projection Feb. 2018 Phase 2 Specific Milestones Phase 2 Modifications:

Hold preliminary/conceptual design Apr. 2016 Started No modifications meeting expected.

Engineering evaluations and associated non-modification changes scope definition by Mar 2017 Unit 1 Design Engineering On-Feb.2017 In Progress No modifications site/Complete expected.

Engineering evaluations and associated non-modification changes by Oct 2017 Unit 1 Walk Through Mar. 2018 Not Started Current Projection Demonstration/Functional Test Feb. 2018 Unit 1 Implementation Outage Mar. 2018 Not Started Current Projection Feb. 2018 Unit 2 Design Engineering On-Feb.2018 Not Started No modifications site/Complete expected.

Engineering evaluations and associated non-modification changes by Oct 2018 E-3

Enclosure to NL-16-1897 Fifth Six-Month Status Report for Vent Order Implementation Milestone Target Activity Comments Completion Status Date Unit 2 Walk Through Mar. 2019 Not Started Current Projection Demonstration/Functional Test Feb.2019 Unit 21mplementation Outage Mar. 2019 Not Started Current Projection Feb.2019 Phase 2 Procedure Changes Operations Procedure Changes Sep.2017 Not Started Current Projection Developed Feb. 2018 Site Specific Maintenance Dec.2017 Not Started Procedure Developed Procedure Changes Active Mar. 2018 Not Started Current Projection Mar. 2019 Phase 2 Training:

Training Complete Dec.2017 Not Started Phase 2 Completion Unit 1 HCVS Implementation Mar. 2018 Not Started Current Projection Feb. 2018 Submit Unit 1 Phase 1 and 2 May 2018 Not Started Current Projection Completion Report Apr. 2018 Unit 2 HCVS Implementation Mar. 2019 Not Started Current Projection Feb. 2019 Full Site HCVS Implementation Mar. 2019 Not Started Current Projection Feb. 2019 Submit Unit 2 and site May 2019 Not Started Current Projection Completion Report [60 days Apr. 2019 after full site compliance]

4 Changes to Compliance Method There are no changes to the compliance method as documented in the Phase 1 and 2 Overall Integrated Plan (Reference 8). But, HNP will utilize additional portable equipment for use at the main stack. Attachment 1 on page 49 of the Phase 1 and 2 OIP (Reference 8) includes a list of HCVS/SAW A/SADV Portable Equipment. Refer to the following table which lists the additional equipment mentioned above:

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Enclosure to NL-16-1897 Fifth Six-Month Status Report for Vent Order Implementation : HCVS/SAW AISADV Portable Equipment List portable BDBEE Severe Performance Maintenance I PM equipment Venting Accident Criteria requirements Venting Stack integrated DG X

TBD Per the EPRI PM trailer with 85kW Database for Standby generator, DG connection cabinets, and Argon bottles 5

Need for Relief/Relaxation and Basis for the Relief/Relaxation Edwin I. Hatch Nuclear Plant-Units 1 and 2, expect to comply with the order implementation date and no relief/relaxation is required at this time.

6 Open Items from Combined Phase 1 and 2 Overall Integrated Plan and Interim Staff Evaluation 1

2 3

The following tables provide a summary of the open items documented in the combined Phase 1 and 2 Overall Integrated Plan, the Phase 1 Interim Staff Evaluation (ISE) and the Phase 2 Staff Evaluation and an updated response to each item.

Hatch 1 & 2 HCVS Phase 1 and 2

Response

OIP Open Items Determine location of Dedicated HCVS Included on page 13 of 66 in the Phase 1 &

Battery transfer switch -

2 OIP (ML15357A212)

Switches are located on ground elevation of Control Building Determine location of back-up nitrogen Included on page 13 of 66 in the Phase 1 &

bottles 2 OIP (ML15357A212)

"Nitrogen Bottles will be located in the Control Building" Evaluate location of Portable DG for All FLEX portal equipment and the DG relied accessibility under Severe Accident HCVS upon for the stack mixing chamber is greater use than 20 feet below the release point (main stack 300+ feet) as referenced in NEI 13-02, HCVS-FAQ-04. Additionally, the FLEX pumps (phase 2 action) and FLEX generators are a substantial distance (>500 ft) from the vent stack release point and generally shielded by vital buildings.

Included on page 13 of 66 in the Phase 1 &

2 OIP (ML15357A212)

"Portable DG will be staged and operated adjacent to the Reactor Building substantially away from the HCVS piping or the main stack release point" E-5

Enclosure to NL-16-1897 Fifth Six-Month Status Report for Vent Order Implementation 4

Confirm suppression pool heat capacity "i. Suppression pool cooling The suppression pool is capable of accepting operation of the RCIC system and SRVs without any suppression pool cooling during the SBO coping duration. Although not required, suppression pool cooling capability can be initiated within 1 h when the AAC source becomes available by meeting the diesel loading margins."

(Reference Section 8.4 of U2 FSAR)

"The current containment and RPV thermal hydraulic analysis for SBO took credit for analysis performed for 10CFR50, Appendix R (fire protection). As part of the extended power uprate, the SBO scenario was reanalyzed assuming that suppression pool cooling was initiated in one hour when the alternate AC is assumed available. The peak pool temperature is 167 F. Even if SPC is not initiated until four hours, the resulting peak pool temperature of 194 F is acceptable for containment and ECCS pump operation." (reference NEDC-32749P, "Extended Power Uprate Safety Analysis Report for Edwin I. Hatch Units 1 and 2",

July 1997 and GE MDE-03-0186 "Safe Shutdown Appendix R Analysis for Edwin I.

Hatch Nuclear Power Station Units 1 and 2")

5 Determine location of HCVS Remote Included on page 16 of 66 in the Phase 1 &

Operating Station 2 OIP (ML15357A212)

"ROS will be located at the 147'elevation of the Control Building, one floor below the elevation of the MCR" and 1 floor above ground level 6

State which approach or combination of Included on page 17 of 66 in the Phase 1 &

approaches Plant Hatch decides to take to 2 OIP (ML15357A212) address the control of flammable gases, clearly demarcating the segments of vent "Plant Hatch plans to use option I of the system to which an approach applies endorsed white paper HCVS-WP-03 and power up the mixing chamber fan in the base of the metrological stack."

In addition, procedurally closing the main stack interconnecting valves and purging the main stack mixing chamber is utilized as defense in depth. HNP will utilize a portable DG deployed to the stack to repower the stack mixing chamber fans and power operators on some of the interconnecting valves E-6

Enclosure to NL-16-1897 Fifth Six-Month Status Report for Vent Order Implementation 7

Evaluate SGTS Valve Leakage utilizing 1 0 valves are being tested per the LLRT criteria from NEI HCVS-FAQ Audit item procedure 42SV-TET-001-2 per ISE 8

Identify qualification method used for HCVS "Demonstration that instrumentation is instruments-Audit item per ISE substantially similar to the design of instrumentation previously qualified."

Site design standards such as IEEE 323-1974 or IEEE 324-1975 were either used in the specifications.

9 Evaluate HCVS monitoring location of For Accessibility and Habitability refer Portable DG for accessibility, habitability, response on item 3.

staffing sufficiency, and communication capability with Vent under Severe Accident Staffing sufficiency and communication HCVS use decision makers - Audit item per capability for the Main Stack DG will be ISE addressed in an HCVS addendum to the updated FLEX Phase 2 staffing study and HNP FLEX verification and validation report.

10 Perform severe accident evaluation for FLEX Refer response on item 3 DG use post 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> actions - Confirmatory Action 11 Determine the control document for HCVS Procedure NMP-OS-019-013 and NMP-OS-out of service time criteria - Audit item per 019-013-GL02 ISE Hatch 1 & 2 HCVS

Response

Phase 1 ISE Open Items 1

Make available for NRC staff audit the

- OIP ltem#5 location of the ROS's Included on page 16 of 66 in the Phase 1 & 2 OIP (ML15357A212)

"ROS will be located at the 147'elevation of the Control Building, one floor below the elevation of the MCR" 2

Make available for NRC staff audit the

- OIP Item# 1 location of the dedicated HCVS Included on page 13 of 66 in the Phase 1 & 2 OIP battery transfer switch (ML15357A212)

Switches are located on ground elevation of Control Building 3

Make available for NRC staff audit

- OIP Item# 2 documentation of the HCVS nitrogen Included on page 13 of 66 in the Phase 1 & 2 OIP pneumatic system design including (ML15357A212) sizing and location "Nitrogen Bottles will be located in the Control Building" Calculations for the accumulator tank and nitrogen bottle sizing are included in SMNH-13-013 and SMNH-13-019.

4 Make available for NRC staff audit the Two portable DGs will be located on the west side deployment location of the portable of the Control Building for Unit 1, one portable DG diesel generators will be located on the south side of the Turbine Building for Unit 2 and one DG will be located at the base of Main Stack.

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Enclosure to NL-16-1897 Fifth Six-Month Status Report for Vent Order Implementation 5

Make available for NRC staff audit an Included on page 16 of 66 in the Phase 1 & 2 OIP evaluation of temperature and (ML15357A212) radiological conditions to ensure that operating personnel can safely access "The HCVS design allows initiating and then and operate controls and support operating and monitoring the HCVS from the Main equipment Control Room (MCR) or the Remote Operating Station (ROS). The MCR location is protected from adverse natural phenomena and is the normal control point for HCVS operation and Plant Emergency Response actions.

The final location of the ROS is the 147'elevation of the Control Building, one floor below the elevation of the MCR. Additional support equipment is located on the 130' elevation Control Building (battery throw-over switch and nitrogen bottle rack).

Reference Assumption HNP-5 from OIP, HCVS-FAQ-08, HCVS-FAQ-04 and General Design Criteria 19.

6 Make available for NRC staff audit

- OIP ltem#4 analyses demonstrating that HCVS "i. Suppression pool cooling has the capacity to vent the The suppression pool is capable of accepting steam/energy equivalent of one operation of the RCIC system and SRVs without percent of licensed/rated thermal any suppression pool cooling during the SBO power (unless a lower value is coping duration. Although not required, justified}, and that the suppression suppression pool cooling capability can be initiated pool and the HCVS together are able within 1 h when the AAC source becomes available to absorb and reject decay heat, such by meeting the diesel loading margins." (Reference that following a reactor shutdown from Section 8.4 of U2 FSAR) full power containment pressure is restored and then maintained below "The current containment and RPV thermal the primary containment design hydraulic analysis for SBO took credit for analysis pressure and the primary containment performed for 1 OCFR50, Appendix R (fire pressure limit protection). As part of the extended power uprate, the SBO scenario was reanalyzed assuming that suppression pool cooling was initiated in one hour when the alternate AC is assumed available. The peak pool temperature is 167 F. Even if SPC is not initiated until four hours, the resulting peak pool temperature of 194 F is acceptable for containment and ECCS pump operation." (reference NEDC-32749P, "Extended Power Uprate Safety Analysis Report for Edwin I. Hatch Units 1 and 2", July 1997 and GE MDE-03-0186 "Safe Shutdown Appendix R Analysis for Edwin I. Hatch Nuclear Power Station Units 1 and 2")

7 Make available for NRC staff audit the The original design for the GL 89-16 vent line was descriptions of local conditions 343F so engineering judgement was used for (temperature, radiation and humidity) qualification to 350F based on downstream cooling anticipated during ELAP and severe of vent piping.

accident for the components (valves, instrumentation, sensors, transmitters, Specification for new equipment and E-8

Enclosure to NL-16-1897 Fifth Six-Month Status Report for Vent Order Implementation indicators, electronics, control instrumentation included environmental conditions devices, etc} required for HCVS expected from License for post-accident design venting including confirmation that the values.

components are capable of performing their functions during New equipment procured to comply with the Order ELAP and severe accident conditions was purchased through new specifications the ROS, batteries, and battery charger. Those specifications contain all the required operating parameters for the equipment for normal operation, design basis accidents as well as BDBEE requirements. The radiation monitor is an "off the shelf' monitor without its own specification. It was procured with a datasheet specific to Hatch for radiation and temperature requirements.

Each item procured with a specification requires test reports be provided that the test specimens performed in compliance with the specification requirements. The radiation monitor also has multiple test reports which document compliance with required operating conditions/parameters.

Other commodities such as conduit, wiring, piping, etc. were procured consistent with the design requirements of the systems and locations they were being installed. For example, items installed in the control building - non-harsh environment with temperature considerations consistent with current SBO temperatures and radiation. These other items like pipe, cable, valves, transmitters were procured AQ as necessary to meet the BDBEE requirements for the location where they are installed. The majority of equipment installed is located outside the reactor building, and therefore does not require additional qualification beyond normal operating/accident conditions of the plant.

8 Make available for NRC staff audit the See Calculation SENH-13-005, Modification final sizing evaluation for HCVS Calculation SENH-16-003, and FLEX DG Sizing batteries/battery charger including Calculation incorporation into FLEX DG loading A-47402.

calculation 9

Make available for NRC staff audit

- OIP Item# 9 documentation that demonstrates Notifications can be made with either the gaitronics adequate communication between the system or via runners to the MCR or ROS to allow remote HCVS operation locations and operation of the HCVS once the portable DGs are HCVS decision makers during ELAP operating.

and severe accident conditions 10 Provide a description of the final

- OIP Item #6 design of the HCVS to address Included on page 17 of 66 in the Phase 1 & 2 OIP hydrogen detonation and deflagration (ML15357A212}

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Enclosure to NL-16-1897 Fifth Six-Month Status Report for Vent Order Implementation "Plant Hatch plans to use option I of the endorsed white paper HCVS-WP-03 and power up the mixing chamber fan in the base of the metrological stack."

In addition, HNP plans to close HCVS boundary valves and main stack interconnecting valves and purge the main stack mixing chamber. HNP will utilize a portable DG deployed to the stack to repower the stack mixing chamber fans and power operators on some of the interconnecting valves.

11 Provide a description of the strategies Refer to response to ISE item# 10 and leakage for hydrogen control that minimizes testing of boundary valves found in the calculations the potential for hydrogen gas in DOEJ M003 and SMNH-13-023.

migration and ingress into the reactor building or other buildings 12 Make available descriptions of design

- OIP Item 7 details that minimize unintended cross The HCVS interface to other systems is described flow of vented fluids within a unit and in section 2, pages 10 and 17 of 66 in the Phase 1 between units

&201P.

The boundary valves will be tested in accordance with the guidance of NEI 13-02, FAQ-HCVS-05 to ensure unintended system cross flow is minimized.

Refer to the response to ISE item # 1 0 and leakage testing of 1 0 boundary valves per the LLRT program procedure 42SV-TET-001-2.

See calculations in DOEJ M003 and SMNH 023.

13 Make available for NRC staff audit Refer to DCP 598056 ILOM for I&C components descriptions of all instrumentation and (I&C and electrical sections) controls (existing and planned) necessary to implement this order "Demonstration that instrumentation is substantially including qualification methods similar to the design of instrumentation previously qualified."

Site design standards such as IEEE 323-1974 or IEEE 324-1975 were either used in the specifications.

14 Make available for NRC staff audit Existing PCIVs that perform a Design Basis documentation of an evaluation function were utilized. Per NEI13-02 no further verifying the existing containment evaluation required.

isolation valves, relied upon for the HCVS, will open under the maximum The expected differential is within the scope of expected differential pressure during containment design for compliance with GL 89-16 BDBEE and severe accident wetwell since containment pressure is managed below the venting design pressure.

Additionally, Hatch is utilizing existing PCIVs which were designed and procured to meet the containment design pressures.

15 Make available for NRC staff audit the

- OIP Item# 11 control document for HCVS out of Procedure NMP-OS-019-013 and NMP-OS-019-service time criteria 013-GL02 E-10

Enclosure to NL-16-1897 Fifth Six-Month Status Report for Vent Order Implementation Hatch 1 & 2 HCVS Phase 2

Response

ISE Open Items 1

Licensee to demonstrate that The wetwell vent has been designed and installed containment failure as a result of to meet NEI 13-02 Rev 1 guidance which will overpressure can be prevented ensure that it is adequately sized to prevent without a drywell vent during severe containment overpressure under severe accident accident conditions Section 3.3.3 conditions.

The SAWM strategy will ensure that the wetwell vent remains functional for the period of sustained operation. HNP will follow the guidance (flow rate and timing) for SAWA/SAWM described in BWROG-TP-15-008 and BWROG-TP-15-011.

These documents have been posted to the ePortal for NRC staff review. The wetwell vent will be opened prior to exceeding the PCPL value of 62 PSIG. Therefore, containment over pressurization is prevented without the need for a drywell vent.

2 Licensee shall demonstrate how the Using Figure 2.1.C from the combined Phase 1 and plant is bounded by the reference 2 OIP, compare the reference plant parameters to plant analysis that shows the SAWM the plant specific parameters.

strategy is successful in making it unlikely that a drywell vent is needed Reference Plant HNP Section 3.3.3.1 Torus freeboard volume T crus freeboard is 525,001gallons volume is >805, 161 2 gallons SAWA flow is 500 GPM SAWA flow is 500 at 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> followed by GPM at 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 100 GPM from 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> followed by 1 00 GPM to 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> from 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> The above parameters for HNP demonstrate that the reference plant values are bounding.

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

3 Licensee to demonstrate that there is HNP utilizes gaitronics paging system or runners to adequate communication between the communicate between the MCR and the Intake MCR and the Intake Structure Structure operator at the FLEX pump. This operator at the FLEX manual valve communication method is the same as accepted in during severe accident conditions.

Order EA-12-049. Gaitronics has been modified Section 3.3.3.4 with a 12-hour UPS battery backup and will be repowered with FLEX portable DGs.

Peach Bottom available freeboard volume 1n gallons 1s estimated from nommal water level of 14.7 feet to 21 feet.

21 feet is the upper range of the wide range torus level instrument and the assumed loss of wetwell vent function.

The Peach Bottom torus is 31 feet in diameter.

2 From HNP Phase 1 &2 OIP page 53 of 66 using lower range of loss of wet well vent.

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Enclosure to NL-16-1897 Fifth Six-Month Status Report for Vent Order Implementation 7 Interim Staff Evaluation Impacts There are no potential impacts to the Interim Staff Evaluation identified at this time.

8 Additionallnformation The interfacing valves in the main stack mixing chamber are connected to long runs of piping that will be evacuated of any combustible gases before combustible gas levels are approached, but for defense in depth and per the testing criteria in HCVS-FAQ-04, the interfacing valves are being leak tested as described in ISE open item 12 above. One set of isolation valves associated with an after filter for HNP Unit 1 did not meet the required leakage in a test performed in the fall of 2016. The isolation valves 1 N62-F5258/1 N62-F5268 to the after filter had a leakage less than twice the allowable limit (3,900 versus 2,425 seem). These valves cannot be repaired until the 2018 refueling outage. In order to address the mitigation of cross flow to Unit 1 while Unit 2 is in compliance the response procedure is being revised to close both valves so both valves with a filter assembly in between will be an additional barrier to cross flow back into Unit 1. This evaluation of the method of mitigating the cross flow is acceptable per NEI 13-02. The valves will be repaired in order to meet the testing requirements of Unit 1 prior to compliance in the 2018 RFO.

9 References The following references support the updates to the Phase 1 and 2 Overall Integrated Plan (Reference 8) described in this enclosure:

1. SNC Letter, Edwin I. Hatch Phase I Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109), dated June 27, 2014 (ML141788464).

2. NRC Order Number EA-13-109, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions, dated June 6, 2013 (ML13143A321).

3. NRC Endorsement, Hardened Containment Venting System (HCVS) Phase 1 Overall Integrated Plan Template (EA-13-109) Revision 0, dated May1, 2014 (ML14128A219).

4. NRC Letter, Edwin I. Hatch Nuclear Plant Units, 1 and 2-Interim Staff Evaluation Relating to Overall Integrated Plan in Response to Phase 1 of Order EA-13-109 (Severe Accident Capable Hardened Vents) (TAG Nos. MF4479 and MF4480), dated March 25, 2015 (ML14335A137).

5. NEI13-02, Industry Guidance for Compliance with NRC Order EA-13-109, To Modify Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions, Revision 1, dated April 2015 (ML151138318).

6. NRC Interim Staff Guidance JLD-ISG-2013-02, Compliance with OrderEA-13-109, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions, Revision 1, dated April 2015 (ML15104A118).

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Enclosure to NL-16-1897 Fifth Six-Month Status Report for Vent Order Implementation

7. NRC Endorsement of "Hardened Containment Venting System (HCVS) Phase 1 and 2 Overall Integrated Plan Template," Revision 1, dated September 22, 2015, and Frequently Asked Questions (FAQs) 10, 11, 12, and 13, dated October 8, 2015 (ML15271A148).

8. SNC Letter with Combined Phase 1 and 2 Overall Integrated Plan, Edwin I. Hatch Nuclear Plant-Units 1 and 2 Third Six-Month Status Report of the Implementation of the Commission Order with Regard to Requirements for Reliable Hardened Containment Vents (EA-13-109), dated December 23, 2015 (ML15357A212).

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