Text

Units I and 2, Overall Integrated Plan for Reliable Hardened Vents
	ML13066A169
Person / Time
Site:	Nine Mile Point
Issue date:	02/28/2013
From:	Korsnick M; Constellation Energy Group, EDF Group
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	Download: ML13066A169 (66)
	v • d • e

Mary G. Korsnick Office 410-470-5133 Chief Nuclear Officer, Fax 443-213-6739 SVP - Chief Operations Officer Email: Maria.Korsnick(Mcenallc.com CENG.

February 28, 2013 U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852 ATTENTION: Document Control Desk

SUBJECT:

Nine Mile Point Nuclear Station, Units I and 2 Renewed Facility Operating License Nos. DPR-63 and NPF-69 Docket Nos. 50-220 and 50-410 Overall Integrated Plan for Reliable Hardened Vents

REFERENCES:

(a) NRC Order Number EA- 12-050, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents, dated March 12, 2012 (b) NRC Interim Staff Guidance JLD-ISG-2012-02, Compliance with Order EA-12-050, Reliable Hardened Containment Vents, Revision 0, dated August 29, 2012 (c) Letter from M. G. Korsnick (CENG) to Document Control Desk (NRC),

Initial Status Report in Response to Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA- 12-050), dated October 26, 2012 On March 12, 2012, the Nuclear Regulatory Commission issued an Order (Reference a), which was immediately effective. The Order directs licensees with Boiling-Water Reactor (BWR) Mark I and Mark II containments to have a reliable hardened vent to remove decay heat and maintain control of containment pressure within acceptable limits following events that result in the loss of active containment heat removal capability or prolonged Station Blackout (SBO). The hardened vent system is required to be accessible and operable under a range of plant conditions, including a prolonged SBO and inadequate containment cooling. The Order also requires that an Overall Integrated Plan be prepared that provides a description of how the requirements of the Order will be achieved.

Reference (a) requires submission of an Overall Integrated Plan by February 28, 2013. The NRC Interim Staff Guidance (Reference b) provides an approach for complying with NRC Order EA- 12-050.

Reference (c) provided the initial status report regarding reliable hardened containment vents, as required by Reference (a).

Constellation Energy Nuclear Group, LLC 100 Constellation Way, Suite 200C, Baltimore, MD 21202 Aoo6

Document Control Desk February 28, 2013 Page 2 The purpose of this letter is to provide the Overall Integrated Plan required by Section IV, Condition C.1, of Reference (a). This letter confirms that the Nine Mile Point Nuclear Station has received Reference (b) and has developed the Overall Integrated Plans presented in Attachments I and 2.

The Integrated Plans are based on conceptual design information. Final design details and associated procedure guidance, as well as any revisions to the information contained in the attachments, will be provided in the six-month Integrated Plan updates required by Reference (a).

This letter contains regulatory commitments as listed in Attachment 3.

If there are any questions regarding this submittal, please contact Everett (Chip) Perkins everett.perkins@cengllc.com at 410-470-3928.

I declare under penalty of perjury that the foregoing is true and correct. Executed on February 28, 2013.

Sincerely, MMary ýor~snick MGK/EMT/bjd

Attachment:

(1) Nine Mile Point Unit I Overall Integrated Plan for Reliable Hardened Vents (2) Nine Mile Point Unit 2 Overall Integrated Plan for Reliable Hardened Vents (3) Regulatory Commitments Contained in this Correspondence cc: M. C. Thadani, NRC Resident Inspector, Nine Mile Point W. M. Dean, NRC

ATTACHMENT 1 NINE MILE POINT UNIT 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Constellation Energy Nuclear Group, LLC February 28, 2013

ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Table of Contents Page References ii Section 1: System Description r Section 2: Design Objectives 5 Requirement 1.1.1 - Minimize the Reliance on Operation Actions 5 Requirement 1.1.2 - Minimize Plant Operators' Exposure to Occupational Hazards 7 Requirement 1.1.3 - Minimize Radiological Consequences 8 Section 3: OperationalCharacteristics 10 Requirement 1.2.1 - Capacity to Vent Equivalent of 1% 10 Requirement 1.2.2 - HCVS Shall be Accessible to Plant Operators 11 Requirement 1.2.3 - Prevent Inadvertent Actuation 13 Requirement 1.2.4 - Monitor the Status of the Vent System 14 Requirement 1.2.5 - Monitor the Effluent Discharge for Radioactivity 15 Requirement 1.2.6 - Minimize Unintended Cross Flow of Vented Fluids 16 Requirement 1.2.7 - Provision for the Operation, Testing, Inspection and Maintenance 17 Requirement 1.2.8 - Design Pressures 18 Requirement 1.2.9 - Discharge Release Point 19 Section 4: Applicable Quality Requirements 20 Requirement 2.1 - Containment Isolation Function 20 Requirement 2.2 - Reliable and Rugged Performance 21, Section 5: Procedures and Training 23 Requirement 3.1 - Develop, Implement, and Maintain Procedures 23 Requirement 3.2 - Train Appropriate Personnel 24 Section 6: Implementation Schedule Milestones 25 Section 7: Figures/Diagrams 26 Section 8: Functional Failure Modes and Alternate Actions Error! Bookmai rk not defined.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS

References:

I. Generic Letter 89-16, Installation of a Hardened Wetwell Vent, dated September 1, 1989

2. Order EA-12-049, Mitigation Strategies for Beyond-Design-Basis External Events, dated March 12, 2012

3. Order EA-12-050, Reliable Hardened Containment Vents, dated March 12, 2012

4. JLD-ISG-2012-02, Compliance with Order EA-12-050, Reliable Hardened Containment Vents, dated August 29, 2012

5. NRC Responses to Public Comments, Japan Lessons-Learned Project Directorates Interim Staff Guidance JLD-ISG-2012-02: Compliance with Order EA-12-050, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents, ADAMS Accession No. MLL12229A477, dated August 29, 2012

6. NEI 12-06, Diverse and Flexible Coping Strategies (FLEX) Implementation Guide, Revision 0, dated August 2012 ii of ii

ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 1: System Description ISG Criteria:

Licensees shall provide a complete description of the system, including important operational characteristics.The level of detail generally considered adequate is consistent with the level of detailcontainedin the licensee's FinalSafety Analysis Report.

Response

System Overview:

The Hardened Containment Vent System (HCVS) is designed to mitigate loss-of-decay-heat removal by providing sufficient containment venting capability to limit containment pressurization. The vent is designed with sufficient capacity to accommodate decay heat input equivalent to 1% of 1850 Megawatts

- thermal (MWt). Thus, the hardened vent capacity is adequate to relieve decay heat for a prolonged station blackout (SBO) event. The HCVS is intended for use as one element of the core damage prevention strategies. Venting the containment to remove decay heat and limit containment pressurization supports core cooling strategies during a prolonged SBO event.

The HCVS flow path from the containment to an elevated release point above the Reactor Building roof is shown in the simplified piping and instrumentation diagram (P&ID) in Figure 1 below. The flow path from the Torus (wetwell) is the path being credited for compliance with NRC Order EA-12-050. A Drywell flow path is also currently planned as an additional means to maintain containment pressure within design limits, but is not being credited nor committed to for compliance with the Order. The HCVS at Nine Mile Point Unit 1 (NMP1) is fully independent of the HCVS from Nine Mile Point Unit 2 (NMP2). The piping flow path is dedicated to the HCVS function downstream of the first containment isolation valve (CIV). The only system interfaces are at the outboard containment isolation valves from the Torus and Drywell, which serve as system isolation valves. No ductwork is used in the system. This ensures that all the HCVS flow out of the containment is discharged to the outside atmosphere above the NMP1 Reactor Building.

Figure 1 1 of 28

ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Equipment and components:

The following equipmenit and components will be provided:

1. HCVS Mechanical Components:,

a) Containment isolation piping, valves and controls - The HCVS vent piping and supports up to and including the second containment isolation valve (CIV),aie designed in accordance with the existing containment penetration design basis. The design of the, CIVs will be consistent with the plant's CIV design basis. The valves are air-operated, spring-to-close, valves [normally closed, fail closed] with DC powered solenoid operated valves (SOV) and will be operated from the Main Control Room (MCR). A manual,

-remote pneumatic mode of operation for the CIVs will be available from a remote panel located outside of the Reactor Building as a backup. This backup means of operation will utilize normally locked manual valves and does not require the SOVs to reposition. The existing outboard containment isolation valves, which will serve as system isolation valves, are motor-operated valves.. These valves will remain unchanged.

b) Other system valves and piping - The HCVS piping and supports downstream of the second containment isolation valve, including valve actuator pneumatic supply components, will be designed and analyzed to conform to requirements consistent with the applicable design codes for the'plant and to ensure functionality following d design

basis earthquake.

c) The HCVS flow path downstream of the CIVs is dedicated to HCVS function and will not interface, with any other fluid system. The only interfacing system valves are the existing outboard containment isolation valves.

d) The HCVS flow path downstream of the CIVs will have a normally closed, air-operated'

-Pressure Control Valve (PCV). The PCV will be capable of controlling upstream pressure. Similar to the CIVs, the PCV will utilize a DC powered sOv to control the pneumatic supply and will be controlled from the MCR. A manual, remote - pneumatic mode of operation for the PCV will be available from a remote panel located outside of the Reactor Building as a backup.

2. Instrumentation to monitor the status of the HCVS and control the flow path:

a) All instrumentation indication required for Operation will be available on the HCVS panel located in the MCR.

b) HCVS valve position indication, flow path temperature, pressure, and effluent radiation instrumentation will monitor the status of the HCVS and aid operator. verification of

venting conditions. A failure, of, valve position indication instrumentation would not prevent opening and closing the valve.,.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS c) The effluent radiation monitor detector will be mounted in close proximity to the HCVS pipe wall. The radiation monitor will allow the operator to discern the presence of, or the onset of, core damage during HCVS operations, and to take appropriate action to cease venting operations. The radiation monitor display' will be located on the HCVS panel located in the MCR.

d) Instrumentation availablewill' include the HCVS support system pneumatic pressure and DC batteiy voltage.

3. Support systems assuming a prolonged SBO:

a) Power forthe HCVS is provided from dedicated permanently installed DC/AC power supplies. These power supplies are normally supplied from a non-vital bus and have battery backup adequate for the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of operation. The power supply for the radiation monitor includes an inverter to convert the battery-supplied DC power to AC.

.The power supplies' will be in an accessible location outside of the Reactor Building, allowing the power to be sustained after 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . Final selection of components will be completed during the detailed engineering and design phase.

b) Motive . air/gas supply for HCVS operation will be provided from a dedicated permanently installed source adequate for at least the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of operation. This motive air/gas source will be in an accessible location outside of the Reactor Building, allowing the motive air/gas to be sustained after 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The number of open/close cycles for the CIVs and the PCV will be determined during the detailed engineering and design phase, as it is dependent upon the strategies employed for FLEX. implementation, use of the PCV, and ultimate pressure control strategies selected. The number of cycles selected and the basis will be provided in subsequent six month updates.

c) Portable equipment will be provided as required to sustain operation after 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The connections for the .portable equipment. will provide pre-engineered connections to minimize manpower efforts.

d) New CIVs and associated SOVs will be purchased safety-related due to their existing design basis functions and safety classification. Piping upstream of the new CIVs will also be purchased safety-related. Other HCVS components will be purchased with augmented quality requirements to reflect design requirements described later in this plan.

System control:

1. The primary means of control and'indication for the'HCVS will be from a'dedicated HCVS control panel located in the MCR. A backup means of operation will be available from an additional

'control panel located outside of the Reactor Building. The specific location of the backup control panel will be determined during the detailed design phase.

2. The CIVs and PCV will be operated in accordance with approved station procedures to control containment pressure following a prolonged SBO. The revised station procedures will address when venting is to be initiated and any imposed limitations on the pressure band.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS

3. The primary means of opening each of the CIVs and PCV requires energizing a DC powered SOV from a switch on a HCVS control panel. The HCVS control panel Will be located in the MCR. A backup means of operating the CIVs and PCV will be available via operation of normally-locked manual valves located on the backup HCVS control panel outside of the Reactor Building. This

backup means of operation does not replicate the control room function, nor does it require energizing or repositioning the SOVs. The backup means provides a way of remotely operating the CIVs and PCV via manual valves in the pneumatic supply and vent lines.

4. Since the new HCVS CIVs will be closed when the design basis requires containment integrity and designed to prevent inadvertent opening, the new outboard CIV will not have an automatic closure signal for containment isolation. Inadvertent operation will be addressed by controlling the associated SOVs with key-locked switches and by locking the manual valves that may be used for backup operation. The existing, shared ClWs already includean automatic closure signal. Periodic CIV testing will be performed in accordance with the Surveillance Test Program.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 2: A description of how the design obiectives contained in Order EA-12-050 Attachment 2.

Requirements 1.1.1. 1.1.2. and 1.1.3, are met Order EA-12-050 1.1.1 Requirement:

The HCVS shall be designedto minimize the relianceon operatoractions.

ISG 1.1.1 Criteria:

During events that significantly challenge plant operations, individual operatorsare more prone to human error.In addition, the plant operations staff may be requiredto implement strategies and/or take many concurrent actions thatfurther places a burden on its personnel. During the prolonged SBO condition at the Fukushima Dai-ichi units, operatorsfaced many significant challenges while attempting to restore numerous plant systems that were necessary to cool the reactor core, including the containment venting systems. The difficulties faced by the operators related to the location of the HCVS valves, ambient temperatures and radiologicalconditions, loss of all alternatingcurrent electricalpower, loss of motive force to open the vent valves, and exhausting DC battery power. The NRC staff recognizes that operator actions will be needed to operate the HCVS valves; however, the licensees shall consider design features for the system that will minimize the need and reliance on operator actions to the extent possible during a variety ofplant conditions, as further discussed in this ISG.

The HCVS shall be designed to be operatedfrom a control panel located in the main control room or a remote but readily accessible location. The HCVS shall be designed to be fully functional and self sufficient with permanently installed equipment in the plant, without the need for portable equipment or connecting thereto, until such time that additional on-site or off-site personnel andportable equipment become available. The HCVS shall be capable of operatingin this mode (i.e., relying on permanently installed equipment) for at least 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months during the prolonged SBO, unless a shorterperiod is justified by the licensee. The HC VS operation in this mode depends on a variety of conditions, such as the causefor the SBO (e.g., seismic event, flood, tornado, high winds), severity of the event, and time requiredfor additional help to reach the plant, move portable equipment into place, and make connections to the HCVS.

When evaluating licenseejustificationfor periods less than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , the NRC staff will consider the number of actions and the cumulative demand on personnel resources that are needed to maintain HCVS functionality (e.g., installation of portable equipment during the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months to restorepower to the HCVS controls and/or instrumentation)as a result of design limitations.For example, the use ofsupplemental portablepower sources may be acceptable if the supplemental power was readily available, could be quickly and easily moved into place, and installedthrough the use of pre-engineered quick disconnects, and the necessary human actions were identified along with the time needed to complete those actions. Conversely, supplemental power sources located in an unattended warehouse that require a qualified electrician to temporarily wire into the panel would not be considered acceptable by the staff because its installation requires a series of complex, time-consuming actions in order to achieve a successful outcome. There are similar examples that could apply to mechanical systems, such as pneumatic/compressed air systems.

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ATTACHMENT 1 NMP-1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Response (ref. ISG Item 1.1.1):

The design of the HCVS will minimize the reliance on operator actions and exposure to hazards identified in 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, and NEI 12-06, Diverse and Flexible Coping Strategies (FLEX) Implementation Guide. Immediate operator actions can be completed by Reactor Operators and include remote-manual initiation from the HCVS control panel located in the MCR using permanently installed equipment for the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . A backup means of operation will be available from an additional panel located outside of the Reactor Building. The specific location of the backup control panel will be determined during the detailed design phase. This location will be protected from environmental hazards.

The steps listed below are required to initiate the HCVS flow path. These steps will be confirmed during the detailed design phase..

Primary Action Location / Component

1. Open Torus inboard CIV by manipulating HCVS Control Panel in MCR (alternate control via key-lock switch manual valves at backup control panel)

2. Open Torus outboard CIV by HCVS Control Panel in MCR (alternate control via manipulating key-lock switch manual valves at backup control panel)

3. Open HCVS PCV HCVS Control Panel in MCR (alternate control via manual valves at backup control panel)

4. Monitor electrical power status, pneumatic HCVS Control Panel in MCR pressure and containment / HCVS conditions Remote-manual is defined in this report as a non-automatic power operation of a component that does not require the operator to be at or in close proximity to the component. No .other operator actions are required to initiate venting.

The HCVS will be designed to allow initiation, isolation, and control at the primary and backup HCVS control panel(s). Monitoring will be available at the primary HCVS control panel in the MCR. The location of the primary HCVS control panel in the MCR and backup control panel outside of the Reactor Building will .minimize the plant operator's exposure to adverse temperature and radiological conditions and will be protected from the assumed hazards. Final location of the remote backup control panel will be determined during detailed design.

Permanently installed DC power and motive air/gas capable will be available to support operation and monitoring of the HCVS for the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

After 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , available personnel will be able to connect supplemental motive air/gas to the HCVS support systems. Connections for supplementing electrical power and motive air/gas required for HCVS will be located in accessible areas with reasonable protection from assumed hazards to minimize personnel exposure to adverse conditions following a prolonged SBO and venting consistent with'the 6 of 28

ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS requirements within NEI 12-06. Connections will use pre-engineered quick disconnects to minimize manpower resources.

Order EA-12-050 1.1.2 Requirement:

The HCVS shall be designed to minimize plant operators' exposure to occupationalhazards, such as extreme heat stress, while operatingthe HCVS system.

ISG 1.1.2 Criteria:

During a prolonged SBO, the drywell, wetwell (torus), and nearby areas in the plant where HCVS components are expected to be located will likely experience an excursion in temperatures due to inadequate containment cooling combined with loss of normal and emergency building ventilation systems. In addition, installed normal and emergency lighting in. the plant may not be available. Licensees should take into considerationplant conditions expected to be experienced during applicable beyond design basis external . events when locating valves, instrument air supplies, and other components that will be required to. safely operate the HCVS system.

Components requiredfor manual operation should be placed in areas that are readily accessible to plant operators, and not require additional actions, such as the installation of ladders or temporary scaffolding, to operate the system.

When developing a design strategy, the NRC staff expects licensees to analyze potential plant conditions and use its acquired knowledge of these areas, in terms of how temperatures would react to extended SBO conditions and the lighting that would be available during beyond design basis external events. This knowledge also provides an input to system operatingprocedures, training,the choice ofprotective clothing, requiredtools and equipment, andportable lighting.

Response (ref. ISG Item 1.1.2):

The HCVS design allows initiating and then operating and monitoring the HCVS from the HCVS panel in the MCR. A backup means of operating the HCVS is located at a control panel outside of the Reactor Building. The locations of the HCVS control panels will minimize plant operators' exposure to adverse temperature and radiological conditions and the panel location is protected from hazards assumed in 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, and NEI 12-06 Diverse and Flexible Coping Strategies (FLEX) Implementation Guide.

In order to minimize operator exposure to temperature excursions due to the impact of the prolonged SBO (i.e., loss of normal and emergency building ventilation systems and/or containment temperature changes)

HCVS valve operation will not require access to the Torus (wetwell) area or other plant areas which may pose severe temperature and radiological hazards to personnel.

Similarly, DC power and motive air/gas sources and the connections to these support systems required for sustained operation will be located in accessible areas protected from severe natural phenomena and which minimize exposure to occupational hazards. Tools required for sustained operation, such as portable headlamps and connection specific tooling will be pre-staged in the NEI 12-06 protected storage locations.

Neither temporary ladders nor scaffold will be required to access these connections or storage locations.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Order EA-12-050 1.1.3 Requirement:

The HCVS shall also be designed to minimize radiological consequences that would impede personnel actions neededfor event response.

ISG 1.1.3 Criteria:

The design of the HCVS should take into considerationthe radiologicalconsequences resulting from the event that could negatively impact event response. During'the Fukushima event, personnel actions to manually operate the vent valves were impeded due to the location of the valves in the torus rooms. The HCVS shall be designed to be placed in operation by operator actions at a control panel, located in the main control room or in a remote location. The system shall be designed to function in this mode with permanently installed equipment providing electricalpower (e.g., DCpower batteries) and valve motive force (e.g., N2/air cylinders). The system shall be designed to function in this mode for a minimum duration of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months with no operator actions required or credited, other than the system initiating actions at the control panel. Durations of less than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months will be considered ifjustified by adequate supporting information from the licensee. To ensure continued operation of the' HCVS beyond 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , licensees may credit manual actions, such as movingportable equipment to supplement electrical power and valve motive power sources.

In response to Generic Letter (GL) 89-16, a number of facilities with Mark I containments installed vent valves in the torus room, near the drywell, or both. Licensees can continue to use these venting locations or select, new locations, provided the requirements of this guidance document are satisfied. The HCVS improves the chances of core cooling by removing heat from containment and lowering containmentpressure,when core cooling is provided by other systems.

If core cooling were to fail and result in the onset ofcore damage, closure ofthe vent valves may become necessary if the system was not designedfor severe accidentservice. In addition,leakage from the HCVS within the plant and the location of the external releasefrom the HCVS could impact the event response from on-site operators'and off-site help arriving at the plant. An adequate strategy to minimize radiologicalconsequences that could impede personnel actions should include the following:

1. Licensees shallprovide permanent radiationshielding where necessary tofacilitatepersonnel access to valves and allow manual operation of the valves locally. Licensee may use alternatives such as providing features to facilitate manual operation of valves from remote locations, as discussedfurther in this guidance under Order Requirement 1.2.2, or relocate the vent valves to areas that are significantly less challengingto operatoraccess/actions.

2. In accordance with Order Requirement 1.2.8, the HCVS shall be designedfor pressures that are consistent with the higher of the primary containment design pressure and the primary containment pressure limit (PCPL),as well as including dynamic loading resultingfrom system actuation. In addition, the system shall be leak-tight. As such, ventilation duct work (i.e., sheet metal) shall not be utilized in the design of the HCVS. Licensees should perform appropriate testing, such as hydrostatic orpneumatic testing, to establish the leak-tightness of the HCVS.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS

3. The HCVS release to outside atmosphere shall be at an elevation higher than adjacentplant structures.Release through existingplant stacks,is consideredacceptable,provided the guidance under Order Requirement 1.2.6 is satisfied If the release from .HCVS is through a vent stack different than the plant stack, the elevation of the stack should be higher than the nearest building or structure.

Response (ref. ISG Item 1.1.3):

I. The HCVS will be designed for reliable remote-manual operation from the HCVS control panel located in the MCR and a backup control panel located outside of the Reactor Building (location to be determined during the detailed design phase). HCVS valve operation will not require access to the Torus (wetwell) area or other plant areas which may pose severe temperature and radiological hazards to personnel. The HCVS consists of a dedicated flow path with no interconnection between the two Nine Mile Point units and with no interconnections to other fluid systems other than a shared containment isolation valve. This design prevents cross-flow into unintended areas, provides containment isolation, and provides reliable and rugged performance as discussed below for Order Requirement 1.2.6.

Dose rates will be evaluated consistent With the assumption that the HCVS is to be used for the prevention of core damage. Shielding or other alternatives to facilitate manual actions will not be required for operation of the vent under these conditions since no core damage has occurred.

2. As discussed below for Order Requirement 1.2.8, the HCVS design pressure will be 62 pounds per square inch gauge (psig) at 360'F. This is the higher of the containment design pressure and the primary containment pressure limit (PCPL) value. The flow path will only use piping components, which excludes the use of any HVAC ducting, and the piping Will be evaluated for dynamic loads. Intersystem valve leakage is precluded by using a dedicated flow path downstream of the inboard CIV and limiting the interface to the existing outboard CIVs. The integrity of the piping will be established as required by the applicable piping standards.

3. As discussed below for Order Requirement 1.2.6, the release to the outside atmosphere is at an elevation above the Reactor Building which is higher than any adjacent plant structure.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 3: Operational characteristics and a description of how each of the Order's technical requirements is being met Order EA-12-050 1.2.1 Requirement:

The HCVS shall have the capacity to vent the steam/energy equivalent of 1 percent of licensed/rated thermal power (unless a lower value is justified by analyses), and. be able to maintain containmentpressurebelow the primary containmentdesign pressure.

ISG 1.2.1 Criteria:

Beyond design basis external events such as a prolonged SBO could result in the loss of active containment heat removal capability. The primary design objective of the HCVS is to provide sufficient venting capacity to prevent a long-term overpressure failure of the containment by keeping the containmentpressure below the primary containment design pressure and the PCPL.

The PCPL may be dictatedby otherfactors, such as the maximum containmentpressure at which the safety reliefvalves (SRVs) and the HCVS valves can be opened and closed The NRC. staff has determined that,for a vent sized under conditions of constant heat input at a rate equal to I percent of rated thermalpower and containmentpressure equal to the lower of the primary containment design pressure and the PCPL, the exhaust-flow through the vent would be sufficient to prevent the containment pressurefrom increasing. This determination is based on studies that have shown that the torus suppression capacity is typically sifficient to *absorbthe decay heat generatedduring at least the first three hoursfollowing the shutdown of the reactor with suppressionpool as the source of injection, that decay heat is typically less than 1 percent of rated thermal power three hours following shutdown of the reactor, and that decay heat continues to decrease to well under 1 percent, thereafter. Licensees shall have an auditable engineering basisfor the decay heat absorbingcapacity of their suppressionpools, selection of venting pressure such that the HCVS will have sufficient venting capacity under such conditions to, maintain containment pressure at or below the primary containment design pressure and the PCPL. If required, venting capacity shall be increased'to an appropriate,level commensurate with the licensee's venting strategy. Licensees may also use a venting capacity sized under conditions of constant heat input at a rate lower than 1 percent of thermal power' if it can be justified by analysis that primary containment design pressure and the PCPL would not be exceeded. In cases where plants were granted,have applied, orplan to apply for power uprates, the licensees shall use.l percent thermal power correspondingto the upratedthermalpower. The basis for the venting capacity shall give appropriateconsideration of where venting is being performedfrom (i.e., wetwell or drywell) and the difference in pressure between the drywell'and the suppression chamber. Vent sizing for multi-unit sites must take into consideration simultaneous venting from all the units, and ensure that venting on one unit does not negatively

'impact the ability to vent on the other units.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Response (ref. ISG Item 1.2.1):

The HCVS flow capacity of the wetwell path will be designed for venting steam/energy at a nominal capacity of 1% of 1850 MWt thermal power at containment pressure of 35 psig. This pressure is the lower of the containment (Torus) design pressure and the PCPL value.

The 1% value assumes that the Torus pressure suppression capacity is sufficient to absorb the decay heat generated during the first 3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months . The vent would then be able to prevent containment, pressure from increasing above the containment design pressure. As part of the detailed design, the duration of Torus decay heat absorption will be confirmed.

Order EA-12-050 1.2.2 Requirement:

The HCVS shall be accessible to plant operatorsand be capable of remote operation and control, or manual operation, duringsustainedoperations.

ISG 1.2.2 Criteria:

The preferred locationfor remote operation and control of the HCVS is from the main control room.

However, alternatelocations to the control room are also acceptable,provided the licensees take into considerationthe following:

1. Sustainedoperations mean the ability to open/close the valves multiple times during the event.

Licensees shall determine the number of open/close cycles necessary during the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of operation and provide supporting basis consistent with the plant-specific containment venting strategy.

2. An assessment of temperature and radiological conditions that operating personnel may encounter both in transit and locally at the controls. Licensee may use alternatives such as providing features to facilitate manual operation of valves from remote locations or relocating/reorientingthe valves.

3. All permanently installedHCVS equipment, including any connections requiredto supplement the HCVS operationduring a prolonged SBO (electric power, N2/air) shall be located above the maximum design basis external flood level or protected from the design basis external flood.

4. During a prolonged SBO, manual operation/action may become necessary to operate .the HCVS. As demonstrated during the Fukushima event, the valves lost motive force including electric power andpneumatic air supply to the valve operators,and control power to solenoid valves. If direct access and local operation of the valves is' not feasible due to temperature or radiological hazards, licensees should include design features to facilitate remote manual operation of the HCVS valves by means such as reach rods, chain links, hand wheels, and portable equipment to provide motive force (e.g., "air/N2bottles, diesel powered compressors, and DC batteries). The connections between the valves and portable equipment should be.

designedfor quick deployment. If a portable motive force (e.g., air or N2 bottles, DC power supplies) is used in the design strategy, licensees shallprovide reasonableprotection of that equipment consistent with the staff's guidance delineated in JLD-ISG-2012-01 for Order EA-12-049.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS

5. The design shall preclude the need for operators to move temporary ladders or operate from atopscaffolding to access the HCVS valves or remote operatinglocations.

Response (ref. ISG Item 1.2.2):

The HCVS design allows initiating and then operating and monitoring the HCVS from the HCVS panel.

The HCVS control panel will be located in the MCR. A backup means of operation will be available from the backup control panel that will be located outside of the Reactor Building. The selected locations will be protected from adverse natural phenomena.

1. The HCVS flow path valves are air-operated valves (AOV) that are air-to.-0pen and spring-to-shut. The primary method of opening the valves requires energizing DC powered SOV and providing motive air/gas. A backup means of operation is also available that does not require energizing or repositioning the SOVs. This means of operating the CIVs and PCV utilizes normally locked manual valves in the pneumatic supply and vent lines.

For the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months following the event, the motive supply for the AOVs will be nitrogen gas bottles that will already be installed and available. The number of open/close cycles for the CIVs and the PCV will be determined during the detailed engineering and design phase, as it is dependent upon the strategies employed for FLEX implementation, use of the PCV, and ultimate pressure control strategies selected. The number of cycles and basis will be provided in subsequent six month updates. The motive force for operation following the initial 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months will be determined during the detailed design and engineering phase. Potential sources include additional nitrogen gas bottles or a portable air compressor that may be locally installed, and powered. Pre-engineered quick disconnects will be provided to connect the supplemental motive force supply.

2. Dedicated DC/AC power supplies with battery back-up capable of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of sustained operation will be provided for HCVS electrical components. These power supplies will be located in an accessible, location outside of the Reactor Building and will be protected from assumed natural hazards, including the design basis flood,, consistent with the requirements contained within NEI 12-06. The power supplies will be capable of being recharged via portable generators using standard electrical connections to ensure operation after 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

3. All permanently installed HCVS equipment, including any connections required to supplement the HCVS operation during a prolonged SBO (electric power, nitrogen/air) will be located in areas reasonably protected from assumed hazards consistent with the requirements of NEI 12-06.

4. Supplemental motive force (e.g., additional nitrogen gas bottles, air compressor), portable generators, and enough fuel for an additional 48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months of operation will be stored on site in an area that is reasonably protected from assumed hazards consistent with the requirements of NEI 12-06.

5. An assessment of temperature and radiological conditions that operating personnel may encounter both in transit and locally at the HCVS panel will be performed. Core damage will not be assumed.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS

6. All valves required to open the flow path are designed for remote-manual operation following a prolonged SBO, i.e., valve operation via handwheel, reach-rod or similar means that requires close proximity to the valve, is not required. Sustainability of remote operation will be addressed by locating the DC power and pneumatic motive sources at an accessible location outside of the Reactor Building. The SOVs are the only electrical active components that may be located in an inaccessible area and that are used to open an AOV. The AOVs, including the CIVs and PCV, do not require torque switches or limit switches. Two SOVs for each AOV will be arranged such that energizing both SOVs from the dedicated DC power supply will open the valve (Refer to response to Public Comment Answer 3 for section 1.2.2). An additional method of operating the AOVs via operation of manual valves in the pneumatic supply and vent lines is available. This does not require the SOVs to be repositioned. The arrangement of these valves is shown in Section 7.

7. Access to the locations described above will not require temporary ladders or scaffolding.

Order EA-12-050 1.2.3 Requirement:

The HCVS shall include a means to prevent inadvertentactuation.

ISG 1.2.3 Criteria:

The design of the HCVS shall incorporatefeatures, such as control panel key-locked switches, locking systems, rupture discs, or administrative controls to prevent the inadvertent use of the vent valves. The system shall be designed to preclude inadvertent actuation of the HCVS due to any single active failure. The design should consider general guidelines such as single point vulnerability andspurious operations of any plant installedequipment associatedwith HCVS.

The objective of the HCVS is to provide sufficient venting of containment andprevent long-term overpressure failure of containment following the loss of active containment heat removal capability or prolonged SBO. However, inadvertent actuation of HCVS due to a design error, equipment malfunction, or operator error during a design basis loss-of-coolant accident (DBLOCA) could have an undesirable effect on the containment accident pressure (CAP) to provide adequate net positive suction head to the emergency core cooling system (ECCS)pumps.

Therefore, prevention of inadvertent actuation, while important for all plants, is essentialfor plants relying on CAP. The licensee submittals on HCVS shall specifically include details on how this issue will be addressed on their individual plants for all situations when CAP credit is required.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Response (ref. ISG Item 1.2.3):

The features that prevent inadvertent HCVS flow path 'actuation due to a design error, equipment malfunction, or operator error include two normally closed/fail closed, in-series CIVs that are air-to-open and spring-to-shut. Two DC SOVs must be energized, to allow the motive air to open the valve.

Although the same DC and motive air source will be used, separate control circuits including key-locked switches will be used for the two redundant valves to address single point vulnerabilities that may cause the flow path to inadvertently open.

NMP 1 does not credit CAP for meeting ECCS pumps net positive suction head (NPSH) requirements for a DBLOCA. However, the revised HCVS operating procedures will provide clear guidance that the HCVS is not to be used to defeat containment integrity requirements for existing design basis transients and accidents.

Order EA-12-050 1.2.4 Requirement:

The HCVS shall include a means to monitor the status of the vent system (e.g., valve position indication)from the control room or other location(s). The monitoring system shall be designed for sustainedoperation during a prolongedSBO.

ISG 1.2.4 Criteria:

Plant operators must be able to readily monitor the status of the HCVS at all times, including being able to understandwhether or not containmentpressure/energyis being vented through the HCVS, and whether or not containment integrity has been restoredfollowing venting operations.

Licensees shall provide a means to allow plant operators to readily determine, or have knowledge of the following system parameters:

(1) HCVS vent valves 'position (open or closed),

(2) system pressure,and (3) effluent temperature Other important information includes the status of supporting systems, such as availability of electricalpower and pneumatic supply pressure. Monitoring by means ofpermanently installed gauges that are at, or nearby the HCVS control panel is acceptable. The staff will consider alternative approaches for system status instrumentation; however, licensees must provide sufficient information andjustificationfor alternative approaches.

The means to monitor system status shall support sustained operations during a prolongedSBO, and be designed to operate under potentially harsh environmental conditions that would be expectedfollowing a loss of containment.heat removal capabilityand SBO. Power supplies to all instruments, controls, and indications shall be from the same power sources supporting the HCVS operation. "Sustained operations" may include the use of portable equipment to provide an alternate source of power to components used to monitor HCVS status. Licensees shall demonstrate instrument reliabilityvia an appropriatecombination of design, analyses, operating experience, and/or testing of channel componentsfor the following sets ofparameters."

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS a radiologicalconditions that the instruments may encounter under normal plant conditions, and duringand after aprolongedSBO event o temperatures and pressure conditions as described under requirement 1.2.8, including dynamic loadingfrom system operation e humidity based on instrumentlocation and effluent conditions in the HCVS Response (ref. ISG Item 1.2.4):

The design of the HCVS will have temperature and radiation monitoring downstream of the last isolation valve. Pressure monitoring will be downstream of the CIVs but upstream of the PCV. All flow path valves will have open and closed position indication. These HCVS indications will be on the same panel as the valve control switches. Motive air/gas pressure and DC power source voltage are also monitored at the HCVS control panel in the MCR.

Power for the instrumentation will be from the same source used for the SOVs to position the AOVs. As described in the response to Order Requirement 1.2.2, dedicated DC/AC power supplies with battery backup capable of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of sustained operation will be provided for HCVS electrical components.

These power supplies will be located in an accessible location outside of the Reactor Building and will be protected from assumed natural hazards, including the design basis flood, consistent with the requirements contained within NEI 12-06. The power supplies will be capable of being recharged via portable generators using standard electrical connections to ensure operation after 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

The approximate range for the temperature indication will be 50'F to 600'F. The approximate range for the pressure indication will be 0 psig to 120 psig. The upper limits were selected to be approximately twice the required HCVS design temperature and pressure. The ranges will be finalized when the detailed design and equipment specifications are prepared.

The detailed design will address the radiological, temperature, pressure, flow induced vibration (if applicable) and internal piping dynamic forces, humidity/condensation and seismic qualification requirements. Assumed radiological conditions are those expected after a prolonged SBO (without fuel failure), which will bound normal plant conditions. Instrument reliability is further discussed in the response to Order Requirement 2.2.

Order EA-12-050 1.2.5 Requirement:

The HCVS shall include a means to monitor the effluent dischargefor radioactivitythat may be releasedfrom operation of the HCVS. The monitoring system shall provide indication in the control room or other location(s), and shall be designed for sustained operation during a prolonged SBO.

ISG 1.2.5 Criteria:

Licensees shall provide an independent means to monitor overall radioactivity that may be releasedfrom the HCVS discharge.The radiationmonitor does not need to meet the requirements of NUREG 0737 for monitored releases, nor does it need to be able monitor releases quantitatively to ensure compliance with Title 10 of the Code of FederalRegulations (10 CFR)

Part 100 or 10 CFR Section 50.67. A wide-range monitoring system to monitor the overall 15 of 28

ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS activity in the releaseproviding indication that effluent from the containment environment that is passing by the monitor is acceptable. The use of other existing radiationmonitoringcapability in lieu of an independent HCVS radiationmonitor is not acceptable because plant operators need accurateinformationabout releasescoming from the containment via the HCVS in order to make informed decisions on operation of the reliablehardenedventing system.

The monitoring system shall provide indication in the control room or a remote location (i.e.,

HCVS controlpanel)for the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of an extended SBO with electric power provided by permanent DC battery sources, and supplemented by portable power sources for sustained operations. Monitoring radiation levels is required only during the events that necessitate operation of the HCVS. The reliability of the effluent monitoring system under the applicable environmentalconditions shall be demonstratedby methods described under Requirement 1.2.4.

Response (ref. ISG Item 1.2.5):

The HCVS radiation monitoring system (RMS) will be dedicated to the HCVS. The approximate range of the RMS is 0.1 millirem/hour (mrem/hr) to 1000 mrem/hr. The detailed design will finalize the range.

This range is considered adequate to determine core integrity per the NRC Responses to Public Comments document.

The detector will be mounted in close proximity to the HCVS piping, accounting for the pipe wall thickness shielding in order to provide a measurement of the- radiation level on the inside of the HCVS piping. The radiation level will be indicated at the HCVS control panel in the MCR1 The RMS will be powered from a dedicated power supply with battery backup capable of 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months operation. Refer to the response to ISG Item 1.2.2 for discussion on sustainability of the dedicated power supplies. The reliability of the radiation monitor is further discussed in the response to ISG Item 2.2.

Order EA-12-050 1.2.6 Requirement:

The HCVS shall include designfeatures to minimize unintended crossflow of ventedfluids within a unit and between units on'the site.

ISG 1.2.6 Criteria:

At Fukushima, an explosion 'occurredin Unit 4, which was in a maintenanceoutage at the time of the event. Although the facts have not been fully established, a likely cause of the explosion in Unit 4 is that hydrogen leakedfrom Unit 3 to Unit 4 through a common venting system. System cross-connectionspresent a potentialfor steam, hydrogen, and airborne radioactivityleakage to other areas of the plant and to adjacent units at multi-unit sites if the units are equipped with common vent piping. In this context, a design that is free ofphysical and control interfaces with other systems eliminates the potential for any cross-flow and is one way to satisfy this requirement.Regardless, system design shallproyide designfeatures to prevent the crossflow of vented fluids and migrationto other areas within the plant or to adjacent units at multi-unit sites.

The current design of the hardened vent at several plants in the U.S. includes cross connections with the standby gas treatment system, which contains sheet metal ducts and filter and fan housings that are not as leak tight as hardpipes. In addition, dual unit plant sites are often equipped with a common plant stack. Examples of acceptable meansfor prevention of crossflow 16 of 28

ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS is by valves, leak-tight dampers, and check valves, which shall be designed to automaticallyclose upon the initiation of the HCVS and shall remain closedfor as long as the HCVS is in operation.

Licensee's shall evaluate the environmentalconditions (e.g. pressure, temperature)at the damper locations during venting operations to ensure that the dampers will remain functional and sufficiently leak-tight, and if necessary, replace the dampers with other suitdble equipment such as valves. If power is requiredfor the interfacing valves to move to isolationposition, it shall be from the same power sources as the vent valves. Leak tightness of any such barriers shall be periodicallyverified by testing as describedunder Requirement 1.2.7.

Response (ref. ISG Item 1.2.6):

The HCVS for both units are fully independent of each other with separate discharge points. Therefore, the capacity at each unit is independent of the status of the other unit's HCVS.

The HCVS has only one interface, which is an existing Motor-Operated Containment Isolation Valve.

This valve is normally closed and is only opened for inerting and de-inerting the containment. The HCVS will be declared out of service when this valve is open or administrative controls established to ensure that operators are available to manually close the valve when open. This reduces any potential for inter-system leakage through valves and dampers, and it eliminates the need to isolate interfacing system valves.

The leak tightness requirements for this isolation valve are discussed in the response to ISG Item 1.2.7.

Order EA-12-050 1.2.7 Requirement:

The HCVS shall include features and provision for the operation, testing, inspection and maintenance adequate to ensure that reliablefunction and capability are maintained ISG 1.2.7 Criteria:

The HCVS piping run shall be designed to eliminate the potentialfor condensationaccumulation, as subsequent water hammer could complicate system operation during intermittent venting or to withstand the potentialfor water hammer without compromising the functionality of the system.

Licensees shallprovide a means (e.g., drain valves, pressure and temperaturegauge connections) to periodically test system components, including exercising (opening and closing) the vent valve(s). In situations where total elimination of condensation is not feasible, HCVS shall be designed to accommodate condensation,including applicable water hammer loads.

The HCVS outboard of the containment boundary shall be tested to ensure that vent flow is released to the outside with minimal leakage, if any, through the interfacing boundaries with other systems or units. Licensees have the option of individually leak testing interfacing valves or testing the overall leakage of the HCVS volume by conventional leak rate testing methods. The test volume shall envelope the HCVS between the outer primary containment isolation barrier and the vent exiting the plant buildings, including the volume up to the interfacingvalves. The test pressure shall be based on the HCVS design pressure. Permissible leakage rates for the interfacingvalves shall be within the requirements ofAmerican Society of Mechanical Engineers Operationand Maintenance of Nuclear PowerPlants Code (ASME OM) - 2009, Subsection ISTC

- 3630 (e) (2), or later edition of the ASME OM Code. When testing the HCVS volume, allowed 17 of 28

ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS leakage shall not exceed the sum of the interfacingvalve leakages as determinedfrom the ASME OM Code. The NRC staff will consider a higher leakage acceptance value if licensees provide acceptablejustification. When reviewing such requests, the NRC staff will consider the impact of the leakage on the habitability of the rooms and areas within the building and operability of equipment in these areas during the event response and subsequent recovery periods. Licensees shall implement the following operation, testing and inspection requirementsfor the HCVS to ensure reliable operationof the system.

Testing and Inspection Requirements Description Frequency Cycle the HCVS valves and the interfacing system Onceperyear valves not used to maintain containment integrity during operations.

Perform visual inspections and a walkdown of HCVS Once per operatingcycle components Test and calibratethe HCVS radiationmonitors.' Once per operatingcycle Leak test the HCVS. (1) Prior to first declaring the system functional;(2) Once every five years thereafter; and (3) After restoration of any breach of system boundary within the buildings Validate the HCVS operatingprocedures by conducting Once per every other operating an open/close test of the HCVS control logic from its cycle control panel and ensuring that all interfacing system valves move to theirproper (intended)positions.

Response (ref. ISG Item 1.2.7):

The detailed design for the HCVS will address condensation accumulation resulting from intermittent venting. In situations where total elimination of condensation is not feasible, the HCVS will be designed to accommodate condensation, including allowance for applicable water hammer loads.

The HCVS CIV will be tested in accordance with the Surveillance Test Program for the plant. This includes the planned Drywell vent path CIVs. Downstream of the CIVs, there are no interfacing systems.

Therefore, no additional leakage testing is required.

HCVS testing and inspections will conform to the, ISG 1.2.7 Table "Testing and Inspection Requirements."

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Order EA-12-050 1.2.8 Requirement:

The HCVS shall be designedfor pressures that are consistent with maximum containment design pressures, as well as, dynamic loadingresultingfrom system actuation.

ISG 1.2.8 Criteria:

The vent system shall be designedfor the higher of the primary containment design pressure or PCPL, and a saturationtemperaturecorrespondingto the HCVS designpressure. However, if the venting location is from the drywell, an additionalmargin of 50 'F shall be added to the design temperature because of the potential for superheated conditions in the drywell. The piping, valves, and the valve actuators shall be designed to withstand the dynamic loading resultingfrom the actuation of the system, including piping reaction loads from valve opening, concurrent hydrodynamic loads from SRV discharges to the suppression pool, and potential for water hammerfrom accumulation of steam condensationduring multiple, venting cycles.

Response (ref. ISG Item 1.2.8):

The HCVS piping design pressure will be 62 psig and design temperature is 360'F. The HCVS design pressure is the higher of the containment design pressure and the PCPL value. The HCVS design temperature is the saturation temperature corresponding to the design pressure plus 507F rounded up.

This temperature allows for the planned addition of a drywell flow path (not part of the order).

The piping, valves, and valve actuators will be designed to withstand the dynamic loading resulting from the actuation of the HCVS, including piping reaction loads from valve opening, concurrent hydrodynamic loads from SRV discharges to the Torus, and potential for water hammer from accumulation of condensation during multiple venting cycles.

Order EA-12-050 1.2.9 Requirement:

The HCVS shall dischargethe effluent to a release point above main plant structures.

ISG 1.2.9 Criteria:

The HCVS release to outside atmosphere shall be at an elevation higher than adjacent plant structures.Release through existing plant stacks is consideredacceptable,provided the guidance under Requirement 1.2.6 is satisfied If the releasefrom HCVS is through a stack different than the plant stack, the elevation of the stack should be higher than the nearest building or structure.

The release point should be situated away from ventilation system intake and exhaust openings, and emergency response facilities. The release stack or structure exposed to outside shall be designed or protected to withstand missiles that could be generated'by the external events causing the prolongedSBO (e.g., tornadoes, high winds).

Response (ref. ISG Item 1.2.9):

The HCVS discharge path piping will be routed to a point just above the Reactor Building, which is higher than any adjacent structure with the exception of the NMP1 stack and the NMP2 Cooling Tower and stack. The Cooling Tower for NMP2 has a higher elevation but it .is not adjacent to the Reactor Building. The NMP1 and NMP2 stacks have a higher elevation but are not adjacent to the Reactor Building. The final discharge point location will be determined during the detailed design phase 19 of 28

ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS considering ventilation system intake and exhaust openings, MCR location, location of FLEX, access routes required following a prolonged SBO, and location of emergency response facilities; however, these must be considered in conjunction with other design criteria (e.g., flow capacity) and pipe routing limitations, to the degree practical.

The detailed design will address tornado winds and missile protection from external events as defined by NEI 12-06 for the outside portions of the release path.

Section 4: Applicable Ouality Requirements (Order EA-12-050 Requirements 2.1 and 2.2)

Order EA-12-050 2.1 Requirement:

The HCVS system design shall not preclude the containment isolation valves, including the vent valve from performing their intended containment isolationfunction consistent with the design basis for the plant. These items include piping, piping supports, containment isolation valves, containment isolation valve actuators and containment isolation valve position indication components.

ISG 2.1 Criteria:

The HCVS vent path up to and including the second containment isolation barrier shall be designed consistent with the design basis of the plant. These items include piping, piping supports, containment isolation valves, containment isolation valve actuators and containment isolation valve position indication components. The HCVS design, out to and including the second containment isolation barrier,shall meet safety-related requirements consistent with the design basis of the plant. The staff notes that in response to GL 89-16, in many cases, the HCVS vent line connections were made to existing systems. In some cases, the connection was made in between two existing containment isolation valves and in others to the vacuum breaker line. The HCVS system design shall not preclude the containment isolation valves, including the vent valve from performing their intended containment isolationfunction consistent with the design basisfor the plant. The design shall include all necessary overrides of containment isolation signals and other interface system signals to enable the vent valves to open upon initiationof the HCVS from its control panel.

Response (ref. ISG Item 2.1):

The HCVS vent path will use a new, dedicated flow path with one shared containment isolation valve and a new outboard containment isolation valve. It also shares. piping with the planned Drywell vent path downstream of the Drywell outboard CIV. The control logic for the existing CIVs is not altered. The HCVS design will not preclude the containment isolation valves from performing their design basis function.

The HCVS vent path piping and supports up to and including the second containment isolation valve will be designed in accordance with existing design basis. As with all other NMPI mechanical penetrations open to the containment atmosphere both HCVS CIVs will be located outside containment. Associated actuators, position indication, and power supplies are also designed consistent with' the requirements to meet the design basis for containment isolation.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS In order to maintain containment isolation when required by the plant design basis, the HCVS CIVs will be normally closed, fail-closed AOVs. As discussed for Order Requirement 1.2.3, the valves will be controlled procedurally and the design will address inadvertent operation to ensure that the flow path remains isolated anytime the design basis requires containment integrity. Due to the above, new automatic containment isolation signals will not be provided to the HCVS CIVs.

The HCVS system design will not preclude any existing CIVs and the new HCVS CIVs from performing their intended containment isolation function when required by the plant design basis. The control circuit for the HCVS CIVs will allow operation of the valves from the HCVS control panels when required, regardless of containment isolation signals.

Order EA-12-050 2.2 Requirement:

All other HCVS components shall be designedfor reliable and rugged performance that is capable of ensuring HCVS functionalityfollowing a seismic event. These items include electrical power supply, valve actuator pneumatic supply, and instrumentation (local and remote) components.

ISG 2.2 Criteria:

All components of the HCVS beyond the second containment isolation barriershall be designed to ensure HCVS functionalityfollowing the plant's design basis seismic event. These components include, in addition to the hardened vent pipe, electric power supply, pneumatic supply and instrumentation. The design ofpower andpneumatic supply lines between the HCVS valves and remote locations (if portable sources were to be employed) shall also be designed to ensure HCVS functionality. Licensees shall ensure that the HCVS will not impact other safety-related structures and components and that the HCVS will not be impacted by non-seismic components.

The staffprefers that the HCVS components, including the piping run, be located in seismically qualified structures. However, short runs of HCVS piping in non-seismic structures are acceptable if the licensee provides adequate justification on the seismic ruggedness of these structures. The hardened vent shall be designed to conform to the requirements consistent with the applicabledesign codes for the plant, such as the American Society of Mechanical Engineers Boiler and Pressure Vessel Code and the applicableSpecifications, Codes and Standards of the American Institute of Steel Construction.

To ensure the functionality of instrumentsfollowing a seismic event, the NRC staff considers any of the following as acceptablemethods:

Use of instruments and supporting components with known operating principles that are supplied by manufacturers with commercial quality assuranceprograms, such as IS09001.

The procurement specifications shall include the seismic requirements and/or instrument design requirements, and specify the need for commercial design standardsand testing under seismic loadings consistent with design basis values at the instrumentlocations.

" Demonstration of the seismic reliability of the instrumentationthrough methods that predict performance by analysis, qualification testing under simulated seismic conditions, a combination of testing and analysis, or the use of experience data. Guidance for these is based on sections 7, 8, 9, and 10 ofIEEE Standard344-2004.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS

Recommended Practicefor Seismic Qualification of Class 1E Equipmentfor Nuclear Power GeneratingStations, or a substantiallysimilar industrialstandardcould be used.

Demonstration that the instrumentation is substantially similar in design to instrumentation that has been previously tested to seismic loading levels in accordance with the plant design basis at the location where the instrument is to be installed (g-levels andfrequency ranges).

Such testing and analysis should be similar to thatperformedfor the plant licensing basis.

Response (ref. ISG Item 2.2):

The HCVS components downstream of the second containment isolation valve and components that interface with the HCVS, included required connections, are routed in seismically qualified structures when contained within a structure.

The HCVS downstream of the second containment isolation valve, including piping and supports, electrical power supply, valve actuator pneumatic supply, and instrumentation (local and remote) components, will be designed/analyzed to ensure functionality following a design basis earthquake and to conform to the applicable plant requirements/design codes.

The HCVS instruments, including valve position indication, process instrumentation, radiation monitoring, and support system monitoring, will be qualified using one of the three methods described in the ISG, which includes:

1. Purchase of instruments and supporting components with known operating principles from manufacturers with commercial quality assurance programs (e.g., IS09001) where the procurement specifications include the applicable seismic requirements, design requirements, and applicable testing.

2. Demonstration of seismic reliability via methods that predict performance described in IEEE 344-2004.

3. Demonstration that instrumentation is substantially similar to the design of instrumentation previously qualified.

Instrument Qualification Method*

HCVS Process Temperature ISo9001 / IEEE 344-2004 / Demonstration HCVS Process Pressure IS09001 / IEEE 344-2004 / Demonstration HCVS Process Radiation Monitor IS09001 / IEEE 344-2004 / Demonstration HCVS Process Valve Position IS09001 / IEEE 344-2004 / Demonstration HCVS Pneumatic Supply Pressure IS09001 / IEEE 344-2004 / Demonstration HCVS Electrical Power Supply IS09001 / IEEE 344-2004 / Demonstration Availability

The specific qualification method used for each required HCVS instrument will be reported in future 6 month status reports.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 5: Procedures and Training (Order EA-12-050 Requirements 3.1 and 3.2)

Order EA-12-050 3.1 Requirement:

Licensees shall develop, implement, and maintainprocedures necessaryfor the safe operation of the HCVS. Proceduresshall be establishedfor system operations when normal and backup power is available,and during SBO conditions.

ISG 3.1 Criteria:

Procedures shall be developed describing when and how to place the HCVS in operation, the location of system components, instrumentation available, normal and backup power supplies, directionsfor sustained operation, including the storage location of portable equipment, training on operating,the portable equipment, and testing of equipment. The procedures shall' identify appropriateconditions and criteriafor use of the HCVS. The procedures shall clearly state the nexus between CAP and ECCS pumps during a DBLOCA and how an inadvertent opening of the vent valve could have an adverse impact on this nexus. The HCVS proceduresshall be developed and implemented in the same manner as other plant procedures necessary to support the execution of the Emergency OperatingProcedures(EOPs).

Licensees shall establish provisions for out-of-service requirements of the HCVS and compensatory measures. These provisions shall be documented in the Technical Requirements Manual (TRM or similar document. The allowed unavailability time for the HCVS shall not exceed 30 days during modes 1, 2, and 3. If the unavailability time exceeds 30 days, the TRM shall direct licensees to perform a cause assessment and take the necessary actions to restore HCVS availability in a timely manner, consistent with plant procedures and prevent future unavailabilityfor similarcauses.

Response (ref. ISG Item 3.1):

Procedures will be established for system operations when normal and backup power is available, and during prolonged SBO conditions.

The HCVS procedures will be developed and implemented following the plant process for initiating or revising procedures and contain the following details:

appropriate conditions and criteria for use of the HCVS,

when and how to place the HCVS in operation,

" the location of system components,

instrumentation available,

" normal and backup power supplies,

" directions for sustained operation (reference NEI 12-06), including the storage location of portable equipment,

" training on operating the portable equipment, and

" testing of portable equipment NMP1 does not credit CAP for ECCS pump NPSH during a DBLOCA. Nevertheless, the procedures will emphasize the need for immediate isolation if the HCVS is inadvertently opened.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS NMP1 does not have a Technical Requirements Manual (TRM) document. The following provisions for out-of-service requirements of the HCVS and associated compensatory measures will be controlled by procedure:

o The allowed unavailability time for the HCVS shall not exceed 30 days during modes 1, 2, and 3.

The HCVS will be declared out of service when motor-operated containment isolation valve IV-201-17 is open or administrative controls' established to ensure that operators are available to manually close the valve when open.

e If the unavailability time exceeds 30 days:,

o The condition resulting in the unavailability of the HCVS will be entered into the site's corrective action system, o The HCVS will'be. restored to an available condition in a timely manner consistent with plant procedures, o A cause assessment of the condition will be performed in accordance with plant procedures to prevent -futureunavailability for similar causes.

Order EA-12-050 3.2 Requirement:

Licensee shall train appropriatepersonnel in the use of the HCVS. The trainingcurricula shall include system operations when. normal and backup power is- available, and during SBO conditions.

ISG 3.2 Criteria:

All personnel expected to operate the HCVS shall receive training in the use ofplant procedures developed for system operations when normal and backup power is available, and during SBO conditions consistent with the plants systematic approach to training. The training shall be refreshedon aperiodic basis and as any changes occur to the HCVS.

Response (ref. ISG Item 3.2h:

The Systematic Approach to Training (SAT) will be used to identify the population to be trained and to determine both the initial and continuing elements of the required training. As determined by the SAT process, the training will consider system operations when normal and backup power is available, and during SBO conditions. Training will be completed prior to placing the HCVS in service.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 6: Implementation Schedule Milestones The following milestone schedule is provided. The dates are planning dates subject to'change as design and implementation details are developed. Any significant changes to this plan, including any changes to the following target dates, will be reflected in the subsequent 6 month Status Reports.

Original Target Date Activity Status October 2012 Conceptual design meeting Complete October 2012 Submit 60 Day Status Report Complete Completed with this February 2013 Submit Overall Integrated Implementation Plan submittal August 2013 Submit 6 Month Status Report February 2014 Submit 6 Month Status Report March 2014, NMPI Design Change Package Issued August 2014 Submit 6 Month Status Report December 2014 NMP1 Major Material On-site1 Procedure Changes and Training Material December 2014 Complete February 2015 Submit 6 Month Status Report N1R23 Outage Spring 2015 NMP1 Design Change Implemented Ni R23 Outage Spring 2015 Procedure Changes Active NMP 1 Demonstration/Functional Test prior to NIR23 Outage Spring 2015 rod withdrawal; Full compliance May 2015 Submit Completion Report Maj or Equipment - Piping, valves and components greater than 3", instrumentation pick-ups and indicators.

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ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 7: Fieures/Diaerams ISG IV.C. 1. Reporting Requirements:

A piping and instrumentationdiagram or a similardiagram that shows system components and interfaces with plant systems and structuresis acceptable.

e IEACTOR 1.11LDING TO MC TTO IV McR M

180,000~A CU.KU FTNYIA SLTO AV DTICLA ON RMALV AR 26 of 28

ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Conceptual Design for Dedicated DC power for the HCVS (the details may change during the detailed design phase and updates will be provided with the 6 month status reports).

CHARGER / BATTERIES n cremra rremrcT125VDC POWER POWER 4160~y- 600vac SOV 210-16 SOV 210-32 SOV 210-71 SOV 210-72 SOV 210-73 4:p 125 VDC TO 24VDC CONVERTER POSITION INDICATING LIGHTS RECORDER FOR IV PRESSURE TRANSMITTERS TEMP-TRANSMITTER CHARGER / BATTERIES 125VDC TO HARDEND VENT CHARGER / BATTERIES / INVERTER EQUIPMENT 120VAC TO HARDEND VENT RADIATION MONITOR 27 of 28

ATTACHMENT 1 NMP 1 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 8: Functional Failure Modes and Alternate Actions Failure with Alternate Functional Failure Action Prevents Mode Failure Cause Alternate Action Containment Venting?

Valves fail to open/close due to loss of None required - system SOVs utilize No normal AC power/DC batteries dedicated 24-hour power supply Valves fail to open/close due to depletion of Recharge system with FLEX provided No dedicated power supply portable generators Valves fail to open/close due to complete Manually operate backup air supply/vent No Fail to Vent (Open) loss of power supplies lines at remote panel on Demand Valves fail to open/close due to loss of No action needed. Valves are provided with dedicated air supply tanks that are sufficient No normal pneumatic.

air supply for up to 6 actuations in a 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period Valves fail to open/close due to loss of Replace bottles as needed and/or recharge No alternate pneumatic air supply (long term) with portable air compressors Valve fails to open/close due to SOV failure Manually operate backup air supply/vent No lines at remote panel Fail to Stop Not credible as there is not a common mode Venting (Close) on failure that would prevent the closure of at N/A No Demand least 1 of the 3 valves needed for venting Not credible as key-locked switches prevent N/A No mispositioning of the HCVS CIVs and PCV Valves fail to remain open due to depletion Recharge system with FLEX provided No portable generators No of dedicated power supply Valves fail to remain open due to complete Manually operate backup air supply/vent Spurious Closure loss of power supplies lines at remote panel No Valves fail to remain open due to loss of Replace bottles as needed and/or recharge No alternate pneumatic.air supply (long term) with portable air compressors 28 of 28

ATTACHMENT 2 NINE MILE POINT UNIT 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Constellation Energy Nuclear Group, LLC February 28, 2013

ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Table of Contents Page References Section 1: System Description Section 2: Design Objectives 5 Requirement 1.1.1 - Minimize the Reliance on Operation Actions 5 Requirement 1.1.2 - Minimize Plant Operators' Exposure to Occupational Hazards 7 Requirement 1.1.3 - Minimize Radiological Consequences 8 Section 3: Operational Characteristics 10 Requirement 1.2.1 - Capacity to Vent Equivalent of 1% 10 Requirement 1.2.2 - HCVS Shall be Accessible to Plant Operators 11 Requirement 1.2.3 - Prevent Inadvertent Actuation 13 Requirement 1.2.4 - Monitor the Status of the Vent System 14 Requirement 1.2.5 - Monitor the Effluent Discharge for Radioactivity 15 Requirement 1.2.6 - Minimize Unintended Cross Flow of Vented Fluids 16 Requirement 1.2.7 - Provision for the Operation, Testing, Inspection and Maintenance 17 Requirement 1.2.8 - Design Pressures 18 Requirement 1.2.9 - Discharge Release Point 19 Section 4: Applicable Quality Requirements 20 Requirement 2.1 - Containment Isolation Function 20 Requirement 2.2 - Reliable and Rugged Performance 21 Section 5: Procedures and Training 23 Requirement 3.1 - Develop, Implement, and Maintain Procedures 23 Requirement 3.2 - Train Appropriate Personnel 24 Section 6: Implementation Schedule Milestones 25 Section 7: Figures/Diagrams 26 Section 8: Functional Failure Modes and Alternate Actions 28 i of ii

ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS

References:

1. Generic Letter 89-16, Installation of a Hardened Wetwell Vent, dated September 1, 1989

2. Order EA-12-049, Mitigation Strategies for Beyond-Design-Basis External Events, dated March 12, 2012

3. Order EA-12-050, Reliable Hardened Containment Vents, dated March 12, 2012

4. JLD-ISG-2012-02, Compliance with Order EA-12-050, Reliable Hardened Containment Vents, dated August 29, 2012

5. NRC Responses to Public Comments, Japan' Lessons-Learned Project Directorate Interim Staff Guidance JLD-ISG-2012-02: Compliance with Order EA-12-050, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents, ADAMS Accession No. ML12229A477, dated August 29, 2012

6. NEI 12-06, Diverse and Flexible Coping Strategies (FLEX) Implementation Guide, Revision 0, dated August 2012 ii of ii

ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 1: System Description ISG Criteria:

Licensees shall provide a complete description of the system, including important operational characteristics.The level of detail generally considered adequate is consistent with the level of detail containedin the licensee's FinalSafety Analysis Report.

Response

System Overview:

The Hardened Containment Vent System (HCVS) is designed to mitigate loss-of-decay-heat removal by providing sufficient containment venting capability to limit containment pressurization. The vent is designed with sufficient capacity to accommodate decay heat input equivalent to 1% of 3988 Megawatts

- thermal (MWt). Thus, the hardened vent capacity will be adequate to relieve decay heat for a prolonged station blackout (SBO) event. The HCVS is intended for use as one element of the core damage prevention strategies. Venting the containment to remove decay heat and limit containment pressurization supports core cooling strategies during a prolonged SBO event.

The HCVS flow paths from the containment to an elevated release point above the Reactor Building roof are shown in the simplified piping and instrumentation diagram (P&ID) in Figure 1 below. The flow path from the Suppression Chamber (wetwell) is the path being credited for compliance with NRC Order EA-12-050. A Drywell flow path is also currently planned as an additional means to maintain containment pressure within design limits, but is not being credited nor committed to for compliance with the Order.

The HCVS at Nine Mile Point Unit 2 (NMP2) is fully independent of the HCVS from Nine Mile Point Unit I (NMPI). The piping flow path is shared with the Containment Purge System up to a newly installed system isolation valve. Dedicated piping is then utilized to the release point. No ductwork is used in the system. This ensures that all the HCVS flow out of the containment is discharged to the outside atmosphere above the NMP2 Reactor Building.

BUILMING NCFC NCFC CONTAIMENT PURGE FMN Figure I I of 28

ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Equipment and components:

The following equipment and components will be provided:

1. HCVS Mechanical Components:

a) Containment isolation piping, valves and controls - The HCVS vent piping and supports up to and including the second containment isolation valve (C1V) are designed in accordance with the existing containment penetration design basis, with one exception.

To comply with the Order EA-12-050, Reliable Hardened Containment Vents, dated March 12, 2012, the inboard containment isolation function will no longer be located inside of containment. With this change to comply with the Order EA-12-050, NMP2 will not meet General Design Criterion (GDC) - 56. As a result, Nine Mile Point Nuclear Station (NMPNS) will submit a request for exemption from 10 CFR 50, Appendix A, GDC - 56 to the NRC for review and approval. NRC approval of this exemption request will be required to implement this change. This design is consistent with other BWR Mark II Containment designs currently in operation. The design of the CIVs will be consistent with the plant's CIV design basis in all other regards. The valves are air-operated, spring-to-close, valves [normally closed, fail closed] with DC powered solenoid operated valves (SOV) and will be operated from the Main Control Room (MCR). A manual, remote pneumatic mode of operation for the CIVs will be available from a remote panel located outside of the Reactor Building as a backup. This backup means of operation will utilize normally locked manual valves and does not require the SOVs to reposition. The existing inboard C1V will either be locked open or removed.

This decision will be made during the detailed design phase.

b) Other system valves and piping - The HCVS piping and supports downstream of the second containment isolation valve, including valve actuator pneumatic supply components, will be designed and analyzed to conform to requirements consistent with the applicable design codes for the plant and to ensure functionality following a design basis earthquake.

c) The HCVS flow path downstream of the CIVs is shared with the Containment Purge System up to a new normally closed, fail-closed, air-operated isolation valve. The flow path is then dedicated out to the release point.

d) The HCVS flow path downstream of the CIVs will have a normally closed, air-operated Pressure Control Valve (PCV). The PCV will be capable of controlling upstream pressure. Similar to the CIVs, the PCV will utilize a DC powered SOV to control the pneumatic supply and will be controlled from the MCR. A manual, remote - pneumatic mode of operation for the PCV will be available from a remote panel located outside of the Reactor Building as a backup.

2. Instrumentation to monitor the status of the HCVS and control the flow path:

a) All instrumentation indication required for operation will be available on the HCVS control panel located in the MCR1 2 of 28

ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS b) HCVS valve position indication, flow path temperature, pressure, and effluent radiation instrumentation will monitor the status of the HCVS and aid operator verification of venting conditions. A failure of valve position indication instrumentation would not prevent opening and closing the valve.

,c) The effluent radiation monitor detector will be mounted in close proximity to the HCVS pipe wall. The radiation monitor will allow the operator to discern the presence of, or the onset of, core damage during HCVS operations, and to take appropriate action to cease venting operations. The radiation monitor display will be located on the HCVS control panel located in the MCR.

d) Instrumentation available will include the HCVS support system pneumatic pressure and DC battery voltage.

3. Support systems assuming a prolonged SBO:

a) Power for the HCVS is provided from dedicated permanently installed DC/AC power supplies. These power supplies are normally supplied from a non-vital bus and have battery backup adequate for the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of operation. The power supply for the radiation monitor includes an inverter to convert the battery-supplied DC power to AC.

The power supplies will be in an accessible location outside of the Reactor Building, allowing the power to be sustained after 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . Final selection of components will be completed during the detailed engineering and design phase.

b) Motive air/gas supply for HCVS operation will be provided from a dedicated permanently installed source adequate for at least the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of operation. This motive air/gas source will be in an accessible location outside of the Reactor Building, allowing the motive air/gas to be sustained after 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The number of open/close cycles for the CIVs and the PCV will be determined during the detailed engineering and design phase, as it is dependent upon the strategies employed for FLEX implementation, use of the PCV, and ultimate pressure control strategies selected. The number of cycles selected and the basis will be provided in subsequent six month updates.

c) Portable equipment will be provided as required to sustain operation after 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The connections for the portable equipment will provide pre-engineered connections to minimize manpower efforts.

d) New CIVs and associated SOVs will be purchased safety-related due to their existing design basis functions and safety classification. Other HCVS components will be purchased with augmented quality requirements to reflect design requirements described later in this plan.

System control:

1. The primary means of control and indication for the HCVS will be from a dedicated HCVS control panel located in the MCR. A backup means of operation will be available from an additional control panel located outside of the Reactor Building. The specific location of the backup control panel will be determined during the detailed design phase.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS

2. The CIVs and PCV will be operated in accordance with approved station procedures to control containment pressure following a prolonged SBO. The revised station procedures will address when venting is to be initiated and any imposed limitations on the pressure band.

3. The primary means of opening each of the CIVs and PCV requires energizing a DC powered SOV from a switch on a HCVS control panel. The'HCVS control panel will be located in the MCR. A backup means of operating the CIVs and PCV will be available via operation of normally-locked manual valves located on the backup HCVS control panel outside of the Reactor Building. This backup means of operation does not replicate the control room function, nor does it require energizing or repositioning the SOV. The backup means provides a way of remotely operating the CIVs and PCV via manual valves in the pneumatic supply and vent lines.

4. Since the HCVS CIVs are shared with the Containment Purge System, both CIVs will have an automatic closure signal for containment isolation. Inadvertent operation will be addressed by controlling the associated SOVs with key-locked switches and by locking the manual valves that may be used for backup operation. Periodic CIV testing will be performed in accordance with the Surveillance Test Program.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 2: A description of how the design objectives contained in Order EA-12-050 Attachment 2, Requirements 1.1.1, 1.1.2. and 1.1.3, are met.

Order EA-12-050 1.1.1 Requirement:

The HCVS shall be designedto minimize the reliance on operatoractions.

ISG 1.1.1 Criteria:

During events that significantly challenge plant operations, individual operatorsare more prone to human error.In addition, the plant operations staff may be requiredto implement strategies and/or take many concurrent actions that further places a burden on its personnel. During the prolonged SBO condition at the Fukushima Dai-ichi units, operatorsfaced many significant challenges while attempting to restore numerous plant systems that were necessary to cool the reactor core, including the containment venting systems. The difficulties faced by the operators related to the location of the HCVS valves, ambient temperatures and radiologicalconditions, loss of all alternatingcurrent electricalpower, loss of motive force to open the vent valves, and exhausting DC battery power. The NRC staff recognizes that operator actions will be needed to operate the HCVS valves, however, the licensees shall consider design features for the system that will minimize the need and reliance on operator actions to the extent possible during a variety ofplant conditions,as further discussed in this ISG.

The HCVS shall be designed to be operatedfrom a control panel located in the main control room or a remote but readily accessible location. The HCVS shall be designed to be fully functional and self sufficient with permanently installed equipment in the plant, without the need for portable equipment or connecting thereto, until such time that additionalon-site or off-site personnel andportable equipment become available. The HCVS shall be capable of operating in this mode (i.e., relying on permanently installed equipment) for at least 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months during the prolonged SBO, unless a shorterperiod is justified by the licensee. The HCVS operation in this mode depends on a variety ofconditions, such as the causefor the SBO (e.g., seismic event, flood, tornado, high winds), severity of the event, and time requiredfor additional help to reach the plant, move portable equipment into place, and make connections to the HCVS.

When evaluating licenseejustificationfor periods less than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , the NRC staff will consider the number of actions and the cumulative demand on personnel resources that are needed to maintain HCVS functionality (e.g., installationof portable equipment during the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months to restore power to the HCVS controls and/or instrumentation)as a result of design limitations. For example, the use of supplemental portablepower sources may be acceptable if the supplemental power was readily available, could be quickly and easily moved into place, and installedthrough the use of pre-engineered quick disconnects, and the necessary human actions were identified along with the time needed to complete those actions. Conversely, supplementalpower sources located in an unattended warehouse that require a qualified electricianto temporarily wire into the panel would not be considered acceptable by the staff because its installation requires a series of complex, time-consuming actions in order to achieve a successful outcome. There are similar examples that could apply to mechanical systems, such as pneumatic/compressedair systems.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Response (ref. ISG Item 1.1.1):

The design of the HCVS will minimize the reliance on operator actions and exposure to hazards identified in JLD-ISG-20.12-01, Compliance with Order EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events, and NEI 12-06, Diverse and Flexible Coping Strategies (FLEX) Implementation Guide. Immediate operator actions can be completed by Reactor Operators and include remote-manual initiation from the HCVS control panel located in the MCR using permanently installed equipment .for the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . A backup means of operation will be available from an additional panel located outside of the Reactor Building. The specific location of the backup control panel will be determined during the detailed design phase. This location will be protected from environmental hazards.

The steps listed below are required to initiate the HCVS flow path. These steps will be confirmed during the detailed design phase.

Primary Action Location / Component

1. Open Suppression Chamber inboard HCVS Control Panel in MCR (alternate control via CIV by manipulating key-lock switch manual valves at backup control panel)

2. Open Suppression Chamber outboard HCVS Control Panel in MCR (alternate control via CIV by manipulating key-lock switch manual valves at backup control panel)

3. Open HCVS PCV HCVS Control Panel in MCR (alternate control via manual valves at backup control panel)

4. Monitor electrical power status, HCVS Control Panel in MCR pneumatic pressure and containment /

HCVS conditions Remote-manual is defined in this report as a non-automatic power operation of a component that does not require the operator to be at or in close proximity to the component. No other operator actions are required to initiate venting.

The HCVS will be designed to allow initiation, isolation, and control at the primary and backup HCVS control panel(s). Monitoring will be available at the primary HCVS control panel in the MCR. The location of the primary HCVS control panel in the MCR and backup control panel outside of the Reactor Building will minimize the plant operator's exposure to adverse temperature and radiological conditions and will be protected from the assumed hazards. Final location of the remote backup control panel will be determined during detailed design.

Permanently installed DC/AC power and motive air/gas capability will be available to support operation and monitoring of the HCVS for the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

After 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , available personnel will be able to connect supplemental motive air/gas and power to the HCVS support systems. Connections for supplementing electrical power and motive air/gas required for HCVS will be located in accessible areas with reasonable protection from assumed hazards to minimize personnel exposure to adverse conditions following a prolonged SBO and venting consistent with the 6 of 28

ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS requirements within NEI 12-06. Connections will use pre-engineered quick disconnects to minimize manpower resources.

Order EA-12-050 1.1.2 Requirement:

The HCVS shall be designedto minimize plant operators' exposure to occupationalhazards, such as extreme heat stress, while operatingthe HCVS system.

ISG 1.1.2 Criteria:

During a prolonged SBO, the drywell, wetwell (torus), and nearby areas in the plant where HCVS components are expected to be located will likely experience an excursion in temperatures due to 'inadequate containment cooling combined with loss of normal and emergency building ventilation systems. In addition, installed normal and emergency lighting in the plant may not be available. Licensees should take into considerationplant conditions expected to be experienced during applicable beyond design basis external events when locating valves, instrument air supplies, and other components that will be required to safely operate the HCVS system.

Components requiredfor manual operationshould be placed in areas that are readily accessible to plant operators, and not require additional actions, such as the installation of ladders or temporary scaffolding, to operate the system.

When developing a design strategy, the NRC staff expects licensees to analyze potential plant conditions and use its acquired knowledge of these areas, in terms 'ofhow temperatures would react to extended SBO conditions and the lighting that would be available during beyond design basis external events. This knowledge also provides an input to system operating procedures, training,the choice ofprotective clothing, requiredtools and equipment, andportable lighting.

Response (ref. ISG Item 1.1.2):

The HCVS design allows initiating and then operating and monitoring the HCVS from the HCVS control panel in theMCR. A backup means of operating the HCVS is located at a control panel outside of the Reactor Building. The locations of the HCVS control panels will minimize plant operators' exposure to adverse temperature and radiological conditions and the panel locations will be protected from hazards assumed in 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, and NEI 12-06 Diverse and Flexible Coping Strategies (FLEX) Implementation Guide.

In order to minimize operator exposure totemperature excursions due to the impact of the prolonged SBO (i.e., loss of normal and emergency building ventilation, systems and/or containment temperature changes), HCVS valve operation will not require access to the Suppression Pool (wetwell) area or other plant areas which may pose severe temperature and radiological hazards to personnel.

Similarly, DC power and motive air/gas sources and the connections to these support systems required for sustained operation will be located in accessible areas protected from severe natural phenomena and which minimize exposure to occupational hazards. Tools required for sustained operation, such as portable headlamps and connection specific tooling will be pre-staged in the NEI 12-06 protected storage locations.

Neither temporary ladders nor scaffold will be required to access these connections or storage locations.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Order EA-12-050 1.1.3 Requirement:

The HCVS shall also be designed to minimize radiologicalconsequences that would impede personnel actions neededfor event response.

ISG 1.1.3 Criteria:

The design of the HCVS should take into consideration the radiologicalconsequences,resulting from the event that could negatively impact event response. During the Fukushima event, personnel actions to manually operate the vent valves were impeded due to the location of the valves in the torus rooms. The HCVS shall be designed to be placed in operation by operator actions at a control panel, located in the main control room or in a remote location. The system shall be deigned to function in this mode with permanently installed equipment providing electricalpower (e.g., DC power batteries) and valve motive force (e.g., N2/air cylinders). The system shall be designed to function in this mode for a minimum duration of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months with no operator actions required or credited, other than the system initiating actions at the control panel. Durations of less than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months will be considered ifjustified by adequate supporting information from the licensee. To ensure continued operation of the HCVS beyond 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , licensees may credit manual actions, such as moving portable equipment to supplement electrical power and valve motive power sources.

In response to Generic Letter (GL) 89-16, a number offacilities with Mark I containments installed vent valves in the torus room, near the drywell, or both. Licensees can continue to use these venting locations or select new locations, provided the requirements of this guidance document are satisfied. The HCVS improves the chances of core cooling by removing heatfrom containment and lowering containmentpressure, when core cooling is provided by other systems.

If core cooling were to fail and result in the onset of core damage, closure of the vent valves may become necessary if the system was not designedfor severe accident service. In addition, leakage from the HCVS within the plant and the location of the external release from the HCVS could impact the event response from on-site operators and off-site help arriving-at the plant. An adequate strategy to minimize radiologicalconsequences that could impede personnel actions should include the following:

1. Licensees shallprovide permanent radiationshielding where necessary to facilitatepersonnel access to valves and allow manual operation of the valves locally. Licensee may use alternatives such as providing features to facilitate manual operation of valves from remote locations, as discussedfurther in this guidance under Order Requirement 1.2.2, or relocate the vent valves to areas that are significantly less challenging to operator access/actions.

2. In accordance with Order Requirement 1.2.8, the HCVS shall be designedfor pressures that are consistent with the higher of the primary containment design pressure and the primary containment pressure limit (PCPL), as well as includingdynamic loading resultingfrom system actuation. In addition, the system shall be leak-tight. As such, ventilation duct work (i.e., sheet metal) shall not be utilized in the design of the HCVS. Licensees should perform appropriate testing,such as hydrostatic or pneumatic testing, to establish the leak-tightness of the HCVS.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS

3. The HCVS release to outside atmosphere shall be at an elevation higher than adjacentplant structures.Release through existing plant stacks is consideredacceptable, provided the guidance under Order Requirement 1.2.6 is satisfied If the release from HCVS is through a vent stack different than the plant stack, the elevation of the stack should be higher than the nearest building or structure.

Response (ref. ISG Item 1.1.3):

1. The HCVS will be designed for reliable remote-manual operation from the HCVS control panel located in the MCR and a backup control panel located outside of the Reactor Building (location to be determined during the detailed design phase). HCVS valve operation will not require access to the Suppression Pool (wetwell) area or other plant areas which may pose severe temperature and radiological hazards to personnel. The HCVS consists of a flow path that is shared with the Containment Purge System up to a new system isolation valve and then new dedicated piping to the release point. There is no interconnection between the NMP2 HCVS and the NMPI HCVs.

Interfaces with existing systems are limited to a new isolation valve that isolates the HCVS from the Containment Purge System and the CIV for the planned Drywell vent path. This design minimizes cross-flow into unintended areas, provides containment isolation, and provides reliable and rugged performance as discussed below for Order Requirement 1.2.6.

Dose rates will be evaluated consistent with the assumption that the HCVS is to be used for the prevention of core damage. Shielding or other alternatives to facilitate manual actions will not.be required for operation of the vent under these conditions since no core damage has occurred.

2. As discussed below for Order Requirement 1.2.8, the HCVS design pressure will be 45 pounds per square inch gauge (psig) at 345'F. This is the higher of the containment design pressure and the primary containment, pressure limit (PCPL) value. The flow path will only use piping components, which excludes the use of any HVAC ducting, and the piping will be evaluated for dynamic loads. Intersystem leakage is limited by interfacing with only one additional system, which is the Containment Purge System. A new system interface valve is being added to isolate Containment Purge from HCVS. The integrity of the piping will be established as required by the applicable piping standards.

3: As discussed below for Order Requirement 1.2.6, the release to the outside atmosphere is.at an elevation above the Reactor Building which is higher than any adjacent plant structure.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 3: Operational characteristics and a description of how each of the Order's technical requirements is being met Order EA-12-050 1.2.1 Requirement:

The HCVS shall have the capacity to vent the steam/energy equivalent of 1 percent of licensed/rated thermal power (unless a lower value is justified by analyses), and be able to maintain containmentpressurebelow the primary containment designpressure.

ISG 1.2.1 Criteria:

Beyond design basis external events such as a prolonged SBO could result in the loss of active containment heat removal capability. The primary design objective of the HCVS is to provide sufficient venting capacity to prevent a long-term overpressurefailure of the containment by keeping the containmentpressure below the primary containmentdesign pressure and the PCPL.

The PCPL may be dictatedby otherfactors, such as the maximum containmentpressureat which the safety reliefvalves (SRVs) and the HCVS valves can be opened and closed.

The NRC staff has determined that,for a vent sized under conditions of constant heat input at a rate equal to 1 percent of rated thermalpower and containmentpressure equal to the lower of the primary containment design pressure and the PCPL, the exhaust-flow through the vent would be sufficient to prevent the containment pressurefrom increasing. This determination is based on studies that have shown that the torus suppression capacity is typically sufficient to absorb the decay heat generatedduring at least the first three hours following the shutdown of the reactor with suppressionpool as the source of injection, that decay heat is typically less than 1 percent of rated thermal power three hours following shutdown of the reactor, and that decay heat continues to decrease to well under 1 percent, thereafter. Licensees shall have an auditable engineering basisfor the decay heat absorbingcapacity of their suppression pools, selection of venting pressure such that the HCVS will have sufficient venting capacity under such conditions to maintain containment pressure at or below the primary containment design pressure and the PCPL. If required, venting capacity shall be increased to an appropriatelevel commensurate with the licensee's venting strategy. Licensees may also' use a venting capacity sized under conditions of constant heat input at a rate lower than 1 percent of thermal power if it can be justified by analysis that primary containment design pressure and the PCPL would not be exceeded In cases where plants were granted,have applied, or plan to applyfor power uprates, the licensees shall use 1 percent thermal power correspondingto the upratedthermal power. The basis for the venting capacity shall give appropriate consideration of where venting is being performedfrom (i.e., wetwell or drywell) and the difference in pressure between the drywell and the suppression chamber. Vent sizing for multi-unit sites must take into consideration simultaneous venting from all the units, and ensure that venting on one -unit does not negatively impact the ability to vent on the other units.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Response (ref. ISG Item 1.2.1):

The HCVS flow capacity of the wetwell path will be designed for venting steam/energy at a nominal capacity of 1% of 3988 MWt thermal power at containment pressure of 45 psig. This pressure is the lower of the containment design pressure and the PCPL value.

The 1% value is bounding because the Suppression Pool pressure suppression capacity is sufficient to absorb the decay heat to a point beyond the time that decay heat has lowered to. 1% of rated output. The vent would then be able to prevent containment pressure from increasing above the containment design pressure.

Order EA-12-050 1.2.2 Requirement:

The HCVS shall be accessible to plant operatorsand be capable of remote operation and control, or manual operation,duringsustainedoperations.

ISG 1.2.2 Criteria:

The preferred locationfor remote operation and control of the HCVS is from the main control room.

However, alternatelocations to the control room are also acceptable,provided the licensees take into considerationthe following.

.1. Sustained operations mean the ability to open/close the valves multiple times during the event.

Licensees shall determine the number of open/close cycles necessary during the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of operation and provide supporting basis consistent with the plant-specific containment venting.

strategy.

2. An assessment of temperature and radiological conditions that operating personnel may encounter both in transit and locally at the controls. Licensee may use alternatives such as providing features to facilitate manual operation of valves from remote locations or.

relocating/reorientingthe valves.

3. All permanently installedHCVS equipment, including.any connections requiredto supplement the HCVS operation during a prolonged SBO (electric power, N2/air) shall be located above the, maximum design basis externalfloodlevel or protectedfrom the design basis externalflood.

4. During aprolonged SBO, manual operation/actionmay become necessary to operate the HCVS.

As demonstrated during the Fukushima event, the valves lost motive force including electric power andpneumatic air supply to the valve operators,and controlpower to solenoid valves. If direct access and local operation of the valves is not feasible due to temperature or radiological hazards, licensees should include design features to facilitate remote manual operation of the HCVS valves by means such as reach rods, chain links, hand wheels, and portable equipment to provide motive force (e.g., air/N2 bottles, diesel powered compressors, and DC batteries). The connections between the valves andportable equipment should be designedfor quick deployment.

If a portable motive force (e.g., air or N2 bottles, DC power supplies) is used in the design strategy, licensees shall provide reasonable protection of thai equipment consistent with the staff's guidance delineatedin JLD-ISG-2012-O1for Order EA-12-049.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS

5. The design shallpreclude the needfor operatorsto move temporary ladders or operatefrom atop scaffolding to access the HCVS valves or remote operating locations.

Response (ref. ISG Item 1.2.2):

The HCVS design allows initiating and then operating and monitoring the HCVS from the HCVS control panel. The HCVS control panel will be located in the MCR. A backup means of operation will be available from the backup control panel that will be located outside of the Reactor Building. The selected locations will be protected from adverse natural phenomena.

1. The HCVS flow path valves are air-operated valves (AOV) with air-to-open and spring-to-shutl.

The primary method of opening the valves requires energizing a DC powered SOV and providing motive air/gas. A backup means of operation is also available that does not require energizing or repositioning the SOV. This means of operating the CIVs and PCV utilizes normally locked manual valves in the pneumatic supply and vent lines.

For the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months following the event, the motive supply for the AOVs will be nitrogen gas bottles that will already be installed and available. The number of open/close cycles for the CIVs and the PCV will be determined during the detailed engineering and design phase, as it is dependent upon the strategies employed for FLEX implementation, use of the PCV, and ultimate pressure control strategies selected. The number of cycles and basis will be provided in subsequent six month updates. The motive force for operation following the initial 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months will be determined during the detailed design and engineering phase. Potential sources include additional nitrogen gas bottles or a portable air compressor that may be locally installed and powered. Pre-engineered quick disconnects will be provided to connect the supplemental motive force supply.

2. Dedicated DC/AC power supplies with battery backup capable of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of sustained operation will be provided for HCVS electrical components. These power supplies will be located in an accessible location outside of the Reactor Building and will be protected from assumed natural hazards, including the design basis flood, consistent with the requirements contained within NEI 12-06. The power supplies will be capable of being recharged via portable generators using standard electrical connections to ensure operation after 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

3. All permanently installed HCVS equipment, including any connections required to supplement the HCVS operation during a prolonged SBO (electric power, nitrogen/air) will be located in areas reasonably protected from assumed hazards consistent with the requirements of NEI 12-06.

4. Supplemental motive force (e.g., additional nitrogen gas bottles, air compressor), portable generators, and enough fuel for an additional 48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months of operation will be stored on site in an area that is reasonably protected from assumed hazards consistent with the requirements of NEI 12-06.

5. An assessment of temperature and radiological conditions that operating personnel may encounter both in transit and locally at the HCVS control panels will be performed as part of the detailed engineering and design phase. Core damage will not be assumed.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS

6. All valves required to open the flow path are designed for remote-manual operation following a prolonged SBO, i.e., valve operation via handwheel, reach-rod or similar means that requires close proximity to the valve, is not required. Sustainability of remote operation will be addressed by locating the DC power and pneumatic motive sources at an accessible location. The SOVs are the only electrical active components that may be located in an inaccessible area and are used to open an AOV. The AOVs, including both the CIVs and the PCV, do not require torque switches or limit switches. A new SOV will be added to each of the existing AOVs in a manner that allows operation of the valve even when power is lost to the normal SOV (Refer to response to Public Comment Answer 3 for Order Requirement 1.2.2). An additional method of operating the AOVs via operation of manual valves in the pneumatic supply and vent lines is available. This does not require the SOVs to be repositioned. The arrangement of these valves is shown in Section 7.

7. Access to the locations described above will not require temporary ladders or scaffolding.

Order EA-12-050 1.2.3 Requirement:

The HCVS shall include a means to prevent inadvertent actuation.

ISG 1.2.3 Criteria:

The design of the HCVS shall incorporatefeatures, such as control panel key-locked switches, locking systems, rupture discs, or administrative controls to prevent the inadvertent use of the vent valves. The system shall be designed to preclude inadvertent actuation of the HCVS due to any single active failure. The design should consider general guidelines such as single point vulnerabilityand spurious operations of any plant installedequipment associatedwith HCVS.

The objective of the HCVS is to provide sufficient venting of containment and prevent long-term overpressure failure of containment following the loss of active containment heat removal capability or prolonged SBO. However, inadvertent actuation of HCVS due to a design error, equipment malfunction, or operator error during a design basis loss-of-coolant accident (DBLOCA) could have an undesirable effect on the containment accident pressure (CAP) to provide adequate net positive suction head to the emergency core cooling system (ECCS)pumps.

Therefore, prevention of inadvertent actuation, while importantfor all plants, is essentialfor plants relying on CAP. The licensee submittals on HCVS shall specifically include details on how this issue will be addressed on their individual plants for all situations when CAP credit is required.

Response (ref. ISG Item 1.2.3):

The features that prevent inadvertent HCVS flow path actuation due to a design error, equipment malfunction, or operator error include two normally closed/fail closed, in-series CIVs that are air-to-open and spring-to-shut. A DC SOV must be energized to allow the motive air to open the valve. Although the same DC and motive air source will be used, separate control circuits including key-locked switches will be used for the two redundant valves to address single point vulnerabilities that may cause the flow path to inadvertently open.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS NMP2 does not credit CAP for meeting ECCS pumps net positive suction head (NPSH) requirements for a DBLOCA. However, the revised HCVS operating procedures will provide clear guidance that the HCVS is not to be used to defeat containment integrity requirements for existing design basis transients and accidents.

Order EA-12-050 1.2.4 Requirement:

The HCVS shall include a means to monitor the status of the vent system (e.g., valve position indication)from the control room or other location(s). The monitoring system shall be designed for sustained operationduring aprolongedSBO.

ISG 1.2.4 Criteria:

Plant operators must be able to readily monitor the status of the HCVS at all times, including being able to understandwhether or not containmentpressure/energyis being vented through the HCVS, and whether or not containment integrity has been restoredfollowing venting operations.

Licensees shall provide a means to allow plant operators to readily determine, or have knowledge of,the following system parameters:

(1) HCVS vent valves 'position (open or closed),

(2) system pressure, and (3) effluent temperature.

Other important information includes the status of supporting systems, such as availability of electricalpower and pneumatic supply pressure. Monitoring by means of permanently installed gauges that are at, or nearby, the HCVS control panel is acceptable. The staff will consider alternative approaches for system status instrumentation; however, licensees must provide sufficient information andjustificationfor alternative approaches.

The means to monitor system status shall support sustainedoperations during a prolongedSBO, and be designed to operate under potentially harsh environmental conditions that would be expectedfollowing a loss of containment heat removal capability and SBO. Power supplies to all instruments, controls, and indications shall be from the same power sources supporting the HCVS operation. "Sustained operations" may include the use of portable equipment to provide an alternate source of power to components used to monitor HCVS status. Licensees shall demonstrate instrument reliabilityvia an appropriatecombination of design, analyses, operating experience, and/or testing of channel componentsfor the following sets ofparameters:

" radiologicalconditions that the instruments may encounter under normal plant conditions, and duringand after aprolongedSBO event

" temperatures and pressure conditions as described under requirement 1.2.8, including dynamic loadingfrom system operation

" humidity based on instrumentlocation and effluent conditions in the HCVS 14 of 28

ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Response (ref. ISG Item 1.2.4):

The design of the HCVS will have temperature and radiation monitoring downstream of the last isolation valve. Pressure monitoring will be downstream of the CIVs but upstream of the PCV. All flow path valves will have open and closed position indication. These HCVS indications will be on the same MCR panel as the valve control switches. Motive air/gas pressure and DC power source voltage are also monitored at the HCVS control panel in the MCR.

Power for the instrumentation will be from the same source used for the SOVs to position the AOVs. As described in the response to Order Requirement 1.2.2, dedicated DC/AC power supplies with battery backup capable of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of sustained operation will be provided for HCVS electrical components.

These power supplies will be located in an accessible location outside of the Reactor Building and will be protected from assumed natural hazards, including the design basis flood, consistent with the requirements contained within NEI 12-06. The power supplies will be capable of being recharged via portable generators using standard electrical connections to ensure operation after 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

The approximate range for the temperature indication will be 50'F to 600'F. The approximate range for the pressure indication will be 0 psig to 100 psig. The upper limits were selected to be approximately twice the required HCVS design temperature and pressure. The ranges will be finalized when the detailed design and equipment specifications are prepared.

The detailed design will address the radiological, temperature, pressure, flow induced vibration (if applicable) and internal piping dynamic forces, humidity/condensation and seismic qualification requirements. Assumed radiological conditions are those expected after a prolonged SBO (without fuel failure), which will bound normal plant conditions. Instrument reliability is further discussed in the response to ISG Item 2.2.

Order EA-12-050 1.2.5 Requirement:

The HCVS shall include a means to monitor the effluent dischargefor radioactivitythat may be releasedfrom operation of the HCVS. The monitoring system shall provide indication in the control room or other location(s), and shall be designed for sustained operation, during a prolonged SBO.

ISG 1.2.5 Criteria:

Licensees shall provide an independent means to monitor overall radioactivity that may be releasedfrom the HCVS discharge.The radiationmonitor does not need to meet the requirements of NUREG 0737 for monitored releases, nor does it need to be able monitor releases quantitatively to ensure compliance with Title 10 of the Code of Federal Regulations (10 CFR)

Part 100 or 10 CFR Section 50.67. A wide-range monitoring system to monitor the overall activity in the release providing indication that effluent from the containment environment that is passing.by the monitor is acceptable. The use of other existing radiationmonitoringcapability in lieu of an independent HCVS radiation monitor is not acceptable because plant operators need accurateinformation about releases comingfrom the containment via the HCVS in order to make informed decisions on operation of the reliable hardenedventing system.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS The monitoring system shall provide indication in the control room or a remote location (i.e.;

HCVS control panel)for the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of an extended SBO with electric power provided by permanent DC battery sources, and supplemented by portable power sources for sustained operations. Monitoring radiation levels is required only during the events that necessitate operation of the HCVS. The reliability of the effluent monitoring system under the applicable environmental conditionsshall be demonstratedby methods described under Requirement 1.2.4.

Response (ref. ISG Item 1.2.5):

The HCVS radiation monitoring system (RMS) will be dedicated to the 'HCVS. The approximate range of the RMS is 0.1 millirem/hour (mrem/hr) to 1000 mrem/hr. The detailed design will finalize the range.

This range is considered adequate to determine core integrity per the NRC Responses to Public Comments document.

The detector will be mounted in close proximity to the HCVS piping, accounting for the pipe wall thickness shielding in order to provide ameasurement of the radiation level on the inside of the HCVS, piping. The radiation level will be indicated at the HCVS control panel in the MCR. The RMS will be powered from a dedicated power supply with battery backup capable of 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months operation. Refer to the response to ISG Item 1.2.2 for discussion on sustainability of the dedicated power supplies. The reliability of the radiation monitor is further discussed in the response to ISG Item 2.2.

Order EA-12-050 1.2.6 Requirement:

The HCVS shall include designfeatures to minimize unintended crossflow of ventedfluids within a unit and between units on the site.

ISG 1.2.6 Criteria:

At Fukushima, an explosion occurredin Unit 4, which was in a maintenance outage at the time of the event. Although the facts have not been fully established,a likely cause of the explosion in Unit 4 is that hydrogen leakedfrom Unit 3 to Unit 4 through a common venting system. System cross-connectionspresent a potentialfor steam, hydrogen, and airborneradioactivityleakage to other areas of the plant and to,'adjacent units at multi-unit sites if the units are equipped with common vent piping. In this context, a design that isfree ofphysical and control interfaces with other systems eliminates the potential for any cross-flow and is one way to satisfy this requirement.Regardless, system design shallprovide design features to prevent the crossflow of vented fluids and migration to other areas within the plant or to adjacent units at multi-unit sites.

The current design of the hardenedvent at several plants in the US. includes cross connections with the standby gas treatment system, which contains sheet metal ducts and filter and fan housings that are not as leak tight as hardpipes. In addition,' dual unit plant sites are often equipped with a common plant stack. Examples of acceptable means for prevention of crossflow is by valves, leak-tight dampers, and check valves, which shall be designedto automaticallyclose upon the initiationof the HCVS and shall remain closedfor as long as the HCVS is in operation.

Licensees shall evaluate the environmentalconditions (e.g. pressure, temperature)at the damper locations during venting operations to ensure that the 'dampers will remain functional and sufficiently leak-tight, and if necessary, replace the dampers with other suitable equipment such as valves. If power is requiredfor the interfacingvalves to move to isolationposition, it shall be 16 of 28

ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS from the same power. sources as the vent valves. Leak tightness of any such barriers shall be periodicallyverified by testing as describedunder Requirement 1.2.7.

Response (ref. ISG Item 1.2.6):

The HCVS for both units are fully independent of each other with separate discharge points. Therefore, the capacity at each unit is independent of the status of the other unit's HCVS.

The interface valve between the HCVS and the Containment Purge System will be a new; normally-closed, fail-closed (spring operated) valve. Upon initiation of an Extended Loss of AC Power (ELAP) and associated loss of instrument air, the valve would automatically shut due to spring pressure.

Therefore, no additional power is necessary. Environmental conditions in which the valve will be expected to remain functional will be assessed during the detailed engineering and design phase.

This reduces any potential for inter-system leakage through valves and dampers.

The leak tightness requirements for this isolation valve are discussed in the response to ISG Item 1.2.7.

Order EA-12-050 1.2.7 Requirement:

The HCVS shall include features and provision for the operation, testing, inspection and maintenance adequate to ensure that reliablefunction and capability are maintained.

ISG 1.2.7 Criteria:

The HCVS piping run shall be designed to eliminate the potentialfor condensation accumulation, as subsequent water hammer could complicate system operation during intermittent venting or to withstand the potentialfor water hammer without compromising the functionality of the system.

Licensees shallprovide a means (e.g., drain valves, pressureand temperaturegauge connections) to periodically test system components, including exercising (opening and -closing) the vent valve(s). In situations where total elimination of condensation is not feasible, HCVS shall be designed to accommodate condensation,including applicablewater hammer loads.

The HCVS outboard of the, containment boundary shall be tested to ensure that vent flow is released to the outside with minimal leakage, if any, through the interfacing boundaries with other systems or units. Licensees have the option of individually leak testing interfacing valves or testing the overall leakage of the HCVS volume by conventional leak rate testing methods. The test volume shall envelope the HCVS between the outer primary containment isolation barrier and the vent exiting the plant buildings, includingthe volume up to the interfacing valves. The test pressure shall be based on the HCVS design pressure. Permissible leakage rates for the interfacingvalves shall be within the requirements ofAmerican Society of Mechanical Engineers Operationand Maintenance of Nuclear Power Plants Code (ASME OM) - 2009, Subsection ISTC

-3630 (e) (2), or later edition of the ASME. OM Code. When testing the HCVS volume, allowed leakage shall not exceed the sum of the interfacingvalve leakages as determinedfrom the ASME OM Code. The NRC staff will consider a higher leakage acceptance value if licensees provide acceptablejustification. When reviewing such requests, the NRC staff will consider the impact of the leakage on the habitability of the rooms and areas within the building and operability of equipment in these areas during the event response and subsequent recovery periods. Licensees 17 of 28

ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS shall implement the following operation, testing and inspection requirements for the HCVS to ensure reliable operation of the system.

Testing and Inspection Requirements Description Frequency Cycle the HCVS valves and the interfacing system valves not used to maintain containment integrity during operations. Once per year Perform visual inspections and a walkdown of HCVS components Once per operatingcycle Test and calibratethe HCVS radiationmonitors. Once per operatingcycle (1) Priortofirst declaring the system functional;(2)

Once every five years thereafter; and (3) After restorationof any breach of system boundary within the Leak test the HCVS. buildings Validate the HCVS operatingprocedures by conducting an open/close test of the HCVS control logicfrom its controlpanel and ensuring that all interfacingsystem valves move to their Once per every other proper (intended)positions. operatingcycle Response (ref. ISG Item 1.2.7):

The detailed design for the HCVS will address condensation accumulation resulting from intermittent venting. In situations where total elimination of condensation is not feasible, the HCVS will be designed to accommodate condensation, including allowance for applicable water hammer loads.

The HCVS CIVs Will be tested in accordance with the Surveillance Test Program for the plant. This includes the planned Drywell vent path C1Vs.

HCVS testing and inspections will conform to the ISG 1.2.7 Table "Testing and Inspection Requirements." NMP2 will "Leak test the HCVS" by leak testing the isolation valve that isolates the Containment Purge System from the HCVS.

Order EA-12-050 1.2.8 Requirement:

The HCVS shall be designedfor pressures that are consistent with maximum containment design pressures,as well as, dynamic loading resultingfrom system actuation.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS ISG 1.2.8 Criteria:

The vent system shall be designedfor the higher of the primarycontainment design pressure or PCPL,and a saturationtemperature correspondingto the HCVS design pressure.However, if the venting location is from the drywell, an additionalmargin of 50YF shall be added to the design.

temperature because of the potential for superheated conditions in the drywell. The piping, valves, and the valve actuatorsshall be designed to withstand the dynamic loading resultingfrom the actuation of the system, including piping reaction loads from valve opening, concurrent hydrodynamic loads from SRV discharges to the suppression pool, and potential for water hammerfrom accumulationof steam condensation duringmultiple venting cycles.

Response (ref. ISG Item 1.2.8):

The HCVS piping desigI pressure will be 45 psig and the design temperature will be 3457F. The HCVS design pressure is the higher of the containment design pressure and the PCPL value. The HCVS design temperature is the saturation temperature corresponding to the design pressure plus 507F rounded up.

This temperature allows for the plannedaddition! of a drywell flow path.

The piping, valves, and valve actuators will be designed to withstand the dynamic loading resulting from the actuation of the HCVS, including piping reaction loads from valve opening, concurrent hydrodynamic loads from SRV discharges to the suppression pool, and potential for water hammer from accumulation of condensation during multiple venting cycles.

Order EA-12-050 1.2.9 Requirement:

The HCVS shall discharge the effluent to a releasepoint above main plant structures.

ISG 1.2.9 Criteria:

The HCVS release to outside atmosphere shall be at an elevation higher than adjacent plant structures. Release through existing plant stacks is consideredacceptable, provided the guidance under Requirement 1.2.6 is satisfied If the.release from HCVS is through a stack different than the plant stack, the elevation of the stack should be higher than the nearest building or structure.

The releasepoint should be situated away from ventilation system intake and exhaust openings, and emergency response facilities. The release stack or structure exposed to outside shall be designed or protected to withstand missiles that could be generated by the external events causing the prolongedSBO (e.g., tornadoes,high winds).

Response (ref. ISG Item 1.2.9):

The HCVS discharge path piping will be routed to a point just above the Reactor Building, which is higher than any adjacent structure. The cooling tower for NMP2 has a higher elevation but it is not adjacent to the Reactor Building. The final discharge point location will be determined during the detailed design phase considering ventilation system intake and exhaust openings, MCR location, location of FLEX, access routes required following a prolonged SBO, and location of emergency response facilities; however, these must be considered in conjunction with other design criteria (e.g., flow capacity) and pipe routing limitations, to the degree practical. /

The detailed design will address tornado winds and missile protection from external events as defined by NEI 12-06 for the outside portions of the release path.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 4: Applicable Ouality Requirements (Order EA-12-050 Requirements 2.1 and 2.2)

Order EA-12-050 2.1 Requirement:

The HCVS system design shall not preclude the containment isolation valves, including'the vent valve from performing their intended containment isolationfunction consistent with the design basis for the plant. These items include piping, piping supports, containment isolation valves, containment isolation valve actuators and containment isolation valve position indication components.

ISG 2.1 Criteria:

The HCVS vent path up to and including the second containment isolation barrier shall be designed consistent with the design basis of the plant. These itemso include piping, piping supports, containment isolation valves, containment isolation valve actuators and containment isolation valve position indication components. The HCVS design, out to and including the second containment isolation barrier,shall meet safety-related requirements consistent with the design basis of the plant. The staff notes that in responsd'to GL 89-16, in many cases, the HCVS vent line connections were made to existing systems. In some cases, the connection was made in between two existing containment isolation valves and in others to the vacuum breaker line. The HCVS system design shall not preclude the containment isolation valves, including the vent valve from performingtheir intended containmentisolationfunction consistent with the design basisfor the plant. The design shall include all necessary overrides of containment isolation signals and other interface system signals to enable the vent valves to open upon initiation of the HCVS from its controlpanel.

Response (ref. ISG Item 2.1):

The HCVS vent path will share a flow path with the Containment Purge System. It also shares piping with the planned Drywell vent path downstream of the Drywell outboard CIV. The control logic for the CIVs is not altered. The HCVS design will not preclude the containment isolation valves from performing their design basis function.

The HCVS vent path piping and supports up to and including the second containment isolation valve will be designed in accordance with existing design basis, with one exception. The inboard CIV will no longer be inside containment. Both HCVS CIVs will be located outside containment. This arrangement will not meet GDC - 56. NMPNS will submit a request for exemption from 10 CFR 50, Appendix A, GDC-56 to comply with the NRC Order EA-12-050, Reliable Hardened Containment Vents dated March 12, 2012. The existing inboard isolation valve will no longer function as a valve, but as a pipe.

Associated actuators, position indication, and power supplies are also designed consistent with the requirements to meet the design basis for containment isolation.

In order to maintain containment isolation when required by the plant design basis, the HCVS CIVs will be normally closed, fail-closed AOVs. As discussed in the response to ISG Item 1.2.3, the valves will be controlled procedurally and the design will address inadvertent operation to ensure that the flow path remains isolated anytime the design basis requires containment integrity. Due to the above, no new automatic containment isolation signals will be provided to the HCVS CIVs.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS The HCVS system design will not preclude the CIVs from performing their intended containment isolation function when required by the plant design basis. The control circuit for the HCVS CIVs will allow operation of the valves from the HCVS control panels when required, regardless of containment isolation signals.

Order EA-12-050 2.2 Requirement:

All other HCVS components shall be designed for reliable and rugged performance that is capable of ensuring HCVSfunctionalityfollowing a seismic event. These items include electrical power supply, valve actuator pneumatic supply, and instrumentation (local and remote) components.

ISG 2.2 Criteria:

All components of the HCVS beyond the second containment isolation barriershall be designed to ensure HCVS functionalityfollowing the plant's design basis seismic event. These components include, in addition to the hardened vent pipe, electric power supply, pneumatic supply and instrumentation. The design ofpower andpneumatic supply lines between the HCVS valves and remote locations (if portable sources were to be employed) shall also be designed to ensure HCVS functionality. Licensees shall ensure that the HCVS will not impact other safety-related structures and components and that the HCVS will not be impacted by non-seismic.components.

The staff prefers that the HCVS components, including the piping run, be located in seismically qualified structures. However, short runs of HCVS piping in non-seismic structures are acceptable if the licensee provides adequate justification on the seismic ruggedness of these structures. The hardened vent shall be designed to conform to the requirements consistent with the applicable design codes for the plant, such as the American Society ofMechanical Engineers Boiler and Pressure Vessel Code and the applicable Specifications, Codes and Standards of the American Institute of Steel Construction.

To ensure the functionality of instrumentsfollowing a seismic event, the NRC staff considers any of the following as acceptable methods:

Use of instruments and supporting components with known operating principles that are supplied by manufacturers with commercial quality assuranceprograms, such as IS09001.

The procurement specifications shall include the seismic requirements and/or instrument design requirements,-and specify the needfor commercial design standardsand testing under seismic loadings consistent with design basis values at the instrument locations.

Demonstration of the seismic reliability of the instrumentation through methods that predict performance by analysis, qualification testing under simulated' seismic conditions, a combination of testing and analysis, or the use of experience data. Guidancefor these is based on sections 7, 8, 9, and 10 of IEEE Standard344-2004,

Recommended Practicefor Seismic Qualification of Class 1E Equipmentfor Nitclear Power GeneratingStations, or a substantiallysimilar industrialstandardcould be used 21 of 28

ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS

Demonstration that the instrumentation is substantiallysimilar in design to instrumentation that has been previously tested to seismic loading levels in accordance with the plant design basis at the location where the instrument is to be installed (g-levels andfrequency ranges).

Such testing and analysis should be similar to thatperformedfor the plant licensing basis.

Response (ref. ISG Item 2.2):

The HCVS components downstream of the second containment isolation valve and components that interface with the HCVS, including required connections, are routed in seismically qualified structures when contained within a structure.

The HCVS downstream of the second containment isolation valve, including piping and supports, electrical power supply, valve actuator pneumatic supply, and instrumentation (local and remote) components, will be designed/analyzed to ensure functionality following a design basis earthquake and to conform to the applicable plant requirements/design codes..

The HCVS instruments, including valve position indication, process instrumentation, radiation monitoring, and support system monitoring, will be qualified using one of the three methods described in the ISG, which includes:

1. Purchase of instruments and supporting components with known operating principles from manufacturers with commercial .quality assurance programs (e.g., IS09001) where the procurement specifications include the applicable seismic requirements, design requirements, and applicable testing

2. Demonstration of seismic reliability via methods that predict performance described in IEEE 344-2004

3. Demonstration that instrumentation is substantially similar to the design of instrumentation previously qualified Instrument Qualification Method*

HCVS Process Temperature IS09001 / IEEE 344-2004 / Demonstration HCVS Process Pressure IS09001 / IEEE 344-2004 / Demonstration HCVS Process Radiation Monitor IS09001 / IEEE 344-2004 / Demonstration HCVS Process Valve Position ISo9001 / IEEE 344-2004 / Demonstration HCVS Pneumatic Supply Pressure IS09001 / IEEE 344-2004 / Demonstration HCVS Electrical Power Supply IS09001 / IEEE 344-2004 / Demonstration Availability

The specific qualification method used for each required HCVS instrument will be reported in future 6 month status reports.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 5: Procedures and Training (Order EA-12-050 Requirements 3.1 and 3.2)

Order EA-12-050 3.1 Requirement:

Licensees shall develop, implement, and maintainprocedures necessaryfor the safe operation of the HCVS. Proceduresshall be establishedfor system operations when normaland backuppower is available,and during SBO conditions.

ISG 3.1 Criteria:

Procedures shall be developed describing when and how to place the HCVS in operation, the location of system components, instrumentation available, normal and backup power supplies, directionsfor sustained operation, including the storage location of portable equipment, training on operating the portable equipment, and testing of equipment. The procedures shall identify appropriateconditions and criteriafor use of the HCVS. The procedures shall clearly state the nexus between CAP and ECCSpumps during a DBLOCA and how an inadvertent opening of the vent valve could have an adverse impact on this nexus. The HCVS proceduresshall be developed and implemented in the same manner as other plant procedures necessary to support the execution of the Emergency OperatingProcedures(EOPs).

Licensees shall establish provisions for out-of-service requirements of the HCVS and compensatory measures. These provisions shall be documented in the Technical Requirements

-Manual (TRM) or similar document. The allowed unavailability time for the HCVS shall not exceed 30 days during modes 1, 2, and 3. If the unavailability time exceeds 30 days, the TRM shall direct licensees to perform a cause assessment and take the necessary actions to restore HCVS availability in a timely manner, consistent with plant procedures and prevent future unavailabilityfor similarcauses.

Response (ref. ISG Item 3.1):

Procedures will be established for system operations when normal and backup power is available, and during prolonged SBO conditions.

The HCVS procedures will be developed and implemented following the plant process for initiating or revising procedures and contain the following details:

appropriate conditions and criteria for use of the HCVS,

" when and how to place the HCVS in operation,

" the location of system components,

instrumentation available,

normal and backup power supplies,

" directions for sustained operation (reference NEI 12-06), including the storage location of portable equipment,

training on operating the portable equipment, and

testing of portable equipment NMP2 does not credit CAP for ECCS pump NPSH during a DBLOCA. Nevertheless, the procedures will emphasize the need for immediate isolation if the HCVS is inadvertently opened.

23 of 28

ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS The following provisions for out-of-service requirements of the HCVS and associated compensatory measures will be documented in the NMP2 TRM:

The allowed unavailability time for the HCVS shall not exceed 30 days during modes 1, 2, and 3

If the unavailability time exceeds 30 days:

o The condition resulting in the unavailability of the HCVS will be entered into the site's corrective action system, o The HCVS will be restored to an available condition in a timely manner consistent with plant procedures, o A cause assessment of the condition will be performed in accordance with plant procedures to prevent future unavailability for similar causes.

Order EA-12-050 3.2 Requirement:

Licensee shall train appropriatepersonnel in the use of the HCVS. The training curriculashall include system operations when normal and backup power is available, and during SBO conditions.

ISG 3.2 Criteria:

All personnel expected to operate the HVCS shall receive trainingin the use of plant procedures developed for system operations when normal and backup power is available, and during SBO conditions consistent with the plants systematic approach to training. The training shall be refreshed on aperiodicbasis and as any changes occur to the HCVS.

Response (ref. ISG Item 3.2):

The Systematic Approach to Training (SAT) will be used to identify the population to be trained and to determine both the initial and continuing elements of the required training. As determined by the SAT process, the training will consider system operations when normal and backup power is available, and during SBO conditions. Training will be completed prior to placing the HCVS in service.

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ATTACHMENT 2 NMP-2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 6: Implementation Schedule Milestones The following milestone schedule is provided. The dates are planning dates subject to change as design and implementation details are developed. Any significant changes to this plan, including any changes to the following target dates, will be reflected in the subsequent 6 month Status Reports.

Original Target Date Activity Status October 2012 Conceptual design meetin'g Complete October 2012 Submit 60 Day Status Report Complete Submit Overall Integrated Implementation Completed with this February 2013 Plan submittal Submit Request for Exemption from 10 July 2013 CFR 50, Appendix A, GDC-56 August 2013 Submit 6 Month Status Report February 2014 Submit 6 Month Status Report NRC Approves Request for Exemption July 2014 from 10 CFR 50, Appendix A, GDC-56 August 2014 Submit 6 Month Status Report February 2015 Submit 6 Month Status Report March 2015 NMP2 Design Change Package Issued August 2015 Submit 6 Month Status Report December 2015 NMP2 Major Material On-site2 Procedure Changes and Training Material December 2015 Complete February 2016 Submit 6 Month Status Report N2RI15 Outage Spring 2016 NMP2 Design Change Implemented N2R 15 Outage Spring 2016 Procedure Changes Active NMP2 Demonstration/Functional Test prior N2R15 Outage Spring 2016 to rod withdrawal; Full compliance.

June 2016 Submit Completion Report 2 Major Equipment - Piping, valves and components greater than 3", Instrumentation pick-ups and indicators.

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ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 7: Fieures/Diagrams ISG IV.C. 1. Reportine Requirements:

A piping and instrumentationdiagram or a similardiagram that shows system components and interfaces with plant systems and structures is acceptable.

REACTOR TO MCR DRYWELL APPROX.

180,000 CU. FT.

TYPICAL ISOLATION VALVE 26 of 28

ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Conceptual Design for Dedicated DC power for the HCVS (the details may change during the detailed design phase and updates will be provided with the 6 month status reports).

2RTX-XSRIA 2STX XNSI 2RTX-XSR 1B SNO 2NPrS-WGOOI. 13.81KV I) NO

............. I 214S-X111 2NJS-X3D 12HA ER I

BUSA BUSS JC CHARGER/ BATTERIES 125 VOCTO 24 VDC CONVERTER D IV 1 DIV. 2 ISOLA ION VA*LVE ISOLATIONVALVE CONTROL/ INDICATION CONTROL/INDICATION 24VDC VENT PRESSURE VEN T EMP. N-SUPPLY RECORDER 14S ITER TRAN TRA*NSMITTER PRESSURE CHARGER/ RPTTERIES 125 VDC TO HARDEND VENT EQUIPMENT RADIATION MON ITOR 27 of 28

ATTACHMENT 2 NMP 2 OVERALL INTEGRATED PLAN FOR RELIABLE HARDENED VENTS Section 8: Functional Failure Modes and Alternate Actions Failure with Alternate Functional Failure Action Prevents Mode Failure Cause Alternate Action Containment Venting?

Val~es fail to open/close due to loss of normal None required - system SOVs utilize AC power/DC batteries dedicated 24-hour power supply No Valves fail to open/close due to depletion of Recharge system with FLEX provided dedicated power supply portable generators No Valves fail to open/close due to complete loss Manually operate backup air supply/vent of power supplies lines at remote panel No Fail to Vent (Open) on Demand No action needed. Valves are provided with Valves fail to open/close due to loss of normal dedicated motive force capable of 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months pneumatic air supply operation No Valves fail to open/close due to loss of Replace bottles as needed and/or recharge alternate pneumatic air supply (long term) with portable air compressors No Manually operate backup air supply/vent Valve fails to open/close due to SOV failure lines at remote panel No Fail to Stop Not credible as there is not a common mode Venting (Close) on failure that would prevent the closure of at Demand least 1 of the 3 valves needed for venting N/A No Spurious Opening Not credible as key-locked switches prevent mispositioning of the HCVS CIVs and PCV N/A No Valves fail to remain open due to depletion of Recharge system with FLEX provided dedicated power supply portable generators No Valves fail to remain open due to complete Manually operate backup air supply/vent Spurious Closure loss of power supplies lines at remote panel No Valves fail to remain open due to loss of Replace bottles as needed and/or recharge alternate pneumatic air supply (long term) with portable air compressors No Page 28 of 28

ATTACHMENT 3 REGULATORY COMMITMENTS CONTAINED IN THIS CORRESPONDENCE Constellation Energy Nuclear Group, LLC February 28, 2013

ATTACHMENT 3 REGULATORY COMMITMENTS CONTAINED IN THIS CORRESPONDENCE The following table identifies actions committed to in this document. Any other statements in this submittal are provided for information purposes and are not considered to be, regulatory commitments.

REGULATORY COMMITMENT DUE DATE Ensure the final design, details and associated Six month intervals from February 28, 2013 procedure guidance for the Reliable Hardened Containment Vents, as well as any revisions to the information contained in the attachments, is provided in the 6-month Integrated Plan updates required by NRC Order EA-12-050 Submit an exemption request to GDC-56 to install July 31, 2013 a new containment isolation valve outside containment and abandon the existing containment isolation valve inside containment in order to comply with NRC Order EA-12-050 Page 1 of 1

ML13066A169

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