BVY 13-016, Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents (Order Number EA-12-050)

Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents (Order Number EA-12-050)

ML13064A303
Person / Time
Site:	Vermont Yankee
Issue date:	02/28/2013
From:	Wamser C Entergy Nuclear Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BVY 13-016, EA-12-050
Download: ML13064A303 (35)

Text

a Entergy Entergy Nuclear Operations, Inc.

Vermont Yankee 320 Governor Hunt Road Vernon, Vermont 05354 Tel: (802)257-7711 Christopher J. Wamser Site Vice President BVY 13-016 February 28, 2013 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike Rockville, MD 20852

SUBJECT:

Vermont Yankee Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents (Order Number EA-12-050)

Vermont Yankee Nuclear Power Station Docket No. 50-271 License No. DPR-28

REFERENCE:

1. NRC Order Number EA-12-050, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents, dated March 12, 2012 (ML12054A694)

2. NRC Interim Staff Guidance JLD-ISG-2012-02, Compliance with Order EA-1 2-050, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents, Revision 0, dated August 29, 2012 (ML12229A475)

3. Initial Status Report in Response to March 12, 2012, Commission Order to Modify Licenses with Regard to Reliable Hardened Containment Vents (Order Number EA-12-050), BVY 12-072, dated October 26, 2012

Dear Sir or Madam:

On March 12, 2012, the Nuclear Regulatory Commission ("NRC" or "Commission")

issued an order (Reference 1) to Entergy Nuclear Operations, Inc. (Entergy). Reference 1 was immediately effective and directs Entergy to have a Reliable Hardened Vent (RHV) 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). Specific requirements are outlined in Attachment 2 of Reference 1.

Reference 1 requires submission of an Overall Integrated Plan by February 28, 2013.

The interim staff guidance (Reference 2) was issued August 29, 2012 which provides direction regarding the content of this Overall Integrated Plan. The purpose of this letter is to provide the Overall Integrated Plan pursuant to Section IV, Condition C.1, of Reference 1. This letter confirms Entergy has an Overall Integrated Plan complying with the guidance, for the purpose of ensuring the functionality of RHV systems to remove Abb t-Al

BVY 13-016 Page 2 of 3 decay heat and control of containment pressure following events that result in loss of active containment heat removal capability or prolonged SBO as described in of Reference 1.

For the purposes of compliance with Order EA-12-050, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents, Entergy plans to use a wetwell vent.

The enclosure contains design information as of the writing of this letter, much of which is still preliminary, pending completion of on-going evaluations and analyses. Due to the synergy between the design of the RHV system and the equipment to be utilized in the Diverse and Flexible Coping Strategies (FLEX) required by Order EA-12-049, some of the design details are still being developed. As further design details and associated procedure guidance are finalized, revisions to the information contained in the enclosure will be communicated to the NRC in the 6-month updates required by the Order.

Should you have any questions regarding this submittal, please contact Mr. Robert J.

Wanczyk at (802) 451-3166.

This letter contains no new regulatory commitments.

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

Sincerely, CJW / JTM

Enclosure:

Vermont Yankee Overall Integrated Plan for Reliable Hardened Containment Vents cc: Mr. William M. Dean Regional Administrator U. S. Nuclear Regulatory Commission, Region 1 2100 Renaissance Boulevard, Suite 100 King of Prussia, PA 19406-2713 U. S. Nuclear Regulatory Commission Attn: Director, Office of Nuclear Reactor Regulation One White Flint North 11555 Rockville Pike Rockville, MD 20852

BVY 13-016 Page 3 of 3 NRC Senior Resident Inspector Vermont Yankee U. S. Nuclear Regulatory Commission ATTN: Richard Guzman Mail Stop 08C2 11555 Rockville Pike Rockville, MD 20852-2378 U. S. Nuclear Regulatory Commission ATTN: Robert J. Fretz Jr.

OWFN - Mailstop 4A15A 11555 Rockville Pike Rockville, MD 20852-2378 U. S. Nuclear Regulatory Commission ATTN: Robert L. Dennig OWFN - Mailstop 1OE1 11555 Rockville Pike Rockville, MD 20852-2378 Mr. Christopher Recchia, Commissioner VT Department of Public Service 112 State Street - Drawer 20 Montpelier, Vermont 05620-2601

A AREVA ANP-3203 Vermont Yankee Nuclear Power Revision 0 Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

February 2013 AREVA NP Inc.

(c) 2013 AREVA NP Inc.

Copyright © 2013 AREVA NP Inc.

All Rights Reserved

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Page i Nature of Changes Section(s)

Item or Page(s) Description and Justification 1 All This is a new document

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Page ii ABSTRACT This document contains the response for Vermont Yankee Nuclear Power Station to the U.S. NRC regarding the Hardened Containment Venting System overall integrated implementation plan.

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Page 1 Table of Contents:

Section 1: System Description Section 2: Design objectives Requirement 1.1.1 - Minimize the Reliance on Operator Actions Requirement 1.1.2 - Minimize Plant Operators' Exposure to Occupational Hazards Requirement 1.1.3 - Minimize Radiological Consequences Section 3: Operational Characteristics Requirement 1.2.1 - Capacity to Vent Equivalent of 1%

Requirement 1.2.2 - HCVS Shall be Accessible to Plant Operators Requirement 1.2.3 - Prevent Inadvertent Actuation Requirement 1.2.4 - Monitor the Status of the Vent System Requirement 1.2.5 - Monitor the Effluent Discharge for Radioactivity Requirement 1.2.6 - Minimize Unintended Cross Flow of Vented Fluids Requirement 1.2.7 - Provision for the Operation, Testing, Inspection and Maintenance Requirement 1.2.8 - Design Pressures Requirement 1.2.9 - Discharge Release Point Section 4: Applicable Quality Requirements Requirement 2.1 - Containment Isolation Function Requirement 2.2 - Reliable and Rugged Performance Section 5: Procedures and Training Requirement 3.1 - Develop, Implement, and Maintain Procedures Requirement 3.2 - Train Appropriate Personnel Section 6: Implementation Schedule Milestones Section 7: Changes/Updates to this Overall Integrated Implementation Plan Section 8: Figures/Diagrams

References:

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

2. Order EA-1 2-049, Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design Basis External Events, dated March 12, 2012

3. Order EA-1 2-050, Issuance of Order to Modify Licenses with Regard to Reliable Hardened Containment Vents, dated March 12, 2012

4. JLD-ISG-2012-02, Compliance with Order EA-1 2-050, 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

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Page 2 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.

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Page 3 Section 1: System Description ISG Criteria:

Licensees shall provide a complete description of the system, including importantoperational characteristics.The level of detail generally consideredadequate is consistent with the level of detail contained in the licensee's FinalSafety Analysis Report.

Response

System Overview:

The reliable Hardened Containment Vent System (HCVS) will be designed to mitigate loss-of-decay-heat removal by providing sufficient containment venting capability to limit containment pressurization and maintain core cooling capability. The vent will be designed with sufficient capacity to accommodate decay heat input equivalent to 19.12 MWt, which is 1% of current licensed thermal power (CLTP). A venting capacity sized under conditions of constant heat input at a rate lower than 1 percent of thermal power, if required, will be justified by analysis that primary containment design pressure and the Primary Containment Pressure Limit (PCPL) would not be exceeded. 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 core damage prevention strategies.

The HCVS flow path from the containment to an elevated release point is shown in the simplified diagram (Figure 1) below. No ductwork will be used in the flow path.

Vermont Yankee UFSAR section 2.3.6.3 states: "The "Index of Tornado Damage Potential" (defined in units of 1000ths of 1% residential property values per year) for the tri-county area is 1 as compared to a value of 33 in "tornado alley" (Oklahoma-Kansas-Nebraska).

Thom divides the United States into 1-degree squares and determines the tornado frequency for each square. Using data from 1953-62, Thom records 12 tornadoes occurring within a 1-degree square (about 3 million acres) encompassing the Vernon site. A mean recurrence interval for a tornado striking a point within this 1-degree square was calculated to be 1040 years.

This seems reasonable if one considers that only 12 tornadoes were reported in about 3 million acres in a 10-year period.

Vermont Yankee UFSAR section 12.2.1 states: "The maximum anticipated wind velocity that is anticipated at the site is 80 mph with gusts to 100 mph... The site is located in a geographic area which has a small probability of being subjected to tornadic wind conditions".

Vermont Yankee UFSAR section 12-2.1 lists the class I structures that have been designed to withstand short-term tornado winds up to 300 mph. The plant stack is a Class I structure but not listed to withstand short-term tornado winds.

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Page 4 Figure 1: Simplified Vent Line Connections to Wetwell and Other Systems Legend kocsa~tlaon!.wycol D-ICSL. 1Pe-to, New CIV-2 rcNC 56T SGT

-78 -7A V16-19-5C AO AO

-38 -3A Standby Gas Treatment System Equipment and components:

The following equipment and components will be provided:

i. HCVS Mechanical Components -

a) Containment isolation piping, valves and controls - The HCVS vent piping and supports up to and including the second containment isolation will be designed in

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Page 5 accordance with the existing plant design basis. Containment isolation valves are provided consistent with the plant's containment isolation valve design basis.

The existing motor operated valve and rupture disk will be replaced by new CIV valves. These valves will be air-operated valves (AOV) [Normally closed, fail closed] with DC powered solenoid valves (SOV), and can be operated from switches in the Main Control Room (MCR).

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

c) Interface valves will provide positive isolation to the interconnected systems. The HCVS shares part of its flow path with the Standby Gas Treatment System (SGTS). The vent pipe is connected to a torus-to-drywell vacuum breaker line at one end and to the 12" SGTS line downstream of the SGTS skids at the other end. Check valves prevent back flow from the hardened vent line into the SGTS.

ii. Instrumentation to monitor the status of the HCVS -

a) Instrumentation indications will be available in both the Main Control Room and remote panel located in the diesel generator room.

b) The location of the effluent radiation monitor of the vent pipe will be downstream the second the Isolation Valve, inside the Reactor Building. The measurement location (inside or outside the vent pipe) will be determined in the detailed design phase.

c) HCVS vent flow path valves position indication, temperature and pressure instrumentation will monitor the status of the HCVS to aid the operator to ensure verification of proper venting operation. A failure of the position indication instrumentation would not prevent opening and closing the valve.

d) Local instrumentation will indicate pressure of nitrogen backup cylinders.

e) Existing pressure indication for the Wetwell and Drywell along with temperature and level indication for the Wetwell will aid the operator to ensure proper venting operation.

iii. Support systems -

a) Normal power for the HCVS valve solenoids will be provided from the existing essential 125 VDC batteries.

b) Back-up power for instrumentation on the remote control station located in the diesel generator room is provided from the alternate shutdown safety related B-AS-2 battery system for at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

c) Motive air/gas supply for HCVS operation will be adequate for at least the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> during operation under prolonged SBO conditions, and is provided from

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Page 6 the normal nitrogen supply system with permanently installed nitrogen cylinders as backup.

d) FLEX equipment will have the capability to provide back-up support equipment for reliable HCVS operation within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Power will be supplied from diesel, generators to maintain the HCVS batteries charged. Motive air/gas for HCVS operation is supplied from normal nitrogen supply or air system and permanently installed nitrogen cylinders as backup. Power for instrumentation will be supplied from an essential DC station battery source for the main control room indication.

The remote panel will be supplied from the alternate shutdown safety related B-AS-2 battery system.

iv. System control -

a) The CIVs will be operated in accordance with Emergency Operating Procedures (EOP) to control containment pressure. The HCVS will be designed for approximately 28 open/close cycles under prolonged SBO conditions. Controlled venting will be permitted in the revised EOPs. A venting strategy will be developed commensurate with the detailed design and associated analysis. The control circuit for the new vent CIVs will allow for manual override operation of the HCVS from its control panel regardless of the containment isolation signal.

b) Passive: No passive component (e.g. rupture disk) will be installed.

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Page 7 Section 2: Design Objective Requirement 1.1.1 - Minimize the Reliance on Operator Actions The HCVS shall be designed to minimize the reliance on operatoractions.

ISG 1.1.1 Criteria:

During events that significantly challenge plant operations,individualoperatorsare more prone to human error. In addition,the plant operationsstaff may be requiredto implement strategies and/ortake many concurrent actions that furtherplaces a burden on its personnel. During the prolongedSBO condition at the Fukushima Dai-ichi units, operatorsfaced many significantchallenges while attemptingto restore numerous plant systems that were necessary to cool the reactorcore, including the containment venting systems. The difficulties faced by the operatorsrelatedto the location of the HCVS valves, ambient temperaturesand 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 operatoractions 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 operatoractions to the extent possible during a variety of plant conditions, as furtherdiscussed in this ISG.

The HC VS 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 personneland portableequipment become available. The HCVS shall be capable of operating in this mode (i.e., relying on permanentlyinstalled equipment) for at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> during the prolonged SBO, unless a shorterperiod is justified by the licensee. The HCVS operation in this mode depends on a variety of conditions, such as the cause for 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 licensee justificationfor periods less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the NRC staff will considerthe number of actions and the cumulative demand on personnel resources that are needed to maintain HCVS functionality (e.g., installationof portableequipment during the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to restorepower to the HCVS controls and/orinstrumentation)as a result of design limitations. For example, the use of supplemental portablepower sources may be acceptable if the supplementalpower was readily available, could be quickly and easily moved into place, and installedthrough the use of pre-engineeredquick 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 temporarilywire into the panel would not be considered acceptable by the staff because its installation requires a series of complex, time-consuming actions in orderto achieve a successful outcome.

There are similar examples that could apply to mechanical systems, such as pneumatic/compressedair systems.

Response (ref. ISG Item 1.1.1):

The operation of the HCVS will be designed to minimize the reliance on operator actions in response to hazards identified in 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 remote control station. The operator actions required to open a vent path are:

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Page 8 Operator Actions Necessary to Vent the Containment during an SBO Vent containment with Vent containment with containment containment pressure at pressure as specified from remote specified pressure from MCR control location in case MCR or DC power is unavailable

1. Open 1 st containment 1. Align valves at remote panel for Isolation Valve from MCR manual operation of CIVs.

2. Open 2 "d containment 2. Open 1st containment Isolation Isolation Valve from MCR Valve from remote panel

3. Monitor electrical power 3. Open 2 nd containment Isolation status, pneumatic pressure and Valve from remote panel containment / HCVS conditions

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

The HCVS will be designed to allow initiation, control, and monitoring of venting from the Main Control Room) and a backup remote control station in the diesel generator room. This location minimizes plant operators' exposure to adverse temperature and radiological conditions and is protected from hazards assumed in NEI 12-06.

Permanently installed power and motive air/gas supply will be available to support operation and monitoring of the HCVS for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Permanently installed and FLEX equipment will supply air and power to HCVS for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The response to NRC EA-12-049 will describe in detail the FLEX efforts to maintain the power source. As described in NEI 12-06, allowance is provided for operator actions to restore power. Staffing studies when completed in response to NRC EA-1 2-049 will demonstrate that sufficient manpower is available to ensure that supplemental DC control power can be established.

After 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, available personnel will be able to connect supplemental motive air/gas to the HCVS. Connections for supplementing electrical power and motive air/gas required for HCVS will be located in accessible areas with reasonable protection per NEI 12-06 that minimizes personnel exposure to adverse conditions following a prolonged SBO and venting. Connections will be pre-engineered quick disconnects to minimize manpower resources.

Requirement 1.1.2 - Minimize Plant Operators' Exposure to Occupational Hazards The HCVS shall be designed to minimize plant operators'exposure to occupationalhazards, such as extreme heat stress, while operating the HCVS system.

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Page 9 ISG 1.1.2 Criteria:

During a prolonged SBO, the drywell, wetwell (torus), and nearby areas in the plant where HVCS 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 experiencedduring applicable beyond design basis external events when locating valves, instrumentair supplies, and other components that will be requiredto safely operate the HCVS system. Components requiredfor manual operation should be placed in areas that are readily accessible to plant operators,and not requireadditionalactions, such as the installationof laddersor temporary scaffolding, to operate the system.

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

Response (ref. ISG Item 1.1.2):

The HCVS design allows initiating and then operating and monitoring the HCVS from the Main Control Room and the backup remote control station in the diesel generator room, which minimizes plant operators' exposure to adverse temperature and radiological conditions and the Main Control Room and diesel generator room, is protected from hazards assumed in NEI 12-06.

Procedures will not require access to suppression pool (wetwell) area and exposure to extreme occupational hazards for normal and backup operation of electrical and pneumatic systems.

Connections for supplemental equipment needed for sustained operation will be located in accessible areas protected from severe natural phenomena and minimize exposure to occupational hazards. Tools required for sustained operation, such as portable headlamps / or specify lighting alternatives will be pre-staged, as necessary, in by NEI 12-06 defined storage locations.

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

Requirement 1.1.3 - Minimize Radiological Consequences The HCVS shall also be designed to minimize radiologicalconsequences that would impede personnel actions needed for 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, personnelactions to manually operate the vent valves were impeded due to the location of the valves in the torus rooms. The HCVS shall be designedto be placed in operation by operatoractions ata controlpanel, located in the main control room or in a remote location- The system shall be deigned to function in this mode with permanently installedequipment providingelectricalpower (e.g., dc powerbatteries) 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 <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with no operatoractions requiredor credited, otherthan the system initiatingactions at the controlpanel.

Durationsof less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> will be consideredif justified by adequatesupporting information from the licensee. To ensure continued operation of the HCVS beyond 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, licensees may credit manual actions, such as moving portable equipment to supplement electricalpower and valve motive power sources.

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Page 10 In response to GenericLetter (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 locationsor select new locations, provided the requirements of this guidance document are satisfied. The HCVS improves the chances of core cooling by removing heat from containmentand lowering containment pressure, when core cooling is provided by other systems. If core cooling were to fail and result in the onset core damage, closure of the vent valves may become necessary if the system was not designed for 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 operatorsand off-site help arrivingat the plant.

An adequatestrategy to minimize radiologicalconsequences that could impede personnel actions should include the following:

1. Licensees shall provide permanentradiationshielding where necessary to facilitate personnel access to valves and allow manual operation of the valves locally. Licensee may use alternativessuch as providing features to facilitatemanual operation of valves from remote locations, as discussedfurther in this guidance under Requirement 1.2.2, or relocate the vent valves to areas that are significantly less challenging to operatoraccess/actions.

2. In accordance with Requirement 1.2.8, the HCVS shall be designed for pressures that are consistent with the higherof the primarycontainment design pressure and the primarycontainmentpressure limit (PCPL),

as well as including dynamic loading resulting from 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 shouldperform appropriatetesting, such as hydrostatic or pneumatic testing, to establish the leak-tightness of the HCVS.

3. The HCVS release to outside atmosphereshall be at an elevation higher than adjacentplant structures.

Release through existing plant stacks is consideredacceptable,provided the guidance underRequirement 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 higherthan the nearest building or structure.

Response (ref. ISG Item 1.1.3):

The HCVS will be designed for reliable remote-manual operation. Operators will not be required to access the suppression pool area. The HCVS will be designed to minimize system cross flow, prevent steam flow into unintended areas, provide containment isolation, and provide reliable and rugged performance as discussed below for Order requirements 1.2.6.

Dose rates are 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 are not required for operation of the vent under these conditions since no core damage has occurred.

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Paqe 11 Section 3: Operational characteristics Requirement 1.2.1 - Capacity to Vent Equivalent of 1%

The HCVS shall have the capacityto vent the steam/energy equivalent of 1 percent of licensed/rated thermal power (unless a lower value isjustified by analyses), and be able to maintain containmentpressure below the primarycontainment design pressure.

ISG 1.2.1 Criteria:

Beyond design basis external events such as a prolongedSBO could resultin the loss of active containment heat removal capability. The primary design objective of the HCVS is to provide sufficient venting capacityto prevent a long-term overpressure failure of the containmentby keeping the containmentpressure below the primarycontainment design pressureand the PCPL. The PCPL may be dictated by other factors, such as the maximum containmentpressure at which the safety relief valves (SRVs) and the HCVS valves can be opened and closed.

The NRC staff has determined that,for a vent sized underconditions of constantheat input at a rate equal to 1 percent of ratedthermalpower and containment pressure equal to the lower of the primarycontainment design pressureand the PCPL, the exhaust-flow through the vent would be sufficient to prevent the containmentpressurefrom increasing. This determination is based on studies that have shown that the torus suppression capacityis typically sufficient to absorb the decay heat generatedduring atleast the first three hours following the shutdown of the reactorwith suppressionpool as the source of injection, that decay heat is typically less than I percent of rated thermal power three hours following shutdown of the reactor,and that decay heatcontinues to decrease to well under 1 percent, thereafter.Licensees shall have an auditable engineering basis for the decay heat absorbing capacityof 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 increasedto an appropriatelevel commensurate with the licensee's venting strategy. Licensees may also use a venting capacitysized underconditions of constant heat input at a rate lower than 1 percent of thermal power if it can be justified by analysis thatprimary containmentdesign pressureand the PCPL would not be exceeded. In cases where plants were granted,have applied, or plan to apply for power uprates, the licensees shall use 1 percent thermal power correspondingto the uprated thermalpower. The basis for the venting capacity shall give appropriateconsiderationof where venting is being performed from (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 considerationsimultaneous venting from all the units, and ensure that venting on one unit does not negatively impact the ability to vent on the other units.

Response (ref. ISG Item 1.2.1):

The HCVS wetwell path will be designed for venting steam/energy at a nominal capacity of 1%

of 1912 MWt thermal power at pressure of 56 psig. This pressure is the lower of the containment design pressure and the PCPL value.

The 1% value assumes that the suppression pool pressure suppression capacity is sufficient to absorb the decay heat generated during the first 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. 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 suppression pool decay heat absorption will be confirmed.

The HCVS is intended for use as one element of a comprehensive core damage prevention strategy as described in the response to NRC Order EA-12-049, which is summarized as follows:

During the initial coping period (Phase 1), installed plant equipment is used to maintain the essential function of core cooling by taking suction from the condensate storage tank via the RCIC and HPCI systems.

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Page 12 During Phase 2, the primary strategy is to transfer water from the west basin to the condensate storage tank to supplement the water available for RCIC suction and injection to cool the core.

For Phase 3 the reactor core cooling strategy is to place one loop of RHR into service. This will be accomplished by powering up a 4160V Class IE Switchgear Bus for RHR and RHR Service Water pumps by utilizing a 4160V RRC FLEX portable diesel generator and supplying the RHR Heat Exchanger with water from the cooling tower deep basin using the RHR Service Water pumps and existing Alternate Cooling System piping.

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Page 13 Requirement 1.2.2 - HCVS Shall be Accessible to Plant Operators The HCVS shall be accessible to plant operatorsand be capable of remote operationand control, or manual operation, during sustainedoperations.

ISG 1.2.2 Criteria:

The preferred location for 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 operationsmean 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 <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of operationand provide supporting basisconsistent with the plant-specificcontainment venting strategy.

2. An assessment of temperatureand radiologicalconditions that operatingpersonnelmay encounterboth in transitand locally at the controls. Licensee may use alternativessuch as providing features to facilitate manualoperationof valves from remote locationsorrelocating/reorientingthe valves.

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

4. Duringa prolongedSBO, manual operation/actionmay become necessary to operate the HCVS. As demonstratedduring the Fukushima event, the valves lost motive force including electricpower and pneumatic air supply to the valve operators,and control power to solenoid valves. If directaccess and local operation of the valves is not feasible due to temperature or radiologicalhazards, 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 and portableequipment should be designed for 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 reasonableprotection of that equipment consistentwith the staffs guidance delineatedin JLD-ISG-2012-01 for Order EA-12-049.

5. The design shallpreclude the need for operatorsto move temporary laddersor operate from atop scaffolding 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 Main Control Room and the backup remote control station in the diesel generator room. This location is also protected from adverse natural phenomena.

1. The HCVS flow path valves are air-operated valves (AOV) with air-to-open and spring-to-shut. Opening the valves requires energizing a DC powered solenoid operated valve (SOV) and providing motive air/gas. The detailed design will provide a permanently installed DC power source for the solenoids.

Power for the instrumentation on the remote control station in the diesel generator room will be provided from the existing alternate shutdown safety related B-AS-2 battery adequate for the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Also motive air/gas adequate for the first 24 will be provided to the remote control station. FLEX will be credited after the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

The response to NRC EA-1 2-049 will demonstrate the capability under the FLEX effort to maintain the DC source. The initial stored motive air/gas will allow for a minimum of approximately 28 valve operating cycles; however, the detailed design will determine the number of required valve cycles for the first 24-hours and the initial stored motive air/gas

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Page 14 will support the required number of valve cycles. The SOVs are the only electrical components required for valve functionality that are located inside the area considered not-accessible following a prolonged SBO. The AOVs do not require torque switches and limit switches to operate. The limit switches will only be used for position indication.

Backup manual operation from the remote control station allows for opening the AOVs without DC power by bypassing the SOVs and directly supplying nitrogen to the valve actuators.

2. An assessment of temperature and radiological conditions that operating personnel may encounter both in transit and locally at the controls will be performed.

3. All permanently installed HCVS equipment, including any connections required to supplement the HCVS operation during a prolonged SBO (electric power, N2/air) will be located in areas reasonably protected from defined hazards from NEI 12-06.

4. All valves required to open the flow path are designed for remote manual operation following a prolonged SBO, i.e., no valve operation via handwheel, reach-rod or similar means that requires close proximity to the valve. Any supplemental connections will be pre-engineered to minimize manpower resources and any needed portable equipment will be reasonably protected from defined hazards from NEI 12-06.

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

6. A manual override motive gas system will be permanently installed to supply motive gas to the HCVS ClVs to address loss of power to the DC SOVs. The nitrogen pneumatic supply will be connected in parallel with the existing pneumatic supply to manually cycle the CIVs. The manual operation will be performed from the remote control station located in the accessible diesel generator room.

Requirement 1.2.3 - Prevent Inadvertent Actuation 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 administrativecontrols to prevent the inadvertentuse 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 considergeneral guidelinessuch as single point vulnerability and spuriousoperationsof any plant installed equipment 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 capabilityor prolongedSBO. However, inadvertentactuation of HCVS due to a design error,equipmentmalfunction, or operatorerrorduring a design basis loss-of-coolant accident (DBLOCA) could have an undesirableeffect on the containmentaccidentpressure (CAP)to provide adequate net positive suction head to the emergency core cooling system (ECCS)pumps. Therefore,prevention of inadvertentactuation, while important for all plants, is essential for plants relying on CAP. The licensee submittals on HCVS shall specifically include details on how this issue will be addressedon their individualplants for all situations when CAP creditis required.

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Page 15 Response (ref. ISG Item 1.2.3):

The HCVS containment isolation valves are normally closed AOVs that are air-to-open and spring-to-shut. The DC SOV must be energized to allow the motive air to open the valve. The MCR switch for each of the two in-series valves will have a key-locked switch. Although the same DC and motive air source will be used, separate control circuits including switches will be used for the two redundant valves to address single point vulnerabilities that may cause the flow path to inadvertently open.

The features that prevent inadvertent actuation are administrative controls and key lock switches in the MCR for the two CIVs in series. Inadvertent action from the remote control station is prevented by administrative controls and several manual steps to open the CIVs.

Emergency operating procedures and Severe Accident Guidelines (SAG) provide clear guidance that the HCVS is not to be used to defeat containment integrity during any design basis transients and accidents. In addition, the HCVS will be designed to provide features to prevent inadvertent actuation due to a design error, equipment malfunction, or operator error, such that any credited containment accident pressure (CAP) that would provide net positive suction head to the emergency core cooling system (ECCS) pumps will be available (inclusive of a design basis loss-of-coolant accident (DBLOCA)). For the long term DBLOCA, credit for suppression pool accident pressure is credited to ensure adequate available NPSH for RHR and CS pumps. For Appendix R and SBO, credit for containment pressure is not required to ensure adequate RHR and CS pump NPSH.

Requirement 1.2.4 - Monitor the Status of the Vent System The HCVS shallinclude 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 operatorsmust 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 containmentintegrity has been restored following venting operations. Licensees shallprovide a means to allow plant operatorsto 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.

Otherimportant information includes the status of supportingsystems, such as availabilityof electricalpower and pneumatic supply pressure. Monitoringby means of permanently installedgauges that are at, or nearby, the HCVS controlpanel is acceptable. The staff will consideralternativeapproachesfor system status instrumentation;however, licensees must provide sufficient information andjustification for alternative approaches.

The means to monitorsystem status shall support sustainedoperationsduring a prolonged SBO, and be designedto operateunderpotentially harsh environmentalconditions that would be expected following a loss of containmentheat removal capabilityand SBO. Power supplies to all instruments, controls, and indicationsshall be from the same power sources supporting the HCVS operation. "Sustainedoperations" may include the use of portableequipment to provide an alternatesource of power to components used to monitorHCVS status. Licensees shall demonstrate instrumentreliabilityvia an appropriatecombination of

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Page 16 design, analyses, operating experience,and/or testing of channel components for the following sets of parameters:

" radiologicalconditions that the instruments may encounter undernormal plant conditions, and during and after a prolonged SBO event.

" temperaturesand pressureconditions as described underrequirement 1.2.8, including dynamic loading from system operation.

" humidity based on instrument locationand effluent conditions in the HCVS.

Response (ref. ISG Item 1.2.4):

The design of the HCVS will have temperature and pressure monitoring downstream of the last containment isolation valve. All flow path valves will have open and closed position indication.

These HCVS indications will be at or near the same location as the valve control switches, which is the MCR and remote control station. Motive air/gas pressure and power source voltage will be monitored (voltage for the 125 VDC station batteries can be monitored from the DC panels located in the cable spreading room).

Power for the instrumentation for the remote control station will be from the safety related B-AS-2 battery, its chargers and switchgear are located in the adjacent Diesel Generator room.

Power from essential DC batteries will be used to supply the SOVs used to position the AOVs.

Refer to the response to 1.2.2 for discussion on the power.

The approximate range for the temperature indication will be 50°F to 600 0 F. The approximate range for the pressure indication will be 0 psig to 120 psig. The upper limits are approximately twice the required design containment 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.

Requirement 1.2.5 - Monitor the Effluent Discharge for Radioactivity The HCVS shall include a means to monitor the effluent discharge for radioactivitythat may be released from operationof the HCVS. The monitoring system shall provide indicationin the control room or other location(s), and shall be designed for sustainedoperation during a prolongedSBO.

ISG 1.2.5 Criteria:

Licensees shall provide an independentmeans to monitor overall radioactivity that may be releasedfrom the HCVS discharge. The radiationmonitor does not need to meet the requirementsof NUREG 0737 for monitored releases,nor does it need to be able monitor releases quantitativelyto 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 activity in the release providingindication that effluent from the containmentenvironment that is passing by the monitor is acceptable-The use of other existing radiation monitoring capabilityin lieu of an independentHCVS radiationmonitor is not acceptablebecauseplant operatorsneed accurateinformation about releases coming from the containment via the HCVS in order to make informed decisions on operation of the reliable hardened venting system.

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Page 17 The monitoring system shallprovide indication in the control room or a remote location (i.e., HCVS control panel) for the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of an extended SBO with electricpower provided by permanentDC battery sources, and supplemented by portablepower sources for sustainedoperations.Monitoring radiationlevels is requiredonly during the events that necessitateoperation of the HCVS. The reliabilityof the effluent monitoringsystem underthe applicable environmentalconditions shall be demonstratedby methods described underRequirement 1.2.4.

Response (ref. ISG Item 1.2.5):

The HCVS RMS (radiation monitoring system) will be dedicated to the HCVS. The approximate range of the radiation monitoring system is 0.1 mrem/hr to 1000 mrem/hr. This range is considered adequate to determine core integrity per the NRC Responses to Public Comments document.

The mounting position of the radiation detector will be determined in the detailed design. The radiation level will be indicated at the MCR and remote control station. The RMS will be powered from the same source as all other powered HCVS components. Refer to the response to 1.2.2 for discussion on sustainability of the power.

Requirement 1.2.6 - Minimize Unintended Cross Flow of Vented Fluids The HCVS shall include design features to minimize unintended cross flow of vented fluids within a unit and between units on the site.

ISG 1.2.6 Criteria:

At Fukushima, an explosion occurred in 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 leaked from Unit 3 to Unit 4 through a common venting system. System cross-connectionspresent a potential for steam, hydrogen, and airbome 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 of physical and controlinterfaces with other systems eliminates the potential for any cross-flow and is one way to satisfy this requirement.Regardless, system design shall provide design features to prevent the cross flow of vented fluids and migration to other areas within the plant or to adjacent units at multi-unit sites.

The currentdesign of the hardenedvent 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 hard pipes. In addition,dual unit plant sites are often equipped with a common plant stack.

Examples of acceptable means for prevention of cross flow is by valves, leak-tight dampers, and check valves, which shall be designed to automaticallyclose upon the initiation of the HCVS and shall remain closed for as long as the HCVS is in operation. Licensee's shall evaluate the environmentalconditions (e.g.

pressure, temperature)at the damperlocations during venting operationsto 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 interfacing valves to move to isolationposition, it shall be from the same power sources as the vent valves. Leak tightness of any such barriersshall be periodically verified by testing as describedunder Requirement 1.2.7.

Response (ref. ISG Item 1.2.6):

The HCVS shares part of its flow path with the Standby Gas Treatment System (SGTS). The HCVS ties into the SGTS downstream the filter trains and shares the discharge pipe going to the plant stack. The SGTS is isolated from the HCVS by check valves. The detailed design phase will review the check valves to determine if the inter-system valves can meet the required

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Page 18 leakage criteria under the limiting HCVS design conditions. If required, the valves will be replaced or upgraded.

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Paqe 19 Requirement 1.2.7 - Provision for the Operation, Testin., Inspection and Maintenance The HCVS shall include features and provision for the operation, testing, inspection and maintenance adequate to ensure that reliable function and capabilityare maintained.

ISG 1.2.7 Criteria:

The HCVS piping run shall be designed to eliminate the potential for condensationaccumulation, as subsequent water hammer could complicate system operationduring intermittent venting or to withstand the potential for water hammer without compromising the functionality of the system. Licensees shall provide a means (e.g., drain valves, pressureand temperature gauge connections)to periodicallytest 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 hammerloads.

The HCVS outboardof the containmentboundary shallbe tested to ensure that vent flow is releasedto the outside with minimal leakage, if any, through the interfacingboundarieswith other systems or units.

Licensees have the option of individually leak testing interfacingvalves 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 primarycontainment isolationbarrierand the vent exiting the plant buildings, includingthe volume up to the interfacingvalves. The test pressure shall be based on the HCVS design pressure.

Permissibleleakage rates for the interfacingvalves shall be within the requirementsof American Society of Mechanical Engineers Operationand Maintenanceof 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 interfacing valve leakages as determinedfrom the ASME OM Code. The NRC staff will considera higher leakage acceptance values if licensees provide acceptable justification. When reviewing such requests, the NRC staff will consider the impact of the leakage on the habitabilityof the rooms and areas within the building and operabilityof 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 operation of the system.

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

Perform visual inspectionsand a walkdown of Once peroperating cycle HCVS components Test and calibratethe HCVS radiationmonitors. Once peroperating cycle Leak test the HCVS. (1) Priorto first declaringthe system functional; (2) Once every five years thereafter; and (3) After restorationof any breach of system boundary within the buildings Validate the HCVS operatingproceduresby Once perevery other operatingcycle conducting an open/close test of the HCVS control logic from its controlpanel and ensuring that all interfacingsystem valves move to their proper(intended)positions.

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Page 20 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 Containment Isolation Valves will be tested in accordance with the licensing and design basis for the plant. The HCVS past the outboard Containment Isolation Valve to where the vent exits the plant Reactor Building will be tested in conformance to one of the ISG methods. The test pressure shall be based on the HCVS design pressure with 56 psig.

Permissible leakage rates for the interfacing valves will be within the requirements of American Society of Mechanical Engineers Operation and 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, the allowed leakage will not exceed the sum of the interfacing valve leakages as determined from the ASME OM Code unless a higher leakage acceptance value is justified to the NRC.

The test types and frequencies will conform to the ISG 1.2.7 Table "Testing and Inspection Requirements" with the clarification that "Leak test the HCVS" applies to the HCVS boundary valves.

Requirement 1.2.8 - Design Pressures The HCVS shall be designed for pressures that are consistent with maximum containmentdesign pressures, as well as, dynamic loading resultingfrom system actuation.

ISG 1.2.8 Criteria:

The vent system shall be designed for the higherof the primarycontainment design pressure or PCPL, and a saturationtemperaturecorrespondingto the HCVS design pressure. However, if the venting location is from the drywell, an additionalmargin of 50 0F shall be added to the design temperaturebecause of the potential for superheatedconditions in the drywell. The piping, valves, and the valve actuators shall be designed to withstand the dynamic loading resultingfrom the actuation of the system, includingpiping reaction loads from valve opening, concurrenthydrodynamic loads from SRV dischargesto the suppression pool, and potential for water hammer from accumulation of steam condensationduring multiple venting cycles.

Response (ref. ISG Item 1.2.8):

The HCVS design pressure is 62 psig and design temperature is 281'F. The HCVS design pressure is the higher of the containment design pressure and the PCPL value. The detailed design will ensure a HCVS design temperature of 309 0 F, corresponding to a design pressure of 62 psig under saturated conditions.

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.

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Paqe 21 Requirement 1.2.9 - Discharge Release Point The HCVS shall dischargethe effluent to a release point above main plant structures.

ISG 1.2.9 Criteria:

The HCVS release to outside atmosphere shallbe at an elevation higher than adjacent plant structures.

Release through existing plant stacks is considered acceptable,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 situatedaway 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 externalevents causing the prolongedSBO (e.g., tornadoes,high winds).

Response (ref. ISG Item 1.2.9):

The HCVS discharge path uses the existing plant stack.

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Page 22 Section 4: Applicable Quality Requirements Requirement 2.1- Containment Isolation Function The HCVS system design shallnot preclude the containmentisolation valves, including the vent valve from performing their intended containment isolation function 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 includingthe second containment isolationbarriershall be designed consistent with the design basisof the plant. These items includepiping, piping supports, containment isolationvalves, containment isolation valve actuatorsand containment isolation valve position indication components. The HCVS design, out to and including the second containmentisolation barrer,shall meet safety-related requirementsconsistent with the design basis of the plant The staff notes that in responseto 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 containmentisolation 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 containmentisolation function consistentwith the design basis for the plant. The design shall include all necessary overrides of containment isolationsignals and other interface system signals to enable the vent valves to open upon initiationof the HCVS from its controlpanel Response (ref. ISG Item 2.1):

The HCVS vent path up to and including the second containment isolation piping and supports is designed in accordance with existing design basis. The HCVS system design will not preclude the containment isolation valves, including the vent valve, from performing their intended containment isolation function consistent with the design basis for the plant.

Associated actuators, position indication, and power supplies are designed consistent with the design basis of the plant as required to maintain their design basis function of maintaining the valves closed. The control circuit will allow operation of the HCVS from its control panel regardless of containment isolation signals.

Requirement 2.2 - Reliable and Rugged Performance All other HCVS components shall be designed for reliableand rugged performance that is capable of ensuringHCVS functionality following a seismic event. These items include electricalpower supply, valve actuatorpneumatic supply, and instrumentation(local and remote) components.

ISG 2.2 Criteria:

All components of the HCVS beyond the second containmentisolation barriershall be designed to ensure HCVS functionality following the plant's design basis seismic event. These components include, in addition to the hardened vent pipe, electric power supply, pneumaticsupply and instrumentation.The design of power and pneumatic supply lines between the HCVS valves and remote locations(if portablesources were to be employed) shall also be designedto ensure HCVS functionality. Licensees shall ensure that the HCVS will not impact other safely-relatedstructures 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 structuresare acceptable if the licensee provides adequatejustification on the seismic ruggedness of these structures. The hardened vent shall be designed to conform to the requirementsconsistent with the applicabledesign codes for the plant, such as the American Society of Mechanical Engineers Boilerand PressureVessel Code and the applicable Specifications, Codes and Standardsof the American Institute of Steel Construction.

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Page 23 To ensure the functionality of instruments following 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 assurance programs, such as IS09001. The procurement specifications shall include the seismic requirements and/or instrument design requirements, and specify the need for commercial design standards and testing under seismic loadings consistent with design basis values at the instrument locations.

" Demonstrationof the seismic reliabilityof the instrumentationthrough methods that predictperformance 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 of IEEE Standard344-2004, "IEEE

• Recommended Practicefor Seismic Qualificationof Class 1E Equipment for NuclearPower Generating Stations,"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 and frequency ranges). Such testing and analysis should be similar to that performed for 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 will be routed in seismically qualified structures except for the permanently installed nitrogen tubing and instrumentation located in the Turbine Building between the Diesel Generator Room and the Reactor Building. For those components, the structure will be analyzed for seismic ruggedness to ensure that any potential failure would not adversely impact the function of the HCVS or other safety related structures or components.

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 conform to the requirements consistent with the applicable design codes (e.g., Non-safety, Cat 1, SS and 300# ASME or B31.1, NEMA 4, etc.) for the plant and to ensure functionality following a design basis earthquake.

The HCVS instruments, including valve position indication, process instrumentation, radiation monitoring, and support system monitoring, will be qualified by 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.

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Paae 24 Instrument Qualification Method*

HCVS Process Temperature IS09001 / IEEE 344-2004 / Demonstration HCVS Process Pressure IS09001 / IEEE 344-2004 1 Demonstration HCVS Process Radiation Monitor IS09001 / IEEE 344-2004 / Demonstration HCVS Process Valve Position ISO9001 / IEEE 344-2004 1 Demonstration HCVS Pneumatic Supply Pressure IS09001 /IEEE 344-2004 1 Demonstration HCVS Electrical Power Supply Availability IS09001 I IEEE 344-2004 / Demonstration Drywell pressure Existing instruments / pre-qualified Wetwell pressure Existing instruments / pre-qualified Wetwell level Existing instruments / pre-qualified Reactor Pressure Existing instruments / pre-qualified

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

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Paqe 25 Section 5: Procedures and Trainina Requirement 3.1- Develop, Implement, and Maintain Procedures Licensees shall develop, implement, and maintainproceduresnecessaryfor the safe operationof the HCVS. Proceduresshall be establishedfor system operationswhen normal and backup power is available, and during SBO conditions.

ISG 3.1 Criteria:

Proceduresshall be developed describing when and how to place the HCVS in operation, the location of system components, instrumentationavailable, normal and backup power supplies, directionsfor sustained operation, including the storage locationof portable equipment, training on operating the portable equipment, and testing of equipment. The proceduresshall identify appropriateconditionsand criteria for use of the HCVS. The proceduresshall clearlystate 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 procedures shall be developed and implemented in the same manner as other plant procedures necessary to support the execution of the EOPs.

Licensees shall establishprovisions for out-of-service requirementsof the HCVS and compensatory measures. These provisions shall be documented in the Technical Requirements Manual (TRM) or similar document. The allowed unavailabilitytime for the HCVS shall not exceed 30 days during modes 1, 2 and 3.

If the unavailabilitytime exceeds 30 days, the TRM shall directlicensees to perform a cause assessment and take the necessaryactions to restore HCVS availabilityin a timely manner, consistent with plant proceduresand prevent future unavailabilityfor similar causes.

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 plants 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 The procedures will state the impact on ECCS, RHR, and CS pumps NPSH (loss of CAP) during a DBLOCA due to an inadvertent opening of the vent.

Licensees will establish provisions for out-of-service requirements of the HCVS and compensatory measures. The following provisions will be documented in the Technical Requirements Manual (TRM) or other controlled 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

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Page 26 o The condition will entered into the corrective action system, o The HCVS availability will be restored in a manner consistent with plant procedures, o A cause assessment will be performed to prevent future unavailability for similar causes.

Requirement 3.2 - Train Appropriate Personnel Licensee shall train appropriatepersonnel in the use of the HCVS. The trainingcurriculashall include system operationswhen normal and backup power is available, and duringSBO conditions.

ISG 3.2 Criteria:

All personnelexpected to operate the HVCS shall receive trainingin the use of plant proceduresdeveloped for system operationswhen normal and backup power is available, and during SBO conditions consistent with the plants systematic approach to training.The trainingshall be refreshed on a periodic basis and as any changes occurto the HCVS.

Response (ref. ISG Item 3.2):

Personnel expected to perform direct execution of the HVCS will receive necessary training in the use of plant procedures for system operations when normal and backup power is available and during prolonged SBO conditions. The training will be refreshed on a periodic basis and as any changes occur to the HCVS. The training will utilize the systematic approach to training.

In addition, per NEI 12-06, all personnel on-site will be available to supplement trained personnel.

AREVA NP Inc. ANP-3203 Revision 0 Vermont Yankee Nuclear Power Station's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Reliable Hardened Containment Vents (Order Number EA-12-050)

Page 27 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 changes to the following target dates will be reflected in the subsequent 6 month status reports.

Original Target Activity Status Date Oct. 2012 Hold preliminary/conceptual design meeting Complete Oct. 2012 Submit 60 Day Status Report Complete Feb. 2013 Submit Overall Integrated Implementation Plan Complete Aug 2013 Submit 6 Month Status Report Oct. 2013 Complete Design, Develop Procedures, Issue Final Modification Feb. 2014 Submit 6 Month Status Report Aug. 2014 Submit 6 Month Status Report Nov. 2014 Complete Implementation of Modifications Jan. 2015 Submit Completion Report Section 7: Changqes/Updates to this Overall Intearated Implementation Plan Any significant changes to this plan will be communicated to the NRC staff in the 6 Month Status Reports.