RS-13-111, 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)

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)

ML13064A270
Person / Time
Site:	Dresden
Issue date:	02/28/2013
From:	Kaegi G Exelon Generation Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
EA-12-050, RS-13-111
Download: ML13064A270 (29)

Text

Exelon Generation Order No. EA-12-050 RS-13-111 February 28, 2013 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-19 and DPR-25 NRC Docket Nos. 50-237 and 50-249

Subject:

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)

References:

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

2. NRC Interim Staff Guidance JLD-ISG-2012-02, "Compliance with Order EA-12-050, Reliable Hardened Containment Vents", Revision 0, dated August 29,2012

3. Exelon Generation Company, LLC's Initial Status Report in Response to March 12,2012 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents (Order Number EA-12-050), dated October 25,2012 On March 12,2012, the Nuclear Regulatory Commission ("NRC" or "Commission") issued an order (Reference 1) to Exelon Generation Company, LLC (EGG). Reference 1 was immediately effective and directs EGC to require BWRs with Mark I and Mark II containments to take certain actions to ensure the operability of reliable hardened containment vent (RHCV) systems to remove decay heat and maintain control of containment pressure following events that result in 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 EGC has received Reference 2 and has an Overall Integrated Plan complying with the guidance for the purpose of ensuring the functionality of reliable hardened containment vent (RHCV) systems to remove decay heat and maintain control of containment pressure following events that result in loss of active containment heat removal capability or prolonged Station Blackout (SBO) as described in Attachment 2 of Reference 1. Reference 3 provided the EGC initial status report regarding reliable hardened containment vents, as required by Reference 1.

U.S. Nuclear Regulatory Commission Integrated Plan Report to EA-12-050 EA-12-050 February 28, 2013 Page 2 Reference Section 4.0 Reference 2, Section 4.0 contains containsthethespecific specificreporting reportingrequirements requirementsfor forthe theOverall OverallIntegrated Integrated Plan. Theinformation Plan. The information in the enclosure provides the enclosure provides thethe Dresden DresdenNuclear NuclearPower PowerStation, Station,Units Units 22 and and 3 Overall Integrated 3 Overall Integrated Plan Plan pursuant pursuant to to Section Section 4.04.0 of of Reference Reference 2. The enclosed

2. The enclosedIntegrated IntegratedPlan Plan is is based based onon conceptual design information.

information. Final Final design design details details andand associated procedure associated procedure

guidance, guidance, as as well well as as any anyrevisions revisionstotothe theinformation information contained containedininthe theEnclosure, Enclosure,will will be beprovided provided in in the the 6-month 6-month Integrated Integrated Plan updates required Plan updates required by by Reference Reference1.1.

Dresden Dresden Nuclear Power Station, Units Units 2 and 3, 3, in in response responseto toNRC NRC Generic Generic Letter Letter 89-16, 89-16, installed installed aa hardened hardened ventvent path path that that allowed allowed venting venting from either the the torus torus or the drywell. For the drywell. For the purposes purposes of of compliance compliancewith with NRC NRC Order Order EA-12-050, EA-12-050, OrderOrderModifying Modifying Licenses Licenses with with Regard Regard to to Requirements Hardened Containment Requirements for Reliable Hardened ContainmentVents,Vents, Dresden DresdenNuclearNuclearPower PowerStation, Station,Units Units 2

2 and 3 plans to to credit the Independentof the torus vent path. Independent ofthe therequirements requirementsof ofNRC NRC Order Order EA-12-050, EA-12-050, Dresden Dresden Nuclear Power Station, Units Units 2 and and 33 isis evaluating evaluating potential potential upgrades upgradestotothe the drywell vent drywell vent path path to to conform conform to to the requirements of the requirements of NRC NRC Order OrderEA-12-050.

EA-12-050.

This letter contains contains no new regulatory commitments.

commitments. IfIf you have any any questions questions regarding regarding thisthis

report, report, please contact David please contact Helker at 610-765-5525.

David P. Helker II declare declare under penalty of perjury that that the the foregoing is true correct. Executed true and correct. Executedon onthe 28thday the28th day of of February February 2013.

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

Enclosure:

1.

1. Dresden Nuclear Power Dresden Nuclear Power Station, Station, Units Units 22 and and 33Hardened HardenedContainment ContainmentVentVentSystem System(HCVS)(HCVS)

Overall Overall Integrated Plan cc:

cc: Director, Director, Office Office ofof Nuclear Nuclear Reactor Reactor Regulation NRC Administrator --Region NRC Regional Administrator RegionIIIIII NRC NRC Senior Senior Resident Inspector - Dresden Nuclear Nuclear Power Power Station NRC Project NRC Project Manager, NRR - Dresden Nuclear Power Station Nuclear Power Station Mr.

Mr. Robert J. Fretz, Fretz, Jr, Jr,NRRIJLD/PMB, NRRIJLD/PMB, NRC NRC Mr. Robert L. Dennig, NRRIDSS/SCVB, Mr. NRRIDSS/SCVB, NRC NRC Illinois IllinoisEmergency Emergency Management Management AgencyAgency --Division Division of Nuclear Nuclear Safety Safety

Enclosure Enclosure 11 Dresden Nuclear Power Station, Units Units 22 and and 33 Hardened Containment Vent System System (HCVS)

(HCVS)

Overall Integrated Plan (26 pages)

(26 pages)

Dresden Dresden Nuclear Power Station, Units Units 22 and and 33 HCVS Overall Integrated HCVS Overall Integrated Plan Table Table of of Contents:

Contents:

Section 1:

Section 1: System

System Description

Description Section 2:

Section 2: Design Design Objectives Requirement 1.1.1 Requirement 1.1 .1 Requirement 1.1.2 Requirement Requirement 1.1.3 Requirement Section 3:

Section Operational Characteristics 3: Operational Characteristics 1.2.1 Requirement 1.2.1 Requirement 1.2.2 Requirement 1.2.2 Requirement 1.2.3 Requirement 1.2.3 Requirement 1.2.4 Requirement 1.2.4 Requirement 1.2.5 Requirement 1.2.5 Requirement 1.2.6 Requirement 1.2.7 Requirement 1.2.7 Requirement Requirement 1.2.8 Requirement Requirement 1.2.9 Section 4:

Section 4: Applicable Applicable Quality Quality Requirements Requirements Requirement 2.1 Requirement 2.1 Requirement Requirement 2.2 2.2 5: Procedures Section 5: Procedures andand Training Training Requirement 3.1 Requirement 3.1 Requirement 3.2 Section 6:

Section Implementation Schedule 6: Implementation Schedule Milestones Milestones Section 7:

Section Changes/Updatestotothis 7: Changes/Updates thisOverall Overall Integrated Integrated Implementation Implementation Plan Plan Section 8:

Section Figures/Diagrams 8: Figures/Diagrams Section 9:

9: Table Table -- HCVS HCVSFailure Failure Modes Modes

References:

1. Generic

1. Generic Letter Letter 89-16, 89-16, Installation Installation of of aa Hardened Wetwell Vent, Hardened Wetwell Vent, dated September1,1,1989 dated September 1989

2. Order

2. Order EA-12-049, EA-12-049, Mitigation Mitigation Strategies Strategies for for Beyond-Design-Basis External Events, Beyond-Design-Basis External Events, dated dated 2012 March 12, 2012 Order EA-12-050,

3. Order EA-12-050, Reliable Reliable Hardened Containment Vents, Hardened Containment Vents, dated datedMarch March12, 12,2012 2012

4. JLD-ISG-2012-02,

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

5. NRC

5. NRC Responses Responses to to Public Public Comments, Comments, JapanJapanLessons-Learned Lessons-LearnedProject ProjectDirectorate Directorate Interim Staff Interim Staff Guidance JLD-ISG-2012-02: Compliance Guidance JLD-ISG-2012-02: Compliance with with Order Order EA-12-050, EA-12-050, Order Order Modifying Licenses Modifying with Regard Licenses with Regard toto Reliable Reliable Hardened HardenedContainment ContainmentVents, Vents,ADAMS ADAMS Accession No.

Accession ML12229A477, dated No. ML12229A477, August 29, dated August 29,2012 2012

6. NEI

6. NEI 12-06, 12-06, Diverse Diverse and and Flexible Flexible Coping Coping Strategies Strategies(FLEX)

(FLEX)Implementation ImplementationGuide, Guide, Revision -,

Revision -, dated dated August August 2012.

2012.

Page 11 of 26 Page 26

Dresden Dresden Nuclear Nuclear Power Power Station, Station, Units 2 and 3 HCVS HCVSOverall Overall Integrated Integrated Plan Plan 7.

7. JLD-ISG-2012-01, JLD-ISG-2012-01, Compliance with Order Compliance with Order EA-12-049, EA-12-049, Order Order Modifying Modifying Licenses Licenseswith with Regard Regard to to Requirements for Mitigation Requirements for Mitigation Strategies for Beyond-Design-Basis Strategies for Beyond-Design-Basis External External Events Events 8.

8. IIEEE EEE Standard Standard 344-2004, IEEE Recommended 344-2004, IEEE Recommended Practice Practicefor for Seismic Seismic Qualification Qualification of of Class 1EEEquipment Class 1 Equipmentfor forNuclear NuclearPower PowerGenerating Generating Stations Stations Page 22 of Page of 26 26

Dresden Dresden Nuclear Nuclear PowerPower Station,Station, UnitsUnits 22 and and 33 HCVS HCVSOverallOverallIntegrated Integrated Plan Plan Section 1:

Section 1: System Description ISG Criteria:

ISG Criteria:

Licensees Licensees shall shall provide provide aa complete description description of ofthe the system, system, including including important important operational operational characteristics.

characteristics. The level of The level ofdetail detailgenerally generallyconsidered consideredadequate adequate isis consistent consistentwithwith the the level level of of detail detail contained contained in in the the licensee's Final Safety licensee's Final Safety Analysis Analysis Report.

Report.

Response

Response:

System Overview:

System Overview:

The The Hardened Hardened ContainmentContainment Vent System System (HCVS)

(HCVS) will willbe be designed designed to to mitigate mitigate loss-of-decay loss-of-decay--

heat removal heat removal by by providing providing sufficient containment venting venting capability capability to to limit limit containment containment pressurization.

pressurization . The vent will be designed with sufficient will be designed with sufficientcapacity capacitytotoaccommodate accommodate decay decay heat heat input input equivalent equivalent to to 11%% of of3016 3016 MWt.

MWt.The Thethermal thermalpower poweraccounts accounts for foraa Measurement Measurement Uncertainty Uncertainty RecoveryRecovery (MUR) (MUR)planned plannedpowerpoweruprateuprate above above the the current licensed thermal current licensed thermal power power (CLTP)

(CLTP)of of2957 2957MWt. MWt.Thus, Thus,the thehardened hardened ventvent capacity capacity will willbe adequate to relieve be adequate to relieve decay heat decay heat for for aa prolonged prolonged station station blackout blackout (SBO)(SBO)event.

event. The HCVSisisintended The HCVS intendedfor foruse use asas one element of one element of core damage prevention strategies. Venting core damage prevention strategies. Venting the the containment containment to to remove remove decay decayheatheatand andlimit limit containment containment pressurization pressurization supports core cooling cooling strategies during aa prolonged strategies during prolonged SBO SBO event.

event.

The HCVS flow The HCVS flowpath pathfromfromthe thecontainment containmenttotoan anelevated elevatedrelease release point point above above the Reactor the Reactor Building Building roof roof isis shown shown in in the the simplified simplified piping pipingand and instrumentation instrumentation diagram diagram (P&ID)

(P&ID) in in Section Section 88 of this report. The HCVS at of this report. The HCVS at each eachunitunitwill will be be fully fully independent independent of of the the other otherunit's unit'sHCVS.

HCVS.The The upstream upstream portion portion of the HCVS HCVS pipingpiping flow flowpathpathisisshared shared with the Standby Gas with the Standby Gas Treatment Treatment System System (SGTS) (SGTS) and and the the Reactor ReactorBuilding Building Ventilation Ventilation System (RBVS), but System (RBVS), but these interconnected these interconnecte d systems are automatically isolated by systems are automatically isolated by aa containment containment isolationisolation valve valve that receives aa containment that receives containment isolation signal. No ductwork isolation ductwork will willbebeused used ininthethe flow flowpath.

path. This This ensures ensures that that essentially essentiallyall all the the HCVS flow out HCVS flow outofofthe thecontainment containmentisisdischarged dischargedtotothe theoutside outsideatmosphere atmosphere above above the the unit's unit's Reactor Building.

Reactor Building.

Equipment and Equipment and components:

components:

The following The following equipment equipment and and components componentswill will bebeprovided:

provided:

i.i. HCVS Mechanical HCVS Mechanical Components Components --

Containment isolation a) Containment isolation piping, piping, valves and and controls controls--The TheHCVSHCVSvent ventpiping pipingandand supports up supports up toto and andincluding including the the second secondcontainment containmentisolation isolationvalve valve(CIV)(CIV) are are designed in accordance with the existing containment designed in accordance with the existing containment penetration penetration design designbasis.

basis.

The design The design of of the the ClVs CIVs will will bebe consistent consistent with with thethe plant's plant's CIVCIVdesign design basis. The basis. The in-series CIVs arenormally in-series ClVs are normally closed, closed,fail fail closed closedair-operated air-operatedvalves valves(AOV).

(AOV).As Aswith with existing penetrations existing penetrations open opento tothe thecontainment containmentatmosphere, atmosphere,both bothCIVsCIVswillwillbebe located outside located outside the thecontainment.

containment.

b) Other system valvesand b) Other system valves andpiping piping--The TheHCVS HCVS piping piping and andsupports supportsdownstream downstreamofof the second the secondCIV, CIV, including including valve actuator actuator pneumatic pneumatic supply supply components, components,will will be be designedand designed andanalyzed analyzedtotoconform conformto torequirements requirementsconsistent consistentwith withthe theapplicable applicable design codes for the plant and toensure design codes for the plant and to ensurefunctionality functionalityfollowing following aa design designbasis basis earthquake.

earthquake.

Page 33 of Page of 2626

Dresden Dresden Nuclear Power Station, Units Units 22 and and 33 HCVS HCVS Overall Overall Integrated Integrated Plan c) c) The HCVS shares The HCVS part of shares part of its flow flow path path with withthetheStandby Standby Gas Gas Treatment Treatment System System (SGTS)

(SGTS) and Reactor Building and the Reactor Building Ventilation Ventilation System (RBVS). These System (RBVS). These interface interface systems systems areareautomatically automaticallyisolated isolatedby byaaCIVCIVfollowing following any any containment containmentisolation isolation signal.

signal.

d) The d) HCVS flow The HCVS flow path path downstream downstream of of the the second secondCIV CIV will will have have aa normally normally closed, closed, fail-closed, fail-closed, air-operated PressureControl air-operated Pressure ControlValve Valve(PCV).

(PCV). The ThePCV PCVwill willcontrol control upstream pressure and upstream pressure and have havean anadjustable adjustablepressure pressuresetpoint setpointtotoallow alloweither eitherfull full open open operation or controlling controllingpressure pressure nearnear the the containment design design pressure.

pressure.

The The PCV will willinclude includeaa back-up, back-up, remote-hydraulic remote-hydraulic means means for for PCV PCV operation.

ii. Instrumentation to monitor the status of the HCVS HCVS and and control control thethe flow flow path-path-a) Instrumentation indications will be available on the HCVS a) HCVS panel.panel. See See "System "System Control" below for discussion of the HCVS panel.

b) b) HCVS HCVS valve valve position position indication, indication, flowflowpath pathtemperature, temperature, pressure, effluent pressure, effluent radiation radiation instrumentation instrumentation will will monitor monitorthe the status status of thethe HCVS and operator and aid operator verification verification ofof venting venting conditions.

conditions. AA failure failure ofof valve position indication indication instrumentation wouldwould notnot prevent opening and closing closing thethe valve.

valve.

c) The effluent radiation monitor will will be be physically physically mounted mounted on on the the outside outside of of the the HCVS pipe wall.

d) The available instrumentation will will include include thethe HCVS HCVSsupportsupport system system pneumatic pressure pressure andand DCDC battery battery voltage.

voltage.

iii. Support Support systems systems assuming prolonged SBO assuming a prolonged SBO --

Paragraphs a) thru c) below apply to all HCVS flow Paragraphs a) thru c) below apply to all HCVS flow path path components except except for for the normal control circuit normal control circuit on on the upstream CIVs the upstream CIVs described describedin in System SystemControl Controliii iii a).

a).

a) DC DC power power valve valve control control and and instrumentation isis providedprovided fromfrom aa dedicated dedicated permanently permanently installed DC power supply adequate adequatefor for the the first first 24 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> hours of of ThisDC operation. This DCpower powersource sourcewill will be in an be in anaccessible accessiblelocation locationallowing allowing the the power to be sustained after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The The details details will will be be developed developed during during the the detailed design phase.

phase.

b) Motive b) Motive air/gas air/gas supply for all HCVS valves and instrumentation valves and instrumentationwill will be be provided provided from aa dedicated from dedicated permanently installed installed source source adequate adequatefor forat atleast leastthethefirst first 24 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> ofof operation. It It will will be be designed designed for 55 open/close open/close cycles cycles under under prolonged prolonged SBO conditions during the the first first 24 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. This motive hours. This motive air/gas air/gas source sourcewill will bebe inin an an accessible location accessible location allowing allowing the the motive motive air/gas air/gas to to be be sustained sustained after after 2424 hours0.0281 days <br />0.673 hours <br />0.00401 weeks <br />9.22332e-4 months <br />.

hours.

The details The details will will be be developed developed duringduring thethe detailed detailed design design phase phaseincluding including confirmation of confirmation of the the number open/close cycles.

number of open/close cycles.

equipment will c) Portable equipment will be be provided provided as required to as required to sustain sustain the thededicated dedicatedHCVS HCVS DC power DC power and and motive motive air/gas air/gas after after 2424 hours0.0281 days <br />0.673 hours <br />0.00401 weeks <br />9.22332e-4 months <br />.

hours. The Theconnections connectionsfor for the the portable portable equipment will equipment will provide provide pre-engineered connectionstotominimize pre-engineered connections minimizemanpowermanpower efforts. The The details willwill be be developed developed during the design phase.

the detailed design phase.

Page 4 of 26 26

Dresden Dresden Nuclear Nuclear Power Power Station, Station. Units Units 2 2 and and 3 3 HCVS HCVSOverall OverallIntegrated Integrated Plan Plan The The upstream upstream CIVs CIVs as as well well as as the the downstream downstream CIV CIV to to the the SGTS SGTS and RBVS are and RBVS are provided provided with with normal normal Instrument Instrument Air Air (IA)

(IA)forforopening openingthe the valves.

valves. IA IA will will be lost be lost following followingaaSBO. SBO.The The dedicated dedicated HCVS HCVS motive motive air/gas air/gas will willbe be used used to allow opening to allow opening the upstream CIV the upstream CIV following following aa SBO. Refer to SBO. Refer to System SystemControlControl iii iii a) a) below below for for discussion discussion on on maintaining maintaining circuit circuit power.

power.

System control:

System i.i. The HCVS CIVs The HCVS CIVs and and PCV PCV will willbe beremote-manually remote-manually operated operated in in accordance accordance with with approved station procedures approved station procedures to to control control containment containment pressure pressurefollowing following aa prolonged prolonged SBO.

SBO. The The revised revised station station procedures procedureswill will address addresswhen whenventing venting isis to to be beinitiated initiated andand any any imposed limitations on imposed limitations on the the pressure pressure band.band.

ii.

ii. With With the the exception exception of of the normal control the normal control circuit circuit on on the upstreamCIV, the upstream CIV, HCVS HCVS controls controls and indications will and indications will be be from from the the "HCVS "HCVS panel".

panel". The The HCVSHCVS panelpanelwill will either either be be part partofof an existing panel an existing panel or or a new, separate a new, separatepanel. panel.ThisThiswill be determined will be determined early early in in the the detailed design phase.

detailed design phase.The TheHCVSHCVSpanel panelwillwill bebe located located in in the the Main Main Control Control RoomRoom (MCR)

(MCR) or or aa location location readily readily accessible accessible from from the MCR. The the MCR. The location location of of the the panel panelwillwill also also bebe determined determined during during the the detailed detailed design phase.

design phase.

iii. Valve Control for the upstream upstream Drywell Drywell and and Torus Torus CIVs:CIVs:

a) a) These valves are These valves are onon aaflowflow path path shared sharedwith with the the HCVS, HCVS, SGTS, SGTS, and and RBVS.

RBVS.

They will retain their existing control logic, existing control circuit at their They will retain their existing control logic, existing control circuit at their locations, locations, and and thethe existing existing containment isolation signal.

containment isolation signal. If If the valve is the valve is open open during during anticipated anticipated modes modes of of operation, operation, the thevalve valvewill will bebe automatically automatically isolatedisolated on aa containment on containment isolationisolation signal. Basedon signal. Based onthe theearlier earlierGL GL89-16 effort, the 89-16effort, the current circuit current circuit controls already allow controls already allow over-riding over-riding the containment isolation the containment isolation signal to signal to open open the the hardened hardenedvent ventpath.

path.The Thedetailed detaileddesign designeffort effortwill will determine how determine how to to ensure ensurethe thecircuit circuitremains remainsavailable availablefollowing following aaprolonged prolonged S80. This SBO. This most mostlikely likely will will result result inin converting converting the existing circuit the existing circuit power power and and SOV from SOV from AC AC to to DC DC and and using using an existing safety-related an existing safety-related DC DC power power source sourcefor for the circuit.

the circuit.

b) b) A second A control circuit second control circuit dedicated dedicated to to the the HCVS HCVS function function will will bebe added added to to these these upstream CIVs.

upstream CIVs. This Thiscircuit circuit will will be located on be located on the theHCVSHCVS panel. panel.The TheHCVSHCVS circuit will circuit willallow allowopening openingthis this upstream upstream CIV CIV using using the dedicatedHCVS the dedicated HCVS DC DC power. The power. The HCVS HCVS controlcontrol circuit circuit will will bebe normally normally de-energized de-energized and and will will have have aa key-locked control key-locked control switch switch to to ensure ensure thatthat itit is is not not inadvertently inadvertently actuated. actuated. This This circuit will circuit willnot have an nothave automatic containment an automatic containment isolation isolation signal.

signal.

iv.

iv. The downstream The downstreamHCVS HCVSCIV CIVcontrol controlcircuit circuit will will allow allow opening opening the the downstream downstreamCIV CIV using the using the dedicated dedicated HCVS HCVS DC DC power power and and pneumatic pneumatic air/gas air/gas support support systems.

systems. The The HCVS control HCVS control circuit circuit will willbe be normally normally de-energized de-energized and andwill will have have aakey-locked key-lockedcontrol control switch to ensure that it is not inadvertently actuated. This circuit will not have an switch to ensure that it is not inadvertently actuated. This circuit will not have an automatic containment automatic containmentisolation isolation signal.

signal.

v.

v. The downstream The downstream CIVs CIVs to to the the SGTS SGTSand andRBVSRBVS are areautomatically automaticallyisolated isolatedby byaa containment isolation containment isolation signal.

signal. The The design designwill will not not bebe changed.

changed.

vi.

vi. Periodic CIV Periodic CIV testing testing will willbe performed in be performed in accordance accordance with with the current licensing the current licensing and and design basis.

design basis.

Page 5 of Page of 26 26

Dresden Dresden Nuclear Nuclear Power Power Station, Station. Units Units 22 and and 33 HCVS Overall Integrated HCVS Overall Integrated Plan Plan Section Section 2: 2: A A description of how how the the design designobjectives objectivescontained containedininOrder Order EA EA-12-050 050 . Requirements 1.1.1, 1.1.2, Attachment 2 Re uirements 1.1.1. 1. 1.2 and 1.1.3. 1.1.3 are are met.

met.

Order EA-12-050 1.1.1 Order 1.1.1 Requirement:

The The HCVS HCVSshall shallbebe designed designed to minimize minimize the the reliance on operatoroperator actions.

actions.

IISG SG 1.1.1 Criteria:

1.1.1 Criteria

During Duringevents events thatthat significantly significantlychallenge challengeplant plant operations, operations, individual individual operators operators are more more prone prone to to human human error.

error. In In addition, addition, the theplant plant operations operations staffstaff may may be be required required to to implement implementstrategies strategies and/or and/or take take many many concurrent concurrent actions actions thatthat further places aa burden furtherplaces burden on its its personnel.

personnel During During the prolonged sao the prolonged SBO condition condition at at the the Fukushima Fukushima Dai-ichi Dai-ichiunits, units,operators operators faced many significant challenges challenges while while attempting to restore restore numerous numerous plant plant systems systems that were necessary necessary to to cool cool the the reactor reactor core, core, including the containment venting the containment venting systems.

systems, The The difficulties difficultiesfaced facedby bythetheoperators operatorsrelated related toto the the location locationof ofthe theHCVS HCVSvalves, valves,ambient ambienttemperatures temperatures and and radiological radiological conditions, conditions, loss loss of a/l all alternating alternating current electrical power, loss loss of of motive motive force force toto open open the the vent vent valves, valves, and exhausting dc battery battery power. The The NRCNRC staff recognizes that that operator operatoractions actionswillwill be needed neededto to operate the HCVS valves; valves; however, however, the licensees licensees shallshall consider considerdesigndesignfeatures featuresfor forthe thesystem systemthat thatwill will minimize minimize the need and the need operator actions and reliance on operator actions to to the the extent extentpossible possibleduringduringaavariety varietyof ofplant plant conditions, conditions, as as further discussed discussed in in this this ISG.

ISG.

The The HCVS HCVS shallshall bebe designed designed to be be operated operatedfrom from aa control control panel panellocated locatedin in the themain maincontrol control room room or or aa remote but readily readily accessible location. The HCVS shall be designed accessible location. designed to to be be fully fullyfunctional functional and and self self sufficient sufficient with withpermanently permanently installed installed eqUipment equipment in in the the plant, plant, without without the the need need for portable equipmenteqUipment or or connecting connecting thereto, thereto, until until such such time time that that additional on-site or additional on-site or off-site off-sitepersonnel personneland and portable portable equipment equipment become become available. The The HGVS HCVS shall shall be be capable of of operating operating in in this this mode mode (i.e.,

(i.e., relying relying onon permanently permanentlyinstalled installed equipment) equipment) for for at 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 prolonged SBO, sao, unless unless aashorter shorterperiod periodisisjustified justified by by the the licensee.

licensee, TheThe HCVSHCVS operation operation in in this this mode mode depends depends on a variety variety of conditions, conditions, such such as cause for as the cause for the the sao seismic event, SBO (e.g., seismic event, flood, flood, tornado, tornado, highhigh winds),

winds), severity severity of of the the event, event, andandtimetimerequired requiredfor foradditional additional help to reach the the plant, move portable portable equipment eqUipment into into place, and andmakemakeconnections connectionstotothe theHCVS.

HGVS.

When When evaluating licensee justification justification for for periods periods less than 24 less than hours, the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, theNRC NRCstaff staffwill will consider consider the the number number of actions and the cumulative cumulative demand demand on personnel resourcesthat personnel resources thatareareneeded neededtotomaintain maintainHCVSHCVS functionality (e.g.,

functionality installation of (e.g., installation ofportable portable equipment equipment during the first first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> hours to to restore restorepower powertotothe theHCVS HGVS and/or instrumentation) as controls and/or as aa result result ofof design design limitations, limitations. For For example, example, the the useuse ofof supplemental supplemental portable power sources sources may may bebe acceptable acceptableififthe the supplemental supplementalpower powerwas wasreadily readily available, available, could be quickly be quickly and easily and easily moved moved into place, place, and and installed through the use use ofof pre-engineered pre-engineered quick quick disconnects, and andthe the necessaryhuman necessary humanactionsactionswere wereidentified identifiedalong alongwithwith thethe time time needed neededtotocomplete complete those those actions.

actions.

Conversely, supplemental Conversely, supplemental power power sources sources located in in an an unattended warehouse warehousethat thatrequire require aaqualified qualified electrician to temporarily temporarily wirewireinto intothe thepanel panelwould wouldnot notbe beconsidered considered acceptable acceptable by the staff because because its its installation requires installation requires a series series ofof complex, time-consuming actions actions in in order order to achieve achieve aa successful successfuloutcome.

outcome.

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

Response (ref. (ref. ISGISG ItemItem 1.1.1):

1.1.1 ):

design of The design of the the HCVSHCVS will will minimize minimizethe the reliance reliance on on operator operator actionsactions in responseresponse to tohazards hazards identified in JLD-ISG-2012-01, JLD-ISG-2012-01, Compliance Compliance with with Order EA-12-049, EA-12-049, Order Order Modifying Modifying LicensesLicenses with Regard to to Requirements Requirementsfor forMitigation Mitigation Strategies Strategiesfor for Beyond-Design-Basis Beyond-Design-BasisExternal External Events, and andNEI NEI12-06, 12-06, DiverseDiverse and andFlexible FlexibleCopingCopingStrategies Strategies(FLEX) (FLEX)Implementation ImplementationGuide, Guide.

Immediate operator actions can can be be completed completed by by Reactor ReactorOperatorsOperatorsand andinclude includeremote-manual remote-manual initiation from initiation from the the HCVS control panel. panel.

The steps The stepslisted listedbelowbeloware arerequired requiredtotoinitiateinitiatethe theHCVSHCVSflow flow path. These Thesesteps stepswill will bebe confirmed during confirmed during the the detailed detailed design phase. phase.

• • Verification that Verification that the the valves valves to the interfacing interfacing systems systems (SGTS (SGTS and andRBVS) RBVS) are areshut shut

• • Energizing the DC Energizing DC power to the HCVS HCVS components components

• • Operating Operating aa key-lockedkey-locked switch switch for for each each of ofthe the two twotorustorusCIVs CIVs Page 66 of Page of 26 26

Dresden Dresden Nuclear Nuclear Power Power Station, Station, Units Units 22 and and 33 HCVS Overall Integrated Plan HCVS Overall Integrated Plan

• • Opening the Opening the PCV PCV and and setting setting the pressure setpoint Remote-manual Remote-manual is defined in is defined in this this report report as as aa non-automatic power power operation operation of of aa component component that that does does not require the operator operator to to bebe at at or or in in close close proximity proximity to to the the component.

component. No No other other operator operator actions are required required to to initiate initiate venting under under primary primary procedural protocol.

The HCVS will The HCVS willbe be designed designed to allow allow initiation initiation and isolation, control, and and monitoring monitoring at at the theHCVSHCVS panel. The location panel. The location of of the HCVSHCVS panel will will minimize minimizeplant plantoperator's operator'sexposure exposure to to adverse adverse temperature radiological conditions temperature and radiological conditions and and wi" willbe be reasonably reasonably protected protected from fromthe the assumed assumed hazards.

hazards.

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

hours.

After After24 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, hours, available available personnel personnel will will be be able able to to connect supplemental motive connect supplemental motive air/gas air/gas to to the the HCVS HCVS support support systems. Connectionsfor systems. Connections for supplementing supplementing electrical electrical power power and and motive motive air/gas air/gas required required for for HCVS HCVSwill willbe locatedininaccessible belocated accessible areas with reasonable areas with protection from reasonable protection from assumed assumed hazards minimize personnel hazards to minimize exposure to personnel exposure to adverse adverseconditionsconditions following following aa prolonged prolonged SSO SBO and and venting. Connections will venting. will use use pre-engineered pre-engineered quick quick disconnects disconnectsto tominimize minimize manpower manpower resources.

Order EA-12-050 1.1.2 Requirement:

The The HCVS HCVSshall shallbebe designed designed to to minimize minimizeplant plantoperators' operators'exposure exposure to to occupational occupationalhazards, hazards, such such asas extreme heat heat stress, stress, while while operating operatingthe theHCVS HCVS system.system.

IISG SG 1.1.2

1.1.2 Criteria

During During aa prolonged prolonged S80, drywell, wetwell SBO, the drywell, wetwell (torus),

(torus),andand nearby nearby areas areas inin the the plant plantwhere where HVCS HVCS components are are expected expectedtotobe belocated locatedwill will likely likely experience an excursionexcursion in in temperatures temperatures due duetoto inadequate containment inadequate containmentcoolingcoolingcombined combinedwith with losslossofofnormal normal and andemergency emergencybuildingbuildingventilation ventilation systems.

systems.

In addition, In addition, installed installed normal and emergencylighting and emergency lighting in in the plant may not be available, available. Licensees Licenseesshould should take take into consideration into consideration plant conditions conditions expected expected to to bebe experienced experienced during during applicable applicable beyond design basis beyond design basis events when external events when locating locating valves, valves, instrument instrument air air supplies, andandother othercomponents componentsthat thatwill will be be required required toto operate the safely operate the HCVS HCVS system, system. Components Componentsrequired requiredfor formanual manualoperation operation should shouldbe beplaced placedinin areas areas that that are readily accessible accessible to to plant plant operators, and andnot notrequire require additional additional actions, such as as the the installation installation of ladders oror temporary temporary scaffolding, scaffolding, to operate the the system.

system.

When developing a design strategy, the the NRC NRC staff staff expects expects licensees licenseestotoanalyze analyzepotential plantconditions potentialplant conditions and use and use its its acquired acquiredknowledge knowledge of of these these areas, areas,ininterms termsof ofhow howtemperatures temperatureswould would react react to to extended extended SBO sao conditions and lighting that would and the lighting would be be available available during during beyond beyond design design basis basis external events. This This knowledge also also provides providesan aninput inputto tosystem systemoperating operatingprocedures, procedures,training, training,the choiceofof thechoice protectiveclothing, protective clothing, required tools required andequipment, tools and equipment, and andportable portablelighting.

lighting.

Response (ref.(ref. ISG ISG ItemItem 1.1.2):

1.1.2):

The HCVS The HCVS design design allowsallows initiating initiating andand thenthen operating operatingand andmonitoring monitoringthe theHCVSHCVSfrom from the theHCVSHCVS The location panel. The location of of the HCVSHCVS panel will will minimize minimizeplant plantoperators' operators' exposure to adverse adverse temperature and temperature andradiological radiological conditions conditions and and the the panel panel location location is is reasonably reasonably protectedprotectedfrom from hazardsassumed hazards assumedininJLD-ISG-2012-01, JLD-ISG-2012-01,Compliance Compliancewith withOrder OrderEA-12-049, EA-12-049,Order OrderModifying Modifying Licenses with Licenses with Regard Regardto to Requirements Requirementsfor forMitigation Mitigation Strategies Strategiesfor forBeyond-Design-Basis 8eyond-Design-Sasis Events, and External Events, andNEI NE112-06 Diverseand 12-06 Diverse andFlexible FlexibleCopingCopingStrategies Strategies(FLEX) (FLEX)Implementation Implementation Guide.

Guide.

In order to minimize In minimize operator exposure to operator exposure to temperature temperatureexcursions excursionsdue duetotothe theimpact impactofofthe the prolonged SBO prolonged SSO (i.e.,

(Le., loss lossof of normal normal and andemergency emergencybuilding building ventilation ventilation systems systemsand/or and/or containment temperature containment temperature changes) changes)HCVS HCVSvalve valve operation operation will will not not require require access access to to the the suppressionpool suppression pool (torus)

(torus) area areaor or other other plant plant areas areaswhich which may may pose posesevere severetemperature temperatureand and radiological hazards radiological hazards to to personnel.

personnel.

Page 7 of Page of 26 26

Dresden Nuclear Power Station.

Dresden Station. Units Units 22 and and 3 HCVS Overall HCVS Overall Integrated Integrated Plan Similarly, Similarly,DC DCpowerpowerand andmotive motiveair/gasair/gassources sourcesand andthe theconnections connections to to these these support systems systems required required for forsustained sustained operationoperation will willbe belocated locatedininaccessibleaccessible areas reasonably protected areas reasonably protectedfrom from severe severe natural phenomena phenomena and and which which minimize minimize exposure exposure to to occupational occupational hazards. hazards. Tools Tools required required for for sustained sustained operation, such as asportable portablelighting lighting and and connection connectionspecific specifictoolingtooling will will be pre-staged pre-staged in in the NEINEI 12-06 storage locations. locations.

Neither Neither temporary temporary ladders ladders nor nor scaffold scaffoldwill willbeberequired requiredtotoaccess accessthese these connections connections or storage storage locations.

locations.

Order EA-12-050 EA-12-050 11.1.3 .1 .3 Requirement:

The The HCVS HCVSshall shallalsoalsobe be designed designed to minimize minimize radiological radiologicalconsequences consequences that would impede personnel personnel actions actions needed needed for event response.

ISG 1.1.3 Criteria:

ISG The The design design of the the HCVS HCVSshould should taketake into intoconsideration consideration the the radiological radiologicalconsequences consequences resulting from from the event event that could negatively negatively impact impacteventevent response.

response. During the Fukushima event, personnel personnel actionsactions to to manually manually operate operate the vent valves were impeded impeded due due to to the the location location of of the valves valves in in the the torus torus rooms.

rooms. The The HCVS shallshall be be designed to be placed placed in in operation by operator actions at at a control control panel, located in panel, located in the the main main control room or control room or ininaa remote remote location.

location. The The system system shall be be deigned deignedto to function function in in this this mode mode withwith permanently permanently installed equipment providing providing electrical electricalpower power (e.g.,

(e.g., dcdo power power batteries) batteries) and and valve valve motive motive force (e.g., N21air force (e.g., N2/air cylinders). The The system system shall be be designed designedtotofunction function in in this this mode modefor for aa minimum minimum durationduration of of 24 hours with 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with no operator actions required or credited, credited, other than the the system system initiating initiating actions at at the the control control panel.

Durations of less less than 24 hourswill 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> will be be considered consideredififjustifiedjustified by by adequate adequatesupporting supportinginformation informationfrom fromthethe licensee. To ensure continued operation of the HCVS ensure continued HCVS beyond beyond 24 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, hours, licensees may may credit manual manual actions, such as as moving moving portable portable equipment equipment to to supplement supplementelectricalelectrical power powerand andvalve valve motive motive power power sources.

sources.

In In response response to to Generic GenericLetter Letter(GL)

(GL) 89-16, 89-16, aa numbernumberof offacilities facilities with with Mark I containments containments installedinstalledvent vent valves in in the the torus torus room, room, near drywell, or near the drywell, or both.

both. Licensees Licensees can continue to use use these theseventing ventinglocations locationsor or select new locations, provided the requirements of select new of this guidance document document are aresatisfied.

satisfied. The TheHCVS HCVS improves the chanceschancesof ofcore corecooling cooling by byremoving removing heat heatfrom from containment containmentand andlowering loweringcontainment containment pressure, when pressure, when core corecooling cooling isis provided provided by by other other systems.

systems. IfIf core core cooling cooling were to to fail fail and result in the onset onset core damage, closure of the vent valves valves may may become become necessary necessary if the the system was not designed designed for severe accident accident service. In In addition, leakage leakage from from the the HCVS HCVS within within thethe plant plant and location of and the location of the external external release release from the HCVS from HCVS could could impact impact thethe event event response response from from on-site on-site operators operatorsand andoff-site off-sitehelp helparriving arriving at at the plant.

the plant.

An adequate strategystrategy to to minimize minimize radiological radiologicalconsequences consequences that could impede personnel actions should should include thethefollowing:

following:

1. Licensees shall

1. shall provide permanent radiation shielding where necessary permanent radiation necessarytotofacilitate facilitate personnel personnel accessaccess to to valves andand allow manual operation of the the valves locally.

locally. Licensee Licensee may may use use alternatives such such as asproviding providing features to to facilitate facilitate manual operation of valves manual operation valves fromfromremote locations, as remote locations, as discussed discussed furtherfurther in this guidance under Requirement under Requirement 1.2.2, or relocate 1.2.2, or relocate the the ventvent valves valves to to areas areasthatthatare aresignificantly significantlyless lesschallenging challengingtoto access/actions.

operator accesslactions.

2. In accordance accordance with with Requirement 1.2.8, the HCVS shall be designed designed for for pressures pressuresthat thatare areconsistent consistentwith with higher of the primary containment design pressure the higher pressureand andthetheprimary primarycontainment containmentpressure pressure limit(PCPL),

limit (PCPL),

as well as well as including dynamic as including dynamic loading loading resulting resulting from fromsystem system actuation.

actuation. In In addition, addition, the the system shall shall bebe leak-tight. As such, ventilation tight. ventilation duct ductwork work(i.e.,

(i.e., sheet sheet metal) shall shall not not be be utilized in in the design of the design ofthe theHCVS.

HCVS.

Licensees should Licensees shouldperformperform appropriate appropriate testing, testing, such such as as hydrostatic or pneumatic pneumatic testing, to to establish establish the the leak-tightness of leak-tightness ofthe theHCVS.

HCVS.

HCVS release to outside atmosphere

3. The HCVS atmosphere shall shall be be at atananelevation elevation higher higherthan than adjacent adjacentplant plantstructures.

structures.

Release through existing plant Release stacks is considered plant stacks considered acceptable, acceptable, provided providedthe the guidance guidanceunder underRequirement Requirement 1.2.6 is satisfied. If the the release from HCVS is through a vent stack release from stack different different than the the plant plantstack, stack, thethe elevation of the stack should should be higher higher than than thethe nearest nearestbuildingbuilding ororstructure.

structure.

Response(ref.

Response (ref. ISG ISGItem Item 1.1.3):

1.1.3):

1. The HCVS

1. HCVS will will be be designed designed for reliable remote-manual remote-manual operation operationfrom from the theHCVSHCVS panel. panel.

HCVS valve HCVS valve operation operation will willnot notrequire requireaccess access to to the suppressionpool the suppression pool (torus)

(torus) area areaoror other plant areas other areas whichwhich may pose severe severe temperature temperatureand andradiological radiological hazards hazardsto to Page 8 of 26 26

Dresden Dresden Nuclear Nuclear Power Power Station, Station, Units Units 2 2 and and 3 3 HCVS HCVS Overall Overall IntegratedIntegrated Plan Plan personnel.

personnel. The The HCVS HCVS will will consist consist of aa dedicateddedicated flow flow path for for each each Dresden Dresdenunit unitwith with no no interconnection interconnection between between the the twotwo Dresden units. Within Within each each unit'sunit's HCVS,HCVS, there are are interconnected interconnected systems systems but these these are automatically automatically isolated isolated by by aa CIV.

CIV. This This design design prevents prevents cross-flow into into unintended areas, provides areas, provides containment containment isolation, isolation, and and provides reliable reliable andand rugged rugged performance performance as as discussed discussedbelow belowfor for Order Order requirements requirements 1.2.6. 1.2.6.

Although Althoughthe the ISG ISGdoes does not not assume assume core damage, damage, the the design designof of thethe HCVSHCVS is predicated on on the possibility of core damage. All HCVS flow path valves that must be possibility of core damage. All HCVS flow path valves that must be operated operated are power power operated operated valves that can can be be remote-manually remote-manually operated operatedwithout without requiring requiring access access near the valves or or the the piping.

piping. Localized Localizedshielding shieldingor orother otheralternatives alternativestotofacilitate facilitate manual actions is not required.

2.

2. As As discussed discussed in in Section 1.2.8, 1.2.8, the the HCVSHCVS design design pressure pressurewill will be be 62 62 psig.

psig. ThisThis is is the the higher higher of ofthe the containment containment design design pressure pressure (62 psig) and and the PCPL value value (60 (60 psig).

psig). The The flow flow pathpath will willonlyonlyuse use piping pipingcomponents, components, which which excludes excludes the the use useof ofanyanyHVAC HVAC ducting, and the piping will willbe be evaluated evaluated for for dynamic dynamicloads. Intersystemvalve loads. Intersystem leakageisislimited valveleakage limited by automatic closure by a CIV on by automatic on a containment isolation isolation signal. The Theintegrity integrity of of the the piping piping willwillbe beestablished established as as required by by the the applicable applicable piping piping standards.

standards.

3.

3. As As discussed discussed in Section Section 1.2.6, the the release release to the outside atmosphere atmosphere is is atat an an elevation elevation above above the Reactor Building which is Reactor Building is higher higher than adjacent plant than any adjacent plant structure.

structure.

Section Section 3:3: Operational Operational characteristics characteristics and and aa description description of of howhow each each of ofthethe Order's Order's technical technical requirements is being met. met.

Order EA-12-050 1.2.1 Requirement: Requirement:

The The HCVS HCVS shallshall have have the capacity to vent the steam/energy steam/energy equivalent equivalent of of 11 percent percent of of licensed/rated licensedlrated thermal power (unless a lower lower value is justified by by analyses),

analyses), and and bebe able able to maintain containment to maintain containment pressurepressure below the primary containment containment design pressure. pressure.

ISG 1.2.1

1.2.1 Criteria

Beyond design design basis external events such as as a prolonged SBO a prolonged SBO could could result result in in the loss of the loss ofactive active containment containment heat removal heat removal capability.

capability. TheThe primary primarydesign designobjective objectiveofofthe theHCVS HCVSisistotoprovide providesufficient sufficientventing venting capacity capacityto to prevent aa long-term prevent long-term overpressure overpressurefailurefailure of of the the containment containment by by keeping keeping the the containment containmentpressure pressurebelow belowthe the primary containment containment design design pressure pressure and andthe the PCPL.

PCPL. The The PCPL PCPL maymay be be dictated dictated by by other other factors, factors, such as as containment pressure the maximum containment pressureatatwhich whichthe thesafety safetyrelief reliefvalves valves(SRVs)

(SRVs)and andthe theHCVS HCVSvalves valves cancan be be opened and opened and closed.

closed.

The NRC NRC staff has has determined determined that, for a vent sized sized under underconditions conditions of of constant constant heat heat input input at at aa rate equal rate equal to 11 percent percent of of rated rated thermal thermal power power and and containment containmentpressurepressureequalequaltotothe thelower lowerof ofthetheprimary primary containment containment pressureand design pressure andthethePCPL, PCPL,the theexhaust-flow exhaust-flowthrough throughthe thevent ventwould wouldbe besufficient sufficient to to prevent prevent the the containment pressure pressure fromfrom increasing. This This determination determination is is based based on on studies studies that that have have shown shown that that the the torus suppression torus suppression capacity capacityisis typically typically sufficient sufficient to toabsorb absorb thethe decay decay heatheat generated generatedduring during at atleast leastthethefirst first hours following three hours following the shutdown of of the reactor reactor with with suppression suppressionpool pool asas the the source source of ofinjection, injection, thatthat decay heat decay heatisistypically typically less than 11 percent percentof ofrated rated thermal thermal power power three three hours hours following following shutdown shutdown of of the the and that reactor, and that decay decay heat heat continues continues to to decrease decreasetotowell well under under i1percent, percent,thereafter.

thereafter. Licensees Licenseesshall shallhave have an auditable an auditable engineering engineering basis basisforfor the the decay decayheat heatabsorbing absorbingcapacity capacityof oftheir their suppression suppressionpools, pools, selection selectionof of venting pressure pressure suchsuchthatthatthe theHCVS HCVSwill will have havesufficient sufficient venting venting capacity capacity underunder suchsuch conditions conditions to to maintain maintain pressureatator containment pressure containment orbelow belowthetheprimary primarycontainment containmentdesign designpressure pressureand andthe thePCPL.

PCPL.IfIfrequired, required, venting capacity shall be increased increasedto to an anappropriate appropriatelevel levelcommensurate commensuratewith withthe thelicensee's licensee'sventing venting Licensees may strategy. Licensees mayalso alsouse useaaventing ventingcapacity capacitysized sizedunder underconditions conditionsof ofconstant constantheat heatinput inputat ataarate rate percentof lower than 11 percent lower ofthermal thermalpowerpowerifif it can be be justified justified by analysis analysis thatthat primary containment design design pressureand pressure andthethePCPL PCPL would would notnot be be exceeded.

exceeded. In caseswhere In cases whereplants plantswereweregranted, granted, have haveapplied, applied, or orplan plan to apply forfor power power uprates, uprates, the licensees shall shall useuse 11percent percentthermal thermal power power corresponding corresponding to to the uprated uprated thermal power.

thermal power. The basis basisforfor the the venting venting capacity capacityshall shallgive give appropriate appropriateconsideration considerationof ofwhere whereventing ventingisis beingperformed being performedfrom from(i.e.,

(i.e., wetwell wetwellor ordrywell) drywell) and and the the difference difference in pressure between the pressure between the drywell drywell and and thethe suppressionchamber.

suppression chamber.Vent Ventsizing sizingforformulti-unit multi-unit sites sitesmust musttaketakeinto intoconsideration considerationsimultaneous simultaneousventing ventingfrom from Page 9 of 26 Page 26

Dresden Dresden Nuclear Nuclear Power Power Station, Station. Units Units 22 and and 33 HCVS Overall Integrated HCVS Overall Integrated Plan all all the the units, units, and and ensure that venting on one unit does does notnot negatively negatively impact the ability ability to to vent vent onon the the other units.

units.

Response (ref.

Response (ref. ISG Item 1.2.1): 1.2.1 ):

HCVS torus The HCVS torus path will willbe be designed designed for for venting venting steam/energy steam/energy at aa nominal nominal capacity capacity of of 1%1% of 3016 MWtMWt power powerat at containment containment pressure pressure of 60 psig. This pressure pressureisisthe thelower lowerof of the the containment containment design design pressure (62 psig) and the PCPL PCPL value (60 (60 psig).

psig). The The thermal thermal power power accounts for a Measurement Measurement Uncertainty Uncertainty RecoveryRecovery (MUR) (MUR) planned power uprate uprate above abovethe the current licensed licensed thermal thermal power power(CLTP) (CLTP) of 2957MWt.

of 2957 MWt.

The 1% %value valueassumes assumes that the suppression suppression pool pool pressure pressuresuppression suppressioncapacity capacityisissufficient sufficienttoto absorb the decay heat heat generated generatedduring during the the first first 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. The Thevent ventwould would then then be be able ableto to prevent prevent containment containment pressure pressure from from increasing increasing above above the the containment containment design design pressure. As Aspart part of of the the detailed design, the duration duration of of suppression suppression pool pool decay decayheat heatabsorption absorptionwill will bebeconfirmed.

confirmed.

EA~ 12-050 1.2.2 Requirement:

Order EA-12-050 The The HCVS shall be HCVS shallto accessible beplant accessible operatorsto plantandoperators and be of be capable capable remote of remote operation operation and and control, control, orormanual manual operation, operation, during during sustained sustained operations.

ISG 1.2.2 Criteria:

The The preferred preferred location for remote remote operation and andcontrol control of of the the HCVS HCVS is from from the mainmain control control room.

room. However, However, alternate locations to to the control control roomroomare are also also acceptable, acceptable, provided the the licensees licensees take take into into consideration consideration the the following:

following:

1.

1. Sustained operations mean Sustained operations meanthe theability ability to to open/close openlclose the the valves valves multiple multiple times times during the event. Licensees Licensees shall shall determine determine the numbernumber of open/close necessaryduring open/close cycles necessary duringthe thefirst first 24 hoursof 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> ofoperation operation and and provide supporting basis basis consistent consistentwith with the the plant-specific plant-specific containment containmentventing venting strategy.

strategy.

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

controls. Licensee Licensee may may use alternatives such such asasproviding providing features features to to facilitate facilitate manual operation of manual operation of valves valves from from remote locations locations or or relocating/reorienting relocatinglreorienting the valves.

3.

3. All permanently All permanently installed installed HCVSHCVSequipment, equipment, including includingany anyconnections connections required required to to supplement supplement the the HCVS HCVS prolonged SBO operation during a prolonged sao (electric (electric power, N21air)

N2/air) shall shallbe be located located above above the maximum design design basis external basis flood level or protected externalflood protected fromfrom the design design basis basis external external flood.

flood.

4. During prolonged sao, During aa prolonged SBO, manual operation/action operation/action may may become necessaryto become necessary to operate operatethe theHCVS.

HCVS. As As demonstrated during demonstrated during the the Fukushima Fukushima event, event, the valves lost lost motive force including including electric electric power power andand pneumatic air pneumatic air supply supply to to the the valve valve operators, operators, andandcontrol controlpower powerto tosolenoid solenoidvalves.

valves.IfIfdirect direct access access and and local operation of the the valves is is not feasible feasible due to temperature or or radiological hazards, licenseesshould hazards, licensees should features to include design features to facilitate facilitate remote manual operation of the HCVS valves valves by means such such as asreach reach chain links, rods, chain links, hand hand wheels, wheels, andandportable portableequipment equipmenttotoprovide providemotive motiveforceforce(e.g.,

(e.g.,airIN2 air/N2bottles, bottles,diesel diesel powered compressors, and powered anddc dc batteries).

batteries). The The connections connections between the the valves valves and and portable equipment equipment should be should be designed deSignedfor forquick deployment. IfIf aa portable quickdeployment. portable motive motive force force (e.g.,

(e.g., air air or or N2N2 bottles, dc dc power power supplies) is used used inin the the design strategy, strategy, licensees licenseesshall shallprovide provide reasonable reasonableprotection protection of ofthat that equipment equipment consistentwith consistent with thethe staff's staff'sguidance guidancedelineated JLD-ISG-20 12-0 1for delineatedininJLD-ISG-2012-01 forOrder OrderFA-12-049.

EA-12-049.

5. The design shallshall preclude the the need needforfor operators operatorsto to move movetemporary temporaryladders laddersor oroperate operatefrom fromatop atop scaffolding to to access access the theHCVS HCVS valves valves ororremote remoteoperating operatinglocations.

locations.

Response

Response (ref. (ref.ISG ISGItem-.1.2.2):

Item 1.2.2):

The HCVS The HCVS design designwill will allow initiating initiating and and then operating operating and andmonitoring monitoring the theHCVS HCVSfrom from the the HCVS panel. This HCVS Thislocation locationofofthe thepanel panelwill will be bethetheMCR MCR or or aalocation location readily readily accessible accessiblefrom from the MCR.

the MCR. The selected selected location location will will bebe reasonably reasonably protected protected from from adverse adverse natural phenomena. phenomena.

1. The

1. The HCVSHCVS flow flow pathpath valves valves are are air-operated air-operatedvalves valves(AOV)(AOV) with with air-to-open and and spring-spring-to-shut. Opening the valves requires to-shut. requires energizing energizing aa DC DC powered powered solenoid solenoid operated operatedvalve valve (SOV) and providing (SOV) providing motive motive air/gas.

air/gas. The The detailed detailed design deSignwill will provide a permanentlypermanently installed DC power power source source and and motive motive air/gas air/gas supply supply adequate adequatefor forthethefirst first24 24hours.

hours.The The Page 10 of 26 26

Dresden Dresden Nuclear Nuclear Power Power Station, Station, UnitsUnits 22 and and 33 HCVS HCVS Overall Overall Integrated Integrated Plan Plan initial initial stored stored motive air/gas will motive air/gas will allow allow for for aa minimum of five five valve valve operating cycles; operating cycles; however, however, the the detailed design design will will determine determine the number number of of required required valve valve cycles cycles for for the the first 24-hours.

24-hours.

2.

2. Although Although the the ISG ISG does does not not assume assume core coredamage, damage,operation operationofofthe theHCVS HCVSisispredicated predicated on on the possibility of the possibility ofcore coredamage.

damage. All All HCVS HCVS flow flowpathpathvalves valvesthat that must must be be operated operated are are power power operated valves remote-manually operated valves remote-manually operated operatedfrom fromthe theHCVSHCVSpanel panelwithout without requiring access near the valves valves or or the the piping.

piping.

3. All permanently

3. All permanently installed installed HCVS HCVS equipment, including any equipment, including any connections connections required required to to supplement supplement the the HCVS HCVS operation operationduring duringaaprolonged prolongedSBO SSO(electric (electricpower,power,N2/air)N2/air)willwill be be located located in in areas areas reasonably reasonably protected from from assumed assumed hazards.hazards.

4.

4. Sustainability Sustainability of of remote remote operation operation wi" willbe be addressed addressed by by locating locating the DC DC power power and and pneumatic pneumatic motivemotive sources sources at at anan accessible accessiblelocation.location.The TheSOV SOYisisthe theonlyonlyelectrically electrica"y active active component component located in an inaccessible area an inaccessible arearequired requiredtotoopen openan anAOV.

AOV. For Forthethe upstream upstream CIV, CIV, twotwo SOVs SOVs for for each each AOV AOV will willbe be arranged arranged such such that that energizing energizingeither eitherSOV SOY from from itsits DC DCpower powersupplysupplycan can open open the the valve.

valve. For Forthe thedownstream downstreamHCVS HCVSCIV, CIV, thethe SOV SOY will willeither either be located in be located in an accessiblelocation an accessible locationor oralternatively alternativelytwo two SOVs SOVsfor for each eachAOV AOV will willbe be arranged arranged such energizing either such that energizing either SOVSOY fromfrom the dedicated dedicatedDC DC power power supply supply can open the can open thevalve.

valve. The TheAOV AOVPCV PCVwill will be beprovided providedwith with aahydraulic hydraulic over-ride over-ride at atan an accessible location in case accessible location case the the airair operated operatedcontrolscontrolsfail. fail. AnyAny supplemental supplemental connections will willbe be pre-engineered pre-engineered to to minimize minimizeman-powerman-power resourcesresources and and any needed neededportableportable equipment will willbe be reasonably reasonably protected protected from from assumed assumed hazards.hazards.

5.

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

Order EA-12-050 1.2.3 1.2.3 Requirement:

Requirement:

The The HGVS HCVS shaJl include aa means shall include means to to prevent preventinadvertent inadvertentactuation.

actuation.

ISG 1.2.3 Criteria:

ISG 1.2.3 Criteria:

The The design of the HGVSHCVS shallshall incorporate incorporate features, features, such as control panel switches, locking panel key-locked switches, locking systems, systems, rupture rupture discs, or administrative controls controls to to prevent prevent the inadvertent use of of the vent vent valves.

valves. The The system shall shall be be designed designedto topreclude precludeinadvertent actuationofofthe inadvertentactuation theHCVS HGVSdue duetotoanyanysingle singleactive activefailure.

failure. The The design should consider general general guidelines such such as as single point vulnerability vulnerability and and spurious spurious operations of any plant installed equipment equipment associated associatedwith with HCVS.

HGVS.

The objective of the HGVSHCVS is is to to provide provide sufficient sufficient venting venting of of containment containment and preventlong-term and prevent long-term overpressure failure of overpressure failure ofcontainment containmentfollowing following the loss of of active active containment containment heat heat removal capability or prolonged SBO.

S80. However, However, inadvertent inadvertentactuation actuationof ofHCVS due to a design HGVS due design error, error, equipment equipmentmalfunction, malfunction, or or operator error during a design operator error design basis basisloss-of-coolant loss-of-coolantaccident accident(DBLOCA)

(DBLOGA) could have have ananundesirable undesirableeffect effecton on the containment accident accident pressure pressure (CAP)(GAP) to to provide provide adequate adequate netnet positive suction head emergency head to the emergency core cooling system (ECCS)

(EGGS) pumps.

pumps. Therefore, Therefore, prevention preventionof ofinadvertent inadvertentactuation, actuation,while whileimportant importantfor for all all essentialfor plants, is essential for plants plantsrelying relying onon CAP.

GAP. The The licensee licenseesubmittals submittalson onHCVS HGVSshall shallspecifically specificallyinclude include issue will details on how this issue will be addressed addressedon ontheir theirindividual individual plants plantsfor for all al/ situations situations when when CAPGAP credit credit is is required.

Response (ref. ISG Item 1.2.3): 1.2.3):

The The primary design feature that design feature that prevents preventsinadvertent inadvertentHCVS HCVSflow flowpath pathopening openingisistwo twonormally normally closed, in-series CIVs closed, in-series CIVs that are are air-to-open air-to-open and andspring-to-close.

spring-to-close.

The upstream HCVS The upstream HCVS CIV CIV is is on on aa flow flow path path shared shared with with the the SGTS and and RBVS RSVS flow flow path.

path. The existing existing control control circuit circuit will willcontrol controlthe thevalve valvefor forthe the HCVS, HCVS, SGTS SGTS and and RBVS functions.functions. This This circuit circuit will willretain retain the the containment containment isolation isolation signal.

signal.Specifically:

Specifically:

Page 11 11 of 26 26

Dresden Dresden Nuclear Nuclear Power Power Station,Station, Units 2 and 3 HCVS Overall Integrated Plan HCVS Overall Integrated Plan

• • The The existing existing control control circuit circuitwillwillbebeused usedduring duringall all"design "designbasis" basis" operating operating modes including modes including all alldesign design basis basis transients transients and and accidents.

accidents.The Thecontainment containmentisolation isolationsignal signalwill will automatically automatically de~energize de-energize the the AC AC powered powered SOV SOV on on this this circuit circuit causing causing the AOV to the AOV to shut.

shut. The The circuit circuit can can be be overridden overridden to to reopen reopen the CIV CIV ifif required requiredfor forventing ventingthe thecontainment containmenttotoatmosphere, atmosphere, but this requires requires deliberate RO action.

• • AAsecond, independentcircuit second, independent circuit will will be used to be used to operate operatethis thisvalve valvebut butonlyonlyfollowing following an an event event that that requires operating the HCVS. HCVS. This Thiscircuit circuit will will not not have have any automatic signal. signal. The The HCVS HCVS control control circuit circuitwill willhave key-lockedswitch haveaakey~locked switchfor forthis thisvalve valvetotoaddress inadvertent address inadvertent operation.

operation. In In addition, addition, the theDC DC power powerwill will normally be isolated.

The The downstream CIV, CIV, dedicated dedicated to to the HCVS, HCVS, must must also also be openedopened to to establish establish the the flow flow path.

The DC power to this circuit is normally de-energized de-energized inin addition addition to torequiring requiring aakey-lock key-lockswitch switch to to be be operated.

operated, Dresden Dresden credits CAP for for meeting ECCS pumps' pumps' net net positive positive suction suction head head(NPSH) (N PSH)for for aa DBLOCA.

DBLOCA. Inadvertent Inadvertent actuation actuation of the HCVS HCVS in a DBLOCA (or a DBLOCA (orany anyother other designdesign basis transient basis transient or or accident) accident) is precluded by by separate separatekey-locked key-lockedswitchesswitchesfor forthe thein-series in-seriesCIVs CIVsand andby bynormally normally maintaining maintaining the the DC power power for for the the SOVs for these these CIV CIV de-energized.

de-energized. In In addition, addition, the therevised revised HCVS HCVS operating operating procedures procedures will will provide provide clear clear guidance guidance that the HCVS HCVS is is not to to be used used to to defeat containment integrity integrity during during any any design design basis basis transients and and accident.

accident.

Order EA-12-050 1.2.4 1.2.4 Requirement:

Requirement:

The HCVS HCVS shall shall include include aa means means to to monitor monitor thethe status status of of the the vent system (e.g., valve system (e.g., valveposition positionindication) indication) from from thethe control room or control room or other other location(s).

location(s). The The monitoring monitoringsystem system shall shall bebe designed designed for for sustained sustainedoperation operation during a prolonged prolonged SBO. saG.

ISG 1.2.4 Criteria:

operators must Plant operators mustbe beable abletotoreadily readilymonitor monitorthethestatus statusofofthe theHCVS HCVSatatall alltimes, times,including includingbeing beingableabletoto understand whether understand whether or or not containment pressure/energy pressure/energy is is being being vented vented through through the the HCVS, HCVS, and whether or not containment integrityintegrity has has been restored following been restored following venting venting operations. Licensees shall operations. Licensees shall provide provide a means a means to allow plant plant operators operators to readily determine, or or have have knowledge knowledge of, of, the the following following systemsystem parameters:

parameters:

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

closed),

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

temperature.

information includes Other important information includes the the status status ofof supporting systems, systems, such suchas asavailability availabilityof ofelectrical electrical power power and pneumatic and pneumatic supply supplypressure.

pressure.Monitoring Monitoring by by means meansof ofpermanently permanently installed installed gauges gaugesthat thatare areat,at,orornearby, nearby, HCVS control panel the HCVS panel isis acceptable.

acceptable, The The staff staff will will consider consider altemative alternativeapproaches approaches for system status system status instrumentation; however, instrumentation; however, licensees mustprovide licenseesmust providesufficient sufficientinformation informationand andJustification justification for for alternative alternative approaches.

approaches.

means to The means to monitor monitor system status status shall shall support support sustained sustainedoperations operationsduringduringaaprolonged prolongedSBO, S80, and andbebe designedto designed tooperate operateunderunderpotentially potentiallyharsh harshenvironmental environmentalconditions conditionsthatthatwould wouldbe beexpected expected followingaa following loss of containment heat loss heat removal removal capability and SBO. S80. Power supplies to to all instruments, controls, controls, and and indications shall be from indications from the same same power powersources sourcessupporting supportingthe theHCVS HCVS operation, operation. "Sustained "Sustained operations" operations" may include may include the use use ofofportable portable equipment eqUipmentto to provide provide an an alternate alternatesource sourceof ofpower powerto tocomponents componentsused usedtoto monitor HCVS monitor HCVS status. Licenseesshall status. Licensees shalldemonstrate demonstrateinstrument instrumentreliability reliability via via anan appropriate appropriatecombination combination of of design, analyses, design, analyses,operating operatingexperience, experience,and/or and/ortesting testingofofchannel channelcomponents componentsfor forthe thefollowing followingsets setsofof parameters:

parameters:

• • radiological radiological conditions that that the instruments Instruments maymayencounter encounterunder undernormal normalplant plantconditions, conditions,and andduring during andafter and afteraaprolonged prolongedSBO S80event.

event.

• • temperatures temperaturesand andpressure pressureconditions conditionsas asdescribed describedunderunderrequirement requirement1.2.8, includingdynamic 1.2.8,including dynamic loading from loading from system systemoperation.

operation.

• • humidity humidity based basedon oninstrument instrumentlocation locationandandeffluent effluentconditions conditionsininthe theHCVS.

HCVS.

Page 12 Page 12 of of 2626

Dresden Dresden Nuclear Power Station. Units 2 and and 33 HCVS HCVS Overall Overall Integrated Integrated Plan Plan Response (ref. ISG Item 1.2.4): 1.2.4):

The design of The design of the the HCVS HCVS will willhavehavetemperature temperature and radiation monitoring and radiation monitoring downstream downstream of of the last the last isolation isolation valve. Pressuremonitoring valve. Pressure monitoring will will bebe downstream downstream of of the CIVsCIVs but upstream upstream of of the the PCV.

PCV.

All Allflow flowpathpathvalves valveswill willhave haveopen open and and closed position position indication.

indication. These These HCVS HCVS indications indicationswill will be on the same same panelpanel as asthe thevalve valve control control switches. Motive Motive air/gas air/gas pressure pressureand andDC DCpowerpower source voltage are also also monitored monitored at at the the HCVS HCVS panel.

Power for for the the instrumentation instrumentation will willbe befrom fromthe thesame same source source used used for for the SOVsSOVs used usedto toposition position the AOVs.

AOVs. Refer Referto to the the response responsetoto1.2.2 1.2.2for fordiscussion discussionon onthe theDC DCpower.

power.

The The approximate range for for the temperature temperature indication indication will will bebe SO°F 50°F to to 600°F.

600°F. The Theapproximate approximate range for the range for the pressure indication will pressure indication willbe be00 psig psig toto 120 120 psig.

psig. The upper upper limits limits were selected to were selected to bebe approximately approximately twice twicethe therequired required HCVS HCVSdesign designtemperature temperature and and pressure.

pressure. The Theranges rangeswill will be be finalized finalized whenwhen the the detailed detailed designdesign and and equipment specifications are prepared. prepared.

The detailed design design will will address address the the radiological, radiological, temperature, temperature, pressure, pressure,flow flowinduced inducedvibrationvibration (if applicable) applicable) and internal piping and internal piping dynamic dynamic forces,forces, humidity/condensation humidity/condensation and and seismic qualification qualification requirements.

requirements. Assumed Assumedradiological radiologicalconditions conditionsfor forinstrument instrumentqualification qualificationwill will bound bound normal operationoperation followed followed by by aa prolonged prolongedSBO SSO(without (withoutfuel fuel failure).

failure).

Order EA-12-050 EA-12-0S0 1.2.5 1.2.S Requirement:

Requirement:

The The HCVS HCVS shallshall include include aa means means to to monitor the effluent discharge for for radioactivity radioactivity that that may may be be released released from operation of the HCVS.

from operation HCVS. The monitoring monitoring system shall provide indication system shall indication in the control control room or or other other location(s),

location(s), and and shall be designed designed for for sustained sustainedoperation operation during during aa prolonged prolongedSBO. SaD.

ISG 1.2.5 1.2.S Criteria:

Licensees Licensees shallshall provide an independent independentmeans meanstotomonitor monitoroverall overall radioactivity radioactivity that may be releasedreleasedfrom from thethe HCVS HCVS discharge.

discharge. TheThe radiation radiation monitor monitordoesdoes not not need meet the need to meet the requirements requirements of ofNUREG NUREG 0737 0737 for monitored releases, releases, nornor does does itit need needto to be be able ablemonitor monitor releases releases quantitatively quantitatively to to ensure compliancewith ensure compliance with Tit/e Title 1010 of ofthe the Code Code of of Federal Federal Regulations (10 CFR) Part 100 100 or or 10 CFR Section 10 CFR Section 50.67.

50.67. AA wide-range wide-range monitoring system to to monitor monitor the the overall overall activity activity in the release releaseproviding providingindication indicationthat thateffluent effluentfromfromthe the containment containment environment environment that that is is passing passing by the monitor is is acceptable.

acceptable. The The use useofofother otherexisting existing radiation radiation monitoring monitoring capability capabilityininlieulieuofofananindependent independent HCVSHCVSradiation radiationmonitor monitorisisnotnotacceptable acceptable because because plant plant operators need needaccurate accurateinformation information about about releases releasescoming comingfromfrom thethecontainment containmentvia viathe theHCVS HCVS in in order orderto to make informed decisions on operation of the reliable reliable hardened venting system.

hardened venting The The monitoring monitoring system shall provide indication in the control room or a remote system shall remote location location (i.e., HCVS control panel) forfor the first 2424 hours0.0281 days <br />0.673 hours <br />0.00401 weeks <br />9.22332e-4 months <br /> of an extended extended SBO sao with with electric electric power power provided provided by by permanent permanent DC DC battery battery sources, and andsupplemented supplementedby byportable portablepower powersources sourcesfor forsustained sustainedoperations.

operations.Monitoring Monitoringradiation radiationlevels levels is required only duringduring thethe events that operationofofthe necessitateoperation that necessitate theHCVS.

HCVS.The Thereliability reliabilityof ofthe theeffluent effluent monitoring monitoringsystem system under under the applicable environmental conditions conditions shallshall bebe demonstrated demonstrated by by methods methods described described underunder Requirement Requirement 1.2.4. 1.2.4.

Response (ref. (ref. ISG ISG ItemItem 1.2.5):

1.2.S):

HCVS radiation monitoring The HCVS monitoring system system (RMS) (RMS) will willbebe dedicated dedicated to HCVS. The approximate to the HCVS. approximate range of of the RMS RMS is 0.1 0.1 mrem/hr to 1000 mrem/hr. The Thedetailed detaileddesign designwill will finalize finalize the the range.

range.

This range This range is is considered considered adequate adequate to to determine determine core core integrity integrity per per the NRC Responses the NRC Responses to to Public Public Comments document,document, dated datedAugust August29, 29,2012 (ML12229A477).

2012 (ML12229A477).

detector will The detector will be be physically mounted mounted on the the outside outsideof of the thepiping, piping, accounting accountingfor forthethepipe pipewall wall thickness shielding thickness shielding in in order order to to provide provide aa measurement measurementof ofthetheradiation radiationlevel levelon onthetheinside insideofofthe the HCVS piping.

HCVS piping. The The radiation radiation level level will will be indicated at the the HCVS HCVS panel. panel. The TheRMS RMSwill willbebe powered from from the thesamesame source source as as all other other powered powered HCVS HCVScomponents.

components. Refer to to the the response response 1.2.2 for to 1.2.2 for discussion discussion on on sustainability sustainability of of the the DCDC power.

power.

Order EA-12-050 EA-12-0S0 1.2.6 1.2.6 Requirement:

Requirement:

Page 13 of 26 26

Dresden Dresden Nuclear Power Power Station,Station, Units Units 22 and and 33 HCVS HCVSOverall Overall Integrated Integrated Plan Plan The The HCVS HCVSshall shall include include designdesign features features to to minimize minimize unintended unintendedcross crossflow flowof ofvented ventedfluids within aa unit fluidswithin unit and and between between unitsunits onon the the site.

site.

ISG 1.2.6 ISG 1.2.6 Criteria:

At AtFukushima, Fukushima, an an explosion explosion occurred in in Unit Unit4,4, which whichwas wasininaamaintenance maintenance outage outage at at the time of the time of the the event.

event.

Although Although the the facts facts have have not been been fully established, aalikely fully established, likely cause causeof ofthe theexplosion explosionin in Unit Unit 44 isis that that hydrogen hydrogen leaked Unit 33 to from Unit leaked from Unit44 through to Unit through aa common venting system. system. System System cross-connections cross-connections present present aa potential potential for forsteam, steam, hydrogen, hydrogen, and radioactivity leakage and airborne radioactivity leakage to other areas areas of of the theplant plantandand toto adjacent adjacent units units at at multi-unit multi-unitsitessites ififthe theunits unitsareare equipped equipped with with common common vent piping. piping. In In this thiscontext, context,aa designdesign that is free of free of physical physical and and control control interfaces interfaces with with other other systems eliminates the systems ellminates the potential potential for for any any cross-flow cross-flow and and isis one one way way to to satisfy satisfy this this requirement.

requirement. Regardless, Regardless, system design shall shall provide design features to to prevent prevent the cross flow of cross flow of vented vented fluids fluids andand migration to other areaswithin other areas within the the plant plantor ortotoadjacent adjacentunits unitsatatmulti-unit multi-unitsites.

sites.

The The current design of currentdesign of the the hardened hardened vent at at several several plants plants in in the the U.S.

U.S. includes includes cross cross connections connectionswith with the the standby standby gas gas treatment system, which which contains contains sheet sheet metal metal ducts ducts and filter and and filter and fanfan housings housings that are not as that are as leak tight as leak tight as hard pipes. In In addition, addition, dual unit plant plant sites sites are often equipped equipped with with a a common plant stack.

Examples of acceptable acceptable means meansfor forprevention prevention of of cross cross flowflow is by valves, leak-tight dampers, dampers, and and check check valves, valves, which which shall shall bebe designed designed to to automatically automatically close close upon uponthe theinitiation initiation of of the the RCVS HCVS and and shall shallremain remain closed closed for for as long long as the HCVS HCVS is is in in operation.

operation. Licensee's Licensee's shall shallevaluate evaluatethe theenvironmental environmentalconditions conditions(e.g.

(e.g.

pressure, temperature) temperature) at atthethedamper damperlocations locationsduringduring venting venting operations operations to to ensure ensurethat thatthethe dampers damperswill will functional and remain functional and sufficiently sufficientlyleak-tight, leak-tight,and andififnecessary, necessary, replace the dampers damperswith with other other suitable suitable equipment equipment such such as valves.

valves. If powerpower is is required required for the the interfacing valves valves to move to to isolation position, it shall shall from the be from same power sources as the same as the vent valves.

the vent valves. Leak Leak tightness tightness of of any any such such barriers barriers shall shall bebe periodically periodically verifiedby verified testingas bytesting as described described underunder Requirement Requirement 1.2.7. 1.2.7.

Response (ref. ISG Item 1.2.6): 1.2.6):

The HCVS for The HCVS for both both units units are are fully fullyindependent independent of of each each other with with separate separate discharge dischargepoints. points.

Therefore, the capacity at each each unit unit is is independent independentof of the the status statusof ofthetheother otherunit's unit'sHCVS.HCVS.

The HCVS shares The HCVS shares the the upstream upstreampart partof of its its flowpath flowpath with with SGTSSGTS and and the RBVS; however, the RBVS; however, these these flow flow paths paths are are automatically isolated by aa CIV CIV on containment isolation on a containment isolation signal. The TheCIVs CIVson on SGTS and the SGTS andRBVS RBVS flow flow path are are AOVs AOVs with with air-to-open air-to-open and and spring-to-shut. On Onaacontainment containment isolation isolation signal, signal, loss of of motive air/N2, or loss of of control power, the valves valves will will shut.

shut. Any Any leakage leakage limited to is limited to the the leakage leakage rate rate thatthatcould couldbe beanticipated anticipatedfor foraaCIV.CIV.

Order EA-12-050 EA-12-050 1.2.7 1.2.7 Requirement:

Requirement:

The HCVS HCVS shall shall include include features features and provision for for the the operation, operation, testing, testing, inspection inspection and and maintenance adequateto adequate toensure ensurethat thatreliable reliablefunction functionand andcapability capabilityare aremaintained.

maintained.

ISG 1.2.7

1.2.7 Criteria

Criteria:

The HCVS piping piping runrun shall shall be designedto be designed to eliminate eliminate the the potential potentialfor for condensation condensationaccumulation, accumulation,as as subsequentwater subsequent waterhammer hammercould couldcomplicate complicatesystem systemoperation operationduring duringintermittent intermittentventing venting or or to to withstand withstand thethe potential for potential for water hammer hammerwithout without compromising the functionality functionality of of the the system.

system. Licensees Licensees shall provide aa shall provide means (e.g.,

means (e.g., drain valves, pressure pressure and andtemperature temperaturegauge gaugeconnections) connections)totoperiodically periodically test test system system components, including components, including exercising exercising(opening (openingand andclosing) closing) the the vent vent valve(s).

valve(s). In In situations situations where where total total elimination of elimination of condensation condensation is not feasible, feasible, HCVS HCVS shallshall be deSigned to be designed to accommodate accommodate condensation,condensation, including applicable water including water hammer hammerloads. loads.

The HCVS The HCVS outboard outboard of of the containment containmentboundary boundaryshall shall be be tested testedto to ensure ensurethat thatvent ventflow flow isis released releasedtotothe the outside with outside with minimal leakage, if if any, through the interfacing interfacing boundaries boundaries with with other other systems systemsor orunits.

units.

Licenseeshave Licensees havethe optionofofindividually theoption individually leak leak testing testing interfacing interfacing valves valves or or testing testing the the overall overall leakage leakageof ofthe the HCVS volume by conventional leak rate HCVS rate testing testing methods.

methods.The Thetesttestvolume volumeshall shallenvelope envelopethe theHCVS HCVS betweenthe between theouter outerprimary primarycontainment containmentisolation isolationbarrier barrierand andthe thevent ventexiting exitingthe theplant plantbuildings, buildings,including including thethe volume up to volume to the the interfacing interfacing valves. The The testtest pressure pressureshall shall bebe based based on on the the HCVS HCVS design design pressure.

pressure.

Permissibleleakage Permissible leakagerates ratesfor forthe theinterfacing interfacingvalves valvesshall shallbebewithin withinthetherequirements reqUirementsofofAmerican AmericanSocietySocietyofof Mechanical Engineers Mechanical EngineersOperation Operationand MaintenanceofofNuclear andMaintenance NuclearPower PowerPlantsPlantsCode Code (ASMEOM)

(ASME OM)--- 2009, 2009, SubsectionISTC Subsection ISTC-- 3630 3630(e) (2),ororlater (e)(2), lateredition editionof ofthe the ASME ASME OM OM Code.

Code. When When testing testingthe theHCVS HCVSvolume, volume, aI/owed leakage allowed leakage shall shallnot notexceed exceedthe thesumsumofofthe theinterfacing interfacingvalve valveleakages leakages as as determined determinedfrom from thetheASME ASME OM Code.

OM Code. The The NRCNRC staff staff will will consider consider aa higherhigher leakage leakage acceptance acceptance values valuesifif licensees licenseesprovide provide acceptable acceptable justification. When justification. When reviewing reviewing such such requests, requests,the theNRCNRCstaffstaffwill will consider considerthe the impact impactof ofthe the leakage leakageon onthe the Page 14 Page 14 ofof 26 26

Dresden Nuclear Dresden Nuclear Power Station. Units 2 and 33 HCVS Overall HCVS Overall Integrated Integrated Plan habitability habitabilityof ofthe therooms rooms andand areas areas within withinthe thebuilding buildingand andoperability operabilityofofequipment equipmentininthese these areas areas during during the the event event response response and and subsequent subsequentrecovery recoveryperiods.

periods. Licensees Licenseesshall shallimplement implementthe thefollowing following operation, operation, testing and testing and inspection requirements for for the HCVS to ensure ensure reliable reliable operation operation of of the the system.

system.

Testing Testing and and Inspection Inspection Requirements Requirements Description Description Frequency Frequency Cycle Cycle the the HCVS HCVS valves valves andand the interfacing interfacing systemsystem valves not used usedto to Once Once per per year year maintain containment integrityintegrity during during operations.

operations.

Perform Perform visual visual inspections inspections andand a walkdown walkdown of HCVS HCVS components components Once Once per per operating cycle Test and Test and calibrate calibrate the HCVS radiation monitors. Once per operating cycle Leak test the HCVS. (1) Prior to first declaring the (1) system functional; (2) Once every five years (2) thereafter; and (3)

(3) After After restoration restoration of of any any breach of system boundary within the buildings Validate Validate thethe HCVS HCVSoperating procedures by conducting an open/close operatingprocedures open/close Once per Once every other per every other test of the HCVS control logic logic from fromits itscontrol controlpanel panel andand ensuring that that operating operating cycle all interfacing system valves valves move move to to their their proper proper(intended)

(intended) positions.

positions.

Response (ref. ISG ISG ItemItem 1.2.7):

1.2.7):

The detailed designdesign for for the HCVS HCVS will will address condensation accumulation address condensation accumulation resultingresulting fromfrom intermittent venting.

intermittent venting. In situations where total elimination of condensation elimination of condensation is not feasible, the the HCVS HCVS willwillbe bedesigned designed to to accommodate accommodate condensation, condensation, including including allowance allowance for for applicable water loads.

hammer loads.

The CIVs that are part part of the HCVS HCVS boundary will will be be tested tested in in accordance accordance with with the current current licensing and licensing and design design basis for the the plant. Outboard of plant. Outboard of the containment boundary, there are no no interfacing boundaries interfacing boundaries to to other systems. Therefore, Therefore,the theISG ISG1.2.71.2.7requirement requirementfor forintersystem intersystem leakage testing valve leakage testing does does not notapply.

apply.

test types The test types and andfrequencies frequencieswill will conform conform to the ISG ISG 1.2.7 1.2.7 Table Table "Testing "Testing and and inspection inspection Requirements" with with the clarification clarification that that "Leak "Leaktest test the the HCVS" HCVS"applies applies toto intersystem boundary boundary valves. TheTheintegrity integrityof of the the piping piping willwill be be demonstrated demonstrated through through compliance compliance with with the testing testing requirements of requirements of the the applicable applicable piping piping code.

Order EA-12-050 EA-12-050 1.2.8 1.2.8 Requirement:

Requirement:

The HCVS shall be designed designed for for pressures pressures that are consistent consistentwith with maximum containment pressures, containment design pressures, as well as well as, as, dynamic dynamic loading loading resulting resulting from from system system actuation.

actuation.

ISG 1.2.8

1.2.8 Criteria

Criteria:

The vent system shall shall be be designed designedfor for the the higher higherof of the the primary primary containment design design pressure pressureor orPCPL, PCPL, andand aa saturation saturation temperature temperaturecorresponding correspondingto tothe theHCVS HCVS design design pressure.

pressure.However, However,ififthe theventing ventinglocation location is is from the drywell, from drywell, an additional additional margin margin of of 50 50 OFof shall added to shall be added to the the design design temperature temperature becausebecauseof ofthe the potential for potential for superheated conditionsin superheated conditions in the thedrywelL drywell. The piping, piping, valves, and and the the valve valve actuators actuatorsshall shallbe be designedto designed towithstand withstandthe thedynamic dynamicloading loadingresulting resulting from from the the actuation actuation ofofthe the system, system,including includingpiping piping reaction loads reaction loads from from valve opening, opening, concurrent hydrodynamic loads from SRV loads from SRV discharges discharges to the suppression suppression Page 15 Page 15 of 26 26

Dresden Dresden Nuclear Nuclear Power Power Station.Station, Units Units 2 and 3 2 and 3 HCVS HCVS Overall Overall Integrated Integrated Plan Plan pool, pool, and and potential for water hammer hammer from accumulation of steam condensationduring steam condensation duringmultiple multiple venting venting cycles.

Response (ref. ISG Item 1.2.8): 1.2.8):

The HCVS HCVS pipingpipingdesign designpressure pressure will willbebe62 62psigpsigand anddesign design temperature temperature is is 360°F.

360°F. The TheHCVS HCVS design pressure is the higher of the containment design pressure (62 psig) and the PCPL value design pressure is the higher of the containment design pressure (62 psig) and the PCPL value (60 (60 psig).

psig). The RCVS HCVS design temperaturetemperature is is the the saturation saturation temperature temperature corresponding corresponding to to the the design pressure plus design pressure plus 50°F 50°F rounded roundedup. up.ThisThistemperature temperatureallows allowsfor forventing ventingfrom fromthe thedrywell.

drywell.

The piping, valves, The piping, valves, and valve actuators and valve actuators will will be designed to be designed to withstand withstand the thedynamic dynamicloading loading resulting resulting from from the the actuation actuation of the HCVS, including piping the HCVS, piping reaction reaction loads from valve opening, concurrent hydrodynamic loads concurrent hydrodynamic loads fromfrom SRV/Electromatic SRV/Electromatic Relief Relief Valve Valve (ERV)

(ERV) discharges discharges to to the the suppression suppression pool, pool, and and potential potential for for water water hammer hammerfrom from accumulation accumulation of of condensation condensationduring during multiple multiple venting venting cycles.

Order EA-12-050 1.2.9 1.2.9 Requirement:

Requirement:

The The HCVS HCVSshallshalldischarge discharge the the effluent effluent toto aa release release point above above main plantplant structures.

ISG 1.2.9 Criteria:

ISG 1.2.9 Criteria:

The HCVS release release to to outside atmosphere atmosphere shall shall bebe at at an an elevation elevation higher higherthan than adjacent adjacentplantplantstructures.

structures.

Release through existing Release through existing plant stacks is considered considered acceptable, acceptable, provided providedthe the guidance guidanceunder underRequirement Requirement 1.2.6 isis satisfied. If the satisfied. If the release release from HCVSHCVS is is through a stack stack different different than thethe plant plant stack, stack, the theelevation elevationof of the stack should be higher than the nearest nearestbuilding building or structure. The releaserelease point point should should bebe situated situated away away from from ventilation ventilationsystem systemintake intakeandandexhaust exhaust openings, openings, and and emergency response response facilities.

facilities. The release stackstack or structure structure exposed exposed to outside shall be designed designed or orprotected protectedto to withstand withstand missiles missiles that that could be generated generated by the external events events causing causingthe theprolonged sao prolongedSBO (e.g., (e.g.,tornadoes, tornadoes,high highwinds).

winds).

Response (ref. ISG Item 1.2.9): 1.2.9):

The The HCVS discharge discharge path path piping piping willwill be routed routed to to aapoint point just justabove abovethe theReactor ReactorBuilding, Building,which which is is higher higher than than any structure. The any adjacent structure. Station's chimney The Station's chimney is is an an adjacent adjacent structure, structure, but but itit is is impractical impractical to to raise raise thethe HCVS HCVS above above the thechimney.

chimney.This Thisdischarge dischargepoint pointlocation locationwill will be be determined determined during the the detailed design phase phaseconsidering consideringventilation ventilation system system intakeintake and andexhaust exhaust openings, main main control control room location, location of of FLEX FLEXequipment, equipment, access routes required access routes required following aa prolonged following prolongedSBO, SBO,and and emergency emergency response facilities; however, response facilities; however, these must be these must be considered in considered in conjunction conjunction with with other other design designcriteria criteria (e.g.,

(e.g.,flow flow capacity) capacity) and andpipe piperouting routing limitations, limitations, to to the the degree practical.

degree practical.

Per NEI NEI 12-06 Section Section 4.1, 4.1, all all severe severe natural phenomenaphenomenathat thatmay mayresult resultin in aaprolonged prolongedSBO SBO must be be identified.

identified. This This includes includesevaluation evaluationifif the the tornado tornado(including (including tornado tornado missiles) missiles) can can cause the cause the failure failure of of the normal, on-site emergency emergency AC AC power sources, sources, the the safety-related safety-related AC AC distribution distribution system, system, or or the the heat sinks required heat sinks required to to support support on-site on-site emergency emergency AC AC sources.

sources. As As aa minimum, all minimum, all external external HCVS HCVS components components will will bebe designed designed for for tornado winds. IfIfititisisdetermined tornado winds. determined that tornado missiles have have the the potential potential to to cause causeaaprolonged prolongedSBO, SBO,any anyexternal externalHCVS HCVSwould would have to also have to be be tornado tornado missile missile protected.

protected. This Thiswillwill be bedetermined determinedearly earlyinin thethedetailed detaileddesigndesign effort.

Section 4:

Section 4: Applicable ApplicableQuality Quality Requirements Requirements (Order (Order EA- EA..12-050 12-050 requirements requirements 2.1 2.1 and and 2.2) 2.2)

EA-12-050 2.1 Order EA-12-050 2.1 Requirement:

Requirement:

The HCVS system design shall system design shallnot notpreclude precludethe thecontainment containmentisolation isolationvalves, valves,including includingthe thevent ventvalve valvefrom from performing their intended containment isolation function containment isolation function consistent with the design consistent with design basis basisfor for the the plant.

plant. These These items include piping, piping, piping supports, containment isolation supports, containment isolation valves, valves, containment containmentisolation isolation valve valve actuators actuators and containment and containmentisolation isolation valve valve position position indication indication components.

components.

ISG 2.1 Criteria:

Criteria:

Page 16 of 26 26

Dresden Dresden Nuclear Nuclear Power Power Station, Station, Units Units 22 and and 33 HCVS HCVS Overall Overall Integrated Integrated Plan Plan The The HCVS HCVSvent ventpath pathupup to toandand including includingthe thesecond second containment containment isolation isolationbarrier barriershall shallbe bedesigned designed consistent consistent with with thethe design design basis basis of of the the plant.

plant. These items include piping, piping, piping supports, containment supports, containment isolation isolation valves, valves, containment isolationisolation valve valve actuators actuators andand containment containmentisolation isolation valve valve position indication components.

components. The The HCVS design, out to and and including including the second containment isolation second containment isolation barrier, barrier, shall meet meet safety-related safety-related requirements requirements consistent consistent with with the the design design basis basis of the the plant.

plant. TheThe staff staffnotes notes that that inin response response to GL 89-16,ininmany GL89-16, manycases, cases, the HCVSHCVS vent line line connections connections were were mademade to existing systems.systems. In In some some cases, cases, the the connection connection was made made in in between between two two existing containment isolationisolation valves valves and in others to the vacuum vacuum breaker line. The HCVS system design breaker line. design shall shallnotnotpreclude precludethethecontainment containmentisolationisolationvalves, valves,including includingthe the vent vent valve valve from from performing performing theirtheirintended intended containment containment isolation function function consistent consistent withwith the design design basis basisforfor the the plant.

plant. The The design shall include all all necessary overrides of necessary overrides of containment containment isolation signals and and other other interface system signalssignals toto enable enablethe thevent ventvalves valvestotoopenopenupon uponinitiation initiationofofthe theHCVS HCVSfrom from itsits control control panel.

Response (ref. ISG Item Item 2.1):

2.1 ):

The HCVS through The HCVS through the the first first CIV CIVshares shares aa common common path path with with the the SGTS SGTS and and RBVS.

RBVS. Downstream Downstream of of the the second second CIV CIV the HCVS has the HCVS has aa dedicated dedicated flow flow path.

path.

The The HCVS vent vent path path piping piping and and supports supports up up to to and including the and including the second containmentisolation second containment isolation valve valve will willbe be designed designed in in accordance accordance with with existing existing designdesign basis.

basis. As Aswith with all all other other Dresden Dresden mechanical penetrations open mechanical penetrations open to to the the containment containment atmosphere atmosphere (i.e., (Le., Generic Generic Design DesignCriteriaCriteria 56 56 penetrations), both HCVS CIVs will be located outside penetrations), both HCVS CIVs will be located outside containment.

containment. Associated Associated actuators,actuators, position position indication, indication,and andpowerpowersupplies supplies are are also also designed consistentwith designed consistent with the the requirements requirements to to meet the design meet the design basis basisfor forcontainment containmentisolation. isolation.

In In order order to to maintain maintain containment containment isolation isolation when when required required by by the the plant's design basis, plant's design basis,both bothCIVs CIVs in in the the flow flow pathpath will willbe benormally normallyclosed, closed,fail-closed fail-closedAOVs. AOVs. As As discussed discussed in in Section Section 1.2.3, 1.2.3,the the existing control circuit existing control circuit for for the the first first CIV CIVwill willnot notbe bechanged, changed, but but aa second secondcontrolcontrolcircuitcircuitwill will bebe added added forfor the the HCVS HCVS function.

function. OpeningOpeningthe theHCVSHCVSflow flow path path valves valveswill be controlled will be controlled procedurally procedurally and and the design will the design will address inadvertent operation address inadvertent operation to to ensure ensurethat thatthe theHCVS HCVSflow flow path remains isolated path remains isolated anytime anytime the design basis the design basis requires requires containment containment integrity. integrity. Due Due to to the the above, automatic above, automaticcontainment containmentisolation isolationsignal signalwill will not notbebeprovided providedtotothe theHCVS HCVSCIV CIVcontrol control circuits.

The HCVS The HCVS systemsystem designdesign will will notnot preclude preclude any any existing existing CIVs CIVs and and the the new new HCVS HCVS CIV CIV from from performing their performing their intended containment isolation.

intended containment isolation. The The control control circuit circuit for for the HCVS CIVs the HCVS CIVs will will allow allow operation of operation of the the valves valves from from its its control control panel panel when when required required following following containment containment pressurization and pressurization and aa containment containment isolation isolation signal.

signal.

Order EA-12-050 EA-12-050 2.2 2.2Requirement:

Requirement:

All other HCVS HCVS components components shall shall bebe designed designedfor for reliable reliable and rugged rugged performance that that is capable of is capable of ensuring HCVS functionality ensuring functionality following followingaaseismic seismic event.

event. These items include These items include electrical electrical power power supply, valve valve actuator pneumatic supply, and actuator andinstrumentation instrumentation (local and and remote) remote) components.

components.

ISG 2.2 Criteria:

Criteria:

All components components of the HCVS HCVS beyondbeyond the the second containment isolation barrier shall be designed second containment designed to to ensure ensure following the HCVS functionality following the plant's design basis plant's design basis seismic seismic event.

event. TheseThesecomponents componentsinclude, include,ininaddition addition hardenedvent to the hardened ventpipe, pipe, electric power supply, electric power supply, pneumatic pneumatic supply supply and andinstrumentation.

instrumentation. The The design designof of power and power andpneumatic pneumaticsupply supplylineslines between betweenthe theHCVS HCVS valves valves and andremote remotelocations locations(if (if portable portable sources sourceswere were employed) shall to be employed) shall also also bebe designed designedtotoensureensureHCVS HCVSfunctionality.

functionality. Licensees Licensees shallshallensure ensure that that the the HCVS HCVS will not will not impact impact other other safety-related safety-related structures and and components componentsand andthat thatthe theHCVS HCVS willwill not not bebe impacted impacted by by non-seismic components.

non-seismic components. The Thestaff staffprefers prefers that thatthetheHCVS HCVS components, components, includingincluding thethe piping piping run, be located located in seismically qualified structures.

in However, short runs of structures. However, of HCVS piping piping in in non-seismic non-seismic structures structures are are acceptableifif the licensee acceptable licensee provides provides adequate adequatejustification justification on the seismic ruggedness ruggedness of ofthese thesestructures.

structures.The The hardenedvent hardened ventshall shallbe bedesigned designedtotoconformconform to to the the requirements requirements consistent consistent with with the applicable design codes codes Page 17 Page 17 of 26 26

Dresden Nuclear Power Station, Dresden Station. Units 2 and 3 HCVS Overall HCVS Overall Integrated Plan for for the the plant, such as plant, such as the the American American Society Societyof ofMechanical MechanicalEngineers EngineersBoilerBoilerand andPressure Pressure Vessel Vessel Code Code and and the the applicable applicable Specifications, Specifications,Codes Codes andand Standards of of the the American American Institute Institute of of Steel Construction.

Steel Construction.

To To ensure functionality of ensure the functionality ofinstruments followingaaseismic instruments following seismicevent, event, the the NRC NRC staff staff considers considers any of the any of following asas acceptable methods:

• Use of instruments Use of instruments and supporting components and supporting components with with known known operating operating prinCiples principles thatthat are supplied by are supplied by manufacturers manufacturers with withcommercial commercialqualityqualityassurance assuranceprograms, programs,such such as IS09001. The as IS09001. The procurement procurement specifications specificationsshall shall include include the seismic requirements the seismic requirements and/or instrument instrument design requirements, requirements, and and specify specify the need for the need for commercial commercial design standards standards and testing under and testing under seismic seismic loadings loadings consistent consistent with with design basis basis values values at the instrument at the instrument locations.

locations.

Demonstration of

• Demonstration of the the seismic reliability of seismic reliability ofthe the instrumentation instrumentation through through methods methods thatthat predict predict performance performance by analysis, analysis, qualification qualification testing testing under under simulated simulated seismic seismic conditions, combination of conditions, aa combination testing and of testing analysis, analysis, or the the use use of experience data. GuidanceGuidance for for these these isis based basedon onsections sections7,7,8,8, 9,9, and 10 of and 10 of IEEE IEEE Standard 344~2004, "IEEE Standard 344-2004, "IEEE Recommended RecommendedPractice PracticeforforSeismic SeismicQualification Qualification of of Class Class 1E1EEquipment Equipmentfor for Nuclear Power Generating Stations," or a substantially similar similar industrial industrialstandard standard could could bebe used.

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

ranges). Such testing and Such testing and should be analysis should be similar similar to to that that performed performed for for the the plant plant licensing licensing basis.

basis.

Response (ref. ISG ISG Item Item 2.2):

2.2):

The HCVS components The HCVS components downstream of the second containment the second containment isolationisolation valve valve and and components components that interface withwith the HCVS HCVS will willbebe routed routed in in or or supported supported from from seismically qualified qualified structures.

structures.

The HCVS downstream The HCVS downstream of the second containment the second containmentisolation isolation valve, valve, including including pipingpiping and supports, electrical power supply, valve actuator supports, electrical actuator pneumatic pneumatic supply, supply, and andinstrumentation instrumentation(local (local and components, will and remote) components, will be designed/analyzed designed/analyzedtotoensure ensurefunctionality functionalityfollowing following a designdesign basis earthquake earthquake and and to to conform conform to the applicable plant requirements/design codes except except as as the HCVS HCVS ISG allows or directs directs other othercriteria.

criteria.

ISG definition The ISG definition for for "seismically "seismicallyrugged rugged design" design" allowsallows thethe use use of of commercial grade grade components and and materials materials beyond beyond the thesecond secondcontainment containmentisolation isolationbarrier barrierincluding including exclusion exclusion from from compliance compliance with Appendix B, with Appendix B, "Quality "QualityAssurance Assurance Criteria Criteriafor forNuclear NuclearPowerPower PlantsPlants andand Fuel Fuel Reprocessing Plants." Plants."

ISG Item Per ISG Item 2.2 direction, the HCVS HCVS instruments, instruments, includingincluding valvevalve position position indication, indication, process process instrumentation, instrumentation, radiation monitoring, monitoring, and support system and support systemmonitoring, monitoring, will will be qualified qualified using one one of the three methods describedininthe methods described theISG,ISG,which which includes:

includes:

1 1.. Purchase Purchase of of instruments instruments and andsupporting supportingcomponents componentswith withknown knownoperating operatingprinciples principles from manufacturers from manufacturers with with commercial commercialquality qualityassurance assurance programs programs (e.g., IS09001) where (e.g., IS09001) where the procurement specifications include the applicable seismic requirements, design design requirements, and and applicable applicable testing.

testing.

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

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

Instrument Qualification Method* Method*

HCVS Process Temperature Temperature IS09001 1809001 // IEEE IEEE 344-2004 344-2004//Demonstration Demonstration HCVS Process HCVS Process Pressure Pressure 1809001 // IEEE IS09001 IEEE 344-2004 344-2004 // Demonstration Demonstration HCVS Process HCVS Radiation Monitor Process Radiation Monitor 1809001 // IEEE IS09001 IEEE 344-2004 344-2004 // Demonstration Demonstration Page 18 of 26 26

Dresden Dresden Nuclear Nuclear Power Power Station, Station,_Units Units 2 and 33 2 and HCVS HCVS OverallOverall Integrated Integrated Plan Plan HCVS HCVS Process Process Valve Valve Position Position 1809001 IS09001 // IEEE IEEE 344-2004 344-2004 // Demonstration Demonstration HCVS Pneumatic Supply 1809001 IS09001 /IIEEE IEEE 344-2004344-20041/ Demonstration Pressure Pressure HGVS HCVS Electrical Electrical Power Supply Power Supply 1809001 IS09001 /IIEEE IEEE 344-2004344-2004 // Demonstration Demonstration Availability

• • The qualification method The specific qualification method used used for for eacheachrequired requiredHCVS HCVSinstrument instrumentwill will bebe reported reported in in future future 66 month month status status reports.

Section Section 5: 5: Procedures Proceduresand andTraining Training(Order- (Order EA .. 12.. 050 requirements EA-12-050 requirements 3.1 3.1 and and 3.2) 3.2)

Order Order EA-12-050 3.1 Requirement:

3.1 Requirement

Licensees Licensees shall develop, implement,implement, and and maintain procedures necessaryfor procedures necessary for the the safe safe operation of the HGVS.

HCVS. Procedures Procedures shallshall bebe established establishedfor forsystem systemoperations operationswhen whennormal normaland andbackup backuppower powerisisavailable, available, and sao during SBO conditions.

and during conditions.

ISG 3.1 Criteria:

ISG 3.1 Criteria:

Procedures Procedures shall shall be be developed developed describing when when and andhow howto to place place the the HCVS HGVS in in operation, the location location of system components, components, instrumentation instrumentation available, available, normal normal and andbackup backuppower powersupplies, supplies,directions directionsforforsustained sustained operation, including the storage storage location location of of portable portable equipment, equipment, trainingtraining on on operating operatingthe theportable portable eqUipment, equipment, and and testing testing ofof equipment.

equipment. The Theprocedures proceduresshall shallidentify identifyappropriate appropriateconditions conditionsandandcriteria criteriafor for HCVS. The use of the HCVS. The procedures procedures shall clearly state state the nexus between between CAP GAP and and ECCS EGGS pumps pumps during during a DBLOGA DBLOCAand andhow howan an inadvertent opening of inadvertent opening of the vent valve could have an an adverse adverseimpact impacton onthis thisnexus.

nexus.

The The HGVS HCVSprocedures procedures shall shall be developed and be developed and implemented in the the same manner as same manner as other plant procedures procedures necessary necessary to to support support thethe execution execution of of the the Emergency Emergency Operating Operating Procedures Procedures (EOPs).

(EOPs).

Licensees Licensees shallshall establish establish provisions provisions for for out-of-service out-of-service requirements of the HCVS HGVS and and compensatory compensatory measures.

measures. These Theseprovisions provisionsshallshallbebedocumented documentedininthe theTechnical TechnicalRequirements RequirementsManual Manual(TRM)

(TRM)or orsimilar similar document. The The allowed allowed unavailability unavailability time time for for the the HGVS HCVSshall shall not not exceed exceed 30 days during during modes modes1,1,2, and3.3.

2, and If If the the unavailability unavailabilitytimetimeexceeds exceeds30 30days, days,thethe TRM TRMshall shalldirect directlicensees licenseestotoperform performa acause causeassessment assessment and and take the the necessary necessaryactions actionstotorestore restoreHCVS HGVSavailability availability in in aa timely timely manner, consistent consistentwith with plant proceduresand procedures andprevent preventfuture futureunavailability unavailability for for similar causes.

causes.

Response (ref. ISG Item Item 3.1):

3.1 ):

Procedures Procedures will will be be established established for system operations operations when when normalnormal and and backup backuppowerpower isis available, available, and and during prolonged SBO conditions. conditions.

The The HCVS procedures procedures will will bebe developed developed and and implemented implementedfollowing following the processfor the plant's process for initiating initiating or or revising revising procedures procedures and andwillwill contain contain the the following following details:

details:

• appropriate conditions conditions and and criteria criteria for for useuseof ofthe theHCVSHCVS

• when and how how to place place the the HCVS HGVS in in operation, operation,

• the location of of system system components, components,

• instrumentation available,

• normal normal and backup power supplies,

• directions directions for for sustained operation (reference sustained operation (referenceNEI NEI 12-06),

12-06), including including the storage the storage location location of of portable portable equipment, equipment,

• • training training on on operating operating the the portable portable equipment, equipment, and and

• testing of portable equipment Dresden credits CAP Dresden credits CAP for ECCS EGGS pump NPSH NPSH duringduring aa DBLOCA.DBLOCA. The procedures procedureswill will emphasize emphasize the needfor the need for immediate immediateisolationisolation ifif the the HCVS HCVS is is inadvertently inadvertently opened. opened.

Page 19 of 26 26

Dresden Nuclear Dresden NuclearPower PowerStation,Station Units Units 22 and and 33 HCVS Overall Integrated Plan HCVS Dresden Dresden Nuclear Power Station will will establish establish provisions for out-of-service requirements requirements of of the the HCVS HCVSand and compensatory compensatory measures.

measures. The Thefollowing following provisions will willbe be documented documented in the Technical Requirements Requirements Manual Manual (TRM)

(TRM) document:

• • The The allowedallowed unavailability unavailabilitytime timeforforthetheHCVS HCVSshall shallnot notexceed exceed 30 30 days during modesmodes1,1,2,2, and and 3. 3.

• • IfIf the the unavailability time exceeds 30 days oo TheThe condition condition will be entered into the corrective corrective action action system, system, oo TheThe HCVS HCVS availability availabilitywill willbeberestored restoredininaamannermanner consistent with plant consistent with procedures, procedures, oo A A cause assessmentwill cause assessment willbebeperformed performedtotoprevent preventfuturefutureunavailability unavailabilityfor forsimilar similar causes.

causes.

Order EA-12-050 3.2 Requirement:

Licensee shall train appropriate personnel personnelin in the the use useofofthe theHCVS.

HCVS. TheThetraining trainingcurricula curricula shall shallinclude include system operations when when normal normal and and backup backup power poweris is available, available, and andduring sao during SBO conditions.

conditions.

ISG 3.2 Criteria:

ISG All Allpersonnel personnel expected expected to to operate the HVCS shall receive trainingtraining in in the the use use of plant plant procedures developed procedures developed for system operations when normal and backup power for system power is available, and and during sao during SBO conditions consistent consistent with with the theplants plants systematic systematic approach training. The approach to training. The training trainingshall shallbe refreshed on aa periodic basis and be refreshed andasas any changes changesoccur occurto tothe theHCVS.

HCVS.

Response (ref. ISG ISG Item Item 3.2):

3.2):

Training Training materials will will be be developed developed for for the the staff staff involved involved in in operating operating the theHCVS HCVSinin allall modes modesofof HCVS HCVS operation.

operation. For For accredited accreditedtraining training programs, programs, the theSystematic SystematicApproachApproachtotoTraining Training(SAT)

(SAT) will be will be used used to to determine determine training trainingneeds. Assignments to personnel responsible needs. Assignments responsible for for implementing the SAT process process at at Dresden Dresdenwill will include include direction direction to to ensure ensurecompliance compliancewith with training requirements of of NRC NRC Order EA-12-050 EA-12-050 Requirement Requirement 3.2 3.2 andandISGISGCriteria Criteria3.2.

3.2.

Page 20 Page 20 of of 26 26

Dresden Dresden NuclearNuclear Power Power Station.

Station, Units Units 22 and and 3 3 HCVS HCVSOverall Overall Integrated Integrated Plan Plan Section Section 6: Implementation Schedule 6: Implementation Schedule Milestones Milestones The The following followingmilestone milestoneschedule scheduleisisprovided.

provided.The Thedates dates are are planning planning dates change dates subject to change as as design and implementation design and implementation details are are developed.

developed. Any Any changes changesto tothe thefollowing following target dates dates will willbe reflectedininthe bereflected thesubsequent subsequent 66 month month status status reports.

Original OriginalTarget Target Date Date Activity Activity Status Status October October 2012 2012 Conceptual Conceptual design meeting Complete Complete October 2012 October Submit 60 Submit 60 Day Status Report Complete Complete February 2013 February Submit Overall Integrated Submit Completed Completed with IImplementation mplementation Plan this this submittal August 2013 Submit 66 Month Status Report Submit February 2014 February Submit 6 Month Status Report August 2014 Submit 6 Month Status Report November 2014 U2 U2 Design Design Change Change Package Package Issued February 2015 Submit 6 Month Status Report June 2015 U2 U2 Design Design Major Material On-siteOn-site 1 June 2015 Procedure Changes and Procedure Changes and Training Training Material Material Complete August 2015 Submit 6 Month Status Report D2R24 outage Fall Fall 2015 U2 U2 Design Change Change Implemented Implemented D2R24 outage Fall Fall 2015 2015 Procedure Changes Active Active D2R24 outage Fall Fall 2015 U2 Demonstration/ Functional Test Test prior prior withdrawal; Full to rod withdrawal; Full compliance.

compliance.

November 2015 U3 Design Change Package Issued Issued February February 2016 2016 Submit 6 Month Status Report Report June 2016 2016 U3 Design Major Major Material Material On-site On-site 1 August 2016 2016 Submit 6 Month Status Report outage Fall D3R24 outage Fall 2016 2016 Change Implemented U3 Design Change Implemented D3R24 outage outage Fall Fall 2016 2016 U3 Demonstration/Functional Test Test prior prior to rod rod withdrawal; withdrawal; Full Full compliance.

compliance.

December December 20162016 Submit Submit Completion Completion Report Report Section 7:

Section 7: Changes/

Changes/Updates Updates to tothis thisOverall OverallIntegrated IntegratedImplementation ImplementationPlan Plan Significant changes Significant changes to to this this plan plan and andadded addeddesign designdetails detailswillwillbe becommunicated communicatedtotothe NRCinin theNRC the 6 month Status Reports.

the 6 month Status Reports.

Major Equipment i1Major Equipment - -Piping, Piping,valves valvesand andcomponents components greater greater than than 3",3", Instrumentationpick-ups Instrumentation pick-upsand andindicators.

indicators.

Page 21 Page 21 of of 26 26

Dresden Nuclear Power Station, Units 2 and 3 HCVS Overall Integrated Plan Section 8: Figures/Diagrams ISG IV.C. 1. Reportinq Requirements:

A piping and instrumentation diagram or a similar diagram that shows system components and interfaces with plant systems and structures is acceptable.

Conceptual One-Line DI~gram for the HCVS Piping Outside-ToSGTS ToRBVS Discharge Point is above the top of the Reactor Building NC, FC, see note 3 NC, FC, see note 3 DW NC, FC see note I NC, FC, see note 2 NC,FC New piping and valves dedicated to the HCVS Reactor Building Torus Note 1: These CIVs have a circuit for "design basis" operation and a second circuit for HCVS operation. The "design basis" circuit can be overridden to open for the HCVS function.

Note 2: The downstream CIV only has a circuit for HCVS operation.

Note 3: The downstream CIV to the RBVS and SGTS only have a "design basis" circuit that is automatically isolated by containment isolation signal.

Page 22 of 26

Dresden Nuclear Power Station. Units 2 and 3 HCVS Overall Integrated Plan Conceptual One Line Diagram for Dedicated N2/Air for the HCVS (r-~

I "1 or'

~

) OU1SI~~'I~~

o lOOD t"lIG 1l.B J.tU I

1

'/2

~--~---,--~-~~r----~----.-~-----r----~----~------~-------'-----'~Y#-

1 To HCVS valve air operators N2 charge connectfon "-.r--J POR1lIE!U:

AIR C:CMPRF.S!"Oq Page 23 of 26

Dresden Nuclear Power Dresden Nuclear Power Station, Station, Units Units 22 andand 33 HCVS Overall Integrated HCVS Overall Integrated Plan Plan Conceptual Conceptual One One Line Line Diagram Diagram forfor Dedicated DedicatedDC DC power powerfor for the theHCVS HCVS

--L MCR means indication on on HCVS RCVS Panel Panel DCI r AC I

k

"-...--' '-~

HCVS 'IIETWELL WETWELL TT' IO:;OLJi.TION ISOLATION IS- L4TF da F* -. t I r ISOlJ\1l0~

ISOLAIIO VALvE ti vALvr I VALVE I

PRESS MONITOR

'-v-"

L' '.a,lRF '<I Ii1L Page 24 of 26 26

Dresden Dresden Nuclear Nuclear Power Power Station, Station, Units Units 22 and and 33 HCVS Overall HCVS Overall Integrated Integrated Plan Plan Section 9:

Section 9: Table Table-- HCVS HCVS Failure Failure Modes The following table summarizes the Integrated Plan response to specific HCVS ReVS valve valve circuit, circuit, valve valvepower powerand andvalve valvemotive motiveairairISG ISG requirements for reliability and sustainability.

and sustainability.

HCVS HCVS Failure Failure Containment Containment I Potential Potential Cause Cause How How Addressed Addressed Modes Modes Venting Ventin g Fails? I The design will The design will prevent prevent aa failure failure ofof aa SV SV from from disabling disabling thethe HCVS HCVS flow flow No No Solenoid Solenoid Valve (SV)

Valve (SV) path.

path. The The Integrated Integrated Plan Plan discusses discusses(a) (a)providing providing redundant redundant SVs SVs such such I failure failure that energizing either that energizing either SV SV would would allow allow opening opening thethe CIV CIV or or (b)

(b) locating locating a a single single SV SV inin an an accessible location. The accessible location. The accessible accessibleSV SVlocation location would would allow access to locally open the SV to the motive motive air air source.

source.

If redundant inaccessible SVs are used, one of of the the SVs SVs will will be be powered powered No from from the the dedicated dedicated DC DC power power supply supply in in an an accessible location sized accessible location sized forfor 24 hours with 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with provisions provisions forforsustaining sustainingthe thecharge charge after after2424 hours.

hours. TheThe other other SV SV will willbebe energized energized from from an an alternate source (Exelon alternate source (Exelon isis reviewing reviewing the options, which the options, which include include converting converting the the existing existing AC AC circuit circuit and and SVSV toto anan CIV CIV fails fails to to Vent Vent existing DC eXisting existing DC source which will source which will be be maintained energized by maintained energized byFLEX, FLEX, or or other other (Open)

(Open) onon loss of power loss of power to to the the means means to to energize energizethatthatSVSVfollowing following aa prolonged prolonged SBO).

SBO).

demand demand or or fail fail SV(s) shut after IfIf the the single single accessible accessible SV SV option option is is selected, selected, itit will will be powered from be powered from thethe opening opening dedicated DC dedicated DC source source andandititwill will allow allow access access to to locally locally open open thethe SV SV toto the the motive air air source.

source.

The accessible The accessibleDC DC power powerlocation location would would allow allow corrective corrective actions actions (e.g.,

(e.g.,

battery change-out) ifjf required.

battery change-out) required.

HCVS valves HCVS will not valves will rely on not rely normal pneumatic on normal pneumaticair airsupply; supply;they theywill will be be No No supplied from supplied from anan accessible accessiblededicated dedicatedmotive motiveairairsupply supplywhich whichisis loss of loss of pneumatic pneumatic air air sufficient for sufficient for aa 24 hour period 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period with with provisions provisions forfor sustaining sustaining the themotive motiveair air supply supply pressure after pressure after 24 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> hours (e.g.,

(e.g., recharge rechargededicated dedicatedmotive motiveairairsupply supplyusing using portable air air compressors compressors and/orand/orreplace replaceN2 N2bottles.

bottles.

Page 25 of 2626

Dresden Dresden NuclearNuclear PowerPower Station, Station, Units Units 22 and and 33 HCVS Overall HCVS Overall Integrated Integrated Plan Plan HCVS HCVS Failure Failure Containment Containment Potential Potential CauseCause How How Addressed Addressed Modes Modes Venting Ventin g Fails?

Fails?

PCV PCV will willuseusededicated dedicated DCDC power power source source and motive air and motive air source being source being No No loss loss of of power power or or motive motive added added forfor the CIVs. The the CIVs. DC power The DC power and and motive motive air air source sourcewillwill be be airair accessible.

accessi bl e.

PCV PCV fails fails to to Vent Vent The The detailed design will detailed design will provide provide aa back-up back-up capability capability for for opening.

opening. Under Under No No (Open) on (Open) on consideration are providing:

demand demand or or fails fails (a)

(a) aa hydraulic hydraulic system system with with hand-pump, hand-pump, located located at at an accessible location, an accessible location, shut after shut after loss loss of a PCVPCV control to to over-ride over-ride the the spring-to-shut function and spring-to-shut function and opening opening circuit circuit component component (b) an (b) an over-ride circuit that over-ride circuit that will willbypass the control bypass the control circuit circuit and provide and provide motive motive airair to to PCV PCV air-operator air-operator that that fully fullyopens opens the the valve.

valve. Containment Containment pressure control would then revert to PCIV cycling.

Not credible as there is is N/A NtA No not not aa common common mode Fail Fail to to stop stop failure failure that would that would venting (Close) venting (Close) prevent the closure of on demand on demand at least 1 of the 3 valves valves needed needed for for venting.

Not credible as key N/A NtA No locked switch on on both both Spurious Spurious CIV's and CIV's other actions and other actions Opening Opening require require at at least three least three discrete steps to to open open the flow path. path.

Upstream CIV Upstream CIV closes closes The upstream The upstream CIV CIV with with containment isolation signal containment isolation has aa containment signal has containment No No on a on a containment containment isolation signal isolation over-ride. In signal over-ride. In addition, addition, the the second second SVSV will will have have aa separate separate isolation signal.

isolation signal. circuit without circuit without automatic closure logic.

automatic closure logic.

CIV closure CIV closure duedue Not credible Not credible forfor the the NtA for N/A for downstream downstream CIV. C IV.

to an to an automatic automatic downstream CIV downstream CIV since since signal signal itit does notnot have have containment containment isolationisolation signal. The signal. The valve valve control control is is simple simple openopen or or shut.

shut.

Page 26 Page 26 of of 26 26