tritium inventories and containment philosophy for the fuel … · – calculation of systems...

Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft

IAEA TM on Fusion Power Plant Safety, July 10-13, 2006 Ioana R. Cristescu slide # 1

FUSION FZK - EURATOM ASSOCIATION

Tritium Inventories and Containment Philosophy for the Fuel cycle of ITER

I. R. Cristescu 1), I. Cristescu 1), L. Doerr 1), M. Glugla 1), D. Murdoch 2)

1) Forschungszentrum Karlsruhe, Tritium Laboratory, Germany2) EFDA CSU Garching, Germany




Outline of the presentation

• Tritium Inventories in The Fuel cycle of ITER– TRIMO – dynamic software for tritium inventory simulation in ITER– Minimization of tritium inventories in FC of ITER

• Tritium confinement principles

• Detritiation systems– Atmosphere Detritiation system– Water Detritiation system

• Closing remarks




Simplified Block Diagram of the ITER Fuel Cycle

Gas InjectionSystem

PelletInjectionSystem

NBI andDiagnostic NBI

TORUS HALL TRITIUM BUILDING

Storage andDeliverySystem

D2DNBI

2 DT T2

TritiumExhaustProcessing

H2

D2

DT

T2

T2

VacuumPumping

HTO

Hto stack

2

N-VDS

DNBI

2

IsotopeSeparationSystem

Water DetritiationSystem




Dynamic Mathematical Modeling of the ITER Fuel Cycle

• Motivation to develop a dynamic code for FC functioning:– ITER is a pulse machine, operating under burn and dwell

• 450s (3000s) during burn fuel is introduced, 1350s (9000s) during dwell no fuelling is taking place

• Necessity to support the detailed system design by validated codes– Calculation of systems performance under different operational conditions

• An ITER fuel cycle simulation model has to address the following topics:– To evaluate the behavior of the sub-systems in dynamic regimes (operating scenarios), whether

the sub-systems, equipment sizes were appropriate (or properly designed). – To assess the cycle time from injection back to the storage and delivery system – To assess tritium inventories in each subsystem in different operating conditions, taking into

account the tritium inventory history of the sub-systems




Dynamic Mathematical Modeling of the ITER Fuel Cycle

• Several steps to develop a dynamic code for FC of fusion machines have been made– Residence-time approach gives high uncertainties– CFTSIM model (2000, under ITER supervision) built on elements from FLOSHEET (CD steady

state) and DYNSIM (dynamic simulator)

• Source code of CFTSIM transferred to TLK in 2004

• TRIMO – Build on elements from CFTSIM (mainly ISS)– Extensive work have been carried out to implement on-going changes in FC design– Developed with EFDA support– Source code owned by TLK– Draft documentation issued




Software life-cycle diagram - TRIMO

RequirementsSpecification

FunctionalSpecification

ArchitecturalDesign

DetailedDesign

Coding and Implementation

IntegrationTesting and

Commissioning

Operation,Maintenance and

Enhancement

To quantify time variation of T inventories in the Fuel Cycle for several operational scenarios

User-friendly graphical interfaces for input parametersGraphical outputs: T inventories, streams composition and flowrates

Modular structure: for each FC subsystem a module is assigned

Library for hydrogenic isotopes mixtures properties at low temperatures (non-idealities)

Documented (logical diagrams)

Modular tests:CD column moduleWDS module




FC design - TRIMO FCSubsystem

Physical and chemical processes Inflows Outflows Model Design characteristics

Fuelling → Freezing of DT gas→Pressurized gas flows SDS Torus Lump Fuelling pattern

Neutral BeamInjection Vacuum flows SDS Torus,

TEPLump, parametric,vacuum flows

Regeneration pattern, roughing pumpcharacteristics

Torus→Plasma →Plasma-wallinteractions →Chargeexchange →Retention

Fuelling,NBI

Vacuumpumping

Lump, power-lawpressure, parametric

Power, Volume, Burn-up rate, Waltemperature

Vacuumpumping Vacuum flows Torus TEP Lump, regeneration,

Vacuum flows

Regeneration pattern, cryopumpcharacteristics, duct geometry, roughingpump characteristics

TokamakExhaustProcessing

→Permeation → Flows →Chemical reactions Vacuum

pumping,NBI ISS Lump, parametric Pumps characteristics, buffer vessels

WaterDetritiationSystem

→Catalytic isotopicexchange →Electrolysis

Storagetanks, ISS

ISS,Stack

Dynamic 1-dimensionalmass transfer inmixtures

Column height, diameter, temperature,pressure, eletrolyser inventory, separationperformances

IsotopeSeparationSystem

→Cryogenic distillation TEP,WDS SDS,WDS

DynamicMulticomponendistillation

Columns height, diameter, temperature,pressure, inventory, separationperformances, intercolumn flows, flowcontrol valves, equilibrators

Storage andDeliverySystem

Adsorbtion, release fromstorage beds ISS

Fuelling,NBI Lump, parametric

Fuel handling strategy, Buffer vesselsimension, storage beds capacity, releaserate




ISS Inventory




Dynamics of Fuel cycle Inventories




Tritium needed for operation• 120 Pam3/s 50%DT – basic fuelling scenario for ITER

Tritium necessary for non-interrupted burn/pulse

Tritium recovered during burn /pulse

Tritium recovered during dwell /pulse

Longpulse 480g 135g 345g*

Shortpulse 72g 12g 60g *

* tritium trapped in Torus and as tritiated impurities should be subtracted

• What influences the speed of tritium recovery in FC:– Tritium trapped in Torus– Vacuum pumping system regeneration pattern– Tritium trapped as impurities CQ4, Q2O– Ability of TEP, ISS to process the fuel fast

• Values of packing hold-up, CD column boiler inventory• Control system of ISS• ISS design




T consumption and inventories within FC

• Besides the tritium from the FC, additionally 1 kg of tritium in Long Term Storage

• 0.39g T/450s burnpulse with a total burntime/ 10 years = 0.15 years

• Estimated total tritium consumption for ITER lifetime = 16 Kg

• Typical analysis where TRIMO is used:– Trade-off studies (ISS-TEP, WDS-ISS)– Various operational scenarios

• 8 typical fuelling cases at various T/D ratio and total flow rates for both short and longpulse

• Tritium inventory procedure in ITER

TotalgfedcbSDSgfedcbISSgfedcbVacuum PumpinggfedcbTEPgfedcbTorusgfedcbFuellinggfedcbIn_OutgfedcTritium Plantgfedc

Time(s)30,00020,00010,0000

g

500

450

400

350

300

250

200

150

100

50

0

– Evaluations of tritium inventory on various FC configuration (e.g. processing of ablated gas from pellet injector in ISS)

– Fuel handling in SDS for buffer vessels minimization

• The ultimate goal of these analysis is ensuring the FC functionality with tritium inventories minimization




Validation on sub-systems: WDS and ISS

WDS for ITER WDS at TLKCECE process CECE processSolid polymer

electrolyserSolid polymer

electrolyserCatalyst/packing properties will be tested

for WDS designTritiated water feed flow rate:

20 Kg/h

Tritiated water feed flow rate:

1.5 Kg/hTritium activity in

water feed: 10 -100 Ci/Kg

Tritium activity in water feed:

1-10 Ci/Kg

ISS for ITER ISS at TLK

4 CryogenicDistillation columns

2 Cryogenic Distillation columns

Packing properties (HETP and hold-up) will be tested for ITER ISS design

Feed flow rate CD1: 280 mol/h

Feed flow rate: 45 mol/h

The influence of the return stream of CD1 ISS to WDS for further tritium depletion will be investigated, also in dynamic regimes (variable flow rates and composition) – integrated tests for TRIMO validation




Effluents and releases

• Project guidelines for ITER tritium releases during normal operation :

– 1 ga-1 as HT– 0.1 ga-1 as HTO

• A detailed release assessment has been performed for each element in the ITER WBS to ensure that no significant release pathway was missed. Estimated ITER tritium releases are:

– 0.18 ga-1 HT mainly from protium discharge of the Isotope Separation System (ISS)

– 0.05 ga-1 as HTO• 0.0004 ga-1 will be waterborne, 85% out of

that is due to blow down of the cooling tower

Contribution in the total HTO releases (%) of various subsystems

Fuelling

Heat transfer system

Remote handling

Vacuum pumping

Tritium plant

Facing

Waste treatment and storage

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00

1

TRIMO can be used to assess the value of releases for the FC as build in variousoperational scenarios




Multiple Barrier Tritium Confinement Concept at TLK

Tritium InfrastructureTritium Transfer SystemIsotope Separation System... Primary System

Secondary System

Glove Box

ExperimentsCaperPetra...

Primary System

Secondary System

Glove Box

TritiumRetentionSystem

Primary SystemLeak Rate < 10-8 mbar l s-1

Tritium compatible materials...

Secondary SystemLeak Rate < 0.1vol % h-1

...

1. Stage(ClosedLoop)

Central Tritium Removal

2. Stage(Once

ThroughThanOut)

PrimaryOff-Gas

Treatment

ProvidesCentral

Under Pressure

LaboratoryVentilationRing Manifold

n-nnnnPIRCA±

TritiumRetentionSystem

k-kkkkPIRCA±

SafetyValve

SafetyValve

Under PressureControl

Under PressureControl

Stack

BuildingWall

TLKHoods

• Detritiation of all primary exhaust gases prior to discharge into the environment

•Detritiation systems for secondary and tertiary containments




Primary and secondary containments

• Specifications for primary containments– Use of tritium compatible materials

• Qualification of materials for work in tritium environment when this is unavoidable (Nafionmembrane for the SPM electrolyser, catalysts - R&D to investigate the lifetime in the EFDA program and at TPL Japan)

– Definition of leak tightness– Outer jacket for tritium bearing components heated to temperatures above 150°C

• Evacuation of the jacket interspace for thermal insulation• Removal of tritium permeated through hot structural materials from the jacket

– protected against over-pressure, over-temperature • Specifications for secondary containments (glove-boxes, hardshell boxes)

– provided with detritiation systems and a purge and pressure control system – nitrogen atmosphere with very little oxygen (needed to convert leaked isotopic hydrogen

and hydrocarbons into water and carbon dioxide) – equipped with sensors to measure tritium level, temperature, pressure




Example of over-pressure protection: ISS

PIR

RD

AV

RD

Rupture disk

Relief valve

Regulation valve

Normal flow

CD

Cold box

Processloop

Tritium monitor

Pump box

AV

Expansion vessel

ADS

RD

Hydrogen vessel

RV

PIR

PIR AV

RV

• Avoiding contamination of the refrigerant with tritium (intermediate hydrogen cooling pool)

• Recovery of process gas after expansion following warm shutdown.

• In case of tritium contamination, the coldbox and the hydrogen vessel discharge the overpressure into the atmosphere detritiation system.




Integrated Atmosphere Detritiation system Configuration

• During normal operation a Normal Vent Detritiation system (700 Nm3/h) processes tritiated streams

• In the case of an off-normal event: – the HVAC systems branch ducts in each

room/area are switch to the re-circulation type room atmosphere detritiation systems (S-ADS 4500m3/h).

– the N-VDS is backed up by the once-through standby vent detritiation system SVDS 3000m3/h).

– the S-ADS and S-VDS ensure that:• Staggered negative pressure is maintained• the extracted air is detritiated to the

required low level before release into the environment

• tritium concentration in the affected room(s) is rapidly decreased.

Containment Volume(46,000 m )3

Secondary Enclosures


TritiumBuilding

TokamakBuilding

DivertorDrying SystemPit Free Volume

Rotary Dryer





Standby Atmosphere Detritiation System




Water Detritiation System

• Tritiated water will be produced in all ITER atmosphere detritiation systems (ADS)

• Typical tritium concentration 10Ci/kg with possibility of processing 500Ci/kg

• Combined Electrolysis Catalytic Exchange Process

– Very high detritiation factors are required to release WDS exhaust to stack

• R&D program to prove the capacity of WDS to further process the ISS hydrogen stream

• WDS is the only system in ITER that releases effluents into the environments without an additional detritiation system




Closing remarks

• Fuel cycle of ITER:– quick recovery of tritium for recycling – low tritium inventory – safe handling and confinement of tritium– low effluents and releases

• Mature technologies for all subsystems• Sound modeling under validation • Existing infrastructure for accompanying R&D and further

developments

tritium inventories and containment philosophy for the fuel … · – calculation of systems...

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