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HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Occupational Radiation Exposure – ALARA in ITER:
further refinement
TW6-TSS-SEA 2.1
Ion Cristescu, FZK
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide1
HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Objectives of FZK Deliverables
• Capacity of the ventilation system to achieve T concentration
suitable for human presence in or without suits
• Expected time evolution of the T concentration airborne and
order of magnitude of the surface contamination
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide2
HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Vault Area Ventilation and Confinement Systems
► Normal ventilation system HVAC-2
► Depression system
► Vault air cooling system
► Vault air detritiation dryers
References : DDD 3.2 N Ventilation and Confinement Systems
HVAC Concept Review – IBERTEF A.I.E. report
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide3
HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Ventilation and Confinement system of Vault areas
HVAC 2
NVDS- 1
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide4
HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Normal ventilation system HVAC-2
► This system is only operated during maintenance work in the vault.
► The isolation dampers (not safety related dampers) incorporated in the
supply and extraction ducts are normally closed and are part of the pressure
boundary and tritium confinement boundary. Hence they are rated at
0.2MPa.
► The HVAC-2 supply and extraction ducts are also equipped with fire/smoke
isolation dampers to prevent spreading of fire and smoke.
► The supply and extraction ducts are routed to the TCWS vault via the vault
annex in the tritium building.
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide5
HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Depression system
► To maintain negative room pressure (-2mbar) relative to the building external
pressure, this system is operated continuously during ITER normal operation
and maintenance work and also in case of fire.
► This system, composed of an air extraction pipe with differential pressure
control valves and chilled water cooled air cooler, is directly connected to
N-VDS 1. Double pressure isolation valves (safety related valves) are installed at
the air extraction nozzles placed inside the vault area to prevent propagation of
over pressure to N-VDS 1
► The vault depression system is SIC, and designed with full redundancy of the
active components, electric components and the associated instrumentation,
utilities and electric power cables.
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide6
HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Configuration of NVDS-1
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide7
HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Vault air cooling system
► This system, composed of chilled-water cooled air coolers, air fans and air
distribution ducts, is operated:
- to remove normal heat loads dissipated from hot pipes (primary cooling
system pipes), electric components (motors, compressors, heaters,
room lighting, etc)
- to cool down room air temperature in case of coolant spillage due to a
pipe break in primary heat transfer systems
► Based on the safety requirement to minimize environmental tritium release from
the vault under an over pressure condition, the cooling time was determined to
regain normal room pressure (0.1MPa) in 24h. Therefore, this is a SIC system
designed with full redundancy of the active components, electric components, the
associated instrumentation, utilities and electric power.
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide8
HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Vault air detritiation dryers
► Is operated (except during an overpressure event) to remove tritiated water vapour
to achieve an acceptable room air tritium concentration level (0.1 DAC-HTO).
The source term of the tritiated water vapour is the leakage of coolant from ITER
primary cooling systems, and the estimated annual leakage volume is 1% of the
cooling system water hold-up.
► This system is composed of
- a rotary dryer,
- a compressor,
- and a chilled-water cooled air cooler.
Adsorption of water vapour and desorption (regeneration) of saturated dryer bed is
continuously carried out. This system is not SIC, because it does not form part of
the tritium confinement boundary.
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide9
HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Tritium sources during maintenance operations
During maintenance activities on NB box, two tritium source
should be considered:
► Tritium out-gassing from NB cryopanels
- Inputs from FZK vacuum pumping group will be
used
► Tritium out-gassing both from NB cryopanels and
Vacuum Vessel
- In addition to reference documentation, JETand
TFTR data related to tritium retention and clean- up
will be used to estimate the values of sources term
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide10
HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Detritiation of NB cell after a tritium spillage
► During maintenance activity a chronic release of tritium is expected
► S-ADS and S-VDS will be used in combination for NB cell decontamination
and to maintain depression.
► The DF of S-ADS is 102 and 103 for S-VDS. Therefore, the NB environment has
to be processed in closed loop until the tritium concentration will be lowered to a
level that allows to discharged it to stack.
► For low tritium contamination, fresh air should be provided by H-VAC and
processed in one through mode in S-ADS and S-VDS.
► In the present configuration the NB cell is not served by the S-ADS. Pipe
connections between NB cell and S-ADS need to be provided.
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide11
HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Atmosphere Detritiation System of ITER
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide12
HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Room Air Detritiation Model for the Combined Operation S-ADS and S-VDS
4500 Nm3h-1
3000 Nm3h-1
Time evolution of tritium concentration in a contaminated area, during the detritiation
processes, will be determined under the following assumption:
- Perfect mixing of tritium within a contaminated area
- Oxidation of elemental tritium and isotopic exchange reaction can be ignored
- The sorption and desorption of tritiated species on/from wall surfaces can be
ignored
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide13
HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Estimation of surface contamination after a tritium spillage event
Two cases of surface contamination will be considered:
► Contamination with tritium in gas phase
- data available at TLK, AECL, TPL and TFTR will be used as
basis for evaluation
► Contamination with HTO
- Information from TPL, operation of CANDU reactors (AECL,
Cernavoda-Romania)
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide14
HVT-TLK
Forschungszentrum Karlsruhe
in der Helmholtz-Gemeinschaft
FZK - EURATOM ASSOCIATION
Inputs required for the FZK Deliverables
Additional information related to the following issues will be highly
beneficially:
► Leak rate for NB cell after separation from vault area
► Out-gassing rate of the in-vessel components during maintenance activity
► Reference documentation
Garching, 10 Nov.2006
TW6-TSS-SEA 2.1
I. Cristescu
Slide15