•Two different single 1:1 irradiation rigs inside a mock-up container are presented.•Pressure drops in the single rig minichannels are measured.•Temperature fields are measured under different heater ...and flow conditions.•Predictability and reproducibility of the cooling flows can be shown.
The hydraulic and thermal testing of two different irradiation rig models A and B, differing in the inlet nozzle design, bottom reflector length and steps inside a mock-up container is part of the HFTM validation activities which support the engineering design of the High Flux Test Module.
The pressure drops for all models in the test section are measured for overall mass flow rates of 1–12g/s and different absolute pressures of 1500hPa and 2500hPa at the pressure port at the inlet section. The pressure drops in different sections of the experiment and in the single rig minichannels are also measured with additional pressure ports on the surfaces of the rig models.
Predictability and reproducibility of the cooling effects of the main cooling channels in the HFTM irradiation zone can be shown. Rig model B with a backward facing step is for high mass flow rates >∼7.5g/s (this is the operation regime of the HFTM) superior to rig model A. Uniform perfusion of the multiple parallel minichannels of the irradiation rigs by helium gas is of importance to obtain uniform and predictable temperatures. Temperature fields under different heater and flow conditions have been measured.
•External instrumentation: 40 strain gage sensors (temperature corrected) and 12 digital dial indicators.•Safety successfully confirmed (pressure test at 0.545MPag @ RT).•Measured strains agree with ...FEM simulation studies.•Measured deformations and surface strains almost completely reversible→no plastic deformation.•maximum measured deflection of 8.5mm during an asymmetric heated run.
The so called High Flux Test Module (HFTM) represents the component of IFMIF (International Fusion Irradiation Facility) in which material specimens are being placed that accumulate high neutron induced damage rates (≥20dpa/fpy). Damage rates of this magnitude are limited to a volume of ∼500cm3 (attenuation in beam direction) behind a beam footprint of 20×5cm2, so the high flux region of the module is contained in a flat faced, cuboid volume of 5.6cm depth. Efforts for a high spatial utilisation and the demand for a high neutron transmission lead to a thin-walled container design. As an efficient, space-saving method to cool the container and the material specimens, an array of mini-channels (1mm gaps) through which low pressure (0.3MPa) helium gas is flowing is established. Installed closely to the target and due to space constraints by other irradiation modules, the HFTM is implemented as a slender and tall construction with features that are challenging for pressure equipment. Experimental studies on a 1:1 prototype of the HFTM-DC (double compartment) have been made in the Helium Loop Karlsruhe – Low Pressure (HELOKA-LP) during 2015. The experiments also included intensive testing to demonstrate the mechanical reliability of the HFTM under IFMIF relevant operation conditions. Therefore, the module was instrumented with numerous sensors which measure displacement, deformation and mechanical strain. The reactions on temperature and pressure loads were studied. In this paper the experimental results will be presented and compared to the numerical (FEM) simulation studies.
•New component level tritium transport model based on OpenFOAM.•Diffusion and convection transport in fluid; diffusion in solid structures.•Fluid-solid interface mass transfer: diffusion limited and ...rate limited.•Two species model.•First verification calculations are shown.
This work describes the development of a numerical model to simulate transient tritium transport on the breeder unit (BU) level for the EU helium cooled pebble bed (HCPB) concept for DEMO. The key output quantities of the model are the tritium concentration in the purge gas and in the coolant and the tritium inventory inside the BU structure. The model capabilities should cover normal operation as well as accident conditions.
The Open Source Field Operation And Manipulation framework OpenFOAM serves as the basis for the model. Equations and boundary conditions required for hydrogen isotopes transport are implemented. Realistic properties data as diffusion constants and Sieverts constants are required, too. A key model issue is solid-fluid interface mass transfer. Two correlations that (1) approaches Sieverts equilibrium in the diffusion limit and (2) a rate dependent correlation that includes the diffusion limit for very high ad-/desorption rate constants are introduced. A two species interface mass transfer correlation based on the single species rate dependent correlation is developed, too. First verification calculations are compared to analytic solutions and TMAP calculations.
This paper presents the engineering design of the IFMIF (International Fusion Materials Irradiation Facility) Tritium Release Test Module (TRTM). The objectives of the TRTM are: (i) in-situ ...measurements of the tritium released from lithium ceramics and beryllium pebble beds during irradiation, (ii) studying the chemical compatibility between lithium ceramics and structural materials under irradiation, and (iii) performing post irradiation examinations for the irradiated materials. The TRTM has eight rigs which are arranged in two rows (2×4) perpendicular to the beam axis and enclosed by a structural container. Each rig includes one capsule that contains lithium ceramic or beryllium pebbles for irradiation. Neutrons reflectors are implemented at different locations to reflect the scattered neutrons back to the active region aiming to improve the tritium production. The TRTM is required to provide irradiation temperature range of 400–900°C for the capsules filled with lithium ceramics and 300–700°C for the ones packed with beryllium. The engineering design of the TRTM components such as container, rigs, capsules, pebble beds, neutrons reflectors, and purge gas and coolant tubes are presented. In addition a test matrix for the irradiation campaign is proposed.
•This contribution gives a comparison of the hydrogen permeation parameters of different RAFM steel.•For future structural calculation and safety issues the paper selects the measurement of “Optifer” ...as “best” result of RAFM steel.•Our contribution publishes a comparison of diffusion constants of chemical elements regarding the kind of lattice and endothermic/exothermic character of elements.
The hydrogen isotopes tritium and deuterium as fuel of future fusion power plants will be in contact with several plant components: Reduced Activation Ferritic Martensitic (RAFM) steel parts of the blanket and austenitic steels used for pipelines and process equipment. Temperatures range from ambient up to 550°C. Since both steel kinds can store and transport hydrogen to a considerable extent, design and safety analyses depend on hydrogen transport parameters for these materials over the full operation temperature range. Therefore, a qualified data base will be necessary for the future work on DEMO.
This contribution presents an overview of available transport parameters of different RAFM and austenitic steels, also regarding exothermic hydride generating alloy elements and pure elements. A pre-selection of materials for a planned permeation chamber is discussed on the base of these data.
In preparation for determining material properties such as Sieverts' constant (solubility) and diffusivity (transport rate) we give a detailed discussion on a model describing some gas release ...experiment. Aiming to simulate the time-dependent hydrogen fluxes and concentration profiles efficiently, we provide an analytical solution for the diffusion equations on a cylindrical specimen and a cylindrical container for three boundary conditions (B.C.). These (B.C.) occur in three phases - loading phase, evacuation phase and gas release phase. In the loading phase the specimen is charged with hydrogen assuring a constant partial pressure of hydrogen. The gas will be quickly removed in the second phase, in the third phase, the hydrogen is released from the specimen to the gaseous phase. The diffusion equation in each phase is a simple homogeneous equation. Due to the complex time-dependent (B.C.), we transform the homogeneous equations to the non-homogeneous ones with a zero Dirichlet (B.C.). Compared with the time consuming numerical methods our analytical approach has an advantage that the flux of desorbed hydrogen can be explicitly given and therefore can be evaluated efficiently. Our analytical solution also assures that the (B.C.) are exactly satisfied. The interaction between specimen and container is taken into account.
Numerical simulations have been carried out for low Reynolds number (Re = 6000-10000) gaseous flows in a heated annular mini-channel using the commercial CFD codes CFX V12.0 and Star-CD V4.10. The ...results were compared with in-house experiments. Detailed comparisons were made between the low Reynolds number k-
ϵ
, k-
ω
-SST, and V2F of Star-CD and CFX in terms of numerical sensitivities and model performance. Particularly, it was found that the inlet turbulence conditions can have a significant impact on the simulation results in the downstream flow for Star-CD low-Re k-
ϵ
and V2F models. For heat transfer predictions, the Star-CD V2F model provides the best predictions under low Reynolds numbers of about 6,000, while for Reynolds numbers of about 10,000 the k-
ω
-SST model performs better than others.
•This paper presents a comprehensive thermo-hydraulic analysis of the IFMIF High Flux Test Module.•The turbulence models were validated by in-house experiments.•Multiple fluid domains were employed ...and simulated with appropriate turbulence (laminar) models individually.•The flow distributions and heat transfer characteristics among various HFTM sub-channels were discussed.
The International Fusion Materials Irradiation Facility (IFMIF) is designated to generate a materials irradiation database for the future fusion reactors. In the High Flux Test Module (HFTM) the test specimens will undergo a severe structural damage caused by neutron fluxes. The HFTM will be with helium gas. This paper presents the comprehensive thermo-hydraulic simulations of the HFTM as a part of the design activities. The turbulence models were assessed by comparing the simulations with in-house annular channel experiments. Since the required coolant flow rates are different for different compartments, multiple fluid domains were employed and simulated with appropriate turbulence (laminar) models individually. The flow distributions and heat transfer characteristics among various HFTM sub-channels will be discussed. Sensitivity study was carried out to assess the impacts of several factors on the simulation results.
•The objective is to measure the purge helium pressure drop across various HCPB-relevant pebble beds packed with lithium orthosilicate and glass pebbles.•The purge helium pressure drop significantly ...increases with decreasing the pebbles diameter from one run to another.•At the same superficial velocity, the pressure drop is directly proportional to the helium inlet pressure.•The Ergun's equation can successfully model the purge helium pressure drop for the HCPB-relevant pebble beds.•The measured values of the purge helium pressure drop for the lithium orthosilicate pebble bed will support the design of the purge gas system for the HCPB breeder units.
The lithium orthosilicate pebble beds of the Helium Cooled Pebble Bed (HCPB) blanket are purged by helium to transport the produced tritium to the tritium extraction system. The pressure drop of the purge helium has a direct impact on the required pumping power and is a limiting factor for the purge mass flow. Therefore, the objective of this study is to measure the helium pressure drop across various HCPB-relevant pebble beds packed with lithium orthosilicate and glass pebbles. The pebble bed was formed by packing the pebbles into a stainless steel cylinder (ID=30mm and L=120mm); then it was integrated into a gas loop that has four variable-speed side-channel compressors to regulate the helium mass flow. The static pressure was measured at two locations (100mm apart) along the pebble bed and at inlet and outlet of the pebble bed. The results demonstrated that: (i) the pressure drop significantly increases with decreasing the pebbles diameter, (ii) for the same superficial velocity, the pressure drop is directly proportional to the inlet pressure, and (iii) predictions of Ergun's equation agree well with the experimental results. The measured pressure drop for the lithium orthosilicate pebble bed will support the design of the purge gas system for the HCPB.
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