S. Welte

Tritium tests with a technical PERMCAT for final clean-up of ITER exhaust gases

One of the design targets for the ITER Tokamak Exhaust Processing system is not to lose more than 10−5 g h−1 into the Normal Vent Detritiation System of the Tritium Plant. The plasma exhaust gas, therefore, needs to be processed in a way that an overall tritium removal efficiency of about 108 is reached. Such a high decontamination factor can only be achieved by multistage processes. The third step of the three step CAPER process developed at the TLK is based on a so-called permeator catalyst (PERMCAT) reactor, a direct combination of a Pd/Ag permeation membrane and a catalyst bed. The PERMCAT principle is based on isotopic swamping in a counter current mode. Previous tritium experiments employing laboratory scale PERMCAT reactors have revealed decontamination factors as high as 105 for the third CAPER step. First tritium tests with a technical scale PERMCAT reactor led to similar decontamination factors and clearly demonstrated that the required overall ITER decontamination factor can be reached with a technical PERMCAT as the final clean-up step of the CAPER process.

Successful experimental verification of the Tokamak exhaust processing concept of iter with the caper facility

One of the design targets for the Tokamak Exhaust Processing (TEP) system of ITER is not to lose more than 10-5gh-1 into the Normal Vent Detritiation system of the Tritium Plant. The plasma exhaust gas therefore needs to be processed in a way that a tritium removal efficiency of about 108 with respect to the flow rate is achieved. Expressed in terms of tritium concentrations this corresponds to a decontamination from about 130 gm-3 down to about 10-4 gm-3 (about 1 Cim-3 = 3.7*1010 Bqm-3). The three step reference process for the TEP system of ITER is called CAPER and has been developed and realized at the Tritium Laboratory Karlsruhe (TLK). After the successful commissioning of the PERMCAT reactor as the key component of the third step detailed parametric tritium testing of the 3 steps involving the processing of more than 300 g tritium has been carried out and decontamination factors beyond the design requirements have been demonstrated for each process step and for the process as a whole. Not only the decontamination factor of 108 as required by ITER, but also the operational mode of TEP as a waste dump for gases from diverse sources has been experimentally validated with the CAPER facility.

A Decade of Tritium Technology Development and Operation at the Tritium Laboratory Karlsruhe

Abstract The Tritium Laboratory Karlsruhe (TLK) has been designed to handle relevant amounts of tritium for the development of tritium technology for fusion reactors. This paper describes the tritium technology development and experience gained during the upgrade of facilities, interventions, replacement of failed components and operation of the TLK since its commissioning with tritium in 1994.

Caper Modifications and First Experimental Results on Highly Tritiated Water Processing with PERMCAT at the Tritium Laboratory Karlsruhe

Abstract The CAPER facility operated at the Tritium Laboratory Karlsruhe for the demonstration of the tokamak exhaust processing system comprises a PERMCAT reactor as final clean-up stage. CAPER has been upgraded to enable the production of highly tritiated water (HTW) to be detritiated with PERMCAT. A staged approach for HTW production in CAPER is ongoing, using currently a metal oxide reactor, and later a micro-channel catalytic reactor. The whole experimental plan using the current single-tube PERMCAT reactor shall cover the HTW processing at flow rates up to 10 mL/min, with HTW up to 1.4 MCi/kg (i.e. stoichiometric DTO). The staged approach and corresponding CAPER modifications are described. The first experimental results obtained using metal oxide reactor are reported and discussed.

Behavior of solid polymer membrane electrolyzers in use with highly tritiated water

Abstract These days more and more modern electrolysis cells are operated with new solid polymer membranes. These membranes prevailing DuPont’s Nafion® are not only used for electrolysis but as well for the wide spectrum of fuel cells due to their good mechanical and chemical stability and the high proton conductivity. For that reason it is intended to use these solid polymer membranes for the electrolyzer units in the ITER Water Detritiation System (WDS). The influence of Tritium during water electrolysis to the membrane material is still not sufficiently investigated. Therefore long-term experiments of solid polymer membranes were performed at Tritium Laboratory Karlsruhe (TLK). The chemical degradation and durability behavior of the used Nafion® 117 membrane are investigated in details under tritiated water conditions. For comparison a second cell was operated with demineralized water for the same period. In addition to the experimental rigs with single Nafion® membranes, two industrial electrolyzer units equipped with Nafion® membranes were operated during different tritium experiments at TLK. Before operation they had been modified to be compatible for tritium operation. After long operation period no degradation in the performance of the electrolyzers is observable.

Tritium processing tests for the validation of upgraded PERMCAT mechanical design

Abstract The PERMCAT process, chosen for the final clean-up stage of the Tritium Exhaust Processing system in ITER, directly combines a Pd/Ag membrane and a catalyst bed for the detritiation of gaseous mixtures containing molecular and chemically bound tritium. Upgraded PERMCAT mechanical designs have been proposed to both increase the robustness and simplify the design of the reactor. One uses a special corrugated Pd/Ag membrane able to withstand change in length of the membrane during both normal operation and in the case of off-normal events. Based on this design, an upgraded PERMCAT reactor has been produced at FZK and successfully tested at TLK with ITER relevant tritiated gaseous mixtures using the CAPER facility.

Experiments on water detritiation and cryogenic distillation at TLK. Impact on ITER fuel cycle subsystems interfaces

Abstract The ITER Isotope Separation System (ISS) and Water Detritiation System (WDS) should be integrated in order to reduce potential chronic tritium emissions from the ISS. This is achieved by routing the top (protium) product from the ISS to a feed point near the bottom end of the WDS Liquid Phase Catalytic Exchange (LPCE) column. This provides an additional barrier against ISS emissions and should mitigate the memory effects due to process parameter fluctuations in the ISS. To support the research activities needed to characterize the performances of various components for WDS and ISS processes under various working conditions and configurations as needed for ITER design, an experimental facility called TRENTA representative of the ITER WDS and ISS protium separation column, has been commissioned and is in operation at TLK. The experimental program on TRENTA facility is conducted to provide the necessary design data related to the relevant ITER operating modes. The operation availability and performances of ISS-WDS have impact on ITER fuel cycle subsystems with consequences on the design integration. The preliminary experimental data on TRENTA facility are presented.

Tritium Laboratory Karlsruhe: Administrative and Technical Framework for Isotope Laboratory Operation

Abstract Originally licensed in 1993 the Tritium Laboratory Karlsruhe (TLK) is a unique pilot scale isotope laboratory focused on tritium handling and processing to conduct a variety of scientific experiments and development tasks. In order to fulfil all requirements regarding the license, a framework of regulations is applied as a basis for the operation of TLK, as well as the setup of new experiments and the design of components. This paper will give an overview on the framework of operation in view of licensing issues, as well as administrative and technical regulations mandatory to legally and reliably operate an isotope laboratory of this scale.

Infrared Spectroscopy in Liquid Hydrogen Isotopologues for the ISS of ITER

Abstract The ITER project aims at demonstrating the technical feasibility of nuclear fusion in a DT plasma. One of the important steps towards a functional fusion power plant is the development of a stable and reliable fuel cycle. Major developments on this field are made at the Tritium Laboratory Karlsruhe (TLK). In this paper the design and installation of an analysis apparatus for tritium concentrations via InfraRed (IR) absorption for engagement in the ITER ISS is described. The IR analysis is performed in the liquid hydrogen phase at the bottom of a cryogenic distillation column similar to those foreseen for ITER ISS. Technical constraints and physical boundary conditions are presented as well as experimental methods and preliminary results. The technical feasibility is shown and suggestions for further development of IR spectroscopy for ITER appliances are given.

Performance Tests of Tritium Separation by LPCE Column at TLK Facility

Abstract The research for the performance improvement of the Liquid Phase Chemical Exchange (LPCE) column has been carried out at Nagoya University in collaboration with National Institute for Fusion Science (NIFS) and Tritium Laboratory Karlsruhe (TLK). Kogel catalysts and Dixon gauze rings were mixed at a certain ratio and packed in the column in a random manner. Performance tests of tritium separation by the column using tritiated water of 26 kBq/cm3 in the electrolyzer were performed at the TLK experimental facility. An effect of axial mixing on the separative performance of the column was examined by a stage-wise model, named “Channeling stage model.” It was suggested by the analyses that quite a long-distance axial mixing generated in the water phase.