D. Demange

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.

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.

Improvement and characterization of small cross-piece ionization chambers at the Tritium Laboratory Karlsruhe

Abstract At the Tritium Laboratory Karlsruhe stainless steel cross-piece ionization chambers have been used to measure the activity concentration of tritiated gases in experiments and processes for more than 10 years. New chambers with an optimized design in terms of the effective chamber volume were produced. Furthermore, they were gold and copper plated to determine the influence of the coatings on the signal and on the memory effect. A new chamber of the old design was built for direct comparison of the signals. The chambers were characterized with different helium-tritium mixtures in 8 runs and the ionisation current as a function of the static gas pressure was measured. When comparing the three new chambers, the gold chamber always showed the highest current, followed by the copper chamber. After exposing the chambers to ~13,100 TBq/m3, the memory effect was investigated by using a similar gas mixture of the earlier runs with ~1,500 TBq/m3. The gold chamber showed the highest memory effect, the copper chamber the lowest. This paper describes the design and the testing procedure of the chambers. It presents the first experimental results on the chamber performance, on the memory effects as well as calibration curves.

Zeolite Membrane Cascade for Tritium Extraction and Recovery Systems

Abstract Membrane separation by zeolite membranes has been proposed as a pre-concentration stage for the tritium extraction from the purge helium of the breeding blanket combined with a final recovery by the catalytic membrane reactor PERMCAT. This fully continuous operation improves the tritium management in fusion machines, minimizing the tritium inventory. In this work permeation measurements for mixtures of hydrogen, helium and water vapor at different compositions are presented. In parallel the first results of a simulation work comprising a model for multistage separation, allowing scaling up towards DEMO application, are discussed.

Tritium Processing for the European Test Blanket Systems: Current Status of the Design and Development Strategy

Abstract Tritium processing technologies of the two European Test Blanket Systems (TBS), HCLL (Helium Cooled Lithium Lead) and HCPB (Helium Cooled Pebble Bed), play an essential role in meeting the main objectives of the TBS experimental campaign in ITER. The compliancy with the ITER interface requirements, in terms of space availability, service fluids, limits on tritium release, constraints on maintenance, is driving the design of the TBS tritium processing systems. Other requirements come from the characteristics of the relevant TBM and the scientific programme that has to be developed and implemented. This paper identifies the main requirements for the design of the TBS tritium systems and equipment and, at the same time, provides an updated overview on the current design status, mainly focusing onto the tritium extractor from Pb-16Li and TBS tritium accountancy. Considerations are also given on the possible extrapolation to DEMO breeding blanket.

Tritium Transport Issues for Helium-Cooled Breeding Blankets

Tritium mobility through breeding blanket (BB) and steam generator heat transfer areas is a crucial aspect for the design of the next generation DEMO fusion power plants. Tritium is generated inside the breeder, dissolves in and permeates through materials, thus leading to a potential hazard for the environment. For this reason, it is important to carry out the tritium migration analysis for a specific DEMO blanket configuration to predict the released amount of tritium during the plant operation. Unfortunately, tritium assessments are often affected by several uncertainties implying very important modeling and parametric issues. In this paper, the main permeation issues are identified and possible solutions are discussed to address the modeling issues and the parametric uncertainties affecting the T migration assessments for the two DEMO helium-cooled BBs: 1) helium-cooled pebble beds and 2) helium-cooled lithium-lead. For these two helium-cooled blanket concepts various tritium migration analyses will be carried out by means of the computational tool FUS-TPC to define proper and feasible tritium mitigation techniques, which are needed to keep the tritium losses lower than the allowable environmental release (i.e., 20 Ci/d).

CAPER as Central and Crucial Facility to Support R&D with Tritium at TLK

Abstract The CAPER facility at TLK originally devoted to R&D on tokamak exhaust processing has been significantly upgraded over the last years. Beside new R&D on highly tritiated water, CAPER is presently largely used to support satellite experiments, mainly those dedicated to R&D on advanced analytics. Mutation from R&D to part of the TLK tritium infrastructure necessitated new features to be installed in order to facilitate and optimize tritiated mixtures preparation and sample filling, and to enable satellites experiments to discharge their waste gas to CAPER for clean-up. This paper presents recent CAPER mutations to become a central and key facility at TLK.

Tritium Activity Determination in a Wastes Drum by Helium-3 Ingrowth Method

ABSTRACT This paper presents a method to quantify the tritium activity in a drum by measurement of its helium-3 leak. A model of helium exchanges with the atmosphere has been developed. It takes into account the diffusion phenomena and the influence of atmospheric pressure changes. The validation has been achieved with a pilot and the comparison between theoretical and experimental data has highlighted a very good agreement. Drum’s helium-3 leak equilibrates after six months and then equals the helium-3 production in the drum and so to the total tritium activity. The measurement technique is also described. It’s based on quantitative helium trace level determinations with an adapted leak detector. After a drum’s confinement period of 5 hours and a cryogenic treatment of gaseous samples, the method allows to detect a 5 GBq activity of tritium in a drum.

Highly tritiated water processing by isotopic exchange

Abstract Three kinds of Pt-catalyzed zeolite were tested as candidates for isotopic exchange of highly tritiated water (HTW), and CBV 100 CY (Na-Y, Si/Al~5.0) shows the best performance. Small-scale tritium testing indicates that this method is efficient for reaching an exchange factor (EF) of 100. Full-scale non-tritium testing implies that an EF of 300 can be achieved in 24 hours of operation if a temperature gradient is applied along the column. For the isotopic exchange, deuterium recycled from the Isotope Separation System (deuterium with 1% T and/or 200 ppm T) should be employed, and the tritiated water regenerated from the Pt-catalyzed zeolite bed after isotopic exchange should be transferred to Water Detritiation System (WDS) for further processing.