Ion Cristescu

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.

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.

Overview of the HCPB Research Activities in EUROfusion

In the framework of the EUROfusion’s Power Plant Physics and Technology, the working package breeding blanket (BB) aims at investigating four different BB concepts for an EU demonstration fusion reactor (DEMO). One of these concepts is the helium-cooled pebble bed (HCPB) BB, which is based on the use of pebble beds of lithiated ternary compounds and Be or beryllides as tritium breeder and multiplier materials, respectively, EUROFER97 as structural steel and He as coolant. This paper aims at giving an overview of the EU HCPB BB Research and Development (R&D) being developed at KIT, in collaboration with Wigner-RCP, BUTE-INT, and CIEMAT. The paper gives an outline of the HCPB BB design evolution, state-of-the-art basic functionalities, requirements and performances, and the associated R&D activities in the areas of design, functional materials, manufacturing, and testing. In addition, attention is given also to the activities dedicated to the development of heat transfer augmentation techniques for the first wall and the corresponding testing. Due to their nature as design drivers, a brief overview in the R&D of key HCPB interfacing areas is given as well, namely, the tritium extraction and recovery system, the primary heat transfer and power conversion systems, and safety topics, as well as some specific activities regarding the integration of in-vessel systems through the BB. As concluding remarks, an outline of the standing challenges and future R&D plans is summarized.

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.

Integrated tests of water detritiation and cryogenic distillation in view of ITER design

Abstract One of the main concerns related to licensing of ITER is the amount of potentially tritium release into the environment and the qualification of the barriers against tritium release. The final barrier of tritium release from fuel cycle is the Water Detritiation System (WDS) which will be operated in combination with the Isotope Separation System (ISS). To investigate the performances of various components of these systems, an experimental facility based on Combined Electrolysis Catalytic Exchange (CECE) process with a Cryogenic Distillation (CD) process was built at Tritium Laboratory Karlsruhe. The investigations are focused on two main issues: to quantify the separation performances of deuterium and tritium within the Liquid Phase Catalytic Exchange (LPCE) and CD processes in steady state and in dynamic mode of operation and to develop an integrated control system to be used in ITER ISS, in order to minimize the tritium inventory and to reduce at maximum extent the tritium releases. At TLK the two systems, CECE and CD have been commissioned and the experimental program and preliminary functionality tests of the main components are presented.

Micro-Channel Catalytic Reactor Integration in Caper and R&D on Highly Tritiated Water Handling and Processing

Abstract The CAPER facility of the Tritium Laboratory Karlsruhe has demonstrated the technology for the tokamak exhaust processing. CAPER has been significantly upgraded to pursue R&D towards highly tritiated water (HTW) handling and processing. The preliminary tests using a metal oxide reactor producing HTW afterward detritiated with PERMCAT were successful. In a later stage, a micro-channel catalytic reactor was installed in view of long term R&D program on HTW. The integration of this new system in CAPER was carried out along with a careful safety analysis due to high risk associated with such experiments. First experiments using the μ-CCR were performed trouble free, and HTW up to 360 kCi/kg was produced at a rate of 0.5 g/h. Such HTW was collected into a platinized zeolite bed (2 g of HTW for 20 g of Pt-zeolite), and in-situ detritiation was performed via isotopic exchange with deuterium. These first experimental results with tritium confirmed the potential for the capture and exchange method to be used for HTW in ITER.

Capture and isotopic exchange method for water and hydrogen isotopes on zeolite catalysts up to technical scale for pre-study of processing highly tritiated water

Abstract Highly tritiated water (HTW) may be generated at ITER by various processes and, due to the excessive radio toxicity, the self-radiolysis and the exceedingly corrosive property of HTW, a potential hazard is associated with its storage and process. Therefore, the capture and exchange method for HTW utilizing Molecular Sieve Beds (MSB) was investigated in view of adsorption capacity, isotopic exchange performance and process parameters. For the MSB, different types of zeolite were selected. All zeolite materials were additionally platinized. The following work comprised the selection of the most efficient zeolite candidate based on detailed parametric studies during the H2/D2O laboratory scale exchange experiments (~25 g zeolite per bed) at the Tritium Laboratory Karlsruhe (TLK). For the zeolite, characterization analytical techniques such as Infrared Spectroscopy, Thermogravimetry and online mass spectrometry were implemented. Followed by further investigation of the selected zeolite catalyst under full technical operation, a MSB (~22 kg zeolite) was processed with hydrogen flow rates up to 60 mol h-1 and deuterated water loads up to 1.6 kg in view of later ITER processing of arising HTW.

Review of the TLK Activities Related to Water Detritiation, Isotope Separation Based on Cryogenic Distillation and Development of Barriers Against Tritium Permeation

Abstract The design of ITER tritium processing systems will benefit from experimental data and process validation based on experimental facilities that are ITER scale relevant. Several rigs and experimental facilities have been enhanced and developed at the Tritium Laboratory Karlsruhe (TLK) in order to explore a wide range of envisaged scenarios of tritium plant systems, such as the Water Detritiation System (WDS), Isotope Separation System (ISS) and highly tritiated water processing. In the last few years, detailed experimental investigations and process modeling have been conducted in relation to the Combined Electrolysis Catalytic Exchange and Isotope Separation (CECE-ISS) systems which were focused on evaluation of the impact of deuterium build-up and accumulation in the CECE system. An enhanced configuration of the ITER WDS has been developed, that allows mitigation of the effects due to deuterium accumulation and reduction of the tritium inventory within the electrolysis system. In addition, the benefits concerning the interface between the WDS and ISS are presented. Significant efforts have been made to enhance the simulation tool TRIMO++ that was calibrated against the experimental results collected from the experimental rigs. The new features of the simulation tools are introduced as well. The main references of a new method aiming to mitigate the tritium permeation from the tritium processes streams into the non-contaminated streams such as steam generators are introduced. The reference configuration of first phase of the experimental rigs and the preliminary experimental activities are presented as well.

Tritium accountancy and relevant instrumentation for the WDF from Cernavoda NPP

Abstract The Cernavoda Tritium Removal Facility (CTRF) will be built at Cernavoda Nuclear Power Plant (NPP) for tritium removal and recovery from tritiated heavy water during the operation of CANDU reactors. A Cryogenic Distillation process in combination with a Liquid Phase Catalytic Exchange (LPCE) process is used for tritium removal/recovery from tritiated water. According with the regulation “Implementation of a Nuclear Material Accountancy and Control System by Operators of Nuclear Installations (2009/120/Euratom)” of the European Commission, the operators of nuclear facilities are obliged to provide to the European Commission, regularly detailed information about their installations and the nuclear material in their possession. Also, according with the regulations of the Commission for Control of the Nuclear Activities (CNCAN) from Romania, a nuclear facility is mandated to apply a control system for nuclear guarantees. Therefore, an important issue for CTRF, should be the tritium accountancy in the facility. In order to quantify the tritium inventory in the facility, the subsystems necessary for tritium accountancy in normal operation and also during facility shut down should be identified. Although the facility is, still in the design and construction phase, it is required to identify adequate instrumentation to ensure the implementation of the safeguards requirements. This technical note presents the methods and relevant tritium measurements instrumentation to quantify the tritium inventories from the main systems of the facility.