The Institute for Nuclear Physics (IKP) operates the European Tritium Laboratory Karlsruhe (TLK), a semi-technical scale facility for processing tritium, the radioactive hydrogen isotope. With its license to handle up to 40 grams of tritium, its present site inventory of about 25 grams of tritium, and its extensive infrastructure and experimental apparatus, TLK is a major facility of the German Helmholtz-Gemeinschaft research organisation. The main tasks of TLK are neutrino physics (KATRIN) and fusion research (ITER), plus other EU-projects. TLK is almost unique - only Japan operates a research laboratory with a similar tritium inventory, however with a much smaller laboratory area.
The Handling of Tritium in TLK
Experimentation with tritium demands an entirely closed tritium processing cycle and a highly developed safety technology. At TLK tritium is always contained within at least two barriers. More than ten glove box systems, total volume of about 125 m³, are operated in an area of 841 m² for experiments and a further area of 615 m² for infrastructure. The glove boxes constitute the secondary tritium containment for the primary systems of tritium components and pipe work.
For economical but also for ecological imperatives each tritium process is designed to be as efficient as reasonably achievable. In principle, the tritium inventory in any experiment should be minimized and all gaseous, liquid and solid waste is detritiated as far as possible. Only when an experimental process has proved these capabilities, the inventory of tritium at TLK becomes available for experiments. The simplified diagram shows the self-contained tritium cycle at TLK where tritium is delivered to experiments, recovered and reprocessed for further use.
Tritium is delivered in the form of metal hydride to TLK from Canada. There it is a waste product of CANDU reactors, which use heavy (deuterated) water as a moderator. Before the transfer to the Tritium Storage System, the quantity of tritium tritium delivered to TLK is first confirmed by calorimetric measurements. In a next step, it is prepared for the purpose of experiments in either its pure form, mixed with other hydrogen isotopes or gases, or converted to tritiated water or tritiated methane. After use, the gases are detritiated passing the recovered hydrogen isotope mixtures to the Isotope Separation System (ISS) before tritium is returned to the Tritium Storage System.
TLK has a multi-disciplinary team and it encourages intensive co-operation with its European partners, plus American and Japanese scientists and engineers who take advantage of the unique laboratory facilities at TLK in specific experimental campaigns.
The TLK has a comprehensive infrastructure, which is focused to support the technical experiments. The infrastructure includes:
- the Tritium Transfer System (TTS), which controls the distribution of tritium to the experiments and other systems,
- the Tritium Storage System (TLG), which stores the tritium not used by experiments or other systems,
- the Tritium Cleaning System (CAPER) removes impurities from gases containing hydrogen isotopes,
- the Tritium Measurement Technique (TMT) analyses the composition of gas samples,
- the Isotope Separation System (ISS) can separate protium, deuterium and tritium from each other,
- the facility for the regeneration of molecular sieves used to absorb tritiated water vapour (AMOR).
Calorimetry of Tritium in the TLK
The TLK has four different ways for accounting tritium. The thermal power of tritium radioactive decay is 0.324 W/g and is used to measure accurately the quantity of a tritium sample. Before a delivery is accepted at TLK, the amount of tritium is measured calorimetrically and is compared with the information provided by the supplier, considering the experimental accuracy and radioactive decay in transit. Only after verification tritium is fed into the transfer system (TTS) and subsequent experiments. The TTS verifies the received amount of tritium with a volumetric measurement and if necessary another calorimetric determination of the emptied transport vessel is done. Every transfer of tritium within the TLK requires a measurement and record of the transferred amount of tritium.
|1984||First concept of a Tritium Laboratory|
|1987||First contracts awarded to the industry|
First successful official approval test of particular sections
Opening of the Tritium Laboratory Karlsruhe
Approval from the Ministry of the Environment for the use of 10 g tritium
Tritium experiments with PETRA and CAPRICE
Increase of the tritium quantity to 20 g
|1996||Increasing of the working permission to 40 g tritium|
Decision for the Tritium Laboratory as location for KATRIN
Proposal for the ITER fuel circle
|2006||Delivery of the KATRIN main spectrometer|
New working permission replaces all previous partial permissions
|2010||Delivery of KATRIN WGTS demonstrator for cryotest|
|2015||Delivery of KATRIN WGTS and CPS|
|2016||KATRIN First Light measurement campaign|
|2018||Inaugaration of KATRIN with first tritium measurements|
|2019||Tritium circulation of up to 2.8 kg within KATRIN|