Improvement of tritium accountancy technology for ITER fuel cycle safety enhancement

Abstract

In order to improve the safe handling and control of tritium for ITER fuel cycle, effective "in-situ" tritium accounting methods have been developed at Tritium Process Laboratory in Japan Atomic Energy Research Institute under one of the ITER-EDA R&D Tasks. A remote and multi-location analysis of process gases by an application of laser Raman spectroscopy developed and tested could provide a measurement of hydrogen isotope gases with a detection limit of 0.3 kPa for 120 seconds analytical periods. An "in-situ" tritium inventory measurement by application of a "self assaying" storage bed with 25 g tritium capacity could provide a measurement with a required detection limit less than 1 % and a design proof of a bed with 100 g tritium capacity.

Safe handling experience of a tritium storage bed

“…On the other hand, there are two beds for 25 g and 10 g of tritium storage, with "in-bed" gas flowing calorimetric function for self-accountancy, as reported in Refs. [11][12][13]. Each capacity is based on ZrCoQ 1.8 (Q = H,D,T).…”

“…However, it also has disadvantages from the safety point of view, such as high pyrophoricity with oxygen, high reactivity with nitrogen, fine powdering, etc., and it is a controlled nuclear material in Japan, even if it is depleted. On the other hand, zirconium-cobalt (ZrCo), an inter-metallic compound, has been investigated and demonstrated as a tritium storage material instead of U at the Tritium Process Laboratory (TPL) of the Japan Atomic Energy Agency (JAEA) for about 20 years [9][10][11][12][13][14] and at the Tritium Laboratory Karlsruhe of the FzK [15][16][17][18]. ZrCo has many attractive characteristics from the safety point of view, such as low reactivity with oxygen and nitrogen, similar equilibrium pressure isotherm, and it is not a nuclear material, so it can be handled everywhere.…”

Dynamic Raman spectroscopy of hydrogen isotopomer mixtures in-line at TILO

“…Of particular note and relevance to the work described in our present paper is the fibre-coupled tritium accounting system developed by O'hira et al [13], which aimed at improving the safe handling and control of tritium for the fuel cycle of the ITER tokomak fusion reaction concept. This system demonstrated that the isotopomeric composition of a tritium gas flow under high flow (up to 200 Pa m 3 s…”

Accurate Reference Gas Mixtures Containing Tritiated Molecules: Their Production and Raman-Based Analysis

“…For example, KATRIN successfully employs Raman spectroscopy monitoring for continuous, in-line compositional analysis of its circulating source gas [ 7 ]. For the accountancy of tritium in the fusion fuel cycle of ITER/DEMO, Raman spectroscopy has been evaluated as one possible analytical tool [ 8 , 9 , 10 ], which is still partially under procurement [ 11 ], or is under development but has not been tested with tritium yet [ 12 ].…”