Consequences of deuterium retention and release from Be-containing mixed materials for ITER Tritium Inventory Control

Abstract

In order to assess the tritium removal procedure currently suggested for ITER (wall baking As a consequence, the baking operation in ITER would work for tritium removal from the first wall and Be-rich deposited layers formed at low temperature areas, while it does not work for C-rich codeposited layers and/or plasma-facing surfaces heated above 623 K during a discharge.

Erosion, formation of deposited layers and fuel retention for beryllium under the influence of plasma impurities

“…The spectra exhibit similar features as observed e.g. in [21,26] with a low-temperature peak, presumably corresponding to the supersaturation binding states, and a shoulder towards higher temperatures corresponding to the decomposition of BeD 2 . The total amount of co-deposited deuterium is comparable for the cases with and without argon, which results in incrementally lower D/Be values in the experiments with higher argon fractions in the plasma (table 1).…”

Wall conditioning for ITER: Current experimental and modeling activities

“…Laboratory experiments suggest that almost all tritium should desorb from co-deposited ''pure'' Be layers at 350°C, up to 90% of the initially co-deposited fuel being thermally released after 24 h at this temperature [11,12]. Desorption of D implanted in Be-containing mixed materials (W, C) was found to be less efficient [13], the amount of released fuel decreasing with the amount of W or C in the layer. For D implanted in Be, the amount of fuel that can be released is reduced if the implantation temperature is increased.…”

Study of deuterium retention in/release from ITER-relevant Be-containing mixed material layers implanted at elevated temperatures

“…The D release profiles of pure Be measured in this study can be well reproduced by combination of these release peaks. It is generally observed [8,15] that the amount of D desorption from states (2) and (3) increases under D implantation at moderately elevated temperatures (up to ~500 K), compared to 320 K implantation (shown in Fig. 3 (a) is significantly reduced at this temperature.…”

“…In this sense, we have previously investigated deuterium (D) retention in and release from Be-containing mixed material layers [8]. In these studies, D loading to the layers was mostly performed at 300 ~ 350 K. However, it is obviously necessary to perform retention studies also under D loading at elevated temperatures, because the temperature on the ITER wall is expected to be higher than 300 K. In the present study, therefore, D implantation to Be-containing mixed material layers are performed at elevated temperatures.…”