Control of Chemical Forms of Tritium in FLiNaK under Low Flux Neutron Irradiation

Abstract

The use of the isotopic exchange between tritium produced in molten salts and hydrogen molecules in a sweep gas has been proposed as a way of recovering tritium in a self-cooled molten salt liquid blanket system [1-3]. In the present study, rate coefficients of the isotopic exchange for molten FLiNaK (LiF-NaF-KF) have been evaluated in a series of low flux neutron irradiation experiments with an AmBe neutron source at the OKTAVIAN facility of Osaka University in Japan. Approximately 300 cm 3 of FLiNaK were irradiated at 773 K in an Inconel 600 crucible, and tritium released from the free surface of FLiNaK has been swept by a pure He gas or He+H 2 (0.1%) gas. The change in the amounts of soluble tritium (TF, HTO) and insoluble tritium (HT) recovered by water bubblers has been evaluated in each sweep gas to evaluate the effectiveness of the tritium recovery with the isotopic exchange.

Radioactivation Analysis of Concrete Wall in OKTAVIAN Facility

“…Fig. 7 2D distributions of radioactivities of 3 H, 22 Na, 26 Al, 36 Cl, 41 Ca, 45 Ca, 54 Mn, 55 Fe, 57 Co, 60 Co, 59 Ni, 63 Ni, 152 Eu, and 154 Eu for the concrete at the floor surface.…”

“…Figure 3 shows the schematic of a tritium sampler system, which is composed of an Ar gas flow system, a closed stainless-steel container, an electric furnace, and water bubbling tubes [25][26][27]. The core sample weighing approximately 8 g in the closed, stainless-steel container was heated by an electric furnace at 400 • C flowing Ar gas.…”

“…Moreover, the radioactivities with half-lives on the order of 10 years, such as 3 H, 60 Co, and 152 Eu, were gradually decreased. Figure 7 shows the 2D distributions of the radioactivities of 3 H, 22 Na, 26 Al, 36 Cl, 41 Ca, 45 Ca, 54 Mn, 55 Fe, 57 Co, 60 Co, 59 Ni, 63 Ni, 152 Eu, and 154 Eu for the concrete at the floor surface. The 2D distributions of the radioactivities based on the neutron capture reactions, such as 3 H and 60 Co, were approximately uniform.…”