Volume 6 Issue 4 ( December 2019 )

Pages 280-284

Feasibility Study of Radioisotope 132Cs Production Using Accelerator-Based Neutrons

Md Kawchar Ahmed Patwary, Tadahiro Kin, Naoto Araki, Katsumi Aoki, Kosuke Yoshinami, Masaya Yamaguchi, Yukinobu Watanabe, Masatoshi Itoh


We propose that 132Cs (Eγ = 668 keV and T1/2 = 6.5 d) can replace 137Cs (Eγ = 662 keV and T1/2 = 30 y) as a new environmental tracer of cesium. The alternative tracer, 132Cs, can potentially reveal the short-time dynamics in an environment, which are considered to dominate radioactive cesium absorption after nuclear accidents. We first investigate the production yield and radioactive purity of 132Cs in a production experiment at the Cyclotron and Radioisotope Center of Tohoku University. The 132Cs was produced via the 133Cs(n,2n) reaction with neutrons generated by bombarding accelerated deuterons onto a 4 mm-thick neutron converter made of carbon. The generated neutrons were then irradiated onto a Cs2CO3 sample. The experiment yielded 102.2 kBq/g of 132Cs, sufficient for tracing environmental cesium. The radioactive purity reached 98%, indicating negligible amounts of by-products. Next, a 132Cs tracer experiment was performed on three different soil samples: an andosol soil, a haplic fluvisol soil, and a gleyic fluvisol soil. This feasibility study confirmed that the new tracer can measure soil cesium distributions as adequately as the 137Cs tracer. Thus, we conclude that 132Cs is a promising alternative environmental tracer of 137Cs.

Keywords: 132Cs, 137Cs, environmental tracer, accelerator-based neutrons.