Estimation of Te-132 Distribution in Fukushima Prefecture at the Early Stage of the Fukushima Daiichi Nuclear Power Plant Reactor Failures

Tellurium-132 (Te-132, half-life: 3.2 d) has been assessed as the radionuclide with the third largest release from the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011; thus it would have made some dose contribution during the early stage of the reactor failures. The available data for Te-132 are, however, limited. In this study, available reported values of other isotopes of Te were compiled to estimate Te-132 concentration (in MBq m(-2)). It was found that Te-132 and Te-129m (half-life: 33.6 d) concentrations were well correlated (R = 0.99, p < 0.001) by t test. Thus, Te-132 concentrations on March 11, 2011 were estimated from Te-129m using the concentration conversion factor (Te-132/Te-129m) of 14.5. It was also found that since deposited Te-129m was well retained in the soil, the data collected in March-May of 2011 were applicable to Te-132 estimation. It was possible to obtain the first Te-132 concentration contour map for the eastern part of Fukushima Prefecture, including data from within the 20-km exclusion zone around the FDNPP, using these newly available estimated Te-132 data sets.