Source term estimation of Xe-135 observed at the noble gas monitoring station in Japan regarding CTBT

Furuno, Akiko; Yamamoto, Yoichi; Tomita, Yutaka; Kurihara, Toshiyuki

no journal, , 

This study aims at the source term estimation of Xe-135 observed at the Takasaki Radionuclide Station of CTBT International Monitoring System and at two temporary stations, Horonobe and Mutsu of the Joint Noble Gas Measurement Project with CTBT, from the viewpoint of atmospheric dispersion. Radioactive xenon has been irregularly and frequently observed at these stations, thus it is very important to expose the source of the release areas in order to ensure the detection of nuclear tests. The most frequently observed isotope of radioactive xenon monitored by CTBT is Xe-133; nuclear facilities in Europe may be possible source as well as in East Asia depending on the meteorological conditions due to its relatively long half-life (5.25 days), making it difficult to specific of the source. On the other hand, Xe-135 has a short half-life of about 9 hours, and the possible release areas are limited to a relatively small area. In this presentation, we will focus on the Xe-135 detection events in the past four years and discuss the possible sources that could affect Japan.