Year
1999
Abstract
In order to establish an international monitoring system for the Comprehensive Nuclear Test Ban Treat (CTBT) verification, JAERI accepted responsibility for the construction of CTBT radionuclide monitoring stations at Takasaki and Okinawa and for the preparation of a CTBT radionuclide laboratory at JAERI-Tokai site. The monitoring stations collect radioactive particles (both of two stations) and noble gas (only for Takasaki) samples from the atmosphere, and channels it into air-filters and a charcoal-trap, respectively, to analyze it with a fully automated gamma-ray spectrometric system. The main target radionuclides are Ba-140, Zr-95, etc., in the particles and Xe-122, 135 in the nobel gas. If abnormal events are observed at CTBT monitoring stations, the divided samples are sent to the several CTBT radionuclide laboratories for further analysis. Trace amounts of radionuclides in air-filtered samples will be measured again precisely by low-background gamma-ray spectrometer. And, if necessary, we will analyze them more accurately using a radiochemical separation and ICP-MS. As for the sample of noble gas, especially xenon, radioactivity measurement of the short-lived xenon nuclides is effective in detecting an underground nuclear weapon test. The gas released from the test should be distinguished from that of other sources. So as to extend the monitoring of noble gases to other sources, an analytical technique with gas mass spectrometry is proposed for the determining of the unique isotopic compositions of the stable noble gas release from nuclear facilities. This paper presents the detailed program for the development of microanalytical techniques for atmospheric radionuclide monitoring.