A crystal detector for measuring beta and internal conversion electrons inflowing air containing fission gases

Low levels of radioactive gases are released from nuclear electric power ge neration, nuclear fuel reprocessing plants, nuclear weapons tests and from diagnostic medical uses of radioactive gas tracers. A prototype model of an inorganic scintillator - Crystal Gas Electron Detector (CGED) - was built for measurements of xenon isotopes in-line by detecting the beta and intern al conversion (IC) electrons present in atmospheric samples. The detection and quantification of the radionuclide spectra are accomplished, during air flow, without complete purification of the fission gases. Initial operatio nal tests and calibrations made permit the integration of the CGED into a p ortable Gas Analysis, Separation and Purification (GASP) system [1-3]. The CGED detector, Pulse Shaping and Timing (PSA) electronics, and mathematical treatment of the accumulated spectra are used to resolve the K and LMNO-IC electrons and beta continuum. These data are used, in-line, for dating the age of an air parcel containing fission gases released from nuclear reacto rs and/or from nuclear weapons tests, as part of the monitoring equipment r equired to enforce the Comprehensive Test Ban Treaty, CTBT. This report is one of a series of papers providing the design features, operational method s, calibration, and applications of radioactive gas analysis system to the International CTBT. (C) 1999 Elsevier Science B.V. All rights reserved.