135Xe measurements with a two-element CZT-based radioxenon detector for nuclear explosion monitoring

Abstract

Measurement of elevated concentrations of xenon radioisotopes (Xe, Xe,Xe and Xe) in the atmosphere has been shown to be a very powerful method for verifying whether or not a detected explosion is nuclear in nature. These isotopes are among the few with enough mobility and with half-lives long enough to make their detection at long distances realistic. Existing radioxenon detection systems used by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) suffer from problems such as complexity, need for high maintenance and memory effect. To study the response of CdZnTe (CZT) detectors to xenon radioisotopes and investigate whether it is capable of mitigating the aforementioned issues with the current radioxenon detection systems, a prototype detector utilizing two coplanar CZT detectors was built and tested at Oregon State University. The detection system measures xenon radioisotopes through beta-gamma coincidence technique by detecting coincidence events between the two detectors. In this paper, we introduce the detector design and report our measurement results with radioactive lab sources andXe produced in the OSU TRIGA reactor. Minimum Detectable Concentration (MDC) for Xe was calculated to be 1.47 ± 0.05 mBq/m.

Gamma-ray Spectroscopy in Low-Power Nuclear Research Reactors

“…Among the identified isotopes are the gaseous Xe, I isotopes, and aerosol Cs isotopes that mostly contribute severe accident calculations and fallout predictions [81], as well as reactor poisoning [82]. This measurement may therefore offer an opportunity for the real-time tracking of the Xe poisoning of the reactor.…”