The rapid, in situ monitoring of dispersed gaseous radionuclides in confined space

• Main Authors: Tsai, Chin-Hsien, 蔡親賢
• Other Authors: Chung, Chien
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/07825080188885056569

碩士 === 國立清華大學 === 原子科學研究所 === 81 === The purpose of this study is to examine the applicabi- lity of real-time monitoring of gaseous radionuclide with a high- purity germanium (HPGe) detector. In the case of normal operations, continuous release of gaseous radio- nuclides of tracer amount of isotopes of Ar,Kr and Xe from reactor is found. The system, consisted of portable HPGe and multichannel analyzer (MCA), is designed for the measurement both in sealed chamber and in outdoors sur- rounded with gaseous radionuclide. Besides, quantitative, qualitative, prompt and on-line measurement can be reached with the movable detectors without air sucking pump and filter paper. The research was divided into two major parts as follows : (1) The HPGe detector was calibrated by using of artificial gaseous Ar-41,Kr-85m and Xe-125,133,135 releas- ed to a sealed chamber. Minimum detectable concentration and possible application field monitoring are discussed. (2) Three various types of HPGe detectors were calibrated , the relationship between detectors' efficiency and the crystal volume was observed. The results show : (1)linear relationship between eff- iciency and energy in log coordinate can be obtained. The detector system is available for the measurement of minimum detectable concentration (MDC) far less than legal maximum permissible concentration (MPC), application to detect the gaseous radionuclide of nuclear disaster and nuclear war.(2) There exists a linear relationship between crystal volume and relative efficiency so that the inter- relation between efficiencys with various detectors can be developed in emergenecy.