Response Analysis of Radioactive Gas Monitors for Short Duration Inflow of Radioactive Gas

概要

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For accurate evaluation of gaseous activity released from nuclear facilities, proper calibration of radioactive gas monitors is required. Most of gas monitors are calibrated with a closed loop method. In this method, it is implicitly assumed that radioactive gases are statically released without rapid change of radioactivity concentration. However, actual radioactive gases are sometimes released in a short time-duration and with sudden change of radioactivity concentration. To confirm the applicability of the conventional closed loop method to such a kind of gas release, the responses of three typical gas monitors were analyzed in the manner of a pulse-like injection of a radioactive gas. The gaseous behavior in the sampling chamber of the monitors was evaluated from detailed observation of response curve. The gaseous activity injected pulse-like into the monitors was compared with that calculated from their response curves with the calibration factor determined by the closed loop method. These results show that the activity concentration in the sampling chamber becomes uniform as soon as the radioactive gas flows into the monitor. That is, the calibration factors determined by the closed loop method are applicable to both static and dynamic release.
一般社団法人日本原子力学会の論文
2001-12-25