Development of a Prototype Instant Working Level Meter with Automatic Individual Radon-Daughter Readout.

摘要

The Instant Working Level Meter (IWLM) evaluates the Working Level and the individual Rn-daughter concentrations in a uranium mine atmosphere within 5minutes. The instrument is portable and fully automatic. The WL and the RaA, RaB,and RaC concentrations (pCi/liter) are displayed in digital form. Calculation of these quantities is performed by a preprogramed CMOS calculator chip using the counts observed in the instruments three channels (RaA, RaB C, RaC). The Rn-daughters are collected on a membrane filter at a flowrate of 12liter/min.; a-spectroscopy is performed with a silicon surface barrier detector,the B + y -counts are detected with a plastic scintillator plus PM tube. No assumptions about Rn-daughter equilibrium are made. Only constancy of the Rn-daughter concentrations during the time of sampling (2minutes) is assumed. The unit is entirely solid state with the exception of the photomultiplier. The range of the instrument is 0.01 - 100WL.