Sagami Chemical Research Center

Tomo Saito

Kazuo Watanabe

Naotake Morikawa

Yumiko Nishiyama

A continuous tritium radioactivity measuring system is disclosed, in which a sample gas containing tritium is mixed with hydrogen gas, water vapor and lower hydrocarbon gases with the assistance of a catalyst for causing an isotope exchange reaction between the tritium contained in the sample gas and hydrogen. The resultant tritium gas and lower hydrocarbons containing tritium are removed from the remaining hydrogen water, and radioactivity detection is performed thereon.

Tritium radioactivity measuring system

A sample material to be dehydrated is enclosed in a container transmissive to microwave and air is past through the container under a microwave radiation to preferentially remove the water content of the sample. The dehydrated sample may be incinerated by switching the air supply to an oxygen supply under the microwave radiation.

Dehydration and incineration of sample material

A first and a second radioactivity detectors are used in series or in parallel which have substantially the same constructive features and the second radioactivity detector includes a fixed standard radioactive source therein. Sample gases each having a common radioactivity and having a different quenching effect are passed through the two radioactivity detectors sequentially to measure the effective radioactivities thereof to thereby obtain counting efficiencies of the two radioactivity detectors. A correction curve is drawn by putting the counting efficiency of the first radioactive detector along one axis of an orthogonal coordinates and the counting efficiency of the second radioactivity detector along the other axis of the coordinates. An unknown sample is treated in the same manner as the above to obtain the counting efficiency of the second detector for the unknown sample and a corresponding counting efficiency of the first radioactivity detector is obtained from the correction curve by the last counting efficiency of the second radioactivity detector. The quenching effect of the unknown sample is compensated for by using the corresponding counting efficiency of the first radioactivity detector.

Method of compensating for quenching effect of substance contained in a

An air sample including substances containing tritium and substances containing carbon-14 is oxidized continuously while measuring a volume thereof and water and carbon dioxide included in the oxidized air sample are collected respectively continuously. After water and carbon dioxide are recovered, the radioactivities thereof are measured respectively.

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Sagamihara, Japan

Tomo Saito