福島第一原子力発電所事故の考証

(4) セシウム同位体比の炉内分布評価

抄録

It is well known that a radioactivity ratio of cesium-134 to cesium-137 is quite a beneficial index when ones want to specify the source of radioactivity including cesium emitted to the environment. Concerning the Fukushima Daiichi nuclear power plant accident, so much research has been carrioud out on this radioactivity ratio. The present paper reviews results of measurements and analyses of this quantitiy, and also shows calculation results of the in-core cesium radioactivity ratio distributions in the units 1, 2 and 3. Calculation results reveal that there is significant dependence of the radioactivity ratio on the fuel shuffling batch and axial loaded position of the fuel.