Dr. Tsubokura's Radiation Lecture Vol.1

Author: Masaharu Tsubokura

Editors: Izumi Yoshida, Mariko Irie

1. The problem is the “quantity” of exposure to radiation Due to the Fukushima Daiichi nuclear disaster, we are now obliged to know about radiation. In this column, I would like to consider the knowledge of daily radiation. The most important thing is not whether your body has been exposed to radiation or not, but how much you were exposed. We should count it as a problem of “quantity.” Radiation cannot be smelled or visualized. This is similar to ultraviolet rays, which we are exposed to under the sun. The effects on the skin really depend on the situation because walking a bit under the sun in winter is much different from staying naked for several hours in the summer. It is true that we got extra exposure due to the nuclear disaster; however, it was not the first time we were exposed. “How much did the nuclear accident increase exposure?” That is important to know.

2. Radioactive materials emit radiation Let us revisit the difference between radiation and radioactive material. When spider fireworks are lit, the central fire burns red and scatters, and sparks are scattered around. The sparks that were scattered at first strongly weaken over time, and the fire disappears at the end. We can say “the burning coal is a radioactive substance,” “the spark is radiation,” and “the time when the momentum weakens by half is called half-life.” Radioactive substances, not radiation, were dispersed in the surrounding environment due to the nuclear accident. You might hear often about iodine, cesium, radon, and potassium as radioactive substances; however, they existed in the environment before the disaster. Each radioactive substance emits radiation, and the radiation hits our body and affects it. After all, the problem is not which radioactive substance is there, but how much radiation the substances emit.


The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on January 11 and 18, 2015, and was reproduced for MRIC Global under the author's permission.

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