The reason why people are concerned about nuclear power is the harmful effects of the radiation that is produced using the uranium fuel.

With nuclear fission, huge amounts of energy in the form of electromagnetic radiation (gamma rays) is released.
[Radioactivity] is the emission of particles as the result of radioactive decay, and the materials that emit such particles are called [radioactive substances].

The half-life of radioactivity is defined as the length of time required for 1/2 of an unstable radioactive material to decay. As the rate of decay is logarithmic, some of the radioactive substances will always remain.

This and the fact that the half-life of these materials can be very long mean that the accumulation of nuclear waste will become an ever more pressing issue over time, endangering workers and the people who live near the storage facilities.

Gamma rays are harmful because of the damage they can cause to DNA. Gamma rays affect the body in two ways.

�@Directly…The electromagnetic radiation causes direct physical damage to the double strands that make up the DNA molecule.

�AIndirectly…Electromagnetic radiation ionizes the water molecules surrounding the DNA and generates free radicals that damage the DNA.

(Approximately 70% of the damage to DNA is by this means.）

The DNA can in certain cases repair the damage. DNA that cannot be repaired can lead to altered cell function and, for example, the generation of cancer cells.

We are continually exposed to background radiation coming from space, rocks, soil, and other sources, and we also are exposed to X-rays emitted by medical equipment. Such exposure is called external exposure.
Internal exposure, on the other hand, comes from the breathing in or eating of radioactive material. Such radioactive substances can be very dangerous because they accumulate in the body over time.

【Illustration of radiation level】

Sv(Sievert)(1Sv=1000mSv)…The standard unit for measuring the effect of radiation

Gy(Gray)…A unit of measurement for absorbed radiation

Bq(Becquerel)…A unit of measurement for radioactivity

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