Contamination and decontamination in Fukushima

Application of International Commission on Radiological Protection (ICRP) recommendation, decontamination, nuclear waste repository, agriculture crisis, and contamination and uncleanness are described. The first failure in application of ICRP recommendation was to decide 20 mSv of reference level, because the work site could not take the special measures by this value. The next failure was to change many reference levels to the lowest values. It was important to decide the values depending on the conditions of sites. A model of nuclear waste repository, which prevents the diffusion of Cs, is proposed. In order to solve the problem of agricultural land containing Cs, we find a control method that the cultivated crops do not absorb the radioactive Cs. The education for basic knowledge of radioactive substances, its health effects and contamination will help to perform the reasonable and best decision making for safety. (S.Y.)