In terms of soil contamination, the nuclear crisis at the Fukushima No. 1 power plant is only about an eighth as severe as the meltdown at the Chernobyl plant, in what is now Ukraine, in 1986, according to a report by the science ministry released Tuesday.

The study, which began in June and was conducted by the ministry in cooperation with universities and semigovernmental bodies including the Japan Atomic Energy Agency, looked at 2,200 sites within a 100-km radius of the Fukushima plant, which had three reactor meltdowns.

The group studied the radioactive isotopes in samples of the top 5 cm of soil at each site.