The owner of Japan’s crippled Fukushima nuclear power plant has admitted the amount of radioactive materials released in the first days of the nuclear disaster was almost two-and-a-half times the initial estimate by Japanese safety regulators. The company, TEPCO, said the nuclear accident released far more Iodine-131 than previously estimated. The radioactive substance can cause thyroid cancer. Based on TEPCO’s current figures, the Fukushima disaster represented about 17 percent of the radiation from the 1986 Chernobyl accident.