Sludge that will be generated in the process of treating radioactive water at the tsunami-hit Fukushima No. 1 Nuclear Power Plant is estimated to contain 100 million becquerels of radioactive substances per cubic centimeter, the plant operator said.

Tokyo Electric Power Co. (TEPCO) made the estimation in a report on the water treatment system submitted to the government's Nuclear and Industrial Safety Agency (NISA).

While trying to begin treating the increasing volumes of radioactive water at an early date, TEPCO has failed to indicate how it will store the toxic sludge or a final disposal site in its road map to bring the crippled plant under control.