The United Nations nuclear watchdog said Thursday the management of radioactive waste and contaminated water at the tsunami-crippled Fukushima No. 1 nuclear power plant could be improved despite "good progress" in cleaning up the site.
Tokyo Electric Power Co. said in February it had found a pool of highly contaminated water on the roof of a plant building and that it had probably leaked into the sea through a gutter when it rained.
The finding comes four years after a massive earthquake and tsunami caused three meltdowns at Tepco's Fukushima No. 1 plant.