TOKYO (AP) -- The U.N.'s nuclear watchdog agency Monday began reviewing the decommissioning process at Japan's crippled nuclear plant, where new problems are triggering growing safety concerns about a cleanup expected to take decades.
The experts will assess and analyze melted reactors, radiation levels and waste management at the Fukushima Dai-ichi plant to make its decommissioning process safer and more stable, team leader Juan Carlos Lentijo told reporters.
The cleanup is "a very difficult challenge," he said, and "it is very important to conduct the decommissioning process in a very safe way."
The mission by the 12-member team is the International Atomic Energy Agency's first review of the plant's decommissioning process.
Japan's nuclear watchdog said there have been at least eight accidents or problems at the plant since mid-March, ranging from extensive power outages and leaks of contaminated water.
The problems are raising concerns about whether the plant, crippled by the March 2011 tsunami, can stay intact through a decommissioning process that could take 40 years. The problems have also prompted officials to compile risk-reduction measures and revise decommissioning plans.
Among the most pressing issue is leakage of tons of highly radioactive water from three of seven underground storage pools into the soil. Plant operator Tokyo Electric Power Co. and regulatory officials said none of it was believed to have reached ocean.
The contaminated water storage has been a headache from right after the accident, but officials finally acknowledged last week that the lack of space has become a "crisis." TEPCO has promised to speed up building more reliable steel tanks and eventually empty the underground tanks, but the leak will continue until then. Runoff from the three reactors melted in the aftermath of the March 2011 earthquake and tsunami and a steady inflow of groundwater seeping into the basement of their damaged buildings produce about 400 tons of contaminated water daily at the plant.
The IAEA team will inspect the plant and hold more talks with TEPCO and government officials during its review. It will compile an assessment and advise the Japanese government in a report next week, and a follow-up evaluation is expected within several months.