TOKYO (AP) -- A government panel proposed additional measures to lessen the contaminated water crisis at Japan's crippled nuclear power plant, saying Tuesday that current plans are not enough to prevent the risk of a disaster.
Officials on the Industry Ministry's contaminated water panel also said that the Fukushima Dai-ichi plant could run out of storage for contaminated water within two years if current plans are not fully workable.
A draft report, made available to reporters after the panel's experts and officials met, proposed covering the ground with asphalt to reduce rain inflow, building giant tanks and other steps. A final report is expected later this month.
The proposal incorporates ideas from some of 780 sets of proposals sent from around the world at the request of the ministry to seek international expertise in tackling the problem of massive contaminated water, which experts say is hampering the plant's decommissioning process.
Contaminated water have been leaking from the wrecked reactors and mixing with groundwater since the 2011 earthquake and tsunami destroyed the plant's power and cooling systems, causing three reactor meltdowns and damaging a fourth reactor building.
Experts say that underground water that flows into the reactor and turbine basements is mostly rainwater, which can be reduced by covering most exposed dirt with asphalt "facing" at the plant compound. Details, including the extent of asphalt coverage, still need to be discussed, panel official Yoshiyuki Toyoguchi said.
Experts also cautioned that decreasing the amount of groundwater could risk the land sinking in some areas with soft structure. Such vulnerable ground include the area where hundreds of tanks contain highly radioactive water, said Hitoshi Tsukamoto, a geologist at the National Institute of Advanced Industrial Science and Technology. He said measures to increase stability underneath the tanks should be taken.
The draft proposals also included building giant tanks with more capacity and installing undersea filters to reduce radioactivity in contaminated water that leaks into the sea.
The proposal is part of the government effort to step up leadership and funding of the plant's cleanup, after criticism that the repeated problems are getting out of the plant operator's capacity. The government in September announced providing 47 billion yen ($470 million) for technically challenging projects such as building a 1.4-kilometer (0.9-mile) ice wall around the four damaged reactor and turbine buildings and developing an upgraded water treatment machine that can remove most radioactive isotopes below detectable levels.
Leaks and other flaws found in several tanks earlier this year have raised concerns about further and more damaging failures, particularly if another big earthquake, tsunami or typhoon hits. The plant has more than 1,000 tanks and other containers storing 370,000 tons of partially treated but still highly contaminated water.
Experts say contaminated water is hampering the plant's decades-long decommissioning, whose first step just begun last month.
Officials on the Industry Ministry's contaminated water panel also said that the Fukushima Dai-ichi plant could run out of storage for contaminated water within two years if current plans are not fully workable. A draft report proposed covering the ground with asphalt to reduce rain inflow, building giant tanks and other steps.