A group of researchers has reported that radiation-contaminated water could still be leaking into the sea from the Fukushima No. 1 power plant.
Data on radioactive cesium in the sea near the plant nearly a year after the March 11 earthquake and tsunami triggered multiple meltdowns show a slower than expected decline in concentrations, according to the group, which includes Michio Aoyama of the Meteorological Research Institute.
Tokyo Electric Power Co. said it does not believe contaminated water is currently leaking into the sea.
Although data for the past three to four months indicate a slower decline in cesium concentrations, current levels are far lower than those recorded just after the disaster, Tepco said.
Last April, Tepco found that contaminated water was leaking into the sea and stopped the flow by injecting chemicals into the ground.
U.S. experts critical
The meltdowns at the Fukushima No. 1 nuclear plant could have been prevented if authorities and Tepco had strengthened safety measures in accordance with international standards, U.S. experts said Tuesday.
“With appropriate foresight by Japan’s authority and industry, it appears that the accident could have been avoided or prevented,” James Acton and Mark Hibbs, experts at the Carnegie Endowment for International Peace, said in a report.
The methods used by Tepco and NISA to assess the risk from tsunami “lagged behind international standards” in at least three important respects, the report says.
“Insufficient attention was paid to evidence of large tsunami inundating the region surrounding the plant about once every thousand years,” it says, adding that computer modeling of the tsunami threat was inadequate.
NISA also failed to review simulations conducted by Tepco and to foster the development of appropriate computer modeling tools, according to the report.
By contrast, European countries “significantly enhanced their plants’ defenses against extreme external events” following a flooding incident at the Blayais Nuclear Power Plant in France in 1999, the report says.