TOKYO — Deep beneath Fukushima’s crippled nuclear power station, a massive underground reservoir of contaminated water that began spilling from the plant’s reactors after the 2011 earthquake and tsunami has been creeping toward the Pacific.
Now, 2 ½ years later, experts fear it is about to reach the ocean and greatly worsen what is fast becoming a new crisis at Fukushima: the inability to contain vast quantities of radioactive water.
The looming crisis is potentially far greater than the discovery earlier this week of a leak from a tank that stores contaminated water used to cool the reactor cores. That 300-ton leak is the fifth and most serious from a tank since the March 2011 disaster, when three of the plant’s reactors melted down.
But experts believe the underground seepage from the reactor and turbine building area is much bigger and possibly more radioactive, confronting the plant’s operator, Tokyo Electric Power Co. (TEPCO), with an invisible, chronic problem and few viable solutions.
It remains unclear what the impact of the contamination on the environment will be because the radioactivity will be diluted as it spreads farther into the sea. Most fishing in the area is already banned, but fishermen in nearby Iwaki City had been hoping to resume test catches next month after favorable sampling results. Those plans have been scrapped after news of the latest tank leak.
To keep the melted nuclear fuel from overheating, TEPCO has rigged a makeshift system of pipes and hoses to funnel water into the broken reactors. The radioactive water is then treated and stored in the aboveground tanks that have now developed leaks. But far more water leaks into the reactor basements during the cooling process — then through cracks into the surrounding earth and groundwater.
Scientists, pointing to stubbornly high radioactive cesium levels in bottom-dwelling fish since the disaster, had for some time suspected the plant was leaking radioactive water into the ocean. Tepco denied that until last month, when it acknowledged contaminated water has been leaking into the ocean from early in the crisis.
The turbine buildings at the Fukushima Daiichi plant are about 500 feet from the ocean. According to a Japan Atomic Energy Agency document, the contaminated underground water is spreading toward the sea at a rate of about 13 feet a month.
At that rate, “the water from that area is just about to reach the coast,” if it hasn’t already, said Atsunao Marui, an underground water expert at the National Institute of Advanced Industrial Science and Technology.
Prime Minister Shinzo Abe announced this month that the government would intervene and provide funding for key projects to deal with the problem.
“This is a race against the clock,” said Toyoshi Fuketa, a commissioner on Japan’s Nuclear Regulation Authority.