Fukushima radioactive leaks 'impossible to stop'

Japanese government officials admitted last month that radioactive water has been leaking into the ocean everyday—at least 300 tons in recent months. Most of the water is being used to prevent overheating at the crippled Fukushima Dai-ichi nuclear power plant.

To add to the plant’s woes, a new tank leak announced two weeks ago spilled another 300 tons of radioactive water into the ground. The leak, along with rising contamination levels, is particularly concerning as Tokyo is set to host the 2020 Olympics.

Water stored in the tanks has been treated to remove cesium, one of the most dangerous of the radioactive elements. Even so, Junko Ogura of CNN reported last week that radiation readings near tanks holding toxic water have jumped to a new high, from 1,800 millisieverts on Saturday to 2,200 millisieverts on Tuesday. The Nuclear Regulation Authority said this week that recent high radiation readings have raised suspicions of more leaks from other water containers.

But the bigger issue is the untreated contaminated water that has made its way into the ocean since the 2011 earthquake and tsunami knocked out the plant's power and cooling functions, leading to nuclear meltdowns and the release of radioactive materials.

The 300 tons of water come from two sources: The plant pumps 400 tons of water onto the crippled reactors each day to prevent overheating, which results in highly contaminated water. The toxic water collects in the reactor basement, and while some of it is pumped out and treated, much escapes through cracks into the surrounding earth and groundwater. Another 1,000 tons of underground water flows into the plant from the mountains, some of which gets contaminated before entering the sea, according to Japan's Agency for Natural Resources and Energy.

The main health concern is that high cesium levels in fish could potentially harm the people who eat them. Cesium levels in fish have been high since the 2011 disaster, further evidence that contaminated water has been leaking into the sea all along. Fisheries off Fukushima are currently closed.

Critics point out plant operator TEPCO has repeatedly lagged in attempts to tackle leakage problems. As a precautionary step, TEPCO created chemical blockades in the ground along the coast to stop any possible leaks, but experts question their effectiveness. After a nearly two-year delay, the company has started the construction of an offshore steel wall designed to contain contaminated water.

The Japanese government announced earlier this month it would contribute $470 million to build an underground ice wall around the reactor and turbine buildings and to develop an advanced water treatment system, but that won’t be ready before 2015. Even if steel or ice walls could be implemented sooner, the efficacy of such measures is still questionable.

“Any contamination in the groundwater would eventually flow into the ocean,” said Ken Buesseler, a marine chemist at the Woods Hole Oceanographic Institution in Massachusetts. “That is very difficult to stop even with barriers.”

The Associated Press contributed to this story.