The underground ice wall, which Tokyo Electric Power Corp (Tepco) has built around the four damaged reactor buildings at the Fukushima Daiichi NPP nuclear to prevent groundwater from entering them, is not proving effective, according to an expert panel of the Japanese Nuclear Regulation Authority (NRA). The members of the panel concluded that the ice wall was not working, and a new plan was necessary to prevent groundwater mixing with radioactive substances in the contaminated water, which has collected in the base of the reactor buildings, the Ahasi Shimbum reported on 21 August.

“The plan to block groundwater with a frozen wall of earth is failing,” said Yoshinori Kitsutaka, a panel member and a professor of engineering at Tokyo Metropolitan University. “They need to come up with another solution, even if they keep going forward with the plan.”

In March, construction company Kajima Corp began building the 1.5km frozen wall of earth around the reactors and has completed most of the barrier. However, little or no success was recorded in the wall’s ability to block the groundwater and the amount reaching the buildings has not changed after the wall was built, experts said.

According to Tepco, 99% of their thermometer readings showed that the wall’s temperatures are at or below the freezing point, meaning the wall is mostly solid. However, the remaining 1% of the readings showed temperatures above freezing point, which means the wall is not solid at those points. This is enough to ruin the entire project, as the unfrozen sections were found in areas with high levels of groundwater concentration.

Tepco is now suggesting that the unfrozen sections can be fixed if coated with concrete. However, last April a chief architect of the project said that gaps in the wall and rainfall will still allow water to creep into the facility and reach the damaged nuclear reactors, which will continue to create up to 50t of contaminated water each day. “It’s not zero,” Yuichi Okamura, a Tepco general manager said, referring to the amount of groundwater flowing into the plant. “It’s a vicious cycle, like a cat-and-mouse game…we have come up against many unexpected problems.”

TEPCO has been repeatedly criticised for its handling of the 2011 Fukushima disaster. The company has admitted that it did not act properly as events unfolded and acknowledged in February that it announced the nuclear meltdowns far too late. It also stated in a 2012 report that it downplayed safety risks caused by the incident, out of fear that additional measures would lead to a shutdown of the plant and further fuel public anxiety and anti-nuclear campaigns.

Despite the ongoing problems Tepco has set 2020 as the goal for ending the plant’s water contamination problem, which critics say is far too optimistic. Water contamination is just one of many problems involved in the dismantling and containing of the Fukushima plant debris which is estimated to take at least 40 years.