Technical flaws, ballooning costs and unconfirmed effectiveness have plagued the “ace card” in preventing groundwater from accumulating within the crippled Fukushima No. 1 nuclear power plant.

An curved arrow pointing right. Engineers at Japan's Fukushima nuclear power plant have designed an "ice wall" to stop the spread of radiation into the groundwater. Produced by Maya Dangerfield.

All of Japan's 54 commercial nuclear power plants were shut down after the Fukushima disaster ... built an anti-tsunami wall ...

A wall of water over 15 meters (50 feet) tall slammed into the coastal Fukushima Daiichi nuclear ... treated radioactive wastewater into the sea last August. The controversial discharges have ...

Tokyo on Tuesday unveiled a half-billion dollar plan to stem radioactive water leaks at Fukushima, creating a wall of ice underneath ... the plant and out to sea, is also causing problems.

Aug. 25, 2015: The government and TEPCO send a statement to Fukushima ... into the sea without their “understanding.” — March 31, 2016: TEPCO introduces an underground wall that is cooled ...