In the teeth of a howling Pacific gale, a giant yellow backhoe grinds its way along the top of a massive new earthen barrier above a rocky beach. But whether the coastal earthworks will be able to protect the future of the nuclear power plant it is designed to defend is by no means certain.

Since a tsunami wrecked the Fukushima Daiichi nuclear power plant a year ago, leading to meltdown in three of its reactors, all eyes in Japan have been on the Hamaoka plant, 300 miles down the coast and similarly located right on the seashore. It has been branded the most dangerous nuclear power station in the world by some seismologists