A worker at the beleaguered Fukushima nuclear power station filed a lawsuit against his former employers today, saying they had failed to protect employees from safety risks.
The man - identified only as Shinichi, 46 - worked for Tokyo Electric Power Co (Tepco) subcontractor Kandenko immediately after an earthquake and tsunami triggered a meltdown at the plant in April 2011.
He wants Japan's labour office to issue Tepco with improvement orders and expects Kandenko company directors to face six-month jail terms or 500,000 yen (£3,900) fines.
He was part of a six-member team sent to lay cables to get the Unit Three reactor's cooling system operational again.
He was sent down to a flooded basement to reconnect electrical switchboards but said he wasn't told about the water and so only two of the group wore knee-high rubber boots.
"If you're a nuclear plant worker, you know that water on the floor is bad news. You just don't touch it," he said.
And he said dosimeters measured unsafe levels of radiation but a supervisor said the equipment must have been faulty and told them to press on.
His lawyers - who are representing a number of Fukushima workers in other cases - said he was illegally sent to work without full protection.
Tepco admitted last week that it had played down the risk posed to the plant by a tsunami because it was worried it might be forced to shut down and incur financial penalties if it had to bring defences up to scratch.