Some called it an “atomic-grade crime” and said it was negligence that led to the catastrophic meltdown of the Fukushima nuclear reactor in Japan in March 2011.

Yet the Tokyo District Court on Thursday acquitted three executives of Tokyo Electric Power Company Holdings, or Tepco, of failing to prevent Japan’s worst peacetime nuclear accident.

Former Tepco Chairman Tsunehisa Katsumata and former vice-presidents Ichiro Takekuro and Sakae Muto had argued before the court they could not have foreseen the perfect storm of events – a massive earthquake and tsunami that killed the power operating the plant’s cooling systems – which crippled the Fukushima No 1 power plant and led to a core meltdown, Kyodo News reported.

Legal storm

Prosecutors had demanded five-year jail terms for all three executives of the nuclear power monopoly. They had been indicted by prosecutors – themselves reacting to public complaints – for failing to implement appropriate disaster-prevention measures at the plant.

Japan is at constant risk of both earthquakes and tsunamis, and the Fukushima plant was sited on the coast.

A 2008 government study had warned that tsunami waves 15.7 meters high could, at some point, hit the plant. The waves that in fact impacted Fukushima in 2011 were more than 10 meters, but less than 15 meters, in height. Government and parliamentary investigations also found that Tepco had a poor safety culture and weak risk management processes.

However, the three defendants argued that pre-disaster data provided to them proved unreliable and Judge Kenichi Nagafuchi said experts were divided over evaluations of various tsunami predictions. Defense attorneys also said that even if the executives had taken related steps, such as building bigger seawalls, the disaster could not have been averted.

Fourteen people died in the incident, 13 were injured and about 160,000 had to be evacuated, Kyodo reported. A total of 44 elderly patients also died during or after their evacuation from a hospital near the plant, AP noted.

As the only country to have suffered atomic bombings, nuclear-related issues are always maximally sensitive in Japan. In the aftermath of the Fukushima disaster, shock waves tore across Japan’s power generation sector, with the future of the country’s nuclear industry very much in doubt.

Toxic justice?

Many were unhappy with Thursday’s verdict. “Unbelievable,” was the reaction of some Fukushima residents who attended the trial, according to AP.

The legal fallout is expected to continue. Hiroyuki Kawai, a lawyer representing the more than 5,700 Fukushima residents who filed the original criminal complaint about the Tepco bosses to prosecutors, had earlier indicated he would appeal.

Meanwhile, a huge cloud still looms over Fukushima and, more broadly, Japan.

The Japanese government remains undecided over how it will dispose of millions of tons of irradiated water in storage tanks at the site. Following comments from the outgoing Environment Minister – who was replaced in that position after a cabinet reshuffle last week by rising young political star Shinjiro Koizumi – there are fears the government will release the water into the Pacific.

Domestic and international environmental NGOs, as well as the neighboring South Korean government, have made clear their strong concerns about any such step. The Japanese government is now awaiting the findings of a panel of experts on how best to proceed.

The risk of a release into the ocean, while real, does not seems to be imminent. For reasons of international PR, observers do not expect Tokyo to take any drastic steps until after the Tokyo 2020 Summer Olympics have concluded.