Even more unnerving than news of the accident at Tokaimura uranium processing plant is the air of complacency with which executives from Japan's nuclear industry have responded to the incident.
This is the latest of six mishaps in two years including an explosion at a reprocessing plant, and the discovery that a waste storage facility had leaked low-level radiation over a period of 30 years. For a country heavily dependent on nuclear power and planning to build a further 20 reactors in the next decade, it is hardly an encouraging record.
There was enough evidence after the terrors of Chernobyl to show the widespread and lasting effects of a major nuclear accident. Radiation spread far across the globe, and persisted for years afterwards.
Though this accident is just over half as serious as the Russian disaster, based on an internationally recognised scale of nuclear mishaps, it is obvious from revelations now surfacing that safety procedures should be tightened and supervision intensified before the Japanese public will be reassured.
The criminal investigation launched by the police will no doubt concentrate the industry's attention on the importance of following government regulations to the letter from now on.
Western scientists claim the nuclear safety practices in Japan are 'a bit lax'; and there can be no excuse for any degree of laxity in such an industry, especially in a country that obviously has the resources to ensure the most rigorous safety precautions are enforced.
The nuclear industry in every country has a responsibility not just to its own citizens, but also to regional neighbours.
There is not much comfort in being told by Japanese officials that the country's regulations are very strict, when executives at the power station had allowed operatives to flaunt safety standards and carry out procedures by hand, simply to speed up the process.
Even if workers had conformed to the rules, these were drawn up for chemical factories, not for nuclear plants. Under the circumstances, it is hard to believe that the error that led to this incident was just 'a simple mistake', as a government spokesman said.
Culpability starts at the top. Tokyo owes it to the region to ensure that no nuclear facility is allowed to function unless it is subject to the strictest nuclear regulations.