Fukushima Caesium discharges 'equivalent 168 Hiroshima’s nuclear bomb

Japan's government guesstimates the total of radioactive caesium-137 discharged by the Fukushima nuclear catastrophe until now is equivalent to that of 168 Hiroshima bombs.

Government nuclear professionals, however, said the World War II bomb explosion and the mishap reactor meltdowns at Fukushima, which has seen continuing radiation seeps out but no casualties so far, were beyond assessment.

The quantity of caesium-137 discharged since the three reactors were crippled by the March 11 earthquake and tsunami has been approximated at 15,000 tera becquerels, the Tokyo Shimbun reported, referring an authorities calculation.

That compares with the 89 tera becquerels discharged by "Little Boy", the uranium bomb the United States dropped on the western Japanese city in the last days of World War II, the report said.

The estimate was put forward by Prime Minister Naoto Kan's cabinet to a lower house committee on backing of technology and modernism, the daily said.

The government, however, disagreed that the comparison was not convincing.

While the Hiroshima bomb declared most of its sufferers in the powerful heat-wave of a mid-air nuclear blast and the extreme radioactive fallout from its flourishing cloud, no such nuclear blasts hit Fukushima.

There, the radiation has leaked from molten fuel inside reactors destroyed by hydrogen blasts.

"An atomic bomb is intended to enable mass-killing and mass-devastation by causing explosion waves and heat rays and discharging neutron radiation," the Tokyo Shimbun daily referred a government official as saying. "It is not rational to do a simple comparison only on basis of the quantity of isotopes discharged."

Government authorities were not instantly available to verify the report.

The blinding explosion of the Hiroshima bomb and its fallout killed some 140,000 people, either immediately or in the days and weeks that gone behind as higher radiation or dreadful burns took their toll.

At Fukushima, Japan pronounced a 20-kilometre (12 mile) evacuation and no-go zone around the plant after the March 11 earthquake and tsunami hit the world's most awful nuclear mishap since Chernobyl 25 years ago.

A newly government survey revealed some regions within the 20-kilometre zone are infected with radiation equal to in excess of 500 millisieverts per year – 25 times more than the government's yearly limit.