April 12: Japan today upgraded the crisis at its Fukushima Dai-ichi nuclear power station, labelling it on a par with the world’s worst nuclear accident in Chernobyl 25 years ago, after reassessing the amount of radioactivity spewed by the tsunami-crippled reactors.

Japan’s nuclear safety agency labelled the crisis at Fukushima as Level 7, the most serious on an international scale that rates nuclear accidents, portending long-term health effects and environmental consequences.

But the estimated amount of radioactive materials discharged by Fukushima is about 10 per cent of what was discharged by the nuclear reactor in Chernobyl in April 1986, the Japanese Nuclear and Industrial Safety Agency said.

Japanese officials said it had taken time to measure radiation from the reactors after an earthquake and tsunami on March 11 crippled their backup power required for cooling their cores after shutdown. The decision to raise the severity of the event from Level 5 assigned earlier to Level 7 today was based on cumulative quantities of radiation released, said Hidehiko Nishiyama, a deputy director general with Japan’s NISA.

“Although the level has been raised today, it doesn’t mean the situation is worse today than it was yesterday, it means the event as a whole is worse than previously thought,” said John Price, a former member of the safety police unit at the UK’s National Nuclear Corporation.

No deaths linked to radiation have been reported since the earthquake struck, and only 21 workers at the nuclear power station have been affected by minor radiation sickness, said Japan’s chief cabinet secretary Yukio Edano. In contrast, about 50 workers had died in Chernobyl, many of them in the month after the disaster, and the cumulative number of cancer deaths linked to Chernobyl was expected to be 4,000.

The International Atomic Energy Agency classifies a Level 7 event as a major release of radioactive material with widespread health and environmental effects that would require “implementation of planned and extended counter measures.”

But several experts said the new rating exaggerated the severity of the Fukushima crisis, which was nowhere near the level of the 1986 Chernobyl accident in Ukraine where design weaknesses and a poorly planned test led to an explosion and core meltdown.

“Chernobyl was terrible — it blew and they had no containment and they were stuck,” said nuclear industry specialist Murray Jennex, an associate professor at the San Diego State University in California. “Their containment has been holding. The only thing that hasn’t is the fuel pool that caught fire.”

The IAEA had itself said on April 1 that radioactive material from Fukushima was gradually spreading outside Japan into the global atmosphere, but at extremely low concentrations that do not present health or transportation safety hazards.

India’s Atomic Energy Regulatory Board said today that there has been no increase in the radiation levels measured at various locations in India by India’s Environmental Radiation Monitoring Network.

“Data from the network till date shows that there has been no increase in radiation levels over India over and above the natural background,” the AERB secretary, R. Bhattacharya, said in a statement issued in Mumbai.

The radiation released by the Fukushima reactors into the atmosphere had peaked on March 15 and 16.

“Radiation is still being released, but the amount now has fallen considerably,” said NISA’s Nishiyama.

But Lam Ching-wan, a chemical pathologist at the University of Hong Kong and a member of the American Board of Toxicology said this level of radiation was harmful. “It means there’s damage to soil, ecosystem, water, food and people. People receive this radiation. You can’t escape it by just shutting the window,” Lam said.

Radiological safety experts say radiation-related health effects depend on the exposure which itself depends on the amount of radiation, weather conditions, a person’s proximity to the plant, and the amount of time of exposure.

The World Health Organisation has said that while there is a risk of exposure to contaminated food, such food would have to be consumed over prolonged periods to represent a risk to human health.