Japan’s nuclear safety agency this week raised the severity rating of the crisis at the Fukushima nuclear plant to the highest level, putting it on a par with the 1986 Chernobyl disaster.
Conditions remain very serious at the plant with the continuation of a major cooling operation and workers battling radioactive water leaks (NCE last week).
The Japanese Nuclear Safety and Industrial Safety Agency (Nisa) increased the rating from level five to level seven on the International Nuclear and Radiological Event Scale (INES).
“We have upgraded the severity level to seven as the impact of radiation leaks has been widespread from the air, vegetables, tap water and the ocean,” said a spokesman at the Japan Nuclear and Industrial Safety Agency (Nisa).
“We have upgraded the severity level to seven as the impact of radiation leaks has been widespread”
Japan Nuclear and Industrial Safety Agency
A level seven event is the most serious level on INES and is used to describe a “major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasure”.
Nisa estimates that the amount of radioactive material released to the atmosphere is around
10% of the Chernobyl accident, which is the only other nuclear accident to have been rated a level seven event.
The move has also led government officials to extend the exclusion zone of 20km around the Fukushima plant to communities further away, following increases in radiation levels.
The Society for Radiological Protection president Rick Hallard said that actions taken by the Japanese authorities in the initial stages of the accident will help save many lives, which was one of the major failings at Chernobyl.
“[The authorities] evacuated people, gave them iodine tables and then banned food and milk from the area…none of which happened after the Chernobyl accident,” said Hallard.
However, there are still major concerns over the extent to which the land near to the power plant is contaminated.
“[The authorities] evacuated people, gave them iodine tables and then banned food and milk from the area…none of which happened after the Chernobyl accident”
Rick Hallard, The Society for Radiological Protection
Hallard said it is likely that the Japanese authorities will abandon and quarantine these areas due to the scale of the difficulties of remediating the land.
One of the most troubling radioactive contaminants is caesium 137, which was transmitted via clouds of steam from the reactors and absorbed by the ground.
“Caesium has a half life of 30 years and it binds with the soil,” said Hallard. “Given the huge areas it might have affected I suspect the Japanese may focus their [clean up] efforts elsewhere.”
Nuclear debate sparked
Full details of the true amount of radiation leaked from the radiation have already sparked debate over nuclear power in the UK and Europe (NCE 17 March). The latest events at Fukushima are likely to fuel the debate further.
The Health and Safety Executive last week announced it intended to postpone the outcome from the Generic Design Assessments (GDA), until government chief scientist Mike Weightman has completed his report into the Fukushima accident, expected in September.
The GDA − a four step licensing process which considers all aspects of new nuclear reactor design excluding site specifics − had been due for completion in June (NCE 6 May 2010).
EdF said it has factored in the change of schedule and still expects Hinkley Point C to be producing electricity by 2018.
Environmental lobbyist Green Cross International, founded by former Soviet Union president Mikhail Gorbachev, said that the latest Fukushima events raised issues around the safety and viability of nuclear energy.
It said along with high decommissioning costs nuclear had also benefited from a “free ride on the back of climate change”.
“Nuclear energy does not add up economically, environmentally or socially,” said its report on the Fukushima accident, published this week.
“Of all the energy options, nuclear is the most capital intensive, decommissioning is prohibitively expensive and nuclear waste carries a multi-faceted burden that continues centuries after a plant is closed.”
Meanwhile, decisions being made in Japan are having a direct impact on UK nuclear work. Sellafield signed a deal with ten Japanese utilities to provide mixed oxide (Mox) fuel last year which would reuse waste nuclear fuel. However, this deal may now be in doubt.
University of Warwick nuclear researcher Paul Dorfman believes that Japan could be pulling out of its commitments to purchase Mox fuel produced in Sellafield.
The 20km exclusion zone has been extended to the the villages of Iitate and Katsurao, the towns of Namie and parts of the town Kawamata and the city of Minami-Soma.