Amonth after the dreadful March 11 earthquake and tsunami which devas- tated a large part of north-eastern Honshu, the main island of Japan, the International Atomic Energy Agency (IAEA) reported that, as of April 13, “the situation at the Fukushima Dai-ichi [nuclear power] plant remains very serious”. The evacuation zone around the plant is being increased from a radius of 20 km to probably 30 km, as an increased precaution.
Global headlines were made when the Nuclear and Industrial Safety Agency (Nisa) of Japan uprated the Fukushima crisis to the highest level on the International Nuclear and Radiological Event Scale (Ines). The Ines was inspired by the Richter scale used to measure earthquakes.
Ines, like the Richter, is a logorhythmic and not a linear scale. Ines starts with the number 0, indicating a deviation in reactor operation which has no safety significance. Ines levels 1 to 3 are classified as incidents, with level 1 being classified as an anomaly, level 2 as an incident, and level 3 as a serious incident. Levels 4 to 7 are accidents, with level 4 being described as an accident without off- (nuclear) site risk but potential risk, level 5 is an accident with off-site risk, level 6 is a severe accident and level 7 is a major accident.
Until now, the only Ines level 7 accident was Chernobyl. According to French physicist and engineer Bertrand Barré, scientific adviser to the chairperson of the French State-owned nuclear energy group, Areva, out of the 600 000 people exposed to radiation by Chernobyl, up to 4 000 could die prematurely from cancer as a result of the accident – but some 150 000 will die from naturally occurring cancers, so Chernobyl might increase the number of cancer deaths by 3%.
Despite being in the same category, Fukushima is still far from being another Chernobyl. “The classification of ‘7’ means there’s a leak of radiation into the wider environment; and, although it will be interpreted as being ‘the same as Chernobyl’, it’s not the same,” University of Surrey physics professor Paddy Regan told the British Broadcasting Corporation (BBC). “The amount of radiation release is a lot less, and the way it’s released is very different. The Chernobyl fire was putting lots of radioactive material into the atmos- phere and taking it over large distances; [at Fukushima], there have been a couple of releases where they’ve vented [gas from] the reactor, and then released some cooling water.”
To be rated as Ines 7, a nuclear accident must see the release of radioactivity into the atmosphere equivalent to several tens of thousands of terabequerels (TBq) of iodine-131. A terabequerel is a million-million bequerels. The bequerel is the unit of measurement of radio- active decay – one bequerel is one atomic nucleus decaying per second.
Nisa decided on the uprating to level 7 after re-examining their data on the accident. The agency has concluded that 370 000 TBq of iodine-131 equivalent was released at Fukushima. Japan’s Nuclear Safety Commission (NSC) puts the figure at 630 000 TBq of iodine-131 equivalent.
Both figures clearly qualify Fukushima Dai-ichi for level 7 categorisation. But the figure for Chernobyl was 5,2-million terabequerels of iodine-131 equivalent – more than eight times greater than the NSC’s estimate for Fukushima and some 14 times greater than Nisa’s figure.
At Chernobyl, in the month after the acci- dent, 134 workers were admitted to hospital with acute radiation sickness, of whom 31 died. “The equivalent figures for Fukushima are none and none,” pointed out BBC environmental correspondent Richard Black. “Although workers have been taken to hospital with radiation burns, this is not the same as acute radiation sickness.”
Radiative particles from Fukushima have been detected in seven Japanese prefectures (provinces) and the sale and consumption of certain foodstuffs produced in certain areas has been banned. But contamination has been, to date, very limited. The IAEA reports that, of 55 samples of vegetables, fruit (strawberries), sea-food and unprocessed raw milk, taken in eight prefectures on April 8 and April 10 to April 12, and examined for iodine-131, caesium-134 and caesium-137, only two displayed contamination above Japan’s regulatory limits. One was a sample of sea-food (a sand lance) and the other a sample of spinach.
Most of the radia- tion released by the accident remains confined to the Fukushima plant site, despite the fact that, in addition to the original March 11 earthquake, which measured 9 on the Richter scale, Fukushima was hit by a Richter 7,1 earthquake on April 7, a Richter 6,2 earthquake on April 11 and a Richter 6 earthquake on April 12, in addition to powerful aftershocks from the original quake. (The youngest of the six reactors at Fukushima is more than 31 years old, while the oldest is 40 years old, and they have been subject to stresses and damage they were never designed to take.)
Radioactive water has been released into the sea, driving up radioactivity in the waters adjacent to the plant, but this will be diluted into insignificance by the gigantic volume of the sea. It should not be forgotten that the world’s oceans already contain about 4,5-billion tons of uranium, dissolved in the seawater.
Moreover, the scale of the disaster must never be forgotten: the earthquake and tsunami devastated entire towns. More than 28 000 people are dead or missing, 150 000 are homeless and the Japanese government estimates that reconstruction will cost up to $295-billion.
Although the battle at Fukushima is far from over, it still looks as if the long-term envi- ronmental effects outside the plant (which clearly has to be written off) will be extremely limited indeed. Japanese police report that radiation levels in the zone within a 10 km radius of the plant are falling, allowing them to start searching for victims of the earthquake and tsunami.
What would the environmental effects have been if there had been an oil refinery at Fukushima Dai-ichi? Or a chemicals complex?
The world’s worst industrial accident was in Bhopal, in India, in 1984, when 40 t of a toxic chemical – methyl isocyanate – leaked from the then Union Carbide pesticide plant; 3 500 people died within days of the leak, and 15 000 more since. The plant was shut down and envi- ronmentalists report the site is still contaminated. That single chemical disaster has killed far more people than all the nuclear accidents to date put together have or will kill.
To repeat my question in my last column: what other industry can match the nuclear industry for resilience and safety?