|Cause||Natural disaster, design flaws||Human error, design flaws|
|Amount of radiation released||The amounts of radioactive iodine and caesium released have approached those at Chernobyl (reports here, here, and here) (and there has been much more released since then). Small amounts of radioactive plutonium have been found.||In addition to volatile iodine and cesium, many other radioactive materials were released, including strontium, plutonium, and ruthenium in particles in smoke and dust (overview in Science article) which caused long-lived contamination of surrounding areas.|
|Workers and responders killed||2 missing? (estimate as of 26 March 2011 see Reuters article, Telegraph article) (These 2 may have been killed by the tsunami not the nuclear accident see BBC story)||34|
|Public health impact||Few direct public health impacts currently anticipated [update Reuters quotes UN expert on minimal health impacts]||"more than 6,000 cases of thyroid cancer" (UNSCEAR) entailing up to 500 premature deaths (Other sources give much higher estimates of premature deaths)|
|Clean-up Cost||Perhaps around $10-15 billion for site cleanup and mothballing (Three Mile Island cost $1 billion to clean up and close--see NYT article) (For estimates of other costs--around
||Tens to hundreds of billions of dollars, including maintenance of exclusion zones, relocation costs, ongoing work at the site (a multi-billion dollar project is currently under way to put a more permanent cover over the damaged reactor building)|
|Exclusion zone||None anticipated at this time, except perhaps the Fukushima #1 site itself.||Considerable areas around the plant, and in neighboring Ukraine, Belarus and Russia, are zones of restricted access where no people can live|
The estimates of health effects and premature deaths due to the radiation released by the Chernobyl disaster vary widely, and may be influenced by ideology and political factors.
The Chernobyl disaster involved a catastrophic and sudden release of a large plume of airborne radioactive material, including smoke and dust, while releases from Fukushima have been gradual, mainly volatile elements, and a substantial fraction have been water-borne and released into the adjacent sea. Also much of the airborne contamination has blown out to sea, rather than over inhabited land. This has minimized population exposure and contamination around the plant.
Also, at Fukushima an area within 20 km of the facility was evacuated promptly, and an additional area between 20 km and 30 km from the plant is currently subject to voluntary evacuation. The disaster at Chernobyl was at first not announced publicly and evacuation was delayed. The city of Pripyat, about 2.5 km from the Chernobyl plant, was not evacuated until 36 hours after the explosion and fire. Thus many more people were exposed to airborne radioactive materials.
Even after the Chernobyl disaster became public many people continued to drink milk from cows which were consuming contaminated feed or forage. The authorities were slow to prevent this route of exposure.
More than 300,000 people were resettled from the contaminated areas around Chernobyl. It is not likely that many will have to be permanently relocated from around Fukushima, but much of the surrounding area will have to be rebuilt due to tsunami and earthquake damage.
In addition to the technical differences between these two disasters which affect the type and degree of radioactive material released and other impacts, there are very significant differences due to the contrasting political and information climates. In 1986 in the Soviet Union little information was conveyed to local populations, or anyone else. The Fukushima disaster is playing out in the glare of international media coverage, and in an age when information is circulating freely via the internet.
Because of this much greater information flow and reasonably effective government intervention, many of the pathways of harmful radiation doses have been blocked. In particular around Fukushima food, water and other potentially contaminated sources of exposure are being monitored, and efforts are being made to prevent exposure by warning consumers against various hazards.
It is not possible to compare the broader economic impacts of these two nuclear energy disasters. Chernobyl had its greatest effects in a primarily rural area, while substantial economic activity (farming, fisheries) may be affected by Fukushima. Also, it is impossible to disentangle many of the economic effects of the Fukushima disaster from the much more severe and widespread effects of the earthquake and tsunami. Contamination of fisheries may be irrelevant, for example, since the fishing industry in the area has been destroyed by the tsunami.
[Update 31 March 2011 1700 GMT]
A recent Reuters article says compensation claims against Tokyo Electric Power Company could be $12 to $36 billion (or even as high as $133 billion according to an analysis by Bank of America Merrill Lynch). This would put the total cost of the Fukushima disaster in the same range as that of Chernobyl, even accounting for the change in the value of the dollar over the intervening 20 years.
[Update 6 April 2011 1800 GMT]
Reuters quotes members of the United Nations Scientific Committee on the Effects of Atomic Radiation, saying that the public health effects of releases of radioactive material from Fukushima are expected to be very minor, based on current information.
Part of the reason that the cost of the Fukushima disaster is high even though its environmental, health and mortality effects are much more limited than Chernobyl is that Fukushima affects a relatively more wealthy and productive economy. The disruption of the Japanese economy due to the disaster at Fukushima creates costs and liabilities much greater than Chernobyl's impacts on the Soviet, Ukranian, Russian and Belorussian economies.
Updated 30 March 2011 0540 GMT
Updated 1 April 2011 0011 GMT with link to "Cost of Fukushima" post.
Updated 3 April 2011 1530 GMT regarding 2 bodies recovered
Updated 6 April 2011 1800 GMT with link to Reuters story on health effects.
Sources and further reading: