Posted 01/04/2011 by Matthew James
The devastating earthquake and tsunami that struck Japan on March 11th led to a crisis at the Fukushima Daiichi nuclear plant that resulted in some radiation contamination of the environment and worldwide media attention and commentary. There are six older-type
Boiling Water Reactors (BWRs) at this site that require cooling systems in order to keep their fuel rods from overheating. While the reactors did turn off during the earthquake, their heat and loss of backup power for the cooling systems has led to some extraordinary measures being taken. These have included water-bombing, mobile water pump spraying and the use of boron-enriched seawater. Some explosions also occurred at the site, probably as a result of hydrogen gas generated at high temperatures by a reaction between the nuclear fuel cladding and steam.
Japanese authorities classified the events at Fukushima at level 4 then 5 on the
International Nuclear and Radiological Event Scale (INES) provided by the
International Atomic Energy Agency (IAEA). The scale of increasing severity runs from 0 to 7. The IAEA is maintaining a daily
Nuclear Accident update log online. The bulletin also provides a comprehensive report of the spread of radioactivity to food, water and the environment both in the vicinity of the plant and to elsewhere. It is not yet clear how the radioactivity escaped from the reactor containment vessels.
The
IAEA notes that On 18 March 2011, the World Health Organization, the International Atomic Energy Agency, the World Meteorological Organization, the International Maritime Organization and the International Civil Aviation Organization provide the assessment that international flight and maritime operations can continue normally into and out of Japan's major airports and sea ports, excluding those damaged by the tsunami. While there is currently no medical basis for imposing restrictions, the United Nations organizations are monitoring the situation closely and will advise of any changes. Screening for radiation of international passengers from Japan is not considered necessary at this time
Nuclear industry coverage of the crisis is available through the
World Nuclear Association (WNA) News. The WNA also provides useful updated background papers on
nuclear power and earthquakes, and more generally on reactor safety. The
Bulletin of the Atomic Scientists provides counterpoint commentaries.
Australia has one
small research reactor, which is of a newer design type. The
Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) provides Australians with information on
ionising radiation and health. Its current
‘Advice on exposure to radiation arising from nuclear incidents in Japan’ says:
As a result of new assessments of the situation in Japan, ARPANSA and the Department of Health and Ageing recommended, as a precautionary measure, that Australians within an 80 km zone from the Fukushima nuclear power plant move out of the area.
No doubt the events in Japan will provoke strong reactions both for and against nuclear power. Already an article
‘Current designs address safety problems in Fukushima Reactors’ has appeared in the 25 March 2011
Science journal. Opposing this is
‘Nuclear power’s record is neither safe nor clean’ in the 18 March
Australian Financial Review. The
debate will long continue, but it is to be hoped that the current crisis will be resolved.
(Image sourced from: DigitalGlobe; www.digitalglobe.com)