The British government made contingency plans at the height of the Fukushima nuclear crisis, which anticipated a "reasonable worst case scenario" of the plant releasing more radiation than the famed disaster at Chernobyl, new documents accessed by the Guardian newspaper reveal.
The assessment was used to push plans by the British embassy in Tokyo to issue protective iodine pills to expatriates and visitors. It also prompted detailed plans by Cobra, the government's emergency committee, to scramble specialist teams to screen passengers returning from Japan at UK airports for radioactive contamination, the report says.
The UK government's response to the unfolding crisis is revealed in documents prepared for Sir John Beddington, the chief scientist and chair of the Scientific Advisory Group for Emergencies (SAGE), and released to the Guardian under the Freedom of Information Act.
The haul of 30 papers includes advice from the National Nuclear Laboratory on damage to the plant, public safety assessments from the Health Protection Agency (HPA), computer models of the radioactive plume from Defra's Radioactive Incident Monitoring Network (RIMNET), and the worst case scenario that might unfold at the plant.
A substantial number of documents were withheld on grounds that they contained "information which, if disclosed, would adversely affect international relations," the government's civil contingencies team said.
The earthquake and tsunami which hit Japan in March, knocking out critical cooling systems at the Fukushima plant, prompted immediate fears that nuclear fuel in the reactors could melt through their pressure vessels and drop onto the concrete floor beneath, causing a "corium explosion" and major release of radiation.