Apr. 11, 2011
1 Risk management matters - With nuclear power, where the consequences of a catastrophic nuclear accident are huge and the likelihood is fairly small, comprehensive risk management is crucial. Most nuclear power stations will never fail during their entire lifespan, but at the same time no nuclear power plant is 100 per cent safe.
In 2002 the Japanese Nuclear Energy Safety Organisation estimated in a report entitled Severe Accident and Accident Management (PDF) that the likelihood of occurrence of a core damage accident was one in 100,000 per year per reactor, while the likelihood of occurrence of an accident leading to containment damage was one in one million per year per reactor. But, as all good chaos theorists know, anything that can happen, can happen.
2 Jumping to conclusions helps no one
Even when the one in a million disaster happens, as at Fukushima, it is possible to keep radiation leaks under a degree of control. No-one has died yet as a result of radiation poisoning from the plant and, while these figures are highly contested, UN data suggests that at Chernobyl, the worst recorded nuclear disaster, only 43 people died as a direct result of radiation poisoning.
According to the most recent data collected on 4 April by a US Department of Energy team on the ground, radiation levels are no higher than 32 microrem per hour - a level that poses no known health risk and is equivalent to around three chest x-rays per day.
3 But persuading the public nuclear risks are over-stated is another matter
Officials and nuclear experts have emphasised that the radioactive leaks into the sea were of no harm to humans or the environment as the levels would become swiftly diluted.
But a fish contaminated with 526 bequerels per kilogram of radioactive caesium was found this week, exceeding the legal limit of 500.
Although this is still considered a safe level, it has prompted widespread concern, leading the government to consider raising the legal limit of radiation in fish to reassure the public and protect fishermen's livelihoods.
But these proposed regulations are unlikely to be enough to assuage concerns. 'Even if the government says the fish is safe, people won't want to buy seafood from Fukushima,' Ichiro Yamagata, a fisherman who lived near the Fukushima plant, told Sky News. 'We probably can't fish there for several years.'
4 International radiation safety regulations are extremely strict
Some experts have suggested that overly strict regulations prompt unnecessary concern, because when they are breached the public assumes something is seriously wrong. Regulations currently suggest an upper limit for the general public of one millisievert per year above natural levels.
This is a very low figure which is often used by the media as a baseline for the ubiquitous 'x million times acceptable/legal levels' comparisons. For example, a British person is exposed to 2.7 millisieverts a year on average. Some scientists, such as Oxford's Wade Allison, say a responsible danger level based on current science would be 100 millisieverts per month, with a lifelong limit of 5,000 millisieverts, rather than one millisievert per year.
At one point Japanese authorities introduced recommendations for restrictions on drinking water because of radiation fears, though they were later lifted. But the radiation dose received by drinking Tokyo water for a year would have been less than that received by someone living in Cornwall for a year.
5 The Fukushima reactors were extremely old
All of the plant's reactors were designed by General Electric, and were built in the 1970s when Japan's first wave of nuclear construction began. Contrary to some reports, they largely survived an earthquake many times stronger than they were designed to withstand, immediately going into shut-down.
The problems really began when the tsunami took out all the back-up diesel generators situated underneath the plant that were meant to provide power to circulate the coolant. Loss of site power is the worst situation for a nuclear power plant, and yet operators have managed to keep on pumping water and prevent catastrophic meltdown and death - so far.
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