12 years ago, the Fukushima Daiichi Nuclear Power Plant was badly damaged in the Tōhoku earthquake and tsunami. Over a million tons of water - enough to fill 500 Olympic-sized pools - have accumulated since March 2011. Now, Japan will begin releasing the treated radioactive water from the nuclear plant into the Pacific Ocean tomorrow despite opposition from its neighbours.
The water will be released over 30 years, after being filtered and diluted, and the plan has been approved by the UN's nuclear watchdog. Tom Scott, professor of nuclear materials at Bristol University, joined RTÉ Radio 1's Morning Ireland to explain what it all means. (This piece includes excerpts from the conversation which have been edited for length and clarity - you can hear the discussion in full above).
Is it dangerous to release the water?
"It's not dangerous. This is approved by the IAEA, the UN watchdog, it's approved by the Japanese authorities, and from a technical standpoint it's perfectly legitimate to do this," says Scott. "The amounts of tritium, the amount of radiation, in the water that we're talking about are incredibly low. I think this is a classic case of people grossly misunderstanding what the actual risk posed by this water is. There is a very largely inflated perceived risk which is just not correct in this case."
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From RTÉ Radio 1's Drivetime, Shaun Burnie, Senior Nuclear Specialist with Greenpeace East Asia, talks about Japan's plans to release waste water
What is in the water from the Fukushima plant?
"What's in the water is tritium, which is the heaviest isotope of hydrogen and it's radioactive. It has a half life of 12 years, so part of the reason to delay releasing the water over a 30 year period, is approximately, you're going through three half lives of radioactive decay before releasing the water," he explains. "So if you just leave this radioactive water for time, then the radioactivity continues to drop day by day, little by little. By doing this over a long period of time, it puts another safety margin on the whole exercise."
Why not wait even longer to release the radioactive water?
"It's partly because they've accumulated so much water that they've actually run out of space to build more containers to store more water," says Scott. "Where this water is coming from, is the damaged reactor cores have water which is constantly flowing through them, to make sure they stay nice and cool, as they prepare to decommission and take the reactor cores apart and take the damaged and partially melted fuel out." This means more water is constantly being accumulated.
"That water goes through an ion exchange system which takes out all of the radioactive salts. It basically takes everything out of the water apart from the tritium. The reason the system can't take the tritium out is because the tritium is the water (H2O). Because it's an isotope of hydrogen, you can't take it out."
Is it time to give nuclear power a chance? @ellamcsweeney Paul Deane @UCC @eriucc @piyushnitjsr @UCC & Kieran O'Connell @WeAreTUDublin look at the role of nuclear when it comes to energy & climate change on the Brainstorm radio show @drivetimerte @rteradio1 Thursday pic.twitter.com/f2AmM0z6MF
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Now there's so much water they've physically run out of space to be able to much more. "That means what they want to do is release the water that they've been holding for longest and get to a dynamic balance, where they're releasing the oldest water, which has the very, very lowest radioactivity. Which in the first place is low to start with," Scott explains. The new water being accumulated can then continue to be stored on-site.
Why has the plan caused uproar in neighbouring countries?
China has been the most vocal opponent and has accused Japan of treating the ocean like "its private sewer". Why is there opposition? "I think it's partly political. I think it's also partly just a technical misunderstanding about the actual risk posed by this water. Because tritium is naturally formed in the upper atmosphere and through rain it is naturally in the sea, in the oceans anyway.
"So once the Japanese start to release this water into the oceans you wouldn't be able to detect it as being any more radioactive than what the natural background levels of radioactivity in the seawater is anyway," he explains. "I think that gives testament to the fact that the risk that's posed by this is really a non-event. There is such little risk posed by this, no one should be getting excited about it."
From Deutsche Welle, why did the IAEA approve Japan's plans to release water from Fukushima?
South Korea's government have endorsed the plan and yet South Korea and China have already banned fish imports from around Fukushima. Scott thinks this is "more political than anything". "Obviously, that area of the world at the moment, countries are at odds with each other and there's political maneuvering. So it's politically a nice lever to pull on to get one over your neighbours, if you like."
What will happen to the Fukushima site itself?
"They still need to address the damaged reactor cores. So we had three reactors, we had fuel meltdowns. So that fuel which was melted and the damage which was caused to the reactor cores - it needs to be decommissioned, it needs to be cleaned up, it needs to be remediated. That's a task which can only be performed by robotic systems at the moment because the residual radioactivity is still very high in the reactor cores, dangerously high."
"So robots have to go in and you have to use novel cleanup techniques, for example laser cleaning, where you can bit by bit and slowly start to take out the radioactive material in a controlled way from the reactor core and package that up as nuclear waste. Which would then go and be stored and then ultimately would be disposed of, presumably similarly to the UK concept where we store it in an underground repository."
