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Is it safe to dump Fukushima waste into the sea? via The Guardian

Japan has called for hundreds of thousands tonnes of irradiated water from the nuclear plant to be released into the Pacific Ocean. Karl Mathiesen looks at the potential impacts

More than 1,000 tanks brimming with irradiated water stand inland from the Fukushima nuclear plant. Each day 300 tonnes of water are pumped through Fukushima’s ruined reactors to keep them cool. As the water washes through the plant it collects a slew of radioactive particles.

The company that owns the plant – The Tokyo Electric Power Company (Tepco) – has deployed filtration devices that have stripped very dangerous isotopes of strontium and caesium from the flow.

But the water being stored in the tanks still contains tritium, an isotope of hydrogen with two neutrons. Tritium is a major by-product of nuclear reactions and is difficult and expensive to remove from water.

Now, Japan’s Nuclear Regulation Authority (NRA) has launched a campaign to convince a sceptical world that dumping up to 800,000 tonnes of contaminated water into the Pacific Ocean is a safe and responsible thing to do.

NRA chairman Shunichi Tanaka has officially called on Tepco to work towards a release. The International Atomic Energy Agency (IAEA) last year also issued a callfor a release to be considered and for Tepco to perform an assessment of the potential impacts. For its part, Tepco has said there are no current plans to release the water. But the Associated Press (AP) reported that company officials are saying in private that they may have no choice.

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To put it in context, the natural global accumulation of tritium is a relatively tiny 2,200 PBq. The isotope has a half life of 12.3 years and is only created naturally on Earth by a rare reaction between cosmic rays and the atmosphere. By far the largest source of tritium in our environment is the nuclear weapons testing programme of last century, which dumped a total of 186,000 PBq into the world’s oceans. Over time this has decayed to roughly 8,000 PBq. Another significant source of tritium are nuclear power stations, which have long dumped tritium-contaminated water into the ocean.

“I would think more has been put into the Irish Sea [from the UK’s Sellafield plant] than would ever be released offJapan,” said Buesseler. So far, the Fukushima disaster has seen 0.1-0.5 PBq leaked or released into the Pacific.

Even if all of the contaminated water were released into the ocean, it would not contain enough tritium to be detectable by the time it dispersed and reached the US west coast about four years later, said Simon Boxall, an oceanographer at the University of Southampton.

“In the broad scale of things, if they do end up putting the material in the Pacific, it will have minimal effect on an ocean basin scale,” said Boxall. “In an ideal world, we wouldn’t be in this situation. But the question is, what is the safest way forward? In many ways this is a pragmatic solution.”

But Boxall said there may be local effects – especially on the already heavily impacted fishing industry – as the contaminated water would take time to disperse.

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