Wall of ice to stop Fukushima radiation leak

Radiation levels are spiking at a Japanese nuclear plant as deadly pollutants seep into the ocean, forcing the government to take desperate measures. Is nuclear energy worth the price?

March 2011: the Fukushima nuclear plant in Japan goes into meltdown. Hit first by a powerful earthquake and then by a devastating tsunami, the plant’s cooling systems fail. Radioactive fuel rods overheat, begin to melt and burn through their containment vessels. Two of the reactor cores explode, spraying toxic waste into the atmosphere. It is the worst nuclear accident in 25 years.

With an often heroic effort, emergency responders wrestled the Fukushima reactors back under control. Weeks passed, and the attention of the world’s media moved on. But inside the ruined buildings, the deadly fuel rods continued to burn. Now, two years after the meltdown, radiation levels at the Fukushima plant have once again started climbing. Even outside the plant, levels in some places have spiked as far as 2,200 millisieverts: enough to kill an unshielded human within hours.

The immediate problem is that the site is still soaked in radioactive water, some pumped in by firefighters and some flowing in underground from nearby hills. This water absorbs deadly radioactive waste from the reactors, spreading it through the subsoil before dumping it into the Pacific Ocean.

To cope with this flood of pollution, the Japanese Government has announced that it will try a novel approach: engineers will use special cooling pipes to freeze a line of soil around the facility, creating an impenetrable barrier going deep into the polluted ground. Frozen soil is harder than concrete and – in theory at least – this ‘ice wall’ should keep water from flowing into or out of the plant.

The frozen barrier could cost over £300 million, but at least the immediate crisis should be solved. In practice, however, this sort of ice wall technology has only ever been used as a temporary measure. And some of the radioactive materials at Fukushima will stay deadly for decades or even centuries. To clean up Fukushima in the long term will take at least forty years, at an estimated cost of tens of billions of pounds.

Paying the price

When nuclear plants were first being developed, they promised a future of energy so plentiful that you could give it away for free. Now, writes one commentator, we see that reactors burn money, not just nuclear fuel. We should abandon this costly and dangerous energy source in favour of sun and wind: safe and inexhaustible.

But defenders of nuclear energy think Fukushima has provoked an overreaction. The disaster has yet, after all, to claim any lives, and the latest reactors are far safer and more efficient than the old Japanese plant. Nuclear could still deliver on its potential, so long as one huge failure doesn’t overshadow decades of quiet success.

You Decide

  1. Should we abandon nuclear power?
  2. Pollution from coal power plants kills around 10,000 people per year in the US alone. Why does that not make any headlines?

Activities

  1. As a class, brainstorm the pros and cons of the main modern energy sources: gas, coal, nuclear, wind, solar and any others you would like to add. Which source comes out on top?
  2. Sketch out a design for a nuclear reactor containment chamber. It should be able to resist natural disasters, meltdowns, explosions and terrorist attacks, but it needs to be able to let coolant in and waste and energy out.

Some People Say...

“With a death toll of zero, Fukushima is no big deal.”

What do you think?

Q & A

Radiation leaking into the ocean? That sounds bad! Should I be worried?
For the moment you needn’t panic, unless you are a Japanese fisherman. Fish from the waters around Fukushima are banned for human consumption, since they contain higher than legal levels of radioactive material. The Pacific is a huge body of water, and radiation from the plant soon becomes so diluted that it is almost undetectable.
Will the fish mutate? Isn’t radiation what created Godzilla?
Sadly, real life mutation is not that exciting. Radiation might cause fish to be infertile, have birth defects or get cancer. In all cases, the fish will die, not smash up Tokyo.
Nothing to worry about then?
Not exactly. Radioactive material damages the environment, and it stays dangerous for a very long time.

Word Watch

Tsunami
A tsunami, often inaccurately called a tidal wave, is a huge wave created by an earthquake under the sea floor. These are among the most devastating natural disasters. The 2011 tsunami in Japan reached heights of up to 40 metres, and killed nearly 16,000 people, while the Boxing Day Tsunami of 2004 killed a quarter of a million.
Worst nuclear accident
The worst nuclear accident in history took place at the Chernobyl nuclear plant in 1986. A reactor explosion there claimed thousands of lives (the total is still bitterly controversial) and has left huge areas of the Ukraine still uninhabitable today.
Fuel rods
Nuclear reactors work by combining nuclear fuel, usually uranium, into dense rods where decaying atoms activate each other in a chain reaction. The effect is like a nuclear bomb going off in slow motion. Once the reaction has started it is very difficult to stop and requires constant cooling to keep under control. The rods will not be exhausted for many years.

Subjects

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