Decommissioning a nuclear reactor

[ Below are excerpts from the 7 March 2012 NewScientist article: How to dismantle a nuclear reactor ]

about the costs and challenges of dismantling nuclear power plants in Europe ]

decommisioning nuclear reactor

By the start of 2012, according to the International Atomic Energy Agency, 138 commercial power reactors had been permanently shut down with at least 80 expected to join the queue for decommissioning in the coming decade – more if other governments join Germany in deciding to phase out nuclear power following the Fukushima disaster in Japan last year.

And yet, so far, only 17 of these have been dismantled and made permanently safe. That’s because decommissioning is difficult, time-consuming and expensive.

A standard American or French-designed pressurised water reactor (PWR) – the most common reactor design now in operation – will produce more than 100,000 tonnes of waste, about a tenth of it significantly radioactive, including the steel reactor vessel, control rods, piping and pumps. Decommissioning just a single one generally costs up to half a billion dollars.

Decommissioning Germany’s Soviet-designed power plant at Greifswald produced more than half a million tonnes of radioactive waste. The UK’s 26 gas-cooled Magnox reactors produce similar amounts and will eventually cost up to a billion dollars each to decommission. That’s because they weren’t designed with decommissioning in mind.

The many variations also mean that there is no agreed-upon standard for how to go about the process. If you want to decommission a nuclear power plant, you have three options. The first is the fastest: remove the fuel, then take the reactor apart as swiftly as possible, storing the radioactive material somewhere safe to await a final burial place.  The second approach is to remove the fuel but lock up the reactor, letting its troublesome radioactive isotopes decay, which makes dismantling easier – much later.  The third option is to simply entomb the reactor where it is.

Even when the reactor can be dismantled, where do you put the radioactive waste? Even the least contaminated material – old overalls, steel heat exchangers and toilets – must be carefully separated and sent to specially licensed landfill sites. Not every country has such designated facilities. Intermediate-level waste, contrary to its name, is even more of a problem because it may require deep ground burial alongside the high-level spent fuel.

In 1976, a British Royal Commission said no more nuclear power plants should be built until the waste disposal problems were resolved. Thirty-five years on, nothing much has changed.


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