Fast Reactors - the answer to the U.K.'s stockpiles?

Prof David Mackay, Cambridge University Professor and Chief Scientific Advisor to the Department of Energy & Climate Change (DECC) has suggested that a new generation of fast reactors might offer the solution for dealing with the U.K.'s stockpile of nuclear waste, and further sweeten the deal for the U.K.'s potential nuclear renaissance. According to Mackay, the transmutation and subsequent fission of a stockpile which currently comprises 100 tonnes of plutonium and 35,000 tonnes of depleted uranium could provide the U.K. with 500 years of low-carbon electricity.

Unlike conventional thermal reactors, fast reactors do not use neutron moderators to reduce the velocity of released neutrons, a technique used to help sustain the fission reaction for uranium 235-rich fuel. These high-speed neutrons are more suited to the conversion of plutonium and other waste material, and the final waste product has a much shorter half-life than the original stockpile, thus providing relief to the substantial issue of waste disposal, as well as the nagging concern over terrorists plundering the stockpile for weapons-grade plutonium.

The favoured design is GE Hitachi's Prism Reactor, which started life as a U.S. government-funded research project. The commercial plant would be much smaller than a typical plant, producing around 311 MWe. A non-moderating coolant with a high heat capacity is required; multiple loops of liquid sodium would be used to transfer the heat from the reactor to a steam generator to power a turbine. Given the compact size of the reactor, multiple reactors could be combined; the present scheme proposes a pair of Prism reactors to be installed in place of the now defunct MOX (Mixed Oxide) Plant at Sellafield.

Fast reactors are less proven and more difficult to harness than the more commercially popular thermal reactors, but GE Hitachi insist that with the latest passive safety systems, reactor meltdowns such as that of Fukushima last year are a virtual impossibility.

Full article on the Guardian website.