On Aug. 3, 2011, the Nuclear Decommissioning Authority (NDA) announced the closure of the Mox nuclear fuel manufacturing plant at the Sellafield complex in Cumbria with the loss of 600 jobs expected. A closure waiting to happen? It would certainly appear to be the case after the Fukushima Daiichi nuclear plant disaster in March this year.

Sellafield is holding 13 tonnes of Japanese plutonium oxide for treatment, capable of generating, once processed, a greater energy output than 26 million tonnes of coal, but the Japanese aren't looking to get their enriched energy source back any time soon. Sellafield's Mox facility appears to have been entirely dependent upon orders from the Japanese company, even to the point where Sellafield's current Mox manufacturing works cannot be economically altered to handle the latest generation of nuclear reactors and so bid for other potential orders.

This is a rather sad state of affairs in a country that once was a leader in nuclear technology. It has also turned out to be a pretty rum deal for the British tax payer. Construction of the Mox facility at Sellafield was completed in 1997 but has had an operational lifespan of under 10 years.

The plant was designed to produce up to 120 tonnes of Mox per year but in its first five years of operation managed to produce only five tonnes, no doubt a lack of rigour in the cost accounting department. The joke, however, is on the taxpayer to the tune of £1.34 billion to date. With virtually nothing to show for this treasure, has the NDA been sleepwalking its way to this decision? Not to mention the small matter of a stockpile of 112 tonnes of (civilian) separated plutonium - the largest of its kind in the world.

What is Mox and why is it important? Mixed Oxide Fuel, to put it as simply as possible, is a nuclear fuel formed by blending (separated) plutonium with natural, reprocessed or depleted uranium. The plutonium has itself been separated, mostly, from the spent nuclear fuel from civilian nuclear power stations. Some plutonium has been sourced from decommissioned nuclear weapons - "weapons grade" plutonium.

A single recycling of plutonium increases the energy derived from the original uranium by 12 per cent and by recycling the uranium-235 after enrichment, together with the plutonium, this then increases to 20 per cent.

The fuel is used in thermal reactors, the most common type of nuclear energy plant producing heat through nuclear fission. A thermal reactor uses "slow" or "thermal" neutrons requiring a neutron moderator in order to achieve the reduction in neutron speed so that a nuclear chain reaction using uranium-235 can be maintained.

Most generally used as a moderator is ordinary (light) water and at the moment there are 359 light water reactors (LWR) in operation in 27 countries with a further 27 under construction. There are two varieties of LWR power plants - pressurised water reactors (PWR) and boiling water reactors (BWR).

The use of ordinary water makes it necessary to enrich the uranium fuel so that the critical nuclear chain reaction can be maintained. This is because light water absorbs too many neutrons to be used with unenriched uranium.

Research continues on a third type, probably a BWR refinement, the supercritical water reactor, holding out the promise of higher thermal efficiency and simpler, so by implication cheaper, design and construction. It will however, require greater fuel enrichment and is still some way off before becoming a reality.

At present, 30 reactors in Western Europe use Mox for about 30 percent of their core reactor fuel and with modifications, some of these reactors will be able to use a 50 per cent Mox core fuel ratio. It is claimed that Canada's 17 pressurised heavy water (D20) deuterium-uranium reactors, can use a 100 per cent Mox fuel core.

Meanwhile, the U.S. is building a Mox plant at the Savannah River Site in South Carolina. This "nuclear reservation" was built during the Cold War to make nuclear weapons, among other things, and covers 310 square miles - not short of room then! Its former Cold War foe, Russia, is still running, quite successfully and with no serious mishaps, its BN-600 sodium-cooled fast breeder reactor at Beloyarsk, Sverdlovsk Oblast - it too can use Mox.

The pity then, is that Sellafield should be on anyone's list in the market for "nuclear reprocessing", "uranium enrichment" and MOX!

The Independent on Aug. 5, 2011, reported that:

"Local politicians and trade unions want the Government to agree to agree to a new mixed-oxide (Mox) fuel plant costing up to £6 billion in the wake of the announcement on Wednesday to close the controversial Sellafield Mox Plant..."

Six billion pounds! I wish them the very best of luck in the current climate but the alarm bells should surely have been ringing many years sooner.