Wednesday, August 08, 2012

UK Can Run Power Grid for 500 Years on Waste Plutonium Stores

Britain's huge plutonium stockpile makes it a vast energy resource. David MacKay, chief scientist at the Department of Energy and Climate Change, recently said British plutonium contains enough energy to run the country's electricity grid for 500 years. _Breakthrough
The UK is going through a difficult, schizoid stage of energy policy planning. On the one hand, the UK government wants to prove how green it is by deploying ruinously expensive arrays of intermittent unreliable forms of energy such as big wind and big solar.

On the other hand, the government truly does want to develop at least one form of energy that actually works -- for that, it is looking at nuclear power.
While most of the world's civilian plutonium waste is still trapped inside highly radioactive spent fuel, much of that British plutonium is in the form of plutonium dioxide powder. It has been extracted from spent fuel with the intention of using it to power an earlier generation of fast reactors that were never built. This makes it much more vulnerable to theft and use in nuclear weapons than plutonium still held inside spent fuel, as most of the U.S. stockpile is.

Fast reactors can be run in different ways, either to destroy plutonium, to maximise energy production, or to produce new plutonium. Under the PRISM proposal now being considered at Sellafield, plutonium destruction would be the priority. "We could deal with the plutonium stockpile in Britain in five years," says Loewen. But equally, he says, it could generate energy, too. The proposed plant has a theoretical generating capacity of 600 megawatts.

Fast reactors could do the same for the U.S. Under the presidency of George W. Bush, the U.S. launched a Global Nuclear Energy Partnership aimed at developing technologies to consume plutonium in spent fuel. But President Obama drastically cut the partnership's funding, while also halting work on the planned Yucca Mountain geological repository. "We are left with a million-year problem," says Loewen. "Right now there isn't a policy framework in the U.S. for solving this issue."

...The PRISM fast reactor is attracting friends among environmentalists formerly opposed to nuclear power. They include leading thinkers such as Stewart Brand and British columnist George Monbiot. And, despite the cold shoulder from the Obama administration, some U.S. government officials seem quietly keen to help the British experiment get under way. They have approved the export of the PRISM technology to Britain and the release of secret technical information from the old research program. And the U.S. Export-Import Bank is reportedly ready to provide financing.

Britain has not made up its mind yet, however. Having decided to try and re-use its stockpile of plutonium dioxide, its Nuclear Decommissioning Authority has embarked on a study to determine which re-use option to support. There is no firm date, but the decision, which will require government approval, should be reached within two years. Apart from a fast-breeder reactor, the main alternative is to blend the plutonium with other fuel to create a mixed-oxide fuel (mox) that will burn in conventional nuclear power plants.

...Only fast reactors can consume the plutonium. Many think that will ultimately be the UK choice. If so, the PRISM plant would take five years to license, five years to build, and could destroy probably the world's most dangerous stockpile of plutonium by the end of the 2020s. GEH has not publicly put a cost on building the plant, but it says it will foot the bill, with Proponents of fast reactors see them as the nuclear application of one of the totems of environmentalism: recycling. the British government only paying by results, as the plutonium is destroyed. The idea of fast breeders as the ultimate goal of nuclear power engineering goes back to the 1950s, when experts predicted that fast-breeders would generate all Britain's electricity by the 1970s. But the Clinton administration eventually shut down the U.S.'s research program in 1994. Britain followed soon after, shutting its Dounreay fast-breeder reactor on the north coast of Scotland in 1995. Other countries have continued with fast-breeder research programs, including France, China, Japan, India, South Korea, and Russia, which has been running a plant at Sverdlovsk for 32 years.

But now climate change, with its urgency to reduce fossil fuel use, and growing plutonium stockpiles have changed perspectives once again. The researchers' blueprints are being dusted off. The PRISM design is based on the Experimental Breeder Reactor No 2, which was switched on at the Argonne National Laboratory in Illinois in 1965 and ran for three decades.

Here is how conventional and fast reactors differ. Conventional nuclear reactors bombard atoms of uranium fuel with neutrons. Under this bombardment, the atoms split, creating more neutrons and energy. The neutrons head off to split more atoms, creating a chain reaction. Meanwhile, the energy heats a coolant passing through the reactor, such as water, which then generates electricity in conventional turbines.

The problem is that in this process only around 1 percent of the potential energy in the uranium fuel is turned into electricity. The rest remains locked up in the fuel, much of it in the form of plutonium, the chief by-product of the once-through cycle. The idea of fast reactors is to grab more of this energy from the spent fuel of the conventional reactor. And it can do this by repeatedly recycling the fuel through the reactor.

The second difference is that in a conventional reactor, the speed of the neutrons has to be slowed down to ensure the chain reactions occur. In a typical pressurized-water reactor, the water itself acts as this moderator. But in a fast reactor, as the name suggests, the best results for generating energy from the plutonium fuel are achieved by bombarding the neutrons much faster. This is done by substituting the water moderator with a liquid metal such as sodium. _Breakthrough
Several types of next generation nuclear reactors are undergoing R&D at this time. Some of those new reactor designs will be scalable in nature, allowing much more versatile deployment to power grids, mini-grids, and remote locations.

The main obstruction to the development of cheaper, safer, more reliable nuclear reactors, appears to be atrocious government policy-making. So far, no one has developed a cure for that hazard to humanity.

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