A nice overview of the French plan to stabilize plutonium inventories.

[NNadir]

The current French process of one time recycling of plutonium to make MOX reactors would, if unchanged, result in a French inventory of about 670 MT of plutonium by 2070.

The Plutonium in question, because of its use in MOX fuel rods of the type now widely used in France, would be less than ideal for diversion to nuclear weapons - were someone to seek to do this - because of isotopic degradation. Even so, it would represent a significant political issue, much as it does now, although the actual risk of such diversion is astronomically low. Also, the unused plutonium represents wasted energy resources, and results in the need for more mining operations, including recovery of uranium from seawater. In addition, because of public demand, nuclear engineers are seeking approaches to spend fuel that will in practice reduce the radiotoxicity of spent fuel in such a way that its radiotoxicity (if eaten) will be lower than that of the natural uranium ores from which it is made in a time period of less than 1000 years.

In many ways this is a win-win-win-win approach: More efficient use of resources, better fuel burn-up, lower risk of weapons diversion, and an overall reduction in the radiotoxicity of the planet as a whole. (In the later case, reduction of "radiotoxicity" I'm not wholly convinced the result is a good one - it is possible life depends on radioactivity in ways we don't exactly understand.)

For this reason nuclear engineers in France have been actively working on many novel technologies, many of which seem quite attractive, especially those that rely, for the next several decades on the existing infrastructure of light water reactors.

Here is a general link that describes some of the approaches: http://www.cea.fr/gb/publications/Clefs46/pdfg/10-reactor.pdf

I personally have no trouble with MOX, since this results in the formation of new plutonium from so called "depleted uranium." But I think it is exciting to look at processes like the CORAIL process which would stabilize - with little further growth - the French plutonium inventory at about 400 metric tons. This is a satisfying level - enough to keep the fires burning, but not enough to create undue anxiety.

Note that the isotopic mixtures at equilibrium will be very different than that typically found in nuclear weapons. In particular the multirecycle offers the potential to create plutonium inventories that have less than 50% plutonium-239, in some cases less than 40% of this isotope. Although nuclear weapons have been demonstrated to work with plutonium-239 concentrations as low as 80%, the type of plutonium now made in nuclear reactors everywhere, the weapons had low yield and their design was complicated and difficult. It is thought that the stability of these weapons for storage is also lower than with conventional nuclear weapons.

The APA route, while it offers a politically palatable smaller 200 MT, is less thrilling in my mind, although I concede that there are certain technical advantages with respect to reactivity margins.

It is likely that if humanity survives global climate change there is no one mix that will fit all circumstances in all countries. The variety of approaches, however, demonstrates that only a small subset of possible nuclear technologies have been explored.

France continues to lead the world in the development of safe, clean nuclear technology. I hope that many other nations will continue to be inspired by the French example.

[phantom power]

1. Are there any analogous plans here in the United States?

[NNadir]

2. Many national laboratories are involved in theoretical work

Our experimental nuclear programs, on the other hand, are rather weak. The United States is pretty much the only nation that is committed to the "once through" nuclear fuel cycle, where only uranium enriched from mining sources is used. The theory behind this is the (silly) idea that the once through cycle, a McDonald's approach to nuclear fuel, will prevent the spread of nuclear weapons. This policy has been irrelevant for many years.

During the Clinton years, the United States agreed to work on plutonium burning thorium fueled reactors of the Radkowsky type configuration. However it agreed to fund this work in Russia. The Radkowsky configuration is another type of advanced fuel cycle, one that has an even lower risk of arms proliferation. In this configuration, thorium fuel rods remain in the reactor for nine years, achieving very high burn-ups, typically more than 100,000 MW-day/ton. This is more than double current burn-ups. The impetus for doing this was that in the nuclear disarmament agreements, the Russians refused to regard their surplus uranium as "waste." They insisted, rightly, that it was a resource. Clinton agreed, and the project was part of the treaty to dismantle nuclear warheads.

After Bush took power, he reneged on the deal. I believe that this is a very promising approach, and I can imagine ways that it might be made to dove-tail with a Corail type approach.

I expect that the primary work on advanced fuel cycles will not take place in the United States. We'll probably end up trying to sell our plutonium (weapons grade included) for food.