Brief comments on the moltex reactor concept and nuclear creativity… – democratic underground electricity formulas grade 9


Light water nuclear reactors and, albeit not on the same scale, heavy water reactors, have been spectacularly successful devices that have saved, according to Pushker Karecha and Jim Hansen’s calculations – which I cite often – close to two million lives that otherwise would have been lost to air pollution.

None of this is meant to imply that nuclear technology is risk free; clearly it isn’t. However, nuclear technology need not be risk free to be vastly superior to all other forms of energy, all of which, in terms of risk, when compared to nuclear energy have vastly – and I do mean vastly – greater risks than nuclear energy, despite the extremely ignorant selective attention paid by the awful and mindless anti-nuke mentality that goes around killing human beings continuously and entirely unnecessarily by the use – and regrettably publicly accepted – of incredibly poor logic.

The huge success of light and heavy water reactors in saving human lives notwithstanding, these reactor types represent only a tiny subset of possible nuclear reactors. Early in what Alvin Weinberg – once the head of the Oak Ridge Laboratory – described as the "first nuclear era," a number of other types of reactors, generally as prototypes, were built and operated with varying degrees of success. Some very interesting and potentially superior forms of nuclear reactors (to the spectacularly successful light and heavy water versions) were built and operated on a pilot scale.

A few other reactor types have also been commercialized, for example, the British commercialized two novel reactor types, Magnox reactors, and AGCR, the Advanced Gas Cooled Reactor. (An American Gas Cooled Reactor which used helium rather than the carbon dioxide coolant in the AGCR was an economic failure.)

The first Magnox reactor, Calder Hall I, was commissioned in 1956 – making it the western world’s first commercial nuclear reactor – and operated until 2003. Although they were developed using 1950’s technology, they were rather successful devices. Calder Hall I shut after 47 years, the record for this primitive technology, and 18 of the 26 examples of this type of reactor operated for 40 years or more before being decommissioned, the last one, Wyfa 12 being shut down in 2012 after 41 years of operation.

In the last decade or so, many people have been focused on the LTMSR, Liquid Thorium Molten Salt Reactor, based on an experiment supervised by Alan Weinberg, the MSRE, which involved a solution phase reactor consisting of a molten salt, a eutectic mixture of lithium fluoride and beryllium fluoride – a mixture called "FLIBE" – in which thorium tetrafluoride and uranium tetrafluoride are dissolved. The uranium in this case is a synthetic isotope, U-233 formed from the capture of a neutron in thorium followed by two beta decays. (The very first commercial nuclear reactor operated in the United States, the Shippingport reactor, ran for one fuel cycle on thorium/U-233 fuel.) U-233 (unlike U-235) is, under the thermal neutron spectra resulting from interaction of fast neutrons with moderating lithium and beryllium, a breeder fuel, and therefore can be used to accumulate fissionable fuel.

Ultimately though, I changed my mind about this reactor, sometimes advertised as "off the shelf," mostly because I cannot endorse a reactor utilizing beryllium, which is an extremely toxic element, and which, although in its natural form is monoisotopic beryllium-9, can absorb a neutron to make the long lived radioisotope beryllium-10. (Also one isotope of lithium, Li-6, generates tritium in a neutron flux. This would be fine in a world in which fusion reactors were a reality, but might otherwise prove problematic, even though the decay product of tritium (half life 12.23 years) is the valuable and rare helium-3 isotope.

To avoid tritium accumulation, it might prove necessary to separate out lithium-6, an expensive process, although one with considerable industrial experience owing to the use of lithium-6 in the manufacture of thermonuclear ("hydrogen" ) bombs.

I’ve spent some time going through the MOLTEX concept. (The document is rather long, well written, well thought out and nicely illustrated.) From my perspective, it’s not the type of reactor I would find to be ideal for various reasons I have no time to discuss, but what is beautiful, absolutely beautiful, is the return of nuclear creativity that was described in Alvin Weinberg’s wonderful book about the early days of nuclear creativity.

The MOLTEX, is not a breeder, by the way, and from my perspective, I am mostly interested in breeder reactors, since I have convinced myself that depleted uranium and thorium waste from the lanthanide mines used to build stuff like wind turbines and electric cars, can eliminate all energy mining for several generations, if not forever.

Unfortunately most breeder reactors built on this planet have been problematic, although a few have had decent, if not great, performance. Creativity has been lacking in these kinds of reactors, since for reasons that escape me, they have all relied on liquid sodium coolants for the most part.

The kind of reactors I dream up all operate at extremely high temperatures, because high temperatures imply high efficiency, and the opportunity to generate electricity as a side product while using nuclear heat for carbon dioxide and/or water splitting as a means of reversing climate change, a very, very, very challenging engineering problem that is just on the edge of "remotely possible."

I’m not sure about the putative ZrCl4 distillation will work. It works in neat solutions, possibly those with enough energy to dissociate the normal hexacoordinate polymer, but it also forms group one hexachlorocomplex ions, particularly with cesium and rubidium, both of which are fission products. I don’t know this a problem but I would b

Some hears ago, I was rather enamored of a gas phase separation between plutonium and uranium from fluoride based reactors continuously during operation in a breeder situation only to learn about the interesting stability of cesium and rubidium complexes of the the (V) actinide fluorides. I abandoned this line of thinking not because the problem is necessarily insurmountable, but because I can think of approaches that can be investigated more cheaply experimentally

Finally I would be concerned about neutron economy. I believe it is incumbent upon humanity to either eliminate or substantially reduce mining energy materials. We have enough depleted uranium and waste thorium from the wind and electric car industry to fuel humanity – almost all of its energy requirements – for many centuries before we’ll even need to consider uranium from seawater. (If however, we choose to process seawater for other purposes, such as desalination, we can collect uranium as a side product; the Indians have such a system already piloted.

Finally, I’ve convinced myself as well that it is entirely feasible to spontaneously separate the most problematic fission products from the fuel more or less continuously so that they can be put to use to address important environmental and energy uses.