Thorium: the other side

.http://www.ieer.org/fctsheet/thorium2009factsheet.pdf  This link is from the Physicians for Social Responsibility, an anti-nuclear group. The information is now two years old.

http://www.world-nuclear.org/info/inf62.html  The world organization for professionals in the nuclear industry published an updated fact sheet on thorium in March/2011. The summary of benefits and problems follows:

Developing a thorium-based fuel cycle

Despite the thorium fuel cycle having a number of attractive features, development has always run into difficulties.

The main attractive features are:

  • The possibility of utilising a very abundant resource which has hitherto been of so little interest that it has never been quantified properly.
  • The production of power with few long-lived transuranic elements in the waste.
  • Reduced radioactive wastes generally.

The problems include:

  • The high cost of fuel fabrication, due partly to the high radioactivity of U-233 chemically separated from the irradiated thorium fuel. Separated U-233 is always contaminated with traces of U-232 (69 year half-life but whose daughter products such as thallium-208 are strong gamma emitters with very short half-lives). Although this confers proliferation resistance to the fuel cycle by making U-233 hard to handle and easy to detect, it results in increased costs.
  • The similar problems in recycling thorium itself due to highly radioactive Th-228 (an alpha emitter with two-year half life) present.
  • Some concern over weapons proliferation risk of U-233 (if it could be separated on its own), although many designs such as the Radkowsky Thorium Reactor address this concern.
  • The technical problems (not yet satisfactorily solved) in reprocessing solid fuels. However, with some designs, in particular the molten salt reactor (MSR), these problems are likely to largely disappear.

Much development work is still required before the thorium fuel cycle can be commercialised, and the effort required seems unlikely while (or where) abundant uranium is available. In this respect, recent international moves to bring India into the ambit of international trade might result in the country ceasing to persist with the thorium cycle, as it now has ready access to traded uranium and conventional reactor designs.

Nevertheless, the thorium fuel cycle, with its potential for breeding fuel without the need for fast neutron reactors, holds considerable potential in the long-term. It is a significant factor in the long-term sustainability of nuclear energy.

One thing is clear. Canada is at the forefront of this research for several reasons:

1) The Candu reactor can function with several different fuel cycles.

2) The scientists of AECL have been working with the Chinese to develop the systems they will be using.

3) The group at AECL is amongst the best in the world and in the past included a Nobel laureate.

The nuclear vs anything but nuclear crowds have put back research by not approaching the problem as a world-wide one, in which many modalities, from wind to solar to water to coal to nuclear will have to be used. All of these have their drawbacks and strengths from the effect of wind on the health of bird( and possibly human) populations, to the nuclear emissions from coal itself, not to mention the pollution from old-style plants, to the disruption of populations of hydro developments to the vast hectares that need to be taken up to produce large amounts of solar. Least we forget, the sun doesn’t shine and the wind doesn’t blow all the time, and all those storage batteries have environmental consequences too.

Our solution may be nuclear, but fusion not fission. A process that produces water as a byproduct has its appeal. As I understand it, the prototypes work but are touchy and shut down with little provocation. They don’t explode or melt down however.

Cutting funding to the scientists when the work is perceived as politically unacceptable as has happened in the past is foolish and short-sighted. Remember the Arrow.

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