Thorium Reactors

I talked a bit about the question of thorium reactors and proliferation in a previous post. I try not to talk too much about pie-in-the-sky nuclear technologies and keep to what is actually happening i.e. the PWR reactors which they are actually thinking of building at Sizewell and Hinkley. However, there has been a video posted on some facebook pages1. For thorium advocates this is quite reasonable and does mention some  of the problems – in fact I agree with a lot that is said.

If you are really interested then have a look at the IAEA document Thorium fuel cycle — Potential benefits and challenges2although it downplays some of the problems.

Thorium is more abundant

The first thing to mention is about conventional fission reactors – they were never intended to work the way they do. It was envisioned that Uranium breeder technology2 would be used but since that technology had not been fully developed the current technologies were used as a stop-gap. However, after over 50 years of trying to develop the Uranium breeder technology little progress has been made. If it had then the problems of dwindling Uranium supplies would not be such an issue and hence one of the major advantages of Thorium would be removed.

Proliferation resistance

I have talked about this in a previous post – Thorium and Proliferation.

Less dangerous waste

As with all fission reactions one of the major problems is the highly radioactive fission products. For thorium this is only slightly different from those produced by fissioning Uranium (see Composition of Spent Fuel). Where the Thorium cycle has an advantage is that it does not produce so much long lived transuranic waste through neutron capture (see Production and Fission of Transuranic Elements In A Nuclear Reactor). However, this  is only an advantage in the long term (after a few hundred years) and there are still some long lived fission products (99Tc, 126Sn, 79Se etc). The thorium cycle also produces 231Pa which has a half-life of 32,700 years.

A tried and failed technology

Most of the people advocating the use of thorium give the impression that nobody has tried to develop thorium reactors. This is far from the truth with the IAEA listing at least 16 reactors2.

Thorium itself is not fissile and has to be converted into 233U via neutron capture – i.e. thorium reactors are breeder reactors. Although there are some advantages over uranium based breeder reactors a lot of the technical difficulties are still there. As the video which sparked off this post says developing such technology would take a lot of time and money.

Cheaper cleaner safer alternatives

Why waste money on developing thorium reactors when there are cheaper, cleaner and safer non nuclear alternatives – see TASC Leaflet – Meeting Our Energy Needs.

Some more good articles on Thorium:

1 The Thorium Conspiracy – Stuff They Don’t Want You to Know

2 Thorium fuel cycle — Potential benefits and challenges, IAEA (

3 For more information see the wikipedia page at


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