This is one of several articles I came across yesterday about thorium reactors. A thorium-fueled reactor turns out to have several advantages over a uranium, plutonium or MOX-fueled one:
- Thorium is three to four times more abundant than uranium, much safer and easier to extract, and unlike uranium, doesn't require any enrichment — so, unlike uranium, it is all usable as fuel. As a matter of fact, it's safer to mine thorium than to mine coal.
- Thorium is not of itself fissile, and requires a neutron "pump" of some sort to maintain a nuclear reaction, so a thorium reactor — particularly an accelerator-driven system — cannot go critical.
- The thorium fuel cycle produces far less and shorter-lived radioisotope byproducts than the uranium cycle, the major significant long-halflife isotope being protactinium-231.
- You can't build a nuclear weapon out of thorium, making it "safe" from the point of view of nuclear proliferation.
- A thorium reactor can "incinerate" plutonium, U235, and other transuranics, providing a safe means to dispose of existing transuranic fuels.
- Thorium reactors ideally operate at a higher burnup than uranium reactors, performing well at burnup levels over 150GWd/t, compared to 40GWd/t for a typical Generation II uranium reactor. This presents some engineering design problems, but means less frequent refuelling (and consequently, lower downtime for refuelling) and better utilization of fuel.
- Thorium dioxide has better chemical and physical properties than uranium oxide; its melting point and thermal conductivity are higher, its coefficient of thermal expansion is smaller, and it is more chemically stable, including that it does not further oxidize.
Looks like an interesting technology that overcomes most of the arguments of both anti-proliferationists and the ZOMG-nukes-will-kill-us-all school of environmentalists. (Of course, it still won't win over the AAAAAUUUGH-YOU-SAID-NUCLEAR set.)
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