"Integral fast reactors" and other "fourth generation" nuclear power concepts have been gaining attention, in part because of comments by US climate scientist James Hansen.
"We need hard-headed evaluation of how to get rid of long-lived nuclear waste and minimise dangers of proliferation and nuclear accidents," Hansen says. "Fourth generation nuclear power seems to have the potential to solve the waste problem and minimise the others."
Integral fast reactors (IFRs) are reactors proposed to be fuelled with a metallic alloy of uranium and plutonium, with liquid sodium as the coolant.
They're "fast" because they would use unmoderated neutrons like other plutonium-fuelled fast neutron reactors (e.g. breeders).
They're "integral" because they would operate together with onsite "pyroprocessing" to separate plutonium and other long-lived radioisotopes and to re-irradiate nuclear waste.
IFRs would breed their own fuel (plutonium), which means there would be less global demand for uranium mining with its attendant problems, and less demand for uranium-enrichment plants.
Another advantage is that the primary fuel source for IFRs would be large, existing, global stockpiles of depleted uranium (used in IFRs as the raw material to produce plutonium).
Pyroprocessing would not separate pure plutonium suitable for direct use in nuclear weapons. Instead it would keep the plutonium mixed with other long-lived radioisotopes so it could not be used directly in weapons.
Recycling of plutonium generates energy and gets rid of the plutonium that could be used for weapons.
These advantages could potentially be achieved with conventional reprocessing and plutonium use in MOX (uranium/plutonium oxide) reactors or fast neutron reactors.
IFR offers one further potential advantage — transmutation of long-lived waste radioisotopes into shorter-lived waste products.
Good on paper, but...
In short, IFRs could produce lots of greenhouse-friendly energy and while they're at it they can "eat" nuclear waste and fissile materials that might otherwise find their way into nuclear weapons.
Too good to be true? Sadly, yes.
Nuclear engineer Dave Lochbaum writes: "The IFR looks good on paper. So good, in fact, that we should leave it on paper. For it only gets ugly in moving from blueprint to backyard."
Complete IFR systems don't exist. Fast neutron reactors exist but experience with them is limited and they have had a troubled history.
The pyroprocessing and waste transmutation technologies intended to operate as part of IFR systems are a long way from being advanced.
But even if the technologies were fully developed and successfully integrated, IFRs would still fail the crucial test — they could too easily be used to produce fissile materials for nuclear weapons.
As with conventional reactors, IFRs can be used to produce weapon-grade plutonium in the fuel (using a shorter-than-usual irradiation time) or by irradiating a uranium or depleted uranium "blanket" or targets.
Conventional PUREX (Plutonium-Uranium Extraction) reprocessing can be used to separate the plutonium. Another option is to separate reactor-grade plutonium from IFR fuel and to use that in weapons instead of weapon-grade plutonium.
IFR supporters propose using them to draw down global stockpiles of fissile material, whether derived from nuclear research, power or weapons programs.
However, IFRs have no need for outside sources of fissile material beyond their initial fuel load. Whether they are used to irradiate outside sources of fissile material to any significant extent would depend on a combination of commercial, political and military interests.
History shows that non-proliferation targets receive low priority. Conventional reprocessing with the use of separated plutonium as fuel (in breeders or MOX reactors) has the same potential to draw down fissile material stockpiles as IFRs. But they have increased, rather than decreased, proliferation risks.
Very little plutonium has been used as reactor fuel in breeders or MOX reactors, and it is used in reactors that produce more plutonium than they consume.
But the separation of plutonium from spent nuclear fuel continues. Stockpiles of separated "civil" plutonium — which can be used directly in weapons — are increasing by about five tonnes annually. It amounts to more than 270 tonnes, enough for 27,000 nuclear weapons.
IFR advocates demonstrate little or no understanding of the realpolitik imposed by commercial, political and military interests.
These interests have, among other things, unnecessarily created this problem of 270-plus tonnes of separated civil plutonium and failed to take the simplest steps to address the problem.
Such steps would be to either suspend reprocessing or reduce the rate of reprocessing so plutonium stockpiles are drawn down rather than continually increased.
The proposed use of IFRs to irradiate fissile materials produced elsewhere still has a familiar problem. Countries with the greatest interest in weapons production will be the least likely to forfeit fissile material stockpiles and vice versa.
Whatever benefits arise from the potential consumption of outside sources of fissile material must be weighed against the problem that IFRs could themselves be used to produce fissile material for weapons.
Countries intent on keeping nuclear weapons won't use IFRs to draw down stockpiles of their own fissile material let alone anyone else's — they will use them to produce plutonium for their own nuclear weapons.
Some IFR supporters propose initially deploying IFR technology in nuclear weapons states and weapons-capable states. But this ignores the fact that every other proposal for selective deployment of dual-use nuclear technology has always been rejected by the countries that would be excluded.
Some IFR advocates downplay the proliferation risks by arguing that fissile material is more easily produced in research reactors.
But producing fissile material for weapons in IFRs would not be difficult. The main challenge would be to get around safeguards.
Proponents of IFR's acknowledge the need for a rigorous safeguards system to detect and deter using IFRs to produce fissile material for weapons. However, the existing safeguards are inadequate.
The director general of the International Atomic Energy Agency, Dr. Mohamed El Baradei, has noted that the IAEA's basic rights of inspection are "fairly limited", that the safeguards system suffers from "vulnerabilities" and "clearly needs reinforcement", that efforts to improve the system have been "half-hearted", and that the safeguards system operates on a "shoestring budget ... comparable to that of a local police department".
IFR advocates imagine that a strong commitment to nuclear non-proliferation will heavily shape the development and deployment of IFR technology.
But in practice it could easily fall prey to the same interests that are responsible for turning attractive theories into the fiasco of ever-growing stockpiles of separated plutonium.
Under the Bush administration in the US, Global Nuclear Energy Partnership proposals for advanced "proliferation-resistant" reprocessing became a plan to expand conventional reprocessing. Advanced reprocessing was relegated to "research and development" plans.
A similar fate could easily befall proposals to run IFRs together with advanced reprocessing.
IFR supporters want to avoid the risks associated with widespread transportation of nuclear and fissile materials by co-locating a pyroprocessing facility with every IFR reactor plant. Yet plant owners would much prefer the cost savings associated with centralised processing.
As one final example, the fissile material needed for the initial IFR fuel loading would ideally come from civil and military stockpiles — but that fissile material requirement could be used to justify the ongoing operation of existing enrichment and reprocessing plants and the construction of new ones.
Other 'fourth generation' reactors
IFRs and other plutonium-based fast neutron reactor concepts fail the weapons of mass destruction proliferation test. They can too easily be used to produce fissile material for nuclear weapons.
So do conventional reactors because they produce plutonium and legitimise the operation of enrichment plants that can produce both low-enriched uranium for reactors and also highly enriched uranium for weapons.
The use of thorium, instead of plutonium, as a nuclear fuel doesn't solve the weapons proliferation problem. Irradiation of thorium (indirectly) produces uranium-233, a fissile material that can be used in nuclear weapons.
The US has successfully tested weapons using uranium-233 (and France may have too). India's thorium program must have a nuclear weapons component — as evidenced by India's refusal to allow IAEA safeguards to apply to its thorium program.
Thorium-fuelled reactors could also be used to irradiate uranium to produce weapons grade plutonium.
Some proponents of nuclear fusion power falsely claim that it would pose no risk of contributing to weapons proliferation.
In fact, there are several risks. These include the use of tritium, a radioactive form of hydrogen, as a fusion power fuel. This raises the risk of its diversion for use in boosted nuclear weapons, or, more importantly, the use of fusion reactors to irradiate uranium to produce plutonium or to irradiate thorium-232 to produce uranium-233.
Fusion power has yet to generate a single Watt of useful electricity but it has already contributed to proliferation problems.
According to Khidhir Hamza, a senior nuclear scientist involved in Iraq's weapons program in the 1980s: "Iraq took full advantage of the IAEA's recommendation in the mid 1980s to start a plasma physics program for 'peaceful' fusion research.
"We thought that buying a plasma focus device — would provide an excellent cover for buying and learning about fast electronics technology, which could be used to trigger atomic bombs."
More information on IFRs and "fourth generation" nuclear reactors is posted at www.energyscience.org.au and www.foe.org.au/anti-nuclear/issues/nfc/power. A debate on IFRs is posted at http://skirsch.com/politics/globalwarming/ifrUCSresponse.pdf.
[Jim Green is an anti-nuclear campaigner with Friends of the Earth.]