Alternative Reactor Types

There is little reason to believe that minimising proliferation risks will be a priority in the evolution of nuclear power technology. The growing stockpiles of unirradiated plutonium provide compelling evidence of the low priority given to non-proliferation initiatives compared to commercial and political (and sometime military) imperatives.

A number of the ‘advanced’ reactor concepts being studied involve fast neutron reactors (a.k.a. fast spectrum reactors or breeder reactors) which use plutonium as the primary fuel. There are various possible configurations of these systems. Most rely on irradiation of a natural or depleted uranium blanket which produces plutonium which can be separated and used as fuel. Fast reactors can potentially produce more plutonium than they consume, and they are generally well suited for the production of weapon grade plutonium.

Fast reactors can be ‘breeders’ (producing more fissile material than they consume) or burners or they can produce as much fissile material as they consume. Burner reactor concepts have some obvious attractions from a non-proliferation standpoint but the claims made about the proliferation resistance of these reactor concepts has been grossly overblown. (Click here for more information.)

Like conventional reactors, proposed ‘Pebble Bed’ reactors are based on uranium fission. The nature of the fuel pebbles may make it somewhat more difficult to separate plutonium from irradiated fuel. However, uranium (or depleted uranium) targets could be inserted to produce weapon-grade plutonium for weapons. The enriched uranium fuel could be further enriched for weapons − particularly since the proposed enrichment level of 9.6% uranium-235 is about twice the level of conventional reactor fuel. The reliance on enriched uranium will encourage the use and perhaps proliferation of enrichment plants, which can be used to produce highly enriched uranium for weapons.

Fusion power systems remain a distant dream, and fusion also poses a number of weapons proliferation risks including the following:

* Using neutron radiation to bombard a uranium blanket (leading to the production of fissile plutonium) or a thorium blanket (leading to the production of fissile uranium-233).

* Research in support of a (thermonuclear) weapon program.

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.”

The use of thorium-232 as a reactor fuel is sometimes suggested as a long-term energy source, partly because of its relative abundance compared to uranium. No thorium-based power system would negate proliferation risks altogether. Neutron bombardment of thorium (indirectly) produces uranium-233, a fissile material which is subject to the same safeguards requirements as uranium-235.

The US has successfully tested weapons using uranium-233 (and France may have too). India’s thorium program must have a WMD 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 weapon grade plutonium. The possible use of HEU or plutonium to initiate a thorium-232/uranium-233 reaction, or proposed systems using thorium in conjunction with HEU or plutonium as fuel, present further risks of diversion of HEU or plutonium for weapons production as well as providing a rationale for the ongoing operation of dual-use enrichment and reprocessing plants and the construction of new plants.

Click here for more information on the proliferation risks associated with thorium.