WASTE

  • The IMSR burns its fuel far more efficiently than conventional reactors and leaves much less plutonium waste per kWh of electricity
  • The IMSR creates power far more efficiently than conventional reactors and leaves much less fission product waste per kWh of electricity
  • With the addition of IMSR waste fuel recycling, the IMSR can consume all its fuel and leave virtually no plutonium waste
  • Recycling liquid fuel waste is technically and economically far more viable than recycling of the solid fuel waste of conventional reactors.

Nuclear waste can be classified into three main categories:

i) Fission product waste that generally requires safe storage for 300 years;

ii) Unused uranium, and; 

iii) Plutonium waste which if not recycled requires safe storage for hundreds of thousands of years. 

Solid fuel reactor waste from conventional reactors is not easily separated into: uranium; plutonium which can be recycled into new solid fuel; and fission product waste that require safe disposal.  In a liquid fuel reactor, the separation of solid and liquid nuclear fuel waste into new liquid fuel and fission product waste becomes technically and economically viable.  This changes the way society will think about nuclear waste.  It offers the possibility of using existing piles of solid fuel waste, and even unwanted plutonium, as fuel for an IMSR, and ultimately a reactor than generates no plutonium waste.

Fission Products

Fission products waste are the true waste of nuclear fission as CO2 is to fossil fuel combustion.  On the one hand this waste is extremely radioactive, while on the other hand, the radiotoxicity of this waste decays quickly, to insignificant levels after hundreds of years. Safe sequestration over a three-century time-frame does not present a technological or social challenge.  With liquid fuel processing, fission products can be separated and safely stored.  While solid fuel reactor waste from Conventional Nuclear reactors can be partially recycled into new fuel for Conventional Nuclear reactors, it is a partial, highly complex and commercially tenuous process.

Unused Uranium

Unused IMSR uranium fuel is not problematic.  Uranium is the 51st most common element, for example it exists in 10 to 20 ppm in granite tops popular in many kitchens.  Uranium is not harmful to touch. Hence, natural uranium waste from an IMSR when separated is no more radiotoxic than before it was mined out of the earth.  

Uranium is not easily separated from the solid fuel waste of a conventional nuclear reactor.  However, it can be separated far more easily from IMSR liquid fuel waste.  Once separated, uranium can simply be recycled into new liquid fuel or contained for long-term storage.

Plutonium 

Plutonium isotopes (and some minor amounts of other transuranics) are the unwelcome by-products of conventional nuclear energy.  These isotopes represent unburned nuclear fuel.  While Plutonium is the smallest proportion of reactor waste, its high levels of radioactivity last for hundreds of thousands of years.   This is the cause of today’s social dilemma with conventional nuclear waste.  How does a responsible society store such waste safety over such a long time frame?

Separating out all plutonium and other transuranics from solid fuel waste and repackaging these as new nuclear fuel cannot be done with conventional nuclear reactors which use solid fuel. However, it is possible to do this when using a liquid fuel. TE’s first model of IMSR will not process its waste fuel. However even in this state, it will be producing much less plutonium fission product waste per kWh of electricity – this is an important reduction in waste footprint and is simply the start.

R&D into IMSR waste fuel recycling is ongoing and offers the possibly that future IMSRs by the end of next decade will generate virtually zero plutonium and transuranic waste.  This is a new paradigm for civilian nuclear energy.