Thorium Nuclear Power generators scale beautifully from small portable generators to full size power plants. One of the first applications was as an airborne nuclear reactor.
Granted this was not a Thorium breeder reactor, but it proves nuclear reactors can be made lightweight. Thorium reactors can be made even lighter as long as they are not of the breeder type.
Lawrence Livermore, Los Alamos, and Argonne national laboratories are designing a self-contained nuclear reactor with tamper-resistant features. Called SSTAR (small, sealed, transportable, autonomous reactor), this next-generation reactor will produce 10 to 100 megawatts electric and can be safely transported on ship or by a heavy-haul transport truck.
This type of reactor can be transported to disaster areas, and provide emergency power, during rescue and rebuilding efforts. This particular reactor still uses solid fuel and steam heat exchanger. A LFTR reactor with a supercritical CO2 gas heat exchanger would be even more compact and efficient.
From these compact designs, Thorium power can be scaled up to any size. The LFTR reactor will be placed on barges and left moored in navigable rivers or in ocean harbors. This will typically be a one or two 250 MW LFTR with reprocessing capabilities. Where there is only road access the LFTR’s will be one or up to six 100 MW LFTR with one reprocessing fuel capability servicing the nuclear units one at a time on a rotary basis. These will come as complete units tested and ready for use on a number of trucks. It is to be noted that no water is necessary for cooling. There can also be 5 and 10 MW power units for freight trains and large towboats. They will not have reprocessing capabilities on board, but will be serviced regularily by refueling and reprocessing stations in key locations. Oceangoing ships will be fitted with LFTR reactors with reprocessing capability. When all of this is done the need for diesel fuel for nearly all shipping by train, barge or ship will be nearly eliminated.
Admittedly there are security risks associated with this arrangement. Locomotives and barges can be stolen, ships can be hijacked, when the whole reactor vessel came on a truck it can be stolen. By having minimum fuel at all time, it increases safety, but it also makes it possible for terrorists and common thieves to steal shipments of fuel and fissile by-products. This means that there must still be strict security measurements for maintaining chain of security for U-233 and Protactinium.
Len Bilén's blog, a blog about faith, politics and the environment. 
