Reactors

The latest advance in uranium reactors is the development of fuel pellets. In a normal reactor the uranium is enriched to 3.5% and the fuel is added all at one time. The danger is when the power is lost and cooling water shut off, the reaction continues and over heats to the point of meltdown. The fuel pellets are added as needed and if the power is lost the feed stops and the reaction shuts down. For these processes to work effectively the uranium must be enriched to 15% which is costly. While TRISO particles are more efficient, produce less waste per unit of energy, and offer better long-term containment of radioactive materials, they often result in a larger volume of waste material (fuel pebbles) that requires disposal. There is always a tradeoff. In this case increased safety is balanced against increased waste, but the waste is easier to contain. One way to improve this situation is to use thorium a fuel. It requires no enrichment and is added continuously to the system. Thorium waste is generally considered easier to contain and manage than uranium waste because it produces significantly fewer, and shorter-lived, long-lived radioactive transuranic elements (such as plutonium and americium) Thorium reactors were the first choice of US scientist back in the 1950’s but the government preferred uranium because uranium reactors could produce plutonium which was used for bombs.