Cost-benefit Analysis

When considering economic factors in the design and operation of a nuclear reactor, total life cycle costs must be considered. Aspects include capital costs such as building, operation, fuel costs, level and experience of staffing required. This cost-benefit analysis will compare LFTR to conventional uranium fuelled Light Water Reactor (LWR).

In contrast to fossil fuels, a small amount of thorium fuel can produce a large amount of energy. One tonne of thorium provides enough energy, 1GW/year when used in a LFTR, to power an entire city. Since less fuel is required for a given output drastically lowers cost, in comparison to coal, LFTR would cost $0.03/kWh (Kilowatt Hour), compared to the $0.10/kWh for coal.

With lower amounts of fuel needed, thorium is relatively expensive, at $5,000/kg due to lack of demand. Currently, uranium fuel is $20/kg unprocessed, directly from uranium ore. However, uranium must be enriched, thus greatly increasing of fuel. Enriched uranium fuel to be used in a reactor is priced at $1633/kg. In the future, cost of uranium will increase dramatically as sources are depleted, while thorium is expected to decrease to a possible $10/kg as supply meets demand. However, uranium is very rare and once reserves are depleted uranium would have to be extracted from sea water, a much more expensive process. Research in Japan has found a technique for extracting uranium from sea water at costs of $100 300/kg. Thorium deposits lye in many developed economies, unlike oil deposits in the Middle East. Listed below are the world deposits of thorium.

With thorium currently expensive, the lower consumption ensures that fuelling a power plant will actually be cheaper. Using a 1GW plant as an example, a uranium plant would cost $30 million/year to fuel while a thorium plant would only cost $1 million/year. Other operating costs for a comparable thorium reactor are on average $50 million/year, again less expensive than a uranium reactor.

Capital costs such as building and staffing are also cheaper for LFTR. Again, using a 1GW power plant in both cases, a uranium reactor would cost about $1.1 billion to construct, while building a similar thorium reactor would cost only about $250 million. The substantial difference is because thorium reactors do not require large containment shields to protect from meltdowns. They will also be low maintenance, reducing staffing costs from $50 million/year for a uranium reactor to a possible $5 million/year in the future.

The only process in which the thorium cycle is more expensive is the closed cycle with reprocessing. Due to the high levels of radioactivity from the daughter products of 232U and small amounts of 228Th and 234Th, remote handling is necessary.Reprocessing is used in order to collect the remaining 232U for reuse. Because 232U is a product of the decay of 232Pa, which has a relatively long half-life of 27 days, the spent fuel must be stored on site for at least 9 months. This is to ensure that the decay heat decreases to a safe level and so that little 232U is lost from the decay of 232Pa which has been separated and disposed of. This storage of highly reactive material that requires heavy shielding on-site and the remote handling causes reprocessing for a thorium closed cycle to be more expensive than the U – Pu closed cycle. However, uranium reprocessing has other problems such as proliferation.