Dubious energy budget of nuclear power plants

The energy required to construct a 1000-MW nuclear power station is about 100,000 gigajoules, or the equivalent of 400,000 tonnes of coal. Assuming a 35-year life and an average load factor of 62% for the nuclear power station, it will produce a total of 7 million gigajoules of electricity, or the equivalent of 26 million tonnes of coal. Hence, about 0.01 units of primary energy are required to build a nuclear power station to generate 1 unit of electricity, clearly showing an energy profit. However, this does not take into account the energy required to mine, refine, enrich and process uranium for the fuel. When this is included, it is found that about 0.26 units of primary energy are needed to produce 1 unit of electricity under current circumstances. This does not include the energy required either to treat and dispose of nuclear waste or to decommission the nuclear power station. Nor does it factor in costs attached to plant operation, possibly breakdown and accidents, and environmental and health effects which are greater than those of an energy-equivalent fossil fuel power station. When these current "unknowns" are known, it may be that the energy required to build and decommission a nuclear power station approaches, or is even greater, than the amount of energy it produces during its life.

The energy requirements of reprocessing can be evaluated, but they depend on the eventual fate of the recovered uranium and plutonium. Methods for the permanent disposal of radioactive wastes are yet to be proven and there is not practical experience on decommissioning commercial nuclear power stations. Hence, these are matters of speculation although it can be predicted that the energy involved with not be insignificant. Another consideration is the quality of the uranium used to produce fuel. The energy consumed in mining and processing is inversely proportional to the percentage or uranium in the ore. Current commercial ore grades average about 0.2% uranium. Reserves of such ores are adequate for the needs of the current depressed nuclear industry but it would be necessary to mine much lower grades of ore in the event of a global expansion of nuclear power.