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Mortimer, Nigel David
(1978).
DOI: https://doi.org/10.21954/ou.ro.0000deae
Abstract
Currently most commercial nuclear power stations are based on thermal reactor designs called burner reactors which are. net consumers of fissile material. These power stations form one part of a larger system that generates electricity from uraniura. However, in addition to producing energy, such systems also consume energy, in the form of various fuels, during construction and operation. This thesis describes the use of energy analysis to determine the total energy required by these systems.
A number of factors are shown to influence energy consumption and, in particular, the effect of extracting uranium from different sources is studied in detail. For ores, an important inverse relationship between energy use and ore grade is investigated and quantified. The physical limit at which the energy input to the system is equal to its output is shown to correspond to an average grade of 15 parts per million of "triuranium octoxide". Analysis of proposals for extracting uranium from seawater indicates that the only schemes giving a positive energy balance are'costly ($500/lb U308) and limited to low production rates.
The effects of feedback within fuel systems are analysed and. the results are used to formulate an economic model in which nuclear electricity prices determine uranium ore costs as well as vice versa. The model demonstrates-that, with present'techniques, the average 6 economic limit to ore grade is 50 ppm U308 with subsequent resources, on current assessment, of only 107 tonnes U308. This contradicts most traditional studies which, by assuming fixed, non-dependent fuel costs, suggest an ore grade limit of less than 4 ppm U308 and economically recoverable resources in excess of 1010 tonnes U308.