The Breeding Ratio with Correlation to Doubling Time and Fuel Cycle Reactivity Variation

The standard definition of the breeding ratio is subject to some suspicion, since in many cases of practical interest it gives an incorrect measure of the fissile fuel doubling time and erroneous trends of the fuel cycle reactivity variation. The reasons for this behavior are given in this study, along with methods for removing the difficulties. In addition to the standard definition, the method of η weighting due to Ott and the method of reactivity weighting due to Baker and Ross (British definition) are examined. It is shown that the η weighting procedure is not much better than the standard definition, whereas the British definition can be used to give very good results for the doubling time and fuel cycle reactivity variation. The standard for comparison is a detailed explicit fuel cycle analysis of both the startup cycle and equilibrium cycle of an oxide fast reactor. With the methods given it is shown that the important quantities needed from a single fuel cycle analysis can be obtained just from a ...