Patent ID: 7940882
Filing Date: 2011-05-10
Classification: G21C,G21F,Y02E

Abstract:
1. A method for selecting and disposing remaining spent nuclear fuel bundles for casks comprising the steps of: numbering spent nuclear fuel bundles in order based on their values of decay heat so that the spent nuclear fuel bundles with lower values of decay heat are given smaller numbers; removing any spent nuclear fuel bundles with values of decay heat higher than a limit of decay heat for the casks to define remaining spent nuclear fuel bundles; calculating the mean value of decay heat of the remaining spent nuclear fuel bundles; evaluating one or more casks, wherein each cask comprises a number of cells to hold the remaining nuclear fuel bundles and determining if the number of cells of each cask is odd or even; reserving a number of the remaining spent nuclear fuel bundles with values of decay heat closest to the calculated mean value of decay heat of the remaining spent nuclear fuel bundles so that the number of reserved remaining spent nuclear fuel bundles is equal to the number of the casks and to redefine the remaining spent nuclear fuel bundles, when the number of the cells of each cask is odd; determining if the number of the remaining spent nuclear fuel bundles is odd or even; removing the remaining spent nuclear fuel bundle with the highest value of decay heat and redefining the remaining spent nuclear fuel bundles, when the number of the remaining spent nuclear fuel bundles is odd; matching the remaining spent nuclear fuel bundles so that the remaining spent nuclear fuel bundle with the highest value of decay heat is matched with the remaining spent nuclear fuel bundle with the lowest value decay heat, and that the remaining spent nuclear fuel bundle with the second highest value of decay heat is matched with the remaining spent nuclear fuel bundle with the second lowest value of decay heat, and that the remaining spent nuclear fuel bundle with the third highest value of decay heat is matched with the remaining spent nuclear fuel bundle with the third lowest value of decay heat, and so on so as to match the remaining spent nuclear fuel bundles in pairs; calculating a mean value of decay heat of each remaining spent nuclear fuel bundle pair; arranging the remaining spent nuclear fuel bundle pairs in order based on their mean value of decay heat; calculating the difference between the mean value of decay heat of each remaining spent nuclear fuel bundle pair and the previously calculated mean value of decay heat of the remaining spent nuclear fuel bundles; determining if the number of the cells of each cask is odd or even; if the number of the cells of each cask is odd, disposing the remaining spent nuclear fuel bundles in the casks in a first way; if the number of the cells of each cask is even; disposing the remaining spent nuclear fuel bundles in the casks in a second way; and determining if the heat load on each cask is smaller than a limit of heat load and reducing the limit of decay heat for the casks and returning to the step of removing any remaining spent nuclear fuel bundles with values of decay heat higher than the limit of decay heat for the casks, when the heat load on each cask is not smaller than the limit of heat load for the casks.