| abstract |
The present invention concerns a fuel assembly (12) for a nuclear power boiling water reactor. The fuel assembly comprises fuel rods (23). At least 95% of the fuel rods comprise nuclear fuel material in the form of U enriched in 235 U. At least 20% of the fuel rods belong to a first set of fuel rods (41, 32, 26, 9). The fuel rods in this first set comprise both U enriched in 235 U and Th. The first set comprises a first and a second subset of fuel rods (41, 32). The ratio, with regard to weight, between Th and U, in each fuel rod (41) of said first subset, is higher than the ratio, with regard to weight, between Th and U, in each fuel rod (32) of said second subset. The invention also concerns a nuclear power boiling water reactor and a manner of operating such a reactor. |