Effect of the Lattice Pitch Variation on the Burn-up of the ETRR-1 Reactor Fuel

The recent development in the field of reactor physics and nuclear safety calculation is providing a modern aspect to the fuel cycle economics through the reactor operations. For that, it is necessary to review the previous design of the old operating reactors. One of these reactors is the ETRR-1, which is operating since 1961. The fuel basket of this reactor contains 16 fuel rods arranged in 4 x 4 shape with a lattice pitch 17.5 mm. The lattice cell parameters and burn-up calculations were performed by using the WIMSD4 code for different lattice pitch configurations including the exist one. This study shows that, the present lattice pitch of the ETRR-1 reactor fuel element is not the best one and the 15 mm lattice pitch is more convenient from the fuel cycle economics point of view