Buckling measurements with a reduced number of fuel elements

Abstract A theoretical analysis of buckling measurements by the progressive substitution technique on heavy-water lattices is presented. The experiments have been carried out at Chalk River in 1965 in co-operation between AECL and Euratom. Natural uranium oxide and carbide fuel elements cooled by heavy water and organic have been investigated. Two methods of interpretation have been compared. 1. (i) The different substitutions (from one to twenty-five replaced rods) are used to determine, by an empirical adjustment, the buckling difference between the test and the reference lattice. 2. (ii) Each substituted core is interpreted in a direct way, by adjusting the k inf of the test zone. For both methods a two-neutron-group homogenized multi-region model has been assumed. From the analysis of the results, it appears that a good accuracy can be obtained even with a number of substituted rods sensibly inferior to twenty-five.