The aim of the benchmark calculations is the comparison of results from different methods and data applied to the identical conditions of a simple core configuration. These specified model conditions aim to represent the equilibrium conditions of the fuel cycle of a 5 X 6 element core of 10 MW, containing 93% HEU, 45% MEU, and 20% LEU fuel in turns. Considering the six remaining sets of results, the following conclusions can be drawn. The spread of k/SUB eff/ values between the different organizations is less than or equal to 0.019 for HEU and MEU and less than or equal to 0.028 for LEU core cases. Comparing BOL, EOL, and fresh core cases on the basis of their reactivity values (1 - 1/k /SUB eff/), the spread is less than or equal to 1.65% for HEU and MEU and less than or equal to2.05% for LEU core cases. The predictions of the k /SUB eff/ drop per cycle (BOL minus EOL value) has a spread of 0.0014, 0.0015, and 0.0025 for HEU, MEU, and LEU cores, respectively. As expected, the more limited spread occurs for the higher enrichments. The prediction of /sup 239/Pu content at 50% burnup in grams permore » fuel element agrees to within about 5% for HEU and 25% for MEU and LEU fuel elements. The flux ratios for the central and core boundary irradiation position agree to within a spread of about 2% and 5%, respectively, for the MEU/HEU flux ratio and to within about 3% and 11%, respectively, for the LEU/HEU flux ratio.« less