Fuel temperature feedbacks in program BIPR

Adequate attention is not devoted to heat transfer through the fuel-cladding gap which affects fuel temperature and thereby also reactivity feedback. For modification of input data in the BIPR program, variants were used ranging from the zero to the maximum possible proportion of Xe in the gap and for a gap width in cold state of from 0.0625 mm to 0.125 mm. Calculations were made for charges at the Mochovce nuclear power plant with half inserted regulating assemblies. The major results (critical concentration of H3BO3, coefficients of unevenness along fuel assemblies, volume-specific critical heat ratio for the most loaded assembly, relative reactor power, deviations in power distribution as against the basic data variant, reactivity coefficients related to fuel temperature) are given in graphs. (E.S.)