Operational reactor physics of Apsara

The paper deals with the operational physics aspects of Apsara reactor. Besides giving brief description of the core, it explains how reactivity worth measurement of fuel assemblies/calibration of reactivity control rod devices can be carried out by employing different methods. Computer simulation of the core along with associated reflector has also been undertaken. Lattice properties of all multiplying assemblies at different burn-up levels and various non-multiplying assemblies in a typical core configuration are obtained using transport lattice theory code WIMSD-4. Computer code TWOTRAN is used for carrying out global calculations. Computed reactivity worths of some of the fuel and other assemblies in the core have been compared with the measured worths and there is good agreement between them. Neutron fluxes have been computed for various irradiation locations of the core. The paper also describes estimation of - reactivity load of irradiation samples, core life, burn-up load, nuclear heating etc. (author)