(a) Discuss the principal operational features of a modern (Generation-II) power- producing nuclear reactor either of the pressurised water (PWR) or gas-cooled (AGR) type, with particular emphasis cn the fuel type and fuel enrichment, the chain reaction, the neutron cycle, the choice and function of the moderating material, the origin and role of delayed neutrons, the nature and function of the control rods, and the nature and impact o reactor poisoning.

Steam is to be condensed by direct injection of cold water. The steam enters the condenser at the rate of (450 kg/hr) with dryness fraction of (0.9) and pressure (1 bar). The estimated heat losses from the condenser to the surroundings is (8500 kJ/hr). If cold water enters at (15"C) and the mixture of condensate and cooling water is to leave at (95"C). Determine the required flow of cooling water.