Simulation of reactivity devices in PHWRS - validation against low power start-up experiments in NAPS-1

The Unit-1 of Narora Atomic Power Station (NAPS-1), Narora, India, achieved criticality on March 12, 1989. A series of physics experiments with various reactivity devices were done in subcritical, low power critical and dynamic power decay conditions of the reactor. These were analysed with our computer code systems. The paper describes briefly the methods of analysis, experiments and comparison of the calculated results with measurements