The aim of this paper is to summarize authors' experience in adaptation of an existing plant-specific VVER-1000/V320 model for simulation of a rare example of a Kalinin 3 NPP transient of 'Switching-off of One of the Four Operating Main Circulation Pumps at Nominal Reactor Power' with an asymmetric core configuration. The fidelity and accuracy of simulation with emphasis on reactor core model is illustrated through comparison with plant-specific data. Simulation results concerning fuel assembly power and axial power distribution during the transient are compared with records from Kalinin 3 in-core monitoring system. Main operating parameters of nuclear steam supply system of a VVER-1000/V320 series units vary to a considerable degree. While Kalinin 3 benchmark specification contains very good description of the transient, as well as record of many parameters of the unit, the document provides only superficial description of the reference unit. In such a case, an approach based on a 'generic' V320 model by default introduces deviations which are difficult to quantify. There are several examples which warrant discussion.
1) individual characteristics of all the main circulation pumps and the reactor coolant loops;
2) variations in fuel assembly characteristics ;
3) dynamic response of instrumentation and control systems;
4) balance-of-plant equipment, instrumentation and control.
Above requirements impose a difficult task to comply with. Nevertheless, any individual nuclear power unit is supposed to maintain a detailed design data base and data requirements for plant specific model development should be considered.