Nuclear start-up of the Leningrad-2 reactor of the Leningrad atomic power station

The main stages are described of the physical startup of the reactor in the second block of the Leningrad Atomic Station named after V.I. Lenin. The preparation of the reactor for the startup is described, as well as the process of its loading, the initial load containing 1455 fuel element assemblies (FEA) (eight channels have been left unloaded). The influence of various parameters on the reactivity has been analysed and it has been revealed that decrease in reactivity is mainly due to decrease in the density of the graphite. An evaluation of the ''steam'' effect of reactivity in the cold state has been made; dewatering of the cooling circuit reduces the reactivity by 2%. The total efficiency of the control and safety rods inserted has been determined; it has turned out to be 8.9%. A comparison of the experimental and calculated fields of energy release obtained with the BOKR-COBZ and QUAM-3 programmes has shown that the RMS discrepancy between the measured and calculated power of FEA's for both programmes is 9.7%. Comparative results are given of the physical start up of the first-and the second-block reactors of the Leningrad atomic station