کوروش قیصری

In this thesis, the thickness variation of fuel rod cladding before LOCA in the Bushehr nuclear reactor simulated and analyzed. By using Monte Carlo calculation method (MCNPX), first the VVER-1000 reactor core simulations have been performed. The neutron flux, under the critical condition and the conditions in which the zirconium cladding of fuel rods reacts with water, has been calculated. At high temperatures, the reaction of the fuel cladding with the water occurs, and consequently the hydrogen gas forms, leading to fuel rod melting. With temperature increase, under cladding meltdown, the neutron flux distribution changes strongly. One reason for considerable change in the flux distribution, is steam reaction with the zirconium before LOCA.