Based on the international research focus

ALFRED（European advanced demonstration lead cooled fast reactor） is used as the model

pure lead is used as the coolant

and the whole core neutron transport model is constructed on the basis of the design parameters of ALFRED core

and Monte Carlo simulation calculation is carried out. Without considering burnable poison and control rod

the effect of reactor coolant temperature and fuel rod size change on the effective multiplication factor k value of reactor was studied. The k value of different fuel rod size and different reactor coolant temperature was obtained and plotted respectively. The simulation results showed that

with the increase of fuel rod diameter

the slope of k value curve first increased and then decreased gradually. With the increase of reactor temperature

k value decreased gradually

and the result was in good agreement with the actual value.