The work is dedicated to study of bending of fuel assemblies (FA) under the non-uniform temperature distribution in the active zone of a periodic pulsed reactor. Numerical calculations of the transverse deformation of the IBR-2 fuel assembly in full geometry were carried out taking into account the coolant flow. The shape of the bend, the displacement of fuel pellets, and the time dependence of deformation after pulsed energy release were found. Since the bending of the FA changes the reactivity and has a negative effect on the reactor dynamics, a possible method for reducing the bending value is proposed using coolant flow profiling. The results can be used in the design of a new neutron source.