[en] With the original VVER-440 follower design the relatively large amount of water in the coupler between the absorber and fuel part of the control assembly can cause sharp power peaking in the fuel rods next to the coupler. The power peaking can be especially high after control rod withdrawal when the coupler reaches a low burnup level region of the adjacent assembly. Though the modernized coupler has a Hf plate in the critical region to suppress the power peak, the complicated structure needs a reference Monte Carlo calculation as a basis of engineering code validation. The coupler mathematical benchmark was solved by the KARATE code system using the same methods and approximations as in case of NPP applications and the results were compared to that of the reference MCNP. The need for treating the Hf burnout in the reflector region was also investigated. (authors)