The present paper is devoted to radiation damage simulation of Fe-9at.%Cr binary alloy with twin grain boundaries (GBs) by the molecular dynamics method. Evaluations of specific energy of five GBs and sizes of corresponding GB regions have been obtained for iron and FeCr alloy at temperatures of 0 and 300 K. The binding energies of the vacancy, self-interstitial atom (SIA) and substitutional Cr atom to the GB in pure Fe have been estimated. The results showed that GB regions are energetically preferable for the point defects. Interaction of 10 keV displacement cascades with the GBs has been studied. The tendency to accumulate at the GB region has been shown for produced defects. Some quantitative results which describe features of radiation damage nearby the GB have been obtained. It is revealed that Cr fraction in SIAs inside the GB region is slightly lower than that in the initial alloy matrix. Cr fraction in interstitial configurations outside the GB region is almost three times as high. However, no remarkable chromium redistribution nearby the GB has been detected.