The company said Tuesday that the incident at the Slaunoe railway station in central Belarus hadn't resulted in any visible damage to the reactor.
The reactor is a replacement for a unit that had to be abandoned in July. While the first reactor was being installed, it slipped down and touched the ground after workers failed to strap it up properly.
Russia's Rosatom company says the new reactor wasn't damaged, but agreed to replace it given the sensitivity of the nuclear power issue for Belarus.
Belarus suffered severe radioactive fallout from the 1986 Chernobyl nuclear disaster in then-Soviet Ukraine.