Hi Milad, The second sentence is not correct because nuclear technology is already developed and put in place. So we don’t have to develop again to reduce the risk of accidents whereas your first sentence clearly says if we have/add upgrades or developments to the existing nuclear technology that will reduce the risk of accidents.So your first sentence is correct.

Hi Milad. The first sentence is correct, With developments in nuclear technology, the risk of accidents is being reduced. The first sentence conveys the message that developments within nuclear technology will reduce accidents. The second sentence means that by developing nuclear technology, accidents will be reduced.This is not the case because developing nuclear technology will not reduce accidents but developments within nuclear technology will reduce accidents.