To determine whether or not Nuclear Energy is good for the environment it is best to determine the negatives. There have been many accidents that have caused radioactive materials to spread. Radiological incidents for a general term. Chernobyl and Fukushima Dai-ichi being the most infamous ones to date. The Chernobyl accident initially irradiated a good portion of the former Soviet Union and other sections of Europe with low amount of radioactive material, but the worst area, the Chernobyl Exclusion Zone, covered an area of 4300 square kilometers with moderate to severe areas of radiation within. This caused significant damage to local fauna and flora with many mutations, most being harmless or bad. There was even an area initially where trees died suddenly from the radiation which came to be called the red forest. The ecological effects of Fukushima were similar to Chernobyl while covering an area of 807 square kilometers. So, in total major radiological incidents cause an increase of mutations that are not good for life and can even outright kill areas if radioactive enough. A great negative for nature when things go bad.