Several researches have proven that nuclear energy is not as dangerous as people think.
Actually there's nothing 'wrong' with this. I just looks odd to a native speaker because research is nearly always uncountable:
Much research has proven that nuclear energy is not as dangerous as people think.
Investigate the differences between research (uncountable) and research (countable). Then try Google's NGRAM viewer to see which form of the word is more common.
Researches (plural) did not appear even once in a search I tried at Netspeak.org. However, the results give us two countable synonyms for researches. Can you find them?