(N/A) Initially,nuclear energy was considered a non-polluting way for generating electricity. Later,it was realized that it has two very serious inherent problems: $(i)$ accidental leakage,as occurred in the Three Mile Island and Chernobyl incidents,and (ii) safe disposal of radioactive wastes.
Radiation from radioactive waste is extremely damaging to organisms because it causes mutations at a very high rate. High doses of nuclear radiation are lethal,but lower doses create various disorders,the most frequent being cancer.
Therefore,nuclear waste is an extremely potent pollutant and must be dealt with extreme caution.
It is recommended that nuclear waste,after pre-treatment,should be stored in suitably shielded containers (tanks) and buried within the rocks about $500 \ m$ deep below the Earth's surface.