alright, two main issues.  1 - meltdowns  it usually occours when the refrigerating system fails, the amount of energy generated depends on how much nuclear fuel is being used, higher amounts of it generates higher amounts of heat and that's why they are kept in large tanks of water. smaller portions of nuclear fuel means also smaller tanks or cells needed to keep it cool. i've read about people using high pressured gas to make the cooling of it nowadays and it's quite genius in my opinion, plus safety ice. 2 - isotopes you know that isotopes are mostly unstable when are too charged or missing charge, understanding how we can make them stable again stops the radioactivy threat and to be quite honest? i do believe we can turn radiation in energy by making it stable, something close that is done with photovoltaic boards and sunlight. (did you know sunlight is radiation?)
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