Radioactive materials that produce enough heat to warm a greenhouse in a conveniently sized package are extremely hazardous if uncontained. It's relatively easy

Radioactive materials that produce enough heat to warm a greenhouse in a conveniently sized package are extremely hazardous if uncontained. It's relatively easy to encapsulate radioactive materials against accidental exposure, but much harder to guard against misinformed or malicious deliberate exposure. Then you get expensive and lethal incidents like these: https://en.wikipedia.org/wiki/List_of_orphan_source_incidents https://en.wikipedia.org/wiki/List_of_orphan_source_incident...