The polonium production due to short half-life of the specific isotope was found to actually increase safety, as it made detection of leaks easier (root cause w

The polonium production due to short half-life of the specific isotope was found to actually increase safety, as it made detection of leaks easier (root cause was fixed and isn't present in later models) and cleanup easier as well (minute amounts of polonium that were easy to spot and cleanup). Most importantly, it undergoes alpha decay, which makes shielding easy.