The battery contains 50 curie (Ci). This radionuclide safety sheet says that anything more than 1 Ci of Ni-63 is a high-level (A) hazard. https://ehs.stanford.

The battery contains 50 curie (Ci). This radionuclide safety sheet says that anything more than 1 Ci of Ni-63 is a high-level (A) hazard. https://ehs.stanford.edu/wp-content/uploads/Ni-63-RSDS.pdf https://ehs.stanford.edu/wp-content/uploads/Ni-63-RSDS.pdf It also gives the annual limit on inhalation as 800 µCi and ingestion as 9 mCi. So the battery contains more than 60,000 max annual inhalation doses, if it was all vaporized, and more than 5,000 max ingestion doses, if it found its way into the water/food supply.