Is a radioactive-powered hand warmer possible? Can it be made to work safely?
Rough estimations on the feasibility, or otherwise, of tritium powered hand warmers/gloves.
You obviously want to minimise radiation, so you could accept that your hands would be kept at 35 degrees Celsius, (that is, around their normal temperature).
The skin area of an average human hand, (allowing for the glove) is say 10 cm long by 6 cm wide (by 4 sides) which amounts to 240 sq. cms, converts to O.024 square metres that you need to keep at this temperature.
The tritium would warm a thin layer of water, as thick gloves are useless, so total volume of water is 0.024 square metres by say 0.5 cm (0.005m) thickness, gives a volume of 0.00012 litres of water.
1 gram of tritium produces Tritium Output a tiny 0.3625 W.
An electric kettle is rated at, wait for it, around 2000 W.
So do you want to carry around (possibly far) more than 1 gram of tritium, even though, says Wikipedia Tritium health risks
Tritium is a low energy beta emitter, it is not dangerous externally (its beta particles are unable to penetrate the skin), but it can be a radiation hazard when inhaled, ingested via food or water, or absorbed through the skin.
Image and Extract Source : Early uses of radium in household items
Early 20th-century doctors also jumped onto the radioactive bandwagon with both feet, producing suppositories, heating pads and radioactive coins (used to “charge” small amounts of water), all intended to treat rheumatism, weakness, malaise and just about any health complaint for which a fast and magical cure was needed.
My thanks to WetSavannaAnimalakaRodVance for this comment:
Many of the radioactive medical treatments did "work" well in the short term: it wasn't for no reason that they caught on. What they were doing, however, was destroying the body's ability to feel pain. Many patients (particularly of back pain and rheumatoid arthritis) enjoyed relatively pain free seemingly returned-to-health life for a little while before the radiation destroyed the body as well.
I wouldn't think a tritium powered hand warmer would fly off the shelves.