[phkahler]

What is the decay chain?

For the one in the article (And I'm sceptical) they say "After the decay period, the 63 isotopes turn into a stable isotope of copper, which is non-radioactive and does not pose any threat or pollution to the environment." How long does that take and what other things are produced?

What if someone throws one into a campfire?

[p1mrx]

It's a single isotope, nickel-63, which decays into regular copper-63. The amount of nickel halves every 96 years.

If you throw it in a fire, you'll disperse nickel-63 into the environment, which isn't good, but the decay process is unaffected.

[Fatnino]

I've seen it said that it takes 10 halflives for something to decay all the way away.

So like 1000 years for this to flush itself.

[jbboehr]

> I've seen it said

You can estimate it yourself:

0.5 ^ 10 = 0.0009765625 (~0.1%)

https://en.wikipedia.org/wiki/Half-life#Probabilistic_nature

> When there are many identical atoms decaying, the law of large numbers suggests that it is a very good approximation to say that half of the atoms remain after one half-life

[nine_k]

Beta decay is emission of electrons. They quickly slow down in the air. A beta emitter can only burn you if you literally pick it with you fingers, or maybe swallow it. Throwing it in a campfire is not a great idea, but nickel is not going to burn or melt in a campfire, so it won't become a dangerous pollutant. Nickel is also chemically pretty stable, so underground waters are not going to carry around any significant amounts of it after you have extinguished the campfire and put some soil on its site.

172m2 Hafnium decays into regular 178 Hafnium, but it readily burns in the air, so if you throw a battery with in into a campfire, chances are you'll add some beta radioactivity to the environment nearby, or inhale part of it yourself.

[mikhailfranco]

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

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.