For SF you could also claim that an external magnetic field has a subtle influence on stability and is sufficient to go from 40 day halflife to indefinite stability. This can also be used as an additional critical element.
Ive been watching too much doctor who and now I want a thermoscan based on black holes for my tea
If you have one of a "mere" 606 million tons, the Hawking radiation is hot enough to directly include fast moving positrons (and has a luminosity of 1.178 GW), while still massive enough to spaghettify you (370g at 10cm).
If the black hole is lower mass, the radiation gets even more energetic. The radiation from 606 thousand ton black holes (sometimes suggested for Hawking radiation drives for spacecraft) is hot enough the radiation will either include antiprotons, or at least the photons will be energetic enough to spontaneously create them on impact: https://kitsunesoftware.wordpress.com/2022/05/14/no-a-black-...
(Yes, there is a well-known paradox/open-problem implied by this.)
Once upon a time I wondered if magenetic fields influenced nuclear reation rates. Some googling suggested the answer is no, but I found very little in the way of actual experimental results testing it. In more recent times I think I did see one referene to an actual effect but I don't recall what it was. So IMHO this door is clearly open for fictional exploration.