You can blast foods with gamma radiation and then can it or otherwise put it in an airtight seal. The gamma radiation kills all foods and microbes that would cause it to decay. Gamma radiation is just photons (unlike alpha and beta radiation) so it doesn't case the food to become radioactive.

It would enable canning food without preservatives.

Typically you put the food in the can and the cans the box and then blast the whole box in one go.

Very useful for countries with limited access to refrigeration.

This is also a common method for sterilizing single use medical stuff, band-aids, sutures, iv tubes etc.

That's not that strange or extra-ordinary. Sometimes radiation is used to sterilize food to increase shelf life. It doesn't make the food radioactive though. The sources of such radiation are similar to those used for medical purposes.

If I remember correctly, this is especially useful for spices. But probably other stuff, also.

https://www.fda.gov/food/buy-store-serve-safe-food/food-irra....

Kills the bugs

That or they're just running fridges with nuclear power ;)