This is very old problem, which affects all bethesda games. Ashes after critical hits with energy weapons(tes - magical) don't dissapear. So this problem should be solved because of hundreds piles in spawn places or in renewable quest target places. Fallout atmosphere suffers. And this affects players who don't use modifications and console commands. Thanks!

I don't know exactly. It depends on the number of ash piles and the location.

On some users they disappearing after a couple of days, on others after weeks of playing. So it seems to be random!

I "googled" it!

I've had to use the console to get rid of all of the ones I experienced, they stayed there for over 120 hours of play time. About 119 hours longer than what's ideal.