I keep mine mostly out in the shop that is several yards from the house. It is locked in a file cabinet. If that is not an option, then where you store it is kinda up to you on the safest place. Powder if not tightly contained will simply "whoosh".
If you were to take a used shotgun shell, drill a hole in the side, fuse it, pack it full of bp, put duct tape over the end to seal it and light it, it will simply go "whoosh" and not explode.
If you were to take a chainsaw and with the tip go straight down in a stump for several inches, put a bunch of bp and finish filling the whole with dirt packed down, you would get it to explode.
My powder in my house is in the basement under my bedroom. It is simply sitting on a shelve and I am not worried about it blowing. It will certainly not blow a hole in the bedroom floor.
Fleener