here is a guide from SAAMI that discusses safe powder storage. most of the info toward the end of the brochure references commercial storage but there are a couple of nuggets in there that talk about home & personal storage.
http://www.saami.org/specifications_and_information/publications/download/SAAMI_ITEM_200-Smokeless_Powder.pdf
Chapter 11
Small Arms Ammunition and Primers, Smokeless Propellants,
and Black Powder Propellants
11-1 Basic Requirements.
11-1.1
In addition to all other applicable requirements of this
code, intrastate transportation of small arms ammunition, small
arms primers, smokeless propellants, and black powder shall com-
ply with US Department of Transportation Hazardous Materials
Regulations, 49 CFR, Parts 100-199.
11-1.2
This chapter applies to the channels of distribution of and
to the users of small arms ammunition, small arms primers, smoke-
less propellants, and black powder.
11-1.3
This chapter does not apply to in-process storage and
intra-plant transportation during manufacture.
11-1.4
This chapter applies to the transportation and storage of
small arms ammunition and components.
11-1.5
This chapter does not apply to safety procedures in the use
of small arms ammunition and components.
11-3 Smokeless Propellants
11-3.1
Quantities of smokeless propellants not exceeding 25 lb.
(11.3 kg) in shipping containers approved by the U.S. Department of
Transportation, may be transported in a private vehicle.
11-3.2
Quantities of smokeless propellants exceeding 25 lb.
(11.3 kg) but not exceeding 50 lb. (22.7 kg), transported in a pri-
vate vehicle, shall be transported in a portable magazine having
wood walls of at least 1 in. (25.4 mm) nominal thickness.
11-3.3
Transportation of more than 50 lb. (22.7 kg) of smokeless
propellants in a private vehicle is prohibited.
11-3.4
Commercial shipments of smokeless propellants in quanti-
ties not exceeding 100 lb. (45.4 kg) may be reclassed for trans-
portation purposes as flammable solids (Division 4.1) when pack-
aged in accordance with the U.S. Department of Transportation
Hazardous Materials Regulation (49 CFR, Part 173.171), and shall
be transported accordingly.
11-3.5
Commercial shipments of smokeless propellants exceeding
100 lb. (45.4 kg); or not packaged in accordance with the regula-
tions cited in 11-3.4 shall be transported in accordance with the
U.S. Department of Transportation regulations for Division 1.3C pro-
pellant explosives.
11-3.6
Smokeless propellants shall be stored in shipping contain-
ers approved by US Department of Transportation.
11-3.7
Smokeless propellants intended for personal use in quantities
not exceeding 20 lb. (9.1 kg) shall be permitted to be stored in original
containers in residences. Quantities exceeding 20 lb. (9.1 kg), but not
exceeding 50 lb. (22.7 kg), shall be permitted to be stored in resi-
dences where kept in a wooden box or cabinet having walls of at least
1 in. (25.4 mm) nominal thickness.
11-3.8
Not more than 20 lb. (9.1 kg) of smokeless propellants, in
containers of a 1 lb. (0.45 kg) maximum capacity shall be dis-
played in commercial establishments.
11-3.9
Commercial stocks of smokeless propellants shall be
stored as follows:
(a) Quantities exceeding 20 lb. (9.1 kg) but not exceeding 100 lb.
(45.4 kg) shall be stored in portable wooden boxes having walls of
at least 1 in. (25.4 mm) thickness.
(b) Quantities exceeding 100 lb. (45.4 kg) but not exceeding 800
lb. (363 kg) shall be stored in non-portable storage cabinets having
walls of at least 1 in. (25.4 mm) thickness. Not more than 400 lb.
(181 kg) shall be permitted to be stored in any one cabinet and
cabinets shall be separated by a distance of at least 25 ft (7.63 m)
or by a fire partition having a fire resistance of at least 1 hour.
(c) Quantities exceeding 800 lb. (363 kg) but not exceeding
5,000 lb. (2,268 kg) shall be permitted to be stored in a building,
provided the following requirements are met:
1.
The warehouse or storage room shall not be accessible to unau-
thorized personnel.
2.
Smokeless propellants shall be stored in non-portable storage
cabinets having wood walls of at least 1 in. (25.4 mm) thickness
and having shelves with no more than 3 ft (0.92 m) of separation
between shelves.
3.
No more than 400 lb. (181 kg) shall be stored in any one cabinet.
4.
Cabinets shall be located against the walls of the storage room or
warehouse with at least 40 ft. (12.2 m) between cabinets.
5.
The separation between cabinets shall be permitted to be
reduced to 20 ft. (6.1 m) where barricades twice the height of the
cabinets are attached to the wall, mid-way between each cabinet.
The barricades shall extend at least 10 ft. (3 m) outward, shall be
firmly attached to the wall, and shall be constructed of 1/4 in (6.4
mm) boiler plate, 2 in (51 mm) thick wood, brick, or concrete block.
6.
Smokeless propellant shall be separated from materials classified by
the US Department of Transportation as flammable liquids, flammable
solids, and oxidizing materials by a distance of 25 ft (7.63 m) or by a
fire partition having a fire resistance of at least 1 hour.
7.
The building shall be protected by an automatic sprinkler system
installed in accordance with NFPA 13,
Standard for the Installation of
Sprinkler Systems
.
(d) Smokeless propellants not stored in accordance with 11-3.9
(a), (b), and (c) shall be stored in a Type 4 magazine constructed
and located in accordance with Chapter 6.