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Nuclear Safeguards Education Portal

Conversion time

Conversion time is the time required to convert different forms of nuclear material to the metallic components of a nuclear explosive device. Conversion time does not include the time required to transport diverted material to the conversion facility or to assemble the device, or any subsequent period. The diversion activity is assumed to be part of a planned sequence of actions chosen to give a high probability of success in manufacturing one or more nuclear explosive devices with minimal risk of discovery until at least one such device is manufactured. The conversion time estimates applicable at present under these assumptions are provided in the table below.

Beginning Material Form Conversion Time
Pu, HEU, or 233U metal Order of days (7-10)
PuO2, Pu(NO3)4, or other pure Pu compounds; HEU or 233U oxide or other pure U compounds; MOX ro other non-irradiated pure mixtures containing Pu, U (233U + 235U >= 20%); Pu, HEU, and/or 233U in scrap or other miscellaneous impure compounds Order of weeks (1-3)a
Pu, HEU, or 233U in irradiated fuel Order of months (1-3)
U containing < 20% 235U and 233U; Th Order of months (3-12)
aThis range is not determined by any single factor but the pure Pu and U compounds will tend to be at the lower end of the range and the mixtures and scrap at the higher end.