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review concluded that cycling through the beta-gamma transition alone near
185C would be less demanding on the container than the alpha-beta transition
cycling because 1) the volume change is significantly less for this transition and
2) the strength of stainless steel decreases more slowly with temperature than
the strength of plutonium. Finite element analysis using the alpha-beta transition
experiment data evaluated the DOE-STD-3013-2000 fatigue loading on the
storage containers and showed that the storage containers meet the
requirements of the ASME B&PV Code, Section VIII, Division 2 [Flanders/
Krishnan 1999]. Confirmatory tests and analyses at the beta-gamma transition
have reinforced the Flanders/Krishnan conclusions [Dane R. Spearing, D. Kirk
Veirs, F. Coyne Prenger, Effect of the Expansion Associated with the Plutonium
Phase Transitions on Storage Can Integrity, "Journal of Nuclear Materials 299
(2001) pp. 111-123.].
3) Metallurgical interactions
Maximum plutonium-container interface temperatures up to approximately 189C
(see Table A-1) have been postulated for plutonium metal storage containers
under bounding conditions. The potential for forming low-melting eutectics has
been evaluated recently based on the available phase diagram data, diffusion
data, and effect of surface oxides [Williamson 1999]. This study concluded that
the storage of Pu metal and Pu-Ga alloys in stainless steel containers will not lead
to the formation of liquids, or result in direct release of plutonium by means of
diffusion mechanisms, as a result of storage at temperatures up to 250C. The
lowest melting liquid system identified in this study (about 400C) results from
the addition of small amounts of Ga (~1 wt%) to a two-phase Pu-Pu6Fe mixture.
The margin of about 150C between the melt temperature and the conservatively
assumed metal storage temperature of 250C is judged to be adequately safe.
However, while directly applicable data are limited, this study could not
categorically exclude the possibility of reduction of inner storage can mechanical
strength due to Fe diffusion into Pu, if a 250C theoretical storage condition
extended for a long time period (10 years or more) and the plutonium metal
intimately contacts the container. However, these analyses were very
conservative in not taking credit for protective oxide films and the small surface

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