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|  DOE-STD-3028-2000
B.4
RADON GENERATION
The longest-lived isotope of radon, 222Rn, has a half-life of 3.8 days. Over a 50-year period, any
Rn intermediate on a decay chain will reach a steady-state concentration that is insignificant by
comparison to the helium that is generated by alpha decay of other radionuclides in the same
decay chain. Thus, the partial pressure contribution of all isotopes of Rn may be neglected.
B.5
AGGREGATE PRESSURE EQUATION
Summing the partial pressures from Equations B.5, B.6, and B.7 and evaluating at a storage temperature,
T1, leads to
(P0 )( T1 ) (R )(T1 ) (m )(X H2O ) m
(R )(T1 )
∑ (bi )(X i )
(B.8)
+
P=
+
T0
V MW H2O MW He
V
Substituting Equation B.4 for volume and combining like terms leads to
T1
RT0 (m)(X H2O ) +
m
(B.9)
∑ (bi )(X i )
P = P0 +
MW
T
m MW H2O
0
Vc -
He
ρ
B.6
BOUNDING PRESSURE CALCULATION USING SRS BAGLESS LOADOUT CAN
This section presents an example calculation of the bounding pressure expected in a SRS
bagless loadout can. A typical can has an inside diameter of 0.874 m (0.287 ft.) and a height of
0.0254 m (0.083 ft.). A loading of 1.5 kg (3.3 lbm) 233U as UO3 (the least dense of the uranium
oxides to minimize free volume), with 0.5 wt % moisture is assumed.
Based on these conditions, the bounding hydrogen partial pressure is 1108 kPa (160.7 psia),
and the bounding helium partial pressure is 9.38 kPa (1.36 psia). In practice, a great deal of
this hydrogen will be adsorbed by oxides or react with oxygen containing species to reform
water. Further assuming the material was packaged at atmospheric conditions and that the
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