Activity-mass relationships for uranium and natural thorium.

The table of activity-mass relationships for uranium and natural thorium are as follows: Thorium and uranium enrichment 1 (Wt% 235 U present) Specific activity TBq/gram Grams/Tbq Ci/gram Grams/Ci 0.45 (depleted) 1.9 × 10 −8 5.4 × 10 7 5.0 × 10 −7 2.0 × 10 6 0.72 (natural) 2.6 × 10 −8 3.8 × 10 7 7.1 × 10 −7 1.4 × 10 6 1.0 2.8 × 10 −8 3.6 × 10 7 7.6 × 10 −7 1.3 × 10 6 1.5 3.7 × 10 −8 2.7 × 10 7 1.0 × 10 −6 1.0 × 10 6 5.0 1.0 × 10 −7 1.0 × 10 7 2.7 × 10 −6 3.7 × 10 5 10.0 1.8 × 10 −7 5.6 × 10 6 4.8 × 10 −6 2.1 × 10 5 20.0 3.7 × 10 −7 2.7 × 10 6 1.0 × 10 −5 1.0 × 10 5 35.0 7.4 × 10 −7 1.4 × 10 6 2.0 × 10 −5 5.0 × 10 4 50.0 9.3 × 10 −7 1.1 × 10 6 2.5 × 10 −5 4.0 × 10 4 90.0 2.1 × 10 −6 4.7 × 10 5 5.8 × 10 −5 1.7 × 10 4 93.0 2.6 × 10 −6 3.9 × 10 5 7.0 × 10 −5 1.4 × 10 4 95.0 3.4 × 10 −6 3.0 × 10 5 9.1 × 10 −5 1.1 × 10 4 Natural thorium 8.1 × 10 −9 1.2 × 10 8 2.2 × 10 −7 4.6 × 10 6 1 The figures for uranium include representative values for the activity of uranium-234 which is concentrated during the enrichment process. The activity for thorium includes the equilibrium concentration of thorium-228. [Amdt. 173-244, 60 FR 50307, Sept. 28, 1995, as amended by 63 FR 52849, Oct. 1, 1998]