Improving Nuclear Safety of Fast Reactors by Slowing Down Fission Chain Reaction

Table 5

Main deposits of uranium, thorium, and mixed uranium-thorium ores. Elemental compositions of minerals and isotope compositions of radiogenic lead.

Deposit	U/Th/Pb (wt.%)	^204Pb/^206Pb/^207Pb/^208Pb (at.%)	Age (×10^9 yr)
Monazite, Guarapari, Brazil	1.3/59.3/1.5	0.005/6.03/0.46/93.5	0.52 to 0.55
Monazite, Manitoba, Canada	0.3/15.6/1.5	0.01/10.2/1.86/87.9	1.83 to 3.18
Monazite, Mt. Isa Mine, Australia	0.0/5.73/0.3	0.038/5.44/0.97/93.6	1.00 to 1.19
Monazite, Las Vegas, Nevada	0.1/9.39/0.4	0.025/9.07/1.13/89.8	0.77 to 1.73
Uraninite, Singar Mine, India	64.3/8.1/8.9	—/89.4/6.44/4.18	0.885
Monazite, South Bug, Ukraine	0.2/8.72/0.9	0.01/6.04/0.94/93.0	1.8 to 2.0