Using the data from Table 18.2, compute the spontaneous fission rate (in Bq/kg) for ²⁴⁰Pu . Compare this with the rate in ²³⁹Pu and in uranium enriched to 85% ²³⁵U. (See Problem 20.10.)

Table 18.2?

Average number of neutrons per fission Half-life Fraction of decays by spontaneous fission Nucleus Natural Neutrons per year per mole abundance (years) 0.7204% 7.04 x 108 7.0 x 10-11 1.86 7.8 x 104 238 U 92 4.46 x 10 1.1 x 108 99.2742% 5.5 x 10-7 2.07 239 Pu 94 2.41 x 10 3 x 10-12 1.1 x 10 2.16 240 Pu 6.56 x 10 5.7 x 10-8 2.21 8.0 x 1012 2.65 x 10 3.09 x 10-2 3.73 1.8 x 1019