Activity ratio of Pm-146/Pm-147 in Pm-147 radiation source

Sato, Tadashi

Activity of Pm-147 in same consumer goods (glow starter for fluorescent light) is measured by Ge- ray spectrometer. Activity of Pm-147 in glow starters scattered between 1.3E3 -5.3E3 Bq. Together with Pm-147, Pm-146 was found in the glow starters. Activity ratio of Pm-146/ Pm-147 ranged from 5.8E-5 to 1.1E-4. The ratio is too high in comparison with ratio of cumulative fission yield of Pm-146/Pm-147 for U-235 thermal fission, 2E-10. Calculation of the ratio of Pm-146/ Pm-147 by ORIGEN2 show 2.47E-5 for PWR(burnup 33 GWD/MT) and 1.53E-5 for BWR(burnup 27.5 GWD/MT). These ratios agree with the ratio found for glow starters taking account of decay of two nuclides Pm-146 t1/2 5.53y, Pm-147 t1/2 2.26y. As no cumulative fission yield of Pm-146 in the ORIGEN2 library, production pass of Pm-146 is not fission but other nuclear reaction such as Pm-147(n,2n)Pm-146.