TABLE I.

Concentrations and isotopic compositions of fission Xe released from untreated U-rich sample from Streltsovka ore field and from the powdered sample treated with 6M HNO₃ for 3 h. Data are corrected for small instrumental mass discrimination and atmospheric contamination. The composition of Xe lost during the treatment is calculated from the total compositions. Stated errors for are 1σ. The uncertainties of Xe concentrations are ~8%, based on the reproducibility of standards over the course of analyses.

T,°C	136Xe, 10−9 cm3 STP/g	134Xe /136Xe	132Xe /136Xe	131Xe /136Xe	129Xe /136Xe
STR-Nk1 - original sample from Streltsovka U ore
600	0.06	0.913 ± 0.049	0.54 ± 0.11	0.180 ± 0.086	0.025 ± 0.020
820	0.53	0.887 ± 0.012	0.582 ± 0.017	0.166 ± 0.012	0.018 ± 0.013
930	0.89	0.914 ± 0.010	0.597 ± 0.009	0.163 ± 0.004	0.019 ± 0.003
1090	5.57	0.912 ± 0.008	0.595 ± 0.006	0.161 ± 0.003	0.018 ± 0.002
1310	2.95	0.906 ± 0.010	0.593 ± 0.007	0.175 ± 0.002	0.018 ± 0.002
1750	0.50	0.906 ± 0.011	0.598 ± 0.017	0.159 ± 0.011	0.019 ± 0.010
Total	10.5	0.909 ± 0.004	0.594 ± 0.004	0.165 ± 0.002	0.018 ± 0.001
STR-Nk2 - sample treated with 6M HNO3 for 3 h
450	0.05	1.1 ± 0.2	0.86 ± 0.07	0.345 ± 0.08	0.66 ± 0.20
600	0.09	1.16 ± 0.09	0.825 ± 0.04	0.272 ± 0.05	0.59 ± 0.11
700	0.11	1.05 ± 0.08	0.725 ± 0.055	0.244 ± 0.04	0.25 ± 0.09
800	0.04	0.8 ± 0.2	0.587 ± 0.078	0.17 ± 0.06	0.14 ± 0.06
900	0.24	0.902 ± 0.007	0.595 ± 0.009	0.164 ± 0.005	0.021 ± 0.005
1000	0.65	0.915 ± 0.006	0.603 ± 0.009	0.159 ± 0.004	0.017 ± 0.003
1150	1.62	0.911 ± 0.004	0.595 ± 0.009	0.162 ± 0.003	0.019 ± 0.003
1400	0.88	0.915 ± 0.008	0.596 ± 0.010	0.155 ± 0.003	0.018 ± 0.003
1750	0.06	0.91 ± 0.02	0.59 ± 0.02	0.148 ± 0.009	0.016 ± 0.008
Total	3.74	0.923 ± 0.005	0.609 ± 0.005	0.167 ± 0.003	0.049 ± 0.005
Xenon lost during etching
	6.76	0.901 ± 0.007	0.586 ± 0.007	0.164 ± 0.004	0.001 ± 0.003
Reference fission compositions [4]
238U spontaneous		0.825 ± 0.006	0.579 ± 0.009	0.082 ± 0.003	0.002 ± 0.001
235U neutron induced		1.241 ± 0.013	0.672 ± 0.002	0.411 ± 0.001	0.105 ± 0.003