Empirical calibration of uranium releases in the terrestrial environment of nuclear fuel cycle facilities

An isotope dilution mass spectrometry overview: tips and applications for the measurement of radionuclides

“…Indeed, the abundance of 235 U in man-modified uranium ranges from ∼0.2% in depleted U to more than 20% for highly enriched U, reaching abundances higher than 90% in nuclear weapons. 165 By contrast, 235 U abundance in naturally occurring uranium shows very small variations around an average value of 0.725% (isotopic abundance). The 236 U isotope is also an excellent fingerprint of anthropogenic nuclear activities.…”

Pushing Limits of ICP–MS/MS for the Determination of Ultralow 236U/238U Isotope Ratios

“…[2][3][4][5][6][7][8][9] In addition, anthropogenic 236 U was locally released into the environment in the vicinity of nuclear fuel reprocessing facilities or after nuclear power plant accidents, with 236 U/ 238 U isotope ratio signatures above 10 -9 . [10][11][12][13][14][15] In uranium ore, high uranium concentrations associated with high neutron flux lead to a higher production of 236 U with 236 U/ 238 U isotope ratios with a typical signature of about 10 -10 . 1,[16][17][18][19][20][21][22][23] In the case of Uores the main sources of neutrons are: (i) (α, n) reactions, with light elements and (ii) spontaneous and neutron-induced fission of 238 U and 235 U respectively.…”

“…The mean 236 U/ 238 U isotope ratio level in Earth crust is 10 –14 – 10 –13 . However, anthropogenic 236 U was globally deposited on Earth surface through atmospheric nuclear weapon tests leading to a characteristic 236 U/ 238 U isotope ratio of 10 –8 –10 –9 in most environmental samples. − In addition, anthropogenic 236 U was locally released into the environment in the vicinity of nuclear fuel reprocessing facilities or after nuclear power plant accidents, with 236 U/ 238 U isotope ratio signatures above 10 –9 . − In uranium ore, high uranium concentrations associated with high neutron flux lead to a higher production of 236 U with 236 U/ 238 U isotope ratios with a typical signature of about 10 –10 . ,− In the case of U-ores the main sources of neutrons are (i) (α, n) reactions, with light elements and (ii) spontaneous and neutron-induced fission of 238 U and 235 U respectively . This high isotopic contrast between the sources makes 236 U/ 238 U isotope ratios a relevant tracer for uranium source identification in the environment. , Uranium isotope investigations are therefore of increasing interest for environmental monitoring, nuclear safeguards and nuclear forensics. , However, due to the low abundance of 236 U in the environment, instruments with high sensitivity and high abundance sensitivity capabilities are required.…”