Laser Spectroscopy for Monitoring of Radiocarbon in Atmospheric Samples

Abstract

In-situ monitoring of radiocarbon emissions is challenging due to the lack of a suitable method for sensitive online detection of this isotope. Here we report on a complete system for automatized continuous on-site monitoring of radiocarbon gaseous emissions from nuclear facilities. By combining radiocarbon detection using mid-infrared cavity ring-down spectroscopy and an advanced sampling system, an elevated amount of radiocarbon in an atmospheric-like gas matrix was detected. Radiocarbon was detected in the form of 14CO2 after extraction of the carbon dioxide from the air sample. The system is also able to discriminate between radiocarbon in organic or inorganic molecular form by converting 14CH4 into 14CO2. This work lays the groundwork for further use of this technology in nuclear facilities for online on-site monitoring of radioactive gaseous emissions as well as future work on in-situ monitoring of atmospheric radiocarbon.

Analysis of regional CO<sub>2</sub> contributions at the high Alpine observatory Jungfraujoch by means of atmospheric transport simulations and δ<sup>13</sup>C

“…Such dual carbon-isotope approaches making use of 120 co-located δ 13 C and  14 C measurements have already proven successful for carbon source apportionment in few gas- (Meijer et al, 1996;Zondervan and Meijer, 1996) and particle phase studies (Winiger et al, 2019;Andersson et al, 2015). Yet, studies are currently limited to infrequent sampling at few locations, since the involved laboratory analyses are costly, and high frequency, in-situ measurement techniques with sufficient precision for atmospheric  14 C-CO2 currently unavailable, despite first developments (e.g., Genoud et al, 2019;Galli et al, 2011).…”

High-resolution analysis of the ν3 band of radiocarbon methane 14CH4

“…In particular, this time we were able to measure accurately several lines of the P branch, which was difficult to address in the first experiment. The only exception is line P (2), which was also excluded in the present study because it severely overlaps with strong water absorption, thus hindering reliable determination of the line components. All other measured line positions are listed in Table 2.…”

“…Optical spectroscopy of the radioactive isotopologue of methane ( 14 CH 4 ) has interesting applications ranging from energy industry to atmospheric sciences. As an example, radioactive gaseous emissions of light water nuclear reactors and their decommissioning sites can be monitored by measuring the 14 CH 4 concentration [1,2]. Since the 14 CH 4 concentration is depleted in fossil sources with a 14 C half-life of 5700 years, measurements of the 14 CH 4 / 12 CH 4 ratio make it possible to determine the biofractions of biogas and natural gas mixtures, as well as to apportion methane emission sources [3,4].…”

“…The feasibility of optical spectroscopic detection of radioactive gas-phase species in low concentrations was investigated already in the early 1980s [7], but actual measurements were demonstrated much later using highly sensitive cavity-enhanced techniques. Laser spectroscopy of radioactive carbon compounds has so far concentrated on radiocarbon dioxide [2,[8][9][10][11][12][13]]. An optical 14 CO 2 detector with sensitivity approaching that of AMS has already been demonstrated [14].…”

Low Energy Beta Emitter Measurement: A Review

“…However, this approach requires a long time for pretreatment and waste generated after the analysis is harmful to the environment [4][5][6][7][8]. Additionally, the specific and large size equipment of the LSC makes it unsuitable for measuring beta-ray emitting isotopes on site due to its complex systems [9]. Furthermore, the LSC is suitable to measure beta-rays due to their low atomic number and density because the elemental composition of plastics is H and C. Additionally, plastic scintillators are easy to manufacture in desired size and can be inexpensively fabricated in a large size [10].…”