Atmospheric 14CH4, 14CO2 and 37Ar measurements around a Swiss pressurized water reactor during an annual revision period
Year: 2024
Type: article
Abstract: Since the 1980s, radiocarbon ( 14 C) has gained attention as a valuable tool to quantify the amount of fossil and non-fossil emissions of CO 2 and CH 4 in the atmosphere. Since the 1970s, however, important 14 C emissions in the atmosphere also occur through the operation of nuclear power plants. The limited knowledge about these emissions challenges the use of 14 C as a universal source apportionment tool. Depending on the reactor type, 14 C is emitted in different forms; in particular, pressurized water reactors emit 14 C as a mixture of 14 CH 4 and 14 CO 2 . However, few atmospheric 14 C measurements close to nuclear power plants are available, which mostly address 14 CO 2 emissions. Argon-37 ( 37 Ar) can also be produced in nuclear reactors; however, its atmospheric measurement is challenging, resulting in limited available data. In this study, we sampled ambient air during 20–75 min into 18 individual bags around the pressurized water reactor in Gösgen, Switzerland, at the beginning of the annual revision period in 2019, when 14 C and 37 Ar emissions can be expected due to the depressurization of the reactor. These samples were analyzed for 14 CH 4 , 14 CO 2 and partly for 37 Ar. About 1 km downwind of the stack, we found background-corrected activities up to 1900, 370, and 93 mBq m −3 respectively. Considering corresponding background activities of 0.3, 48 and 2 mBq m −3 for 14 CH 4 , 14 CO 2 , and 37 Ar, this represents an excess of about 6300, 7.4, and 47 times, respectively. Using an atmospheric dispersion model, we satisfactorily simulated the 14 CH 4 and 14 CO 2 activities in the surroundings of the reactor during this event. Our measurements emphasize the importance of nuclear power plants in the interpretation of atmospheric 14 C measurements and show that pressurized water reactors represent a serious limitation in the use of 14 C for source apportionment of CH 4 sources. Our results also provide insights into the approximate magnitude of civilian 37 Ar emissions from nuclear facilities specifically during maintenance operations. • Air samples around a Swiss nuclear reactor were analyzed during an annual revision. • The atmospheric samples were analyzed for 14 CH 4 , 14 CO 2 and partly for 37 Ar. • About 6300, 7.4, and 47 times higher activities than background values were found. • Nuclear reactors represent a limitation in the use of 14 C for source apportionment.
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: hybrid
Estimated APC paid: $3,850
OpenAlex ID: W4404657487