Advanced atmospheric 14C monitoring around the Paks Nuclear Power Plant, Hungary. (March 2020)

• Record Type: Journal Article
• Authors: Varga, Tamás; Orsovszki, Gergely; Major, István; Veres, Mihály; Bujtás, Tibor; Végh, Gábor; Manga, László; Jull, A.J. Timothy; Palcsu, László; Molnár, Mihály
• Is Part Of: Journal of environmental radioactivity. Volume 213(2020)
• Publication Date: 2020-03
• Subjects: Nuclear power plant -- Monitoring -- Radiocarbon -- Modelling -- Hydrocarbon -- CO2; Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2019.106138
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: Atmospheric air samples were collected at 9 monitoring stations (A1 to A9) less than 2 km from the Paks Nuclear Power Plant (Paks NPP) and a background station (B24). The monthly integrated CO2 and total carbon (CO2 +hydrocarbons (Cn Hm )) samples were collected to determine the excess 14 C activity at the vicinity of the NPP. The measurements providing the 14 C/ 12 C ratio of the monthly integrated samples were carried out on a MICADAS type AMS at HEKAL. Due to the relatively low 14 CO2 emission of PWR type Paks reactors and the local Suess effect, there was negligible excess 14 C activity at the investigated stations in the pure CO2 fraction during the investigated 2 years period (2015–2016). On the contrary, there was a detectable (although minor) excess at every station in the Cn Hm fraction. In case of CO2, the average Δ 14 C excess was 3.8‰ and the highest measured value was 91.2‰ at the A3 station in February 2015. In case of Cn Hm, the average excess was 31.1‰ and the highest measured value was 319.1‰ at the A4 station in February 2016. We applied PC-CREAM 08 modelling to investigate the observed excess 14 C activity at the environmental sampling stations, which depends on the distance from the NPP and the meteorological conditions, such as wind direction and wind speed. Meteorology data was collected at the operating area of the Paks NPP in a meteorology tower. The direct C-14 emission through the 120 m high stacks was measured in the NPP by liquid scintillation counting. These emission data and our model calculations explain the excess activity in the Cn Hm fraction at the A4 station, which is located only 915 m far from the NPP's stacks in the prevailing wind direction. The excess activity at A3 station (the farthest unit) probably came from the nearby NPP wastewater discharge point. The recently observed average excess and highest excess data is similar to the published data in former studies (Molnár et al., 2007; Veres et al., 1995) on Paks NPP, the highest 14 CO2 and 14 Cn Hm excess are just a little higher than it was in the earlier studies, but in these former studies, the A3 station was not equipped with a radiocarbon monitoring unit and the level of radiocarbon emission was almost invisible from the wastewater discharge point. Graphical abstract: Image 1 Highlights: Radiocarbon emission was measured in the stack of the NPP. Environmental radiocarbon level was measured in the vicinity of the Paks NPP. C-14 was measured in the CO2 and Cn Hm form. The PLUM PC modelling was used for the investigation of the dispersion of C-14.