Abstract
This study conducted a nationwide car-borne radiation survey to assess background radiation levels originating from naturally occurring radionuclides across South Korea. Two survey vehicles were developed, each equipped with NaI(Tl) detectors and high-pressure ionization chambers (HPICs), and deployed over a period of approximately four years. As a result, a total of 723,052 gamma-ray spectra and ambient dose rate measurements were collected. A post-processing tool incorporating an automatic peak-channel tracking algorithm and net count rate (CPS) calculation was developed to extract radionuclide-specific net count rates. These values, along with the dose rates, were converted into concentrations of equivalent uranium (eU), equivalent thorium (eTh), and potassium-40 (40K) as well as corrected ambient dose rates, using established conversion factors and shielding correction models from previous studies. The resulting geospatial database contains activity concentrations in soil and ambient gamma dose rates at each measurement points. The average concentrations were 51.2 Bq kg-1 for eU (range: 0.003–927 Bq kg-1), 58.9 Bq kg-1 for eTh (range: 0.02–556 Bq kg-1), and 877 Bq kg-1 for 40K (range: 21–3,135 Bq kg-1), with an average dose rate of 131 nSv h-1. The uncertainties represent standard deviations (k = 1). Four distribution maps were produced to visualize the spatial distribution of terrestrial radiation. The comprehensive and high-resolution data obtained through this study provide a quantitative foundation for assessing public radiation exposure and for informing national policy on the management of existing exposure situations.
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Data availability
The dataset generated during the current study are not publicly available due to national-level sensitivity regarding regional variations in radiation levels, but are available from the corresponding author on reasonable request.
References
KINS. Radiation Environment of Korea (in Korean). KINS/GR-356. Korea Institute of Nuclear Safety (2009).
UNSCEAR. Exposure from natural radiation sources. Annex B in Sources and effects of ionizing radiation. UNSCEAR 2000 Report to the General Assembly with Scientific Annexes. United Nations Scientific Committee on the Effects of Atomic Radiation. United Nations, New York (2000a).
ICRP. The 2007 recommendations of the international commission on radiological protection. ICRP publication 103. Ann. ICRP 37, 1–332 (2007).
WHO. Handbook on Indoor Radon: A Public Health Perspective. World Health Organization (2009).
Kim, Y. J., Chang, B. U., Park, H. M., Kim, C. K. & Tokonami, S. National radon survey in Korea. Radiat. Prot. Dosim. 146, 6–10 (2011).
ICRP. Protection against Radon-222 at Home and at Work. ICRP Publication 65. Ann. ICRP. Int. Comm. Radiologic. Prot. 23, 1–45 (1993).
Bochicchio, F. et al. National radon programmes and policies: The RADPAR recommendations. Radiat. Prot. Dosim. 160, 14–17 (2014).
Hassan, N. M., Kim, Y. J., Jang, J., Chang, B. U. & Chae, J. S. Comparative study of precise measurements of natural radionuclides and radiation dose using in-situ and laboratory γ-ray spectroscopy techniques. Sci. Rep. 8, 14115 (2018).
USGS. Airborne gamma-ray spectometry maps of North America. U.S. Geological Survey Open-File Report 2005–1413. Available at: https://pubs.usgs.gov/of/2005/1413/maps.htm. United States Geological Survey (2005).
Cinelli, G. et al. Digital version of the European atlas of natural radiation. J. Environ. Radioact. 196, 240–252 (2019).
IAEA. Guidelines for radioelement mapping using gamma ray spectrometry data. IAEA-TECDOC-1363. International Atomic Energy Agency (2003).
Park, J. W. et al. Assessment of population exposure to terrestrial gamma radiation in South Korea. J. Radiol. Prot. 45, 031506 (2025).
KINS. Establishment of technical basis for implementation on safety management for radiation in the natural environment (in Korean). KINS/ER-337. Korea Institute of Nuclear Safety (2016).
Casanovas, R., Morant, J. J. & Salvadó, M. Temperature peak-shift correction methods for NaI(Tl) and LaBr 3(Ce) gamma-ray spectrum stabilisation. Radiat. Meas. 47, 588–595 (2012).
ICRU. Gamma-ray spectrometry in the Environment. ICRU Report 53. Int. Comm. Radiat. Units Measure. 27, 84 (1994).
Huang, Y.-J. et al. Natural radioactivity and radiological hazards assessment of bone-coal from a vanadium mine in central China. Radiat. Phys. Chem. 107, 82–88 (2015).
UNSCEAR. Exposures of the public and workers from various sources of radiation. Annex B in Sources and effects of ionizing radiation. UNSCEAR 2008 Report to the General Assembly with Scientific Annexes. United Nations Scientific Committee on the Effects of Atomic Radiation. United Nations, New York (2000b).
Acknowledgements
This work was supported by the Nuclear Safety Research Program through the Korea Foundation of Nuclear Safety (KoFONS), granted financial resources from the Nuclear Safety and Security Commission (NSSC), Republic of Korea. (No. 1505004).
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The design of the study was done by B.U. Chang and Y.J. Kim. The development of the car-borne system and the car-borne surveys were done by all authors. The development of the data processing tool and the processing of the entire dataset were done by J. Jang. The establishment of database was done by J. Jang and J. Park. The generation of radiation maps was done by J. Park. The main manuscript was written by J. Jang, and the whole processes ware supervised by B.U. Chang and Y.J. Kim. All authors reviewed the manuscript.
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Jang, J., Park, J., Chang, BU. et al. Nationwide mapping of terrestrial gamma radiation in South Korea using a car-borne survey system. Sci Rep (2026). https://doi.org/10.1038/s41598-025-34666-0
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DOI: https://doi.org/10.1038/s41598-025-34666-0
