Public exposure in the Orenburg region due to natural sources of ionizing radiation. Part 1: Results of the comprehensive survey of settlements in the eastern districts of the Orenburg region

The paper presents results of a comprehensive radiation survey conducted in 2019 six districts the eastern part Orenburg region 37 settlements with previously found elevated levels activity concentration natural radionuclides tap water from groundwater sources drinking supply. included measurements indoor radon concentrations and EEC residential public buildings, as well ambient dose equivalent rate gamma indoors outdoors. revealed that annual average many buildings 23 25 exceeded hygienic norm (action level) 200 Bq/m3 adopted Russia for existing buildings. highest values were obtained Novovinnitskoe (1242 Bq/m3), Bratslavka (987 Bq/m3) Anikhovka (942 Adamovsky district, Kvarkeno (2291 Kvarkensky Karabutak (1114 (923 district. established norms terms outdoors not surveyed settlements. Results showed main reason high is related to usage supply radionuclides.