Nielsen, Sven Poul1; Andersson, Kasper Grann1; Miller, Arne1
1 Center for Nuclear Technologies, Technical University of Denmark2 Radioecology and Tracer Studies, Center for Nuclear Technologies, Technical University of Denmark3 Radiation Physics, Center for Nuclear Technologies, Technical University of Denmark
The environmental surveillance of the Risø environment was continued in January-June 2013. The mean concentrations in air were: 0.55±0.51 μBq m–3 of 137Cs, 2.96±1.18 μBq m–3 of 7Be and 0.26±0.25 μBq m–3 of 210Pb (±1 S.D.; N = 26). The depositions by precipitation at Risø in the first half of 2013 were: 0.074 Bq m–2 of 137Cs, 425 Bq m–2 of 7Be, 35.0 Bq m–2 of 210Pb and < 0.7 kBq m–2 of 3H. The average background dose rate (TLD) at Risø (Zone I) was measured as 136 nSv h–1 compared with 119 ± 16 nSv h–1 (±1 S.D.; N = 4) in the four zones around Risø. TLD results for the period November 2012 – April 2013 are significantly higher than results for the periods before and after this one. No errors could be identified in raw data or calculations. It should be noted that the results for the following period (May-October 2013) are already available and generally show no increase in the levels compared with previous years. It is therefore assumed that the increase in dose values as shown in this report are related to an error on the TL measurement instrument that was found immediately after the measurements.