Radiological environmental monitoring at the ESS facility – Annual report 2020

Results from the radiological environmental monitoring of the European Spallation Source (ESS) are presented for year 2020.

Among the 63 environmental samples analysed for gamma emitting radionuclides, no elevated levels of anthropogenic radioactivity were observed. All samples (except two samples of lichen) had activity concentrations below the MDA for the natural radionuclides as well as ¹³⁷Cs, and normal levels of ⁴⁰K. In sewage sludge, detectable levels of ¹⁷⁷Lu and ¹³¹1 were observed in samples that were measured within one week after sampling.

Mobile gamma spectrometry surveys were carried out around ESS and MAX IV (when operating at high frequency during a test run). No deviating radiation levels were observed.

The samples analysed for their ³H activity concentration (120 samples) were generally below the detection limit using the current procedure, instrumentation and analysis time (MDA typically 1.6 Bq L^-1). The results show no evidence of any local contamination of ³H in Lund during 2020.

The ¹⁴C data in the 26 samples of grass, fruits, berries, crops, milk, honey and meat of in the Lund area and in southern Sweden is consistent with the declining ¹⁴C specific activity in atmospheric CO₂. Seasonal variations were observed in the ¹⁴C data. No evidence of anthropogenic 14C contamination in the Lund area was noted during 2020.

The report presents the first base-line measurements of ¹²⁹I (10 samples) in the ESS environmental monitoring programme. The ¹²⁹I activity concentrations ranged between (3.18 ± 0.20)∙10¹¹ atoms/kg d.w. for grass and (1.31 ± 0.03)∙10¹³ atoms/kg d.w. for moss. These values are in the expected range.