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Radionuclides released and discharged into the environment from nuclear and other radiation-related facilities, such as the European Spallation Source (ESS), may accumulate in aquatic bottom sediments. Sediments should therefore, as recommended by the IAEA, be monitored regularly. This report describes the setting up of a methodology for zero-point assessments of the radiation levels in sediments of relevance for possible future releases from the ESS.Two types of sediment sampling devices have been tested: a grab sampler of the Lamotte type, and a stationary bottom trap consisting of a 5-L bucket placed on the bottom of a pond. The Lamotte grab sampler worked well in the absence of obstacles such as vegetation and stones. Sampling from boat may be advantageous in finding suitable sampling spots for the grab sampler. The stationary bottom trap, tested for more than two years at one of the ponds at the ESS facility, proved functional. To be certain to obtain sufficient sediment during collection period of one year, we recommend using three 5-L buckets per pond. The bottom trap is most likely not suitable for sampling in rivers with flowing water.For the sample preparation, sieving the sediment in a laboratory was found to be more efficient and more convenient compared to sieving at the sampling site. Freeze-drying was found superior, in terms of efficiency and dried sample texture, to drying the sediment in open air. Measurements of total carbon, total nitrogen, and the carbon to nitrogen ratio proved to have the potential to provide relevant information about the sources of the sediment. The results of gamma-ray spectrometry confirmed sediments as a useful indicator of radionuclides, with activity concentrations above the MDA levels for all reported radionuclides and samples, except for one site. Gamma-ray spectrometry measurements on the samples can provide information on local elevated levels of anthropogenic radionuclides and add information to the sources of the

This study provides information about the concentration of Tungsten (W), Hafnium (Hf) and Tantal (Ta) in the ESS soil and recommendations on the most appropriate sample preparation and measurement technique to assess contamination by these elements. The current levels of W, Hf and Ta measured in this study are in agreement with the estimated values from previous geological surveys. ICP MS showed low limits of detection for W, Hf and Ta and is thus an appropriate technique for environmental monitoring. However, the three metals are difficult to extract from soil and require the use of specific sample preparation methods (based on hydrofluoric acid for example). The transfer of stable W, Hf and Ta from soil to plant is poorly known and only a handful of publications can be found that are relevant to the plants grown around the ESS. The transfer of the radioisotopes of W, Hf and Ta in particular to animals (and man) is even less studied. However, the existing articles indicate a fast excretion of radio-W and radio-Ta while the excretion is slow for radio-Hf.The Minimum Detectable Activity (MDA) for gamma emitter released from the ESS facility will depend not only on the performances of the detection equipment but also on the composition of tungsten target at the time of the release. The determination of limits of detection of ESS related gamma emitters was performed using a strategy based on simulation of spectra. Semi-synthetic gamma spectra were obtained by combining real soil measurements with simulated data for mixtures of ESS radionuclides using the software Nucleonica. The simulation of 187W spectra was used as a proof of concept for the method. With this approach, it is possible to estimate limits of detection by gamma spectroscopy for a given target composition. The limits of detection of four relevant radionuclides were successfully determined for two different compositions of the ESS target and at three different activity concentrations in soil.

Results from the radiological environmental monitoring of the European Spallation Source (ESS) are presented for 2021. Previous zero-point assessments (2017-2020) have mainly focussed on terrestrial samples. New sample types for 2021 include a sediment sample from a pond at the ESS and brown seaweed (Fucus) from Lomma bay and from the east coast of Scania (Skillinge). For gamma-emitting radionuclides, increased levels of anthropogenic radioactivity (177Lu and 131I) originating from hospital use, were only observed in sewage sludge samples. For tritium, the majority of the samples had activity concentrations that were below the minimum detectable activity (MDA) of 1.62 Bq l-1. Expected environmental levels, without any evidence of local contamination, were also seen in the 14C data.

The support from SSM has made it possible to continue collecting brown algaefrom the place on the Swedish west coast where regular collections began asearly as 1967. The support has also enabled more extensive analyses ofpreviously collected material than was possible before. This applies to bothsupplementary analyses of previously reported radionuclides and analysis ofnew ones. The project has also enabled a start of more comprehensive analysesof the overall results. This has provided better information about long-termprocesses and seasonal variations for different radionuclides in both toothedwrack (Fucus serratus) and bladderwrack (Fucus vesiculosus). What is new isthat the sample material has now also been used to analyse metals, both thosewith known toxic effects such as lead, cadmium and mercury, as well as thosethat are of interest in assessing transport routes for radionuclides generated innew radiation sources, such as gadolinium isotopes from the EuropeanSpallation Source (ESS).Regarding the long-term development of various radionuclides in the marineenvironment on the Swedish west coast, the studies show rapidly increasinglevels of iodine-129, decreasing levels of cesium-137, technetium-99 andplutonium-239+240. The carbon-14 analyses suggest a continued inflow of thisradionuclide from the North Sea. The study also shows that the brown algaecould be important for the monitoring of emissions of naturally occurringradioactive materials (NORM) from the offshore oil and gas industry bysystematically studying long-term and seasonal variations of the content ofradium-228 and in the future also radium- 226 and lead-210. Interesting andhitherto unexplained variations in the beryllium-7 content in Fucus have beenmade. The tritium content in Fucus and in seawater has been analysed in alimited number of samples from 2020. No levels beyond the expected normalambient level for tritium have been found.During the 10-year period 2011-2020, there was a doubling of the leve

The results of the project SSM2019-5225, “Marine 14C levels around the Swedish coast”, financed by the Swedish Radiation Safety Authority (SSM), are presented in the paper “Spatial and temporal variations of 14C in Fucus spp. in Swedish coastal waters” published in the Journal of Environmental Radioactivity. The project SSM2019-5225 focussed on spatial variations in 14C in Fucus spp. samples collected in 2020 along the entire Swedish west coast, in coastal waters in the very south of Sweden, and for the east coast up into the Gulf of Bothnia. In this report we present results from additional measurements of the Fucus spp. samples, using gamma-ray spectrometry (of 7Be, 40K, 60Co, 137Cs and 131I) and inductively coupled plasma mass spectrometry (ICP-MS) (of Co, Ni, Cd, Gd, Hg and Pb). The gamma spectrometry showed in addition to the expected content of natural 40K also 137Cs and 7Be, and at some places also 60Co and 131I. The ICP-MS analysis revealed a correlation between F14C and Gd, and the highest values of F14C and Gd were found close to Ringhals nuclear power plant. This strengthens the hypothesis that that a significant part of the observed peak in F14C on the west coast originates from Ringhals nuclear power plant.

The European Spallation Source (ESS) is a neutron research facility under construction in southern Sweden. The facility will produce a wide range ofradionuclides that could be released into the environment. Some radionuclides are of particular concern such as the rare earth gadolinium-148. In this article, the local environment was investigated in terms of food production and rare earth element concentration in soil. The collected data will later be used to model thetransfer of radioactive contaminations from the ESS.

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.

Gadolinium-148 is one of the radionuclides of most concern that will be produced in the tungsten target of the European Spallation Source (ESS), as a by-product of the spallation reaction used by the facility to produce neutrons. Since 148Gd a pure alpha emitter, it is both very radiotoxic and difficult to measure. With its half-life of 75 years, it will remain in the environment for a long time if released from the facility during normal operation or after an accident. There are still uncertainties regarding the amounts that actually will be produced by spallation in the tungsten targets of the facility. As Gd-148 does not occur naturally in the environment, there is no information available about its analysis in environmental samples but a few studies provide data from irradiated target material analysed by alpha spectroscopy or inductively coupled plasma mass spectrometry (ICP-MS). This report is a continuation of the SSM project as described in the SSM report 2020:08, entitled “Identifying radiologically important ESS-specific radionuclides and relevant detection methods” that focused on the ESS-related radionuclides that will be the most relevant to study and monitor in the environment as well as the analytical techniques to detect them. The present report focuses on the rare earth elements (REEs), including their radioactive isotopes, in particular Gd-148, and is intended to highlight the knowledge gaps that exist regarding their fate in the specific environment of the ESS area. In the first part of the report, the available literature on radioecological models was reviewed, with emphasis on ESS-related radionuclides. The existing modelling programmes were surveyed as well as the most relevant environmental parameters and experimental radioecological data required to build models specific to the ESS.In the second part of the report, the area in the vicinity of the ESS was surveyed to identify the important producers of foodstuff, what plant species are grown i

The European Spallation Source (ESS) is under construction in the outskirts of Lund in southern Sweden. When ESS has entered the operational phase in a few years, an intense beam of high-energy protons will not only produce the desired spallation neutrons from a large target of tungsten, but a substantial number of different radioactive by-products will also be generated. A small part of these will be released to the environment during normal operation. During an accident scenario, a wide range of gases and aerosols may be released from the tungsten target. The palette of radionuclides generated in the ESS target will differ from that of e.g. medical cyclotrons or nuclear power plants, thus presenting new challenges e.g. in the required environmental monitoring to ensure that dose limits to the public are not exceeded. This project (SSM2018-1636), financed by the Swedish Radiation Safety Authority (SSM), aimed to strengthen competence at Lund University for measurement and analysis of ESS-specific radionuclides. First, an extensive literature review, including modelling as well as experimental analyses, of ESS-relevant radionuclides was performed. We found that radionuclide production in particle accelerators is well-known, while experience with tungsten targets is very limited. As a second part of the project, an independent simplified model of the ESS target sector for the calculations of radionuclide production in the ESS tungsten target was developed using the FLUKA code. We conclude that we have a fairly good agreement with results of other authors, except for 148Gd, and that the calculated radionuclide composition is sensitive to the nuclear interaction models used.In the third part of the project, known environmental measurement technologies for various ESS-relevant radionuclides were reviewed, focussing on pure difficult-to-measure alpha- and beta-emitters. Liquid scintillation counting (LSC) is a suitable technique e.g. for the important beta emitters 3H, 1

The stable isotope of carbon, C-13, has been used in several studies for source characterization of carbonaceous aerosol since there are specific signatures for different sources. In rural areas, the influence of different sources is complex and the application of delta C-13 for source characterization of the total carbonaceous aerosol (TC) can therefore be difficult, especially the separation between biomass burning and biogenic sources. We measured delta C-13 from 25 filter samples collected during one year at a rural background site in southern Sweden. Throughout the year, the measured delta C-13 showed low variability (-26.73 to -25.64%). We found that the measured delta C-13 did not correlate with other commonly used source apportionment tracers (C-14, levoglucosan). delta C-13 values showed lower variability during the cold months compared to the summer, and this narrowing of the delta C-13 values together with elevated levoglucosan concentrations may indicate contribution from sources with lower delta C-13 variation, such as biomass or fossil fuel combustion. Comparison of two Monte Carlo based source apportionment models showed no significant difference in results when delta C-13 was incorporated in the model. The insignificant change of redistributed fraction of carbon between the sources was mainly a consequence of relatively narrow range of delta C-13 values and was complicated by an unaccounted kinetic isotopic effect and overlapping delta C-13 end-member values for biomass burning and biogenic sources.