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

Project SSM2019-5225: “Marine 14C levels around the Swedish coast” – Additional gamma spectrometric measurements and ICP-MS analysis of brown algae (Fucus spp.)

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

Long-time variations of radionuclides and metals in the marine environment of the Swedish west-coast studied using brown algae : (Fucus serratus and Fucus vesiculosus)

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 levels of leadand nickel and a 50% increase in the levels of cadmium and cobalt in Fucus. Formercury a 10-fold decrease is registered between 2011 and 2016 and then adoubling of the concentration between 2016 and 2020. The decreasing trend formercury probably indicates an effect of the gradual phasing out of mercury inSweden and other countries. However, some businesses and companies have anexemption for continued use. For gadolinium there is an increase with a factor ofaround 5 from 2011 to 2020, most likely explained by the increased use ofgadolinium-containing contrast agents in magnetic resonance imaging inhealthcare

Radiological environmental monitoring at the ESS facility – Annual report 2021

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

Region-specific radioecological evaluation of accidental releases of radionuclides from ESS

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 in the area and also the local husbandry and hunting practices, in order to identify critical pathways after a radioactive dispersion into the environment in connection with a potential accident at the ESS. In the third part of this report, after a thorough literature review and preliminary assays, we propose to investigate the use of ICP-MS for assessment of Gd-148 in the event of an accidental release, knowing that this analytical technique is already used for the measurement of stable Gd and REEs in the environment. The existing methods to extract REEs from environmental samples (soil, water, plants, and animal products) and to properly assess their concentration are described in the form of a literature review. The presented examples of methods were selected to fit the type of environment found around the ESS facility and the local agricultural and horticultural practices. A pilot study was also conducted to test extraction and measurement methods on the specific type of soil around ESS. These results are presented at the end of this report

Evaluation of the region-specific risks of accidental radioactive releases from the European Spallation Source

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

Identifying radiologically important ESS-specific radionuclides and relevant detection methods

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, 14C, 35S, 31P and 33P. Several ESS radionuclides of relevance for dose estimates have never been investigated by environmental analytical techniques, due to their absence in the normal environment. Alpha spectrometry seems promising for the analysis of alpha-emitting lanthanides, in particular for 148Gd. Among the many types of mass spectrometry techniques, ICP-MS (inductively coupled plasma mass spectrometry) and AMS (accelerator mass spectrometry) seem to be the most suitable for the analysis of long-lived ESS radionuclides in environmental samples (e.g. 243Am and possibly lanthanides for ICP-MS and 10Be, 14C, 32Si, 36Cl, 60Fe and 129I for AMS).Three experimental parts were performed during the project, related to initiation of radioactivity measurements of aerosols at Lund University, mapping of environmental tritium in the Lund area, and establishment of a method to measure tritium in urine followed by a study of tritium in persons presently living or working in Lund. Aerosols were collected at a rural background station (Hyltemossa near Perstorp, northern Skåne) using a high-volume aerosol sampler with automatic filter change (DHA-80, Digitel). Gamma spectrometry measurements of 7Be agreed rather well with results from a nearby air monitoring station (SSM/FOI). Tritium (radioactive hydrogen) is expected to dominate the source term from the ESS target station to the environment. We have performed several investigations to monitor the current situation of tritium in Lund using LSC: the matrices investigated included air humidity, precipitation, pond water, indoor air at one accelerator facility and urine from the general public as well as from persons who may be occupationally exposed to tritium. Environmental tritium was generally very low (<3.4 Bq L-1), with somewhat higher concentration in the springtime than during the rest of the year. Tritium in the vast majority of the 55 urine samples was also very low: only a few exposed workers were found to have up to 11 Bq L-1 in their urine, which still is very low compared to e.g. reactor workers. Suggestions for further actions and work related to measurement and analysis of ESS relevant radionuclides are presented