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[en] In this report, 99Tc results for lobsters caught along the Norwegian coast between 2001 and 2005 are presented. The high accumulation of 99Tc in lobsters compared to other crustecea is confirmed in this report, as well as the clear differences between males and females. Concentration factors have been estimated for each gender and also for different organs. (author)
[en] This report presents a summary of the main sources of radioactivity in the Norwegian marine environment. The input of Cs-137 andTc-99 in 9 different sea and coastal regions, from the Barents Sea in the north, to the Skagerak in the south, has been estimated by using the NRPA-box model. The input of Ra-226 and Ra-228 from the Norwegian oil and gas industry to different regions is also included. The results show that outflowing seawater from the Baltic Sea is the largest source of Cs-137. ForTc-99 the liquid discharge from Sellafield is the only source of importance. Knowledge gaps concerning transfer of radioactivity into Norwegian marine areas have also been identified. (author)
[en] This report details the demonstration of a spatial interpolation method towards the optimisation of temporal sampling for the determination of concentrations of technetium-99 in the Arctic marine environment. The impact of various sampling regimes on the quality of data produced using geostatistical interpolation is ascertained and the use of kriging error minimisation as a decision criterion is demonstrated. The use of an oceanographic model for the a priori determination of parameters relevant to the system used is also demonstrated. (Author)
[en] Highlights: • Indoor radon was measured in randomly selected newly built houses in 2008 and 2016. • New building regulations with preventive measures on radon was introduced in 2010. • A significant reduction of radon concentrations was found in detached houses. - Abstract: Results from two national surveys of radon in newly built homes in Norway, performed in 2008 and 2016, were used in this study to investigate the effect of the 2010 building regulations introducing limit values on radon and requirements for radon prevention measures upon construction of new buildings. In both surveys, homes were randomly selected from the National Building Registry. The overall result was a considerable reduction of radon concentrations after the implementation of new regulations, but the results varied between the different dwelling categories. A statistically significant reduction was found for detached houses where the average radon concentration was almost halved from 76 to 40 Bq/m3. The fraction of detached houses which had at least one frequently occupied room with a radon concentration above the Action Level (100 Bq/m3) fell from 23.9% to 6.4%, while the fraction above the Upper Limit Value (200 Bq/m3) was reduced from 7.6% to 2.5%. In 2008 the average radon concentration measured in terraced and semi-detached houses was 44 and in 2016 it was 29 Bq/m3, but the reduction was not statistically significant. For multifamily houses, it was not possible to draw a conclusion due to insufficient number of measurements.
[en] The Soviet nuclear submarine Komsomolets sank on the 7 April 1989, 180 km southwest of Bear Island in the Norwegian Sea to a depth of about 1655 m. The submarine contains one nuclear reactor containing long-lived radionuclides such as cesium-137 (137Cs) along with other fission and activation products, in addition to 2 mixed uranium/plutonium nuclear warheads containing weapons grade plutonium. Although several model studies have shown that a radioactive leakage from Komsomolets will have insignificant impact on fish and other marine organisms, there are still public concerns about the condition of the submarine and the potential for radioactive leakage. In order to document the contamination levels and to meet public concerns, monitoring of radioactive contamination in the area adjacent to the submarine has been ongoing since 1993. Samples of bottom seawater and sediments have been collected annually by the Institute of Marine Research (IMR) and have been analysed for 137Cs and plutonium-239,240 (239,240Pu). So far, activity concentrations in the samples have been comparable to levels found in other samples from the Norwegian and Barents Seas. During sampling from R/V 'G. O. Sars' in April 2013, an area of about 1 km2 of the seabed around Komsomolets was mapped to precisely locate the submarine using a Kongsberg EM302 multibeam echo sounder, a Simrad EK60 single beam echo sounder and an Olex 3D bottom-mapping system. For sediment sampling, a Simrad MST342 mini-transponder was attached to a Smoegen box corer to allow for precise positioning of the corer. With the aid of the Kongsberg HiPAP (High Precision Acoustic Positioning) system, 4 box cores were collected around the submarine at a distance of 10 to 20 m. In addition, one box core was collected from a reference station about 100 m upstream of the submarine. Surface sediments and sediment cores were collected from the box cores taken at each sampling location. Sediment cores (diameter 10 cm) were cut into 1 cm thick slices and will be analysed for gamma emitters and selected transuranics. This study summarises results from the monitoring in the period 1993 to 2013. The sampling method used in 2013 can be used to sample in the vicinity of any other point target at the seabed, or in the water column. The method is a cheap and simple substitute for ROV-sampling. (authors)
[en] Norwegian marine waters are home to some of the world's richest fishing grounds. In 2011, Norway was the world's twelfth largest fishery nation, and the world's second largest exporter of seafood. Knowledge and documentation of the levels of radioactive contamination in fish and seafood is therefore of major importance to Norwegian consumers and the fishery industry. Monitoring of radioactive pollution in Norwegian fish and seafood has been ongoing in various ways since the early 1960's. During the 1960's, different species of fish from the Barents Sea were analysed for 'total mean beta activity minus potassium-40 (40K)'. Although not directly comparable to current measurements, these were probably the highest observed concentrations in fish during the whole monitoring period. Contamination levels decreased substantially during the late 1960's as a result of the decrease in global fallout, biological elimination of the radioactive elements and the short physical half-lives of some beta-emitters. Monitoring was more or less terminated in the following years, and little data exists from the 1970's and early 1980's, though monitoring was resumed following the Chernobyl accident in 1986. Today, different species of commercially important fish and crustacean species (as well as other species), are sampled on a regular basis from the Barents Sea, the Norwegian Sea, the North Sea and Norwegian fjords. The samples are analysed mainly for cesium-137 (137Cs) and, additionally, a selection of the samples are analysed for technetium-99 (99Tc), plutonium-239,240 (239,240Pu) and polonium-210 (210Po). This study summarizes results from the monitoring during the period 1960 to 2013. Activity concentrations of 137Cs in fish and seafood from Norwegian marine waters have been generally low during the past 20 to 25 years (up to 0.15 Bq kg-1(fresh weight) in different species of fish in the Barents Sea in 2012). However, time trends and geographical trends are clearly evident in the datasets. For example, the impact of fallout from the Chernobyl accident could be observed, particularly in samples collected in coastal areas and the Kattegat/Skagerrak and the North Sea. In recent decades there has been a slow decrease in the activity concentrations of most anthropogenic radionuclides in fish and seafood as a result of decreasing discharges from European reprocessing plants for spent nuclear fuel and the reduced impact of fallout from the Chernobyl accident. In the case of 99Tc however, activity concentrations in seawater and certain biota increased to peak values around 2000 as a result of increased discharges from Sellafield (UK) in the 1990's. In open sea areas, the activity concentrations of 137Cs in fish and seafood have been highest in the Skagerrak and the North Sea due to the proximity to the reprocessing plants at Sellafield and Cap la Hague (France) and outflowing Chernobyl-contaminated seawater from the Baltic Sea. Activity concentrations of 137Cs in fish and seafood collected in fjords in mid-Norway are up to an order of magnitude higher than in the open sea areas due to terrestrial run-off from Chernobyl fallout in Norway. (authors)
[en] We test whether airborne gamma ray spectrometer measurements can be used to estimate levels of radon hazard in the Oslofjord region of Norway. We compile 43,000 line kilometres of gamma ray spectrometer data from 8 airborne surveys covering 10,000 km2 and compare them with 6326 indoor radon measurements. We find a clear spatial correlation between areas with elevated concentrations of uranium daughters in the near surface of the ground and regions with high incidence of elevated radon concentrations in dwellings. This correlation permits cautious use of the airborne data in radon hazard evaluation where direct measurements of indoor radon concentrations are few or absent. In radon hazard evaluation there is a natural synergy between the mapping of radon in indoor air, bedrock and drift geology mapping and airborne gamma ray surveying. We produce radon hazard forecast maps for the Oslofjord region based on a spatial union of hazard indicators from all four of these data sources. Indication of elevated radon hazard in any one of the data sets leads to the classification of a region as having an elevated radon hazard potential. This approach is inclusive in nature and we find that the majority of actual radon hazards lie in the assumed elevated risk regions
[en] Radon (222Rn), thoron (220Rn) and their decay products may reach high levels in areas of high natural background radiation, with increased risk associated with mining areas. Historically, the focus has mostly been placed upon radon and progeny (RnP), but recently there have been reports of significant contributions to dose from thoron progeny (TnP). However, few direct measurements of TnP exist under outdoor conditions. Therefore, we assessed the outdoor activity concentrations of radon, thoron and TnP in an area of igneous bedrock with extreme levels of radionuclides in the thorium decay series. The area is characterized by decommissioned mines and waste rock deposits, which provide a large surface area for radon and thoron emanation and high porosity enhancing exhalation. Extreme levels of thorium and thoron have previously been reported from this area and to improve dose rate estimates we also measured TnP using filter sampling and time-integrating alpha track detectors. We found high to extreme levels of thoron and TnP and the associated dose rates relevant for inhalation were up to 8 μSvh−1 at 100 cm height. Taking gamma irradiation and RnP into account, significant combined doses may result from occupancies in this area. This applies to recreational use of the area and especially previous and planned road-works, which in the worst case could involve doses as large as 23.4 mSv y−1. However, radon and thoron levels were much more intense on a hot September day than during time-integrated measurements made the subsequent colder and wetter month, especially along the ground. This may be explained by cold air observed flowing out from inside the mines through a drainage pipe adjacent to the measurement stations. During warm periods, activity concentrations may therefore be due to both local exhalation from the ground and air ventilating from the mines. However, a substantially lower level of TnP was measured on the September day using filter sampling, as compared to what was measured with time-integrative alpha track detectors. A possible explanation could be reduced filter efficiency related to the attached progeny of some aerosol sizes, but a more likely cause is an upwards bias on TnP detectors associated with assumed deposition velocity, which may be different in outdoor conditions with wind or a larger fraction of unattached progeny. There is thus a need for better instrumentation when dealing with outdoor TnP. - Highlights: • The area has extreme levels of primordial radionuclides, and decommissioned mines. • We report high to extreme levels of outdoor radon, thoron and progeny (TnP). • Levels may be explained by waste rock deposit exhalation and mine air ventilation. • Dose estimates are based on TnP rather than thoron concentrations. • Results on outdoor TnP activity concentrations differ between methods.
[en] Highlights: • The 137Cs levels in Norwegian farmed Atlantic salmon (Salmo salar) and fish feed are low. • The 137Cs levels in farmed salmon are similar to levels found in wild fish caught in open Norwegian waters. • The difference in 137Cs levels in farmed salmon between different Norwegian counties was not statistically significant. • The activity concentrations of 90Sr, 238Pu, 239,240Pu and 241Am were below detection limits in farmed salmon and fish feed. • The 210Po levels in farmed salmon are lower than those observed in wild-caught fish species in Norway. - Abstract: Norway is one of the main producers of farmed fish and the world's second-largest exporter of seafood. Farmed Atlantic salmon (Salmo salar) represents the most exported species. This is the first comprehensive survey of anthropogenic (137Cs, 90Sr, 238Pu, 239,240Pu and 241Am) and natural (40K, 226Ra, 228Ra, 210Pb, 210Po) radionuclides in farmed salmon and manufactured fish feed from Norway. The only anthropogenic radionuclide detected in salmon and fish feed was 137Cs. The levels were low with arithmetic means in salmon and feed of 0.13 and 0.30 Bq/kg fresh weight (fw), respectively. The natural radionuclide 40K exhibited the highest levels with arithmetic means in salmon and feed of 115 and 239 Bq/kg fw, respectively. The arithmetic means of 210Po and 210Pb in salmon were 0.013 and 0.044 Bq/kg fw, respectively, with a mean 210Po:210Pb activity ratio of 0.32. For fish feed, the situation was reversed: the arithmetic means of 210Po and 210Pb were 3.8 and 0.67 Bq/kg fw, respectively, with a mean 210Po:210Pb activity ratio of 5.7. The radionuclide levels found in farmed salmon in the present study are comparable to or lower than the levels found in other fish species in the North Atlantic Ocean. A highly conservative dose estimate for consumption showed that doses were no higher than 1.2 μSv/year for toddlers and 4.0 μSv/year for adults. This suggests that the risk associated with radioactivity in farmed salmon is very low even when considering individuals with high consumption and the highest radionuclide levels found in this study.