Ingar Amundsen

Accumulation and long term behaviour of radiocaesium in Norwegian fungi

Abstract The accumulation and long term behaviour of radiocaesium in mushrooms were studied at selected sites in Norway. A large variation in transfer factors from soil to mushroom were found with the lowest value of 0.002 m 2 /kg for Leccinum versipelle up to 0.5 m 2 /kg for species of Amanita fulva and Amanita vaginata. Rozites caperata and Cortinarius armillatus were also found to accumulate radiocaesium very efficiently. For the study of long term behaviour of radiocaesium in mushrooms the same species were collected from the same location from 1989 to 1995. Two of four data sets showed a significant decrease in activity levels in the study period with an estimated effective ecological half-life in the range of 1.5–8 years, while a non-significant decrease and no decrease were indicated by the other two.

Biogeochemical behaviour of 137Cs and 90Sr in the artificial reservoirs of Mayak PA, Russia

The Mayak Production Association (PA) in the southern Urals, Russia was the site of the first weapons-grade plutonium production reactor complex in Russia. The site and surrounding area have been significantly contaminated by direct discharges of radionuclides for over 40 years, the Techa River alone having received more than 100 PBq of waste in the period 1949–1956. The aim of this study was to consider the levels of 90Sr and 137Cs in water, sediment and biota samples for two industrial reservoirs in the Mayak PA area, thus allowing a biogeochemical assessment of the behaviour of radionuclides in the system. Four sediment cores were collected and sectioned along with four water samples and seven fish samples (pike, perch and roach). Samples were analysed using (i) standard gamma-spectrometric techniques (HPGe and NaI(Tl) detectors) for 137Cs determination; and (ii) radiochemical separation and beta-counting (low-background, anti-coincidence and Geiger–Muller counters) for 90Sr determination. Maximum specific activities (dry weight) of 3350 kBq kg−1 137Cs and 720 kBq kg−1 90Sr were measured in sediments from Reservoir 10. Activity levels of sediment-bound radionuclides in Reservoir 11 were 403 kBq kg−1 137Cs and 670 kBq kg−1 90Sr. Water concentrations in Reservoir 10 were as high as 100 Bq l−1 137Cs and 8.4–14 kBq l−1 90Sr. A dramatic decrease in 137Cs concentrations was observed in Reservoir 11, i.e. 1.1–1.5 Bq l−1, but 90Sr levels fell to a lesser extent, i.e. 1.9–2.4 kBq l−1. Sediment and water activity data allowed the calculation of distribution coefficients (Kd values). This parameter fluctuated for both radionuclides reflecting the heterogeneous nature of the sediment deposits in the reservoirs. Caesium-137 Concentration Factors (CFs) as high as 1400 l kg−1 were calculated for pike from Reservoir 10. A pronounced ‘trophic level’ effect was evident in Reservoir 11 (pike CF=1000, roach CF=240).

The accidental sinking of the nuclear submarine, the Kursk: monitoring of radioactivity and the preliminary assessment of the potential impact of radioactive releases.

Measurements of samples taken from the close vicinity of the Kursk during two expeditions to the site in August and October 2000, indicate that no leakage of radionuclides from the reactors has been observed. Only background levels in the range 0.0-0.1 microSv/h have been measured by use of the remote operating vehicle (ROV) or by the divers working on and inside the submarine. Preliminary model calculations based on two different scenarios, representing short- and long-term releases of 100% of the reactors radionuclide inventory, show that the impact on man and the environment from the Kursk should not be deemed very serious. The conservative estimates indicate a maximum 137Cs activity concentration in fish in the order of about 80-100 Bq/kg and a total collective dose of 97 manSv.

Floating nuclear power plants: Potential implications for radioactive pollution of the northern marine environment

Recent media reports as to the development, construction and possible deployment of floating nuclear power plants in the northern regions has generated significant interest in the matter. This paper presents background to the concept of floating nuclear power plants, information as to possible designs and iterations and some aspects of potential concern with respect to safety and the potential for environmental or other impacts as a result of the development and use of such systems in the northern regions.

Environmental, health and safety assessment of decommissioning radioisotope thermoelectric generators (RTGs) in northwest Russia

This paper presents findings from public health and environmental assessment work that has been conducted as part of a joint Norwegian-Russian project to decommission radioisotope thermoelectric generators (RTG) in northwest Russia. RTGs utilise heat energy from radioactive isotopes, in this case 90Sr and its daughter nuclide 90Y, to generate electricity as a power source. Different accident scenarios based on the decommissioning process for RTGs are assessed in terms of possible radiation effects to humans and the environment. Doses to humans and biota under the worst-case scenario were lower than threshold limits given in ICRP and IAEA literature.

Atmospheric transport of radioactive debris to Norway in case of a hypothetical accident related to the recovery of the Russian submarine K-27

The Russian nuclear submarine K-27 suffered a loss of coolant accident in 1968 and with nuclear fuel in both reactors it was scuttled in 1981 in the outer part of Stepovogo Bay located on the eastern coast of Novaya Zemlya. The inventory of spent nuclear fuel on board the submarine is of concern because it represents a potential source of radioactive contamination of the Kara Sea and a criticality accident with potential for long-range atmospheric transport of radioactive particles cannot be ruled out. To address these concerns and to provide a better basis for evaluating possible radiological impacts of potential releases in case a salvage operation is initiated, we assessed the atmospheric transport of radionuclides and deposition in Norway from a hypothetical criticality accident on board the K-27. To achieve this, a long term (33 years) meteorological database has been prepared and used for selection of the worst case meteorological scenarios for each of three selected locations of the potential accident. Next, the dispersion model SNAP was run with the source term for the worst-case accident scenario and selected meteorological scenarios. The results showed predictions to be very sensitive to the estimation of the source term for the worst-case accident and especially to the sizes and densities of released radioactive particles. The results indicated that a large area of Norway could be affected, but that the deposition in Northern Norway would be considerably higher than in other areas of the country. The simulations showed that deposition from the worst-case scenario of a hypothetical K-27 accident would be at least two orders of magnitude lower than the deposition observed in Norway following the Chernobyl accident.

Norway's role in international collaboration towards rehabilitation of Andreeva Bay

Andreeva Bay is one of the largest and most hazardous nuclear legacy sites in northwest Russia. The site is the location of large amounts of Spent Nuclear Fuel (SNF) and radioactive wastes and the risks associated with the site have precipitated an extensive international collaborative effort towards securing and rehabilitating the site. Given the location and proximity of the site, Norway has and continues to contribute in a number of ways towards this effort. Norways activities in relation to rehabilitative efforts at Andreeva Bay are focused on both infrastructural and remediative initiatives as well as regulatory collaboration with Russia towards ensuring effective and safe operations during handling and removal of SNF and radioactive materials. This article describes Norways role within international efforts in the context of the rehabilitation of Andreeva Bay and outlines previous activities and Norways future direction with respect to the site.

Site survey of former naval base in Andreyev Bay, northwest-Russia - Radiation levels and radionuclide concentrations on and below the surface level

This paper presents the main results of the program to examine radiation levels and radionuclide concentrations on and below the surface level at the former Russian naval base in Andreyev Bay, Murmansk County. Presently, this base represents an exceptional case regarding future remediation and cleanup operations due to the accident risk (∼ max. fuel inventory of 100 submarine cores) and degree of contamination (over 25 years with continuous release — still ongoing — of radionuclides into the terrestrial and marine environment). The first part of the survey consists of about 1030 measurement points established as a grid with 10 m and 5 m mesh size for the measurement of dose rate in two heights above the ground level (0.1 m, 1 m), radionuclide concentrations, drilling of 50 boreholes for further examination of the radionuclide releases on site and the establishment of a 1:500 map of the area. These surveys were completed 2002–04. The results for dose rate measurements taken 1 m above the ground level varies between background levels and 3 mSv/h. Additional measurements were completed around the main building structures at the site and as part of a geological survey of the site. The activity concentration levels for Cs-137 and Sr-90 were measured in 250 points being part of the same measurement grid as above. The results for both isotopes range from normal fallout levels from atmospheric nuclear weapons testing to above 1 MBq/kg. The main conclusion is that continuous releases of fission products from spent nuclear fuel and fuel residues in defect storage pools have, together with inadequate storage facilities for large amounts of solid radioactive waste, led to heavy contamination of fission products in large areas. The 1:500 map is not public accessible. Thus, the second part of the survey was to analyse and document the results in adequate maps. These maps, geo-referenced to the UTM WGS84 system, have been established on the basis of commercial available satellite images from 2004 and show the measurement grid and results for radiation and activity levels in addition to coastline contour and selected infrastructure elements.Copyright

Towards solving the problems of the solid radioactive wastes from decommissioned Soviet-designed nuclear submarines

This paper describes the cooperation and inspection arrangements for verifying the dismantlement of non-strategic Russian submarines, including waste handling, in accordance with the provisions given in the bilateral agreement between the Governments of Russia and Norway and the Norwegian Plan of Action for Nuclear Safety. The main concerns during the project implementation are nuclear safety, the individual safety of workers and the safe and secure handling of radioactive and toxic wastes. Based on data provided by the shipyard on individual exposure, one dismantlement project results in average in an effective dose for shipyard workers between 1,1 and 1,9 mSv, depending on the scope of the work for each worker. The main conclusion is that the present handling of solid radioactive waste is not optimal as such waste now is being put into the reactor compartments without the possibility for adequate control, including the retrieval for repacking or transfer to adequate storage facilities, after the reactor compartments have been placed in the long term storage facility in Saida Bay. Today there is no repository in Northwest-Russia for defence-related radioactive waste. (authors)

Environmental Assessment of Decommissioning Radioisotope Thermoelectric Generators (RTG) in Northwest Russia

This article presents some results from assessment work conducted as part of a joint Norwegian-Russian project to decommission radioisotope thermoelectric generators (RTG) in Northwest Russia. Potential worst case accident scenarios, based on the decommissioning procedures for RTGs, were assessed to study possible radiation effects to the environment. Close contact with exposed RTG sources will result in detrimental health effects. However, doses to marine biota from ingestion of radioactivity under the worst-case marine scenario studied were lower than threshold limits given in IAEA literature.Copyright