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, georeferenced to the UTM WGS 84 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.