Radiation survey and environmental impact assessment at the site of temporary storage at Andreeva Bay (16 years of studies)

Abstract

The site of temporary storage for spent fuel and radioactive waste at Andreeva Bay is a largest nuclear legacy site in the Russian Northwest. The radiation situation within the industrial site and in the surrounding health protection zone (HPZ) is characterised by significant local contamination of the topsoil, which is a source of environmental contamination and potential spread of radioactivity within and outside the HPZ, including the adjacent marine environment. The highest levels of radioactive contamination of soil due to manmade radionuclides have been registered around the spent nuclear fuel storage facilities, where the specific activity of Cs-137 reaches 5 × 107 Bq kg−1, and that of Sr-90, 5.7 × 106 Bq kg−1. Determination of the mobility of these main dose-forming radionuclides has demonstrated that about 90% of the Sr-90 and 30% of the Cs-137 in the soil are in a mobile form. The corresponding figures for bottom sediments are 75% and 60%. The assessment of the impact of contamination in the different areas of the Andreeva Bay site, and the assessment of the adequacy of the previously developed remediation criteria for environmental protection (Sneve et al 2015 J. Radiol. Prot. 35 571) demonstrated that when carrying out remedial work according to any scenario provided for in the Guidelines ‘Criteria and norms for remediation of sites and facilities contaminated with manmade radionuclides’, of the Federal State Unitary Enterprise ‘The Northern Federal Enterprise for Radioactive Waste Management’ for the supervision area, recommendations for environmental protection are followed. For scenarios such as conversion and conservation, reference levels of biota exposure for some species of representative organisms could be exceeded, based on a preliminary conservative assessment.

Further development and application of a method for assessing radionuclide surface activity distribution and source location based on measurements of ambient dose equivalent rate. Examples for Andreeva Bay, Chernobyl NPP and Istiklol

“…In this paper, similar to two our previous papers [6,12], the Tikhonov regularisation method was used to solve ill-posed SLAE. In addition to this method, methods of convex multidimensional optimisation are used for solving such kind of problems [22].…”

“…In other words, in reality, the industrial site may be contaminated with radioactive substances over the surface and in the depth of the soil, and containers with SRW or individual large-sized fragments of SRW may be located on the surface of the industrial site. However, the approximate solution of the integral equation according to equation (1) 12 from the first part of this article, which is submitted for publication and is under review by J Radiol Prot (JRP-102885.R1) [7] reduces the real picture of radioactive contamination of the industrial site to the distribution of 'effective' SAD.…”

“…In the location under consideration, a peculiar picture is observed: closer to the 7E site, the Rel values are close to unity, and at some distance from the site, the Rel values increase. 12…”

“…In order to support the remediation of the STS Andreeva Bay, we have developed a method for the reconstruction of the surface activity density (SAD) based on the ADER data. This method was applied at STS Andreeva Bay, where the main radioactive and most radiological significant contamination is due to a single radionuclide-137 Cs 8 [11,12]. In order to increase the accuracy of the calculations, we have developed a method for solving the Fredholm equation in the barrier geometry for the ADER-SAD based on the representation of the industrial site, buildings and radiation fields in the form of a raster 9 and the use of a visibility matrix (VM) of the raster cells to describe the barrier geometry.…”

The effect of climate change on sources of radionuclides to the marine environment

“…Such wastes include material from military nuclear activities, phosphogypsum from the processing of phosphate rock, uranium, and other metal mine tailings, and fly ash from coal-fired power plants and other industries 35,[188][189][190][191][192] . In many cases, such wastes have already led to the input of some radioactive material into the marine environment 93,193,194 .…”