NORM risk assessment for the Søve mining complex, Norway

Abstract

Abstract. The Søve site is a disused mining complex in Telemark County, Norway, exhibiting enhanced levels of naturally occurring radionuclides from the 238 U and 232 Th decay series. The nascent General Assessment Methodology Process ('GAMP'), developed under IAEA's EMRAS II programme, has been applied at the site. The a priori fixed screening criteria were exceeded in the scenario, precipitating the requirement to undertake a more detailed assessment. The USDOE's RESRAD-OFFSITE code was employed to investigate potential changes in activity concentrations in various environmental compartments over time and the contribution of various exposure pathways to effective doses. Owing to problems associated with model parameterisation and results interpretation a simple leaching and groundwater migration compartmental model was also applied. This allowed activity concentrations in three waste compartments to be calculated with time. Furthermore, an existing external dose-rate model that correlates information on activity concentrations with depth in soil to dose rates in air above ground has been used to estimate prospective external dose-rates to humans and evaluate the efficacy of applying various remediation options.

Practical radioecology support in the management and regulatory supervision of legacy sites

“…The selection of appropriate remedial options is commonly based on comparison of site-specific data and/or modelling results with pre-defined remediation criteria. An evaluation of remedial options, informed by radioecological data and assessment modelling, has been undertaken for the Søve former niobium (Nb) mining site in Norway, which exhibits enhanced levels of naturally occurring radionuclides from the 238 U and thorium-232 ( 232 Th) decay series (Brown et al 2011). Although some remediation work was conducted following the closure of the mine in the mid-1960s, radioactive waste mixed with surface soils over time and, consequently, high NORM activity concentrations in soil, elevated gamma dose rates and radon levels have been measured at the site (Mrdakovic Popic et al 2011, 2012.…”

“…Although some remediation work was conducted following the closure of the mine in the mid-1960s, radioactive waste mixed with surface soils over time and, consequently, high NORM activity concentrations in soil, elevated gamma dose rates and radon levels have been measured at the site (Mrdakovic Popic et al 2011, 2012. Three remedial options were selected for evaluation (Brown et al 2011): (1) no action, if assessment indicated no need for clean-up; (2) a local countermeasure solution that would involve removal of materials and re-disposal in the area originally allocated for the waste disposal; or (3) complete removal of radioactive waste and disposal at an approved repository.…”

“…The proposed local solution (option 2) was explored through the application of an external dose rate model and use of the highest soil activity concentrations measured at the site to evaluate the external exposure to a representative person when different assumptions around the thickness of clean soil coverage (ranging from 1 to 100 cm) were applied (Brown et al 2011). The assessment indicated that application of approximately 50 cm of clean topsoil would reduce the effective dose equivalent by a factor of approximately 100 leading to cleaning criteria being met.…”