Doses and risks from the ingestion of Dounreay fuel fragments

Abstract

The radiological implications of ingestion of nuclear fuel fragments present in the marine environment around Dounreay have been reassessed by using the Monte Carlo code MCNP to obtain improved estimates of the doses to target cells in the walls of the lower large intestine resulting from the passage of a fragment. The approach takes account of the reduction in dose due to attenuation within the intestinal wall and self-absorption of radiation in the fuel fragment itself. In addition, dose is calculated on the basis of a realistic estimate of the anatomical volume of the lumen, rather than being based on the average mass of the contents, as in the current ICRP model. Our best estimates of doses from the ingestion of the largest Dounreay particles are at least a factor of 30 lower than those predicted using the current ICRP model. The new ICRP model will address the issues raised here and provide improved estimates of dose.

Solid state speciation and potential bioavailability of depleted uranium particles from Kosovo and Kuwait

“…For leaching experiments, about 0.04 g soil (contaminated with 4000 mg DU/kg soil following impact with tank; Ceja Mountains, Kosovo), 0.5 g sand (collected in the vicinity of the site of the DU ammunition storage fire; Al Doha, Kuwait) and 2 g sand (collected from below a corroded DU penetrator; Manageesh, Kuwait) of samples known to be contaminated with DU particles were transferred to centrifuge tubes and extracted with 20 mL of simulated human gastrointestinal (GI) tract fluid (0.16 M HCl secretion of the digestive tract (White et al, 1968)) for 2, 24 and 168 h. An incubation time of 2 h was selected as being representative of a residence time in the stomach, while 24 h incubation mimics the transit times through the intestines (Darley et al, 2003). By continuing the extraction for one week (168 h), information on the long term potential mobility of U could be obtained.…”

Linking heterogeneous distribution of radiocaesium in soils and pond sediments in the Fukushima Daiichi exclusion zone to mobility and potential bioavailability

“…1 g) were weighed into acid-washed centrifuged tubes (Nalgene) and reacted for 65 h with 10 mL of 0.16 M HCl, which simulates the extracting strength of human gastrointestinal tract fluid. These conditions mimic the maximum transit time through the intestines (Darley et al, 2003). Solution extract was separated from solids by centrifugation (10,000 g, 30 min; Beckman Coulter Allegra 64R centrifuge) and both were measured for 137 Cs activity by gamma spectrometry (section 2.5).…”

Characterising radium-226 particles from legacy contamination to support radiation dose assessments

“…In these circumstances, data on the source term characteristics, including any radioactive particles present, need to be obtained to undertake an assessment of potential radiation doses against the reference level and take appropriate actions, if necessary. A significant amount of research has been undertaken to characterise radioactive particles from a number of existing exposure situations that have arisen due to past emergencies, events and practices: nuclear power reactor accidents at Chernobyl, Ukraine (Pöml and Burakov, 2017;Shiryaev et al, 2018) and Fukushima, Japan (Kaltofen and Gundersen, 2017;Martin et al, 2016;Yamaguchi et al, 2016); accidents involving nuclear weapons at Palomares, Spain (Aragón et al, 2008;Jimenez-Ramos et al, 2010;Jiménez-Ramos et al, 2012Lind et al, 2007;López et al, 2007;Pöllänen et al, 2006) and Thule, Greenland (Eriksson et al, 2005;Lind et al, 2005); nuclear weapons testing (Burns et al, 1995;Conway et al, 2009;Jernström et al, 2006); the use of depleted uranium in military operations (Lind et al, 2009;Sajih et al, 2010;Salbu et al, 2005Salbu et al, , 2003Török et al, 2004); and legacy contamination from past practices at Sellafield, England (Clacher, 2011(Clacher, , 2010Cowper, 2009), Dounreay (Aydarous et al, 2008;J. Darley et al, 2003) and Dalgety Bay, Scotland (Wilson et al, 2013).…”