Monte-Carlo simulations of external dose contributions from the surrounding ground areas of residential homes in a typical Northern European suburban area after a radioactive fallout scenario

Abstract

The emissions of $$^{137}\hbox {Cs}$$ 137 Cs into the environment from the nuclear accidents in Chernobyl in 1986 and Fukushima in 2011 led to the need to decontaminate large areas to avert radiation doses to the population in the affected areas. To be able to perform cost-effective and sustainable remediation, knowledge is needed about how radiation doses can be minimized through optimized interventions such that the greatest possible reduction in radiation dose is obtained with the smallest possible negative impact on the area. Theoretical calculations have been performed to determine how radiation doses in single family houses in a typical Swedish residential suburb arise from a hypothetical $$^{137}\hbox {Cs}$$ 137 Cs deposition on the ground. The intention was to highlight how remediation of different parts of the surroundings affects the radiation dose to the residents in a particular property. A Monte Carlo model of the houses and the environment in a suburban area was set up to allow calculations of the dose contributions from different contaminated ground areas such as their own property, neighbouring properties, streets and surrounding recreational areas. Calculations were performed for eleven observation points inside different rooms of the house and one observation point in the garden outside the house, for four houses in the neighbourhood, and for two types of building construction material. The influence of the time spent in different rooms of the house and the contamination of areas surrounding the house was studied. The results show that in general the main dose contribution originates from their own property, but that a significant part (30–80%, depending on the observation point) can come from other areas, showing the importance of considering the surroundings in remediation actions. More detailed analysis of the results showed that the dose contribution from a source region is in general highly dependent on the position of windows in a brick house, whereas for a wooden house the distance to the source region is also of relevance.

Maximizing avertable doses with a minimum amount of waste for remediation of land areas around typical single family houses after radioactive fallout based on Monte Carlo simulations

“…In addition, the dose contribution from other contaminated surfaces needs to be included. However, this knowledge can support the decision maker in prioritizing areas for decontamination measures, although as shown in our previous studies 6,7 , the occupancy of the residents must also be considered.…”

“…12,827 m 2 are assumed to be unpaved (79%). Further details about the model of the houses and entire neighbourhood, including material compositions, can be found in our previous studies 6,7 .…”

“…The gamma-emitting source was defined as in our previous study 7 . An energy of 0.662 MeV represents the gamma rays being emitted by a metastable isomer of 137 Ba as a product of 94.4% of the beta minus decays of the fission product 137 Cs.…”

“…The detector regions were defined as air-filled spheres with a diameter of 30 cm, positioned 1 m above ground level on properties P12-P15. These were located according to the observation points (OP) in our previous studies 6,7 in the middle of the different rooms inside the house (Fig. 8), and an observation point was added in the middle of the garden of the houses P12-P15 (Fig.…”

“…The method uses the contaminated ground around a dwelling as source for external exposure, such as inside a house for example. This concept was applied to typical northern European single-family houses 6 and was furthermore extended to a typical northern European suburban area 7 in follow-up studies. The aim of this study is to find optimum sizes of areas for topsoil removal around northern European single-family houses with respect to the reduction of future radiation exposure and waste generation; thus, we also seek to minimize monetary costs and the adverse effects on the environment.…”