Radiation Protection
Protecting workers and the general public from exposure to ionising radiation is essential in the industrial use and disposal of radionuclides. All industrial practices are justified by the prior estimation and continuous monitoring of exposure, and safety cases for radioactive waste disposal are supported by the predictions of radiation doses for up to a million years post-disposal. Kemakta can provide calculations of radiation doses:
- To workers handling/exposed to radioactive materials
- From the disposal of radioactive materials. This includes the long term dose profiles for the general public, the immediate dose received by workers handling the waste and at a landfill site, and doses in a future intrusion scenario, i.e. if houses were built on a landfill site.
- From areas affected by past activities
- From the reuse or disposal of materials that are exempt or cleared from the regulation requirements for radioactive materials.
Radioactive wastes in landfill sites
Kemakta has developed the DOS2U dose calculation model with a specific focus on the disposal of wastes in landfill sites, accounting for disequilibria and ingrowth in the decay chains over time and space. The model allows each landfill site to be defined in terms of its size, position relative to potential water-source recipients (surface water and a well), rainwater infiltration rate and the hydrology of the surrounding area. The leach characteristics of each waste and the Kd values controlling radionuclide groundwater transport to the water-source recipients are optimised for each case study. The radionuclide content of the water source recipients defines the input to the biosphere and exposure of the most exposed individuals. The routes of exposure are drinking water and consuming fish from the water recipients, and via an agricultural pathway generated by the irrigation of the farmland with the surface or well water and animals’ drinking water. The agricultural pathway considers inhalation of dust, ingestion of soil and external exposure, and transfer through the biosphere followed by ingestion of root and leafy vegetables, meat and milk. Here, site specific parameters are used where available. The model provides calculations of the dose to the most exposed individuals over time, identifying the evolution of the dose both in terms of dose pathway and radioisotopes delivering the dose.
Kemakta has used DOS2U to support decisions on landfills options for the disposal of wastes from Westinghouse and Ranstad.
 Conceptual approach in DOS2U model. |
Clearance of areas contaminated by past activities
On behalf of the Swedish Radiation Protection Authority, Kemakta has developed a model to assess doses from exposure to soil contaminated by radionuclides as a result of past industrial or research activities. The model is a further development of the Swedish Environment Agency’s model for the assessment of risks from land contaminated with non-radioactive pollutants. The model is intended to inform decisions about clearance or remediation of smaller land areas, and estimates potential future doses to individuals in future land use scenarios. Two scenarios are considered, sensitive land use (e.g. housing, schools) and less sensitive land use (e.g. industrial areas, roads, car parks). Doses are calculated for six age groups using realistically conservative assumptions about exposure pathways for the two scenarios.
Doses from reuse and disposal of other materials
Kemakta has been involved in several projects in which doses from radioactive materials have been estimated in order to inform decisions about clearance or exemption of low activity materials. Examples are calculations of dose from the reuse of scrap metal, from the disposal or reuse materials from the demolition of buildings, or from the use and disposal of materials containing naturally occurring radioactive elements.
