PhD ceremony: Mr. P. de Jong, 13.15 uur, Academiegebouw, Broerstraat 5, Groningen
Thesis: Exposure to natural radioactivity in the Netherlands:the impact of building materials
Promotor(s): prof. R.J. de Meijer
Faculty: Mathematics and Natural Sciences
A significant amount of the natural radiation load a Dutch person is exposed to is the result of living in a house. This radiation load is the result of the presence of minute amounts of uranium, thorium and potassium in the ground and in construction materials.
Three different components can be differentiated, i.e. 1) exposure to external gamma rays, 2) inhalation of short-lived radon daughter nuclides, and 3) inhalation of short-lived thoron daughter nuclides.
Construction materials contribute about 55 and 70% of the first two categories; exposure to thoron is virtually entirely contributable to construction materials. In his PhD thesis, Peter de Jong describes research that develops methods to determine the external radiation levels and radon emissions caused by building materials. In addition, he examined the extent to which the design of a home can influence radiation load and whether the radon emissions from construction materials can be reduced.
The most important conclusions of the research are:
- the building materials available on the Dutch market differ strongly in radiological compilation and radon emission, even within the same material class
- building materials in the Netherlands contribute on average about 40% of the natural radiation load
- the design of a home has more influence on the radiation load than the habits and preferences of the inhabitant
- the paint types used in the Netherlands to finish walls and ceilings do not affect the radon emissions
- the lower the ratio of water/cement in concrete, the lower the radon emissions
- the thoron contribution is probably higher than currently assumed
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