Civil Engineering Reference
In-Depth Information
input parameters such as radium content, density, and emanation factor and dif-
fusion length of radon in building materials which are not easy to measure.
The new model is based on the analytical solution to 3D radon diffusion
equation applicable to a building material system and can be applied to any
arbitrary wall thickness irrespective of sample size and any value of radon dif-
fusion length in the building material.
In order to maintain a high quality level of radon measurements, periodical
calibration is deemed necessary (Gennaro
2007
).
Collignan et al. (
2012
) reported that the use of a AlphaGuard monitor was first
calibrated by the Institut de Radioprotection et de Sûreté Nucléaire IRSN.
For the determination of radon gas concentration, other authors and Abdallah
et al. (
2012
) used a monitor consisting of an aluminum sphere which incorporates
a surface barrier detector isolated in a PVC mounting. The monitor calibration has
been carried out by introducing a known amount of radon into the sphere. From
several calibrations, the average value of the detection efficiency was 720 Bq,
which was fairly independent of the flow rate. At 1-h counting time interval, the
sensitivity for radon was 1.1 mBq/L.
Sorimachi et al. (
2012
) made intercomparisons of two types of passive
222
Rn-
220
Rn detectors (commercially available as Raduet and Radopot detectors),
developed by the National Institute of Radiological Sciences, Japan (NIRS), using
the Physikalisch Technische Bundesanstalt (PTB), Germany,
222
Rn chamber. The
experimental uncertainties at the relative standard deviation ranged from 2 to 8 %
for the Raduet detectors and 5-13 % for Radopot detectors in
222
Rn concentration
at each activity level.
This shows how much the radon still needs further investigations in order to
have a clear picture of the real contribution of masonry and decorative materials to
indoor radon concentration.
5.2 Other Construction Materials
It is believed that, in general, construction materials do not show alarming
radioactivity levels (Papaefthmiou and Gouseti
2008
; Damla et al.
2011
). The
same, however, cannot be said about some industrial by-products used for concrete
production such as some kind of blast furnace slags and some fly ashes (Table
6
).
Since mineral coal contains radionuclides, this means that the fly ashes pro-
duced in thermal power plants must be analyzed regarding this parameter (Mahur
et al.
2008
).
Some studies (Kovler et al.
2005a
,
b
) show that concrete with 60 % cement
replacement by fly ash has a radon concentration which is two times higher when
compared to control concrete. However, there is not a direct correlation between
the concentration and exhalation rates because this parameter is also influenced by
the concrete internal structure and thus meaning that it is possible to have a
