Radiological Protection against Radon Exposure

China Society on Radiation Protection (CSRP) had a technical meeting in February 2012, Beijing, China. It was discussed the draft of ICRP Radiological Protection against Radon Exposure. The comments from the meeting are as follows.

1. The radon exposure to workers in all the NORM industry may be mostly regarded as occupational exposure.

At the first hand, based on the definition of occupational exposure, the exposures in workplace being regarded as occupational exposure basically depends upon that whether or not the exposure to workers can reasonably regarded as being the responsibility of the operating management. But in the draft report the prerequisite underlying in the specific graded approach is assumed that worker’s exposure to radon in workplaces are not considered as occupational exposures. So that it is not inconsistent with the definition of Occupational exposure. At the second hand, as we all known that the exposures to Uranium miners are already occupationally managed in most countries and regions, and the present occupational exposure level in Uranium mining industry can be essentially controlled below 10mSv per year. So if based on the specific graded approach in the draft report, practically most of the exposure to the Uranium miners will not yet be occupational exposure.

2. It is necessary to set the radon exhalation rate as indicator to control the quality of building materials

As we all known in European countries and North American countries indoor radon exposure is mainly from the radon in the soil because the major types of dwellings are houses in these countries, but in China and some other Asian countries there are many of multi-storey buildings and high-storey buildings, for example, after 2000, the new building account for 70%, and most of them is high-storey buildings in China. And then the indoor radon exposure is mainly from the radon in the building materials not the soil in this situation. So that in China it is very important to control the radon exposure in dwellings from the building materials.
In order to effectively control the radon exposure in dwellings in China and some Asian countries, basically it is to control the contents of natural nuclides in the raw materials used to produce the building materials and to reduce the radon exhalation rate for the building materials. As the promotion of recycling economics in all over the world to keep the sustainable development, most of the waste residues in which it often contains relatively high natural radionuclides should be recycled and reused to make building materials. So that to reduce the surface radon exhalation rate for building materials is a sole and important mean to control the radon concentration in dwellings.

3. Wording is needed to improved, such as:

(a) in Fig. 1, Fig. 2 and Fig. 3, for some nuclides, their half-lives are not accurate, for example the half-live of ²²⁰Rn is 55.6s, but it is marked as 50s in Fig.3.
(b) the specific name for ²²⁰Rn is Thoron.
(c) in the line 816 and 817, 5 10-4 may be 5x10^-4

Table 1 the standards now in effective for control of radon concentration in dwelling in China