Environmental impact of NORM in Israeli dwellings

E. Neeman1, v. Steiner2

(1) Dept. of Radiation Safety, Ministry of the Environment, [email protected] (2) Dept. of Radiation Safety, Ministry of the Environment, [email protected]

Keywords: Environment, Radionuclides, NORM, Materials, Radon.

Introduction In the last decade the construction of public dwellings in has been intensified. New construction sites are being created and new construction materials, local or imported, are being used. Since the origin of the building materials is essentially the soil, they inherit the radioactive properties of the environment.

The level of Natural Occurring Radioactive Materials (NORM), from the decay chains 238 232 235 40 of the ubiquitous radionuclides U , Th , U and K, as well as artificial radioisotopes like Cs137, in building materials needs to be controlled, in order to limit the gamma and Radon radiation dose of the general public in dwellings.

The Ministry of the Environment collaborates with other institutions to evaluate, document and control the NORM content in our environment [1], based on international standards [2, 3]. The operation of quarries is controlled to ensure a low NORM content in raw building materials. The use of bottom and fly ash, abundantly produced in electrical power stations, in constructions is also being controlled. A new Israeli standard controls the NORM content in building materials such as to limit the radiation dose in dwellings from this practice to 0.45 mSv / year [4]. Special construction solutions are developed and used in areas with high Radon concentration in the soil. The aim is to maintain the Radon concentration in dwellings below the “Action Limit” of 200 Bq/m 3.

Description of the Work After a brief survey of typical NORM activity concentrations measured in various parts of the country, we show NORM values encountered in several building materials. Finally, we show results on monitoring Radon concentrations in regular rooms and in security shelters.

Results Quarries in Israel produce raw materials in which the NORM concentration needs to be controlled. Soil may also be extracted from locations not registered as quarries. As an example, the concrete (a mixture of cement, sand or aggregates) may have different NORM concentration, depending on the location of the quarry. The sand extracted from phosphate areas has a higher Ra226 concentration, resulting in higher Radon exhalation from concrete in homes. Normally, the raw building materials are used locally and do not change the natural NORM content. However transport of raw materials (aggregates, sand, etc) from high NORM areas (like the Negev) to low NO RM areas (like the coast region) may enhance the local radiation dose of the public. In Table 1 we show examples of NORM activity concentrations in soil in various parts of the country, as measured in our lab via HPGe spectroscopy.

1

Location K-40 Th-232 Ra-226 (Bq/kg) (Bq/kg) (Bq/kg) , Kishon river 512 1 14 112 9 97 124 5 42 182 15 15 89 14 33 113 11 54 Arad, Nahalat Biniamin 75 7.7 155 35 5.1 211 103 5.3 247 Beer Sheva, Ramat Hovav 128 77 148 134 36 67 250 20 18 276 14 15 313 14 17 Hod Hasharon 217 17 22 323 17 28 Kfar Kara 161 19 17 180 14 29 185 15 53 56 3.7 41 – Armon Hanaziv 343 23 38 258 20 40 Jerusalem – Talpiot Mizrach 282 21 90 Jerusalem - Maale Adumim 142 8.5 102 Modii n 59 2.5 5.3 21 1.6 5.6 234 22.2 18.4 6.4 0.4 3.0 19 3.5 69 45 3.1 16 147 13 16 158 10 20

Table 1 Activity concentration of radionuclides in soil

We investigated the activity concentration of radionuclides in construction materials, by measuring samples from various producers and locations in the country, or imported. Typical values are shown in Table 2.

Radon concentrations are higher in ground level dwellings located in “sensitive areas”, like Arad, Eastern Jerusalem and Carmiel where the Ra226 concentration in soil is higher. In Fig. 1 we show a typical transient due to Radon penetration from soil in a room with normal closure. A second source of Radon in dwellings is emanation from building materials, in particular from concrete. In Fig. 2 we show a typical transient in a security shelter closed hermetically. The increase is slow, reaching about 200 Bq/m3 after 24 hours. The high values reached are characteristic for the hermetical closure condition in which the only Radon loss is due to radioactive decay. Producer Material K-40 Th-232 Ra-226 (Bq/kg) (Bq/kg) (Bq/kg) ReadyMix, Arad Sumsum 75 5.4 25 Polya 7.7 - 14 Adas 3.1 - 8.6 Gipsum - - 2.9 Sand, sea 112 - 3.4 Sand,quarry 187 5.4 12 Sand, beton 75 3.7 13 Sand, Arad 63 4.5 21 Sand, filling 89 6.1 23 Turkey Pumis 1159 37 50 887 44 53 690 61 56 890 79 70 , Haifa Cement 300 143 9.8 22 Cement 250 123 13 44 Gipsum 420 1.0 17 Nesher Cement 300 103 8.4 23 Cement 250 94 7.3 19 Turkey Cement 233 11 58 Greece Cement 94 3.5 6.1 Nesher, Ramle Cement 300 109 14 34 Cement 300 93 10 35 Nesher, Karlov Cement 250 126 12 63 Cement 250 131 11 69 Nesher, Cement 300 130 6.4 21 Cement 250 105 9.0 29 Cement 250 116 7.5 32 Nesher, Haifa Cement 250 137 14 35 Cement 300 87 9.1 37 Cement 250 113 16 53 Kadima Concrete 52 4 12 Cement 101 - 28 Sand 67 1 2 Modiin Concrete 68 4.5 13 Cement 90 15 38 Sand 78 2.1 2.7 Sand 91 1.1 1.7 Aggregate 68 4.5 13 Univ. Concrete 48 - 17 Road 55 bottom ash 118 92 136 fly ash 208 90 119

Table 2 Activity concentration of radionuclides in building materials.

Conclusions The Ministry of the Environment is actively engaged in developing and enforcing regulations that limit and control the radiation dose of the general public from building materials. This activity encompasses the control of NORM concentrations in local quarries, in imported and produced materials, the use of fly and bottom ash and the Radon levels in public places, education institutions and private dwellings. The law enforcement is achieved via standards, licenses and inspections. Talpiot Mizrach, Jerusalem, ground floor

1300 1200

3 1100 1000 900 800 700 600 500 400 300

Radon conc, Bq per m 200 100 0 0 10 20 30 40 50 60 70 80 90 100 110 Hours

Fig. 1 Radon concentration in a normal ground level room in Talpiot, Jerusalem.

Moshav Kadima, Mamad

3 2000

1500

1000

500 Radon conc, Bq per m 0 1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 Sample / 3 hours

Fig. 2 Radon concentration in a shelter in Moshav Kadima.

References: [1] E. Neeman, V.Steiner, L. Lehrer, Ionizing radiation in Israel, Environmental report 1999-2001, Ministry of the Environment. [2] BSS 115, International basic safety standards for protection againt ionizing radiation and for the safety of radiation sources, IAEA, Vienna, 1996. [3] International Commission on Radiation Protection, Protection of the public in situation or prolonged radiation exposure, Kiawah, South Carolina, USA, April 2, 1999. [4] E. Stern et al., Content of radioactive elements in buildings materials, Standard 5098, Israel Standards Institution, 2002.