Measurements of radioactivity and dose assessments in some building materials in Bitlis, Turkey

Investigation of natural and artificial radioactivity levels in travertines of the Cappadocia region in Turkey

This study determined natural and artificial radionuclide concentrations to evaluate natural radioactivity and health risk levels of nine travertines in the Yaprakhisar and Balkayası regions in Turkey. The samples coded B1-M, B2, B5, B7, B8, and B10 represent waste derived from the Yaprakhisar travertines, as well as samples T5-M, T12, and Z1 travertines derived from Balkayası. The levels of natural and artificial radionuclide concentrations (232Th, 40K, and 137Cs) were measured using a high-purity germanium (HpGe) detector system. The travertine activity ranged from 2.09 to 12.07 Bq kg-1 for 232Th, 4.21 to 13.41 Bq kg-1 for 40K, and 0.42-3.26 Bq kg-1 for 137Cs. The results showed that the activity concentration values for 232Th, 40K, and 137Cs were coherent with the travertine analysis results in the UNSCEAR, 2000; 2008 publications. The values obtained were lower than the average values in the UNSEAR reports. The radiological hazard parameters calculated in this study were absorbed gamma dose rate (D), radium equivalent activity (Raeq), annual gonadal dose equivalent (AGDE), exposure dose (ER), total annual effective dose (AEDEtotal), excess lifetime cancer risk (ELCRtotal), gamma representative level (GRL), internal hazard index (Hin) and external hazard index (Hex).

Radiological impact of an active quarry in the Papuk Nature Park, Croatia

Papuk Nature Park, unlike most similar parks and preserves in the world, contains active quarries. Quarries dig stone from the ground, creating dust and exposing deeper, potentially more radioactive layers. Since the forest trails in the Park lead right up to the quarries, we believed it was important to determine the radiological impact of the quarries on the Park environment. We measured ambient dose rate equivalent H*(10) and sampled moss at 26 Park locations along two of four quarries, along the road between them, and near Lake Orahovac, a very popular tourist destination close to the quarries. Moss is a standard bioindicator of exposure to heavy metals, including radionuclides. Using-gamma ray spectrometry we determined the activity concentration of ¹³⁷Cs and of representative naturally occurring radionuclides – ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²³²Th, and ⁴⁰K – in sampled moss. H*(10) at selected locations was similar to the background H*(10) measured continuously all over Croatia. The ranges of measured activity concentrations of ¹³⁷Cs and naturally occurring radionuclides in moss did not differ significantly from other parts of Croatia and nearby countries.

Radon and thoron exhalation rate, emanation factor and radioactivity risks of building materials of the Iberian Peninsula

Radon (²²²Rn) and thoron (²²⁰Rn) are radioactive gases emanating from geological materials. Inhalation of these gases is closely related to an increase in the probability of lung cancer if the levels are high. The majority of studies focus on radon, and the thoron is normally ignored because of its short half-life (55.6 s). However, thoron decay products can also cause a significant increase in dose. In buildings with high radon levels, the main mechanism for entry of radon is pressure-driven flow of soil gas through cracks in the floor. Both radon and thoron can also be released from building materials to the indoor atmosphere. In this work, we study the radon and thoron exhalation and emanation properties of an extended variety of common building materials manufactured in the Iberian Peninsula (Portugal and Spain) but exported and used in all countries of the world. Radon and thoron emission from samples collected in the closed chamber was measured by an active method that uses a continuous radon/thoron monitor. The correlations between exhalation rates of these gases and their parent nuclide exhalation (radium/thorium) concentrations were examined. Finally, indoor radon and thoron and the annual effective dose were calculated from radon/thoron concentrations in the closed chamber. Zircon is the material with the highest concentration values of ²²⁶Ra and ²³²Th and the exhalation and emanation rates. Also in the case of zircon and some granites, the annual effective dose was higher than the annual exposure limit for the general public of 1 mSv y⁻¹, recommended by the European regulations.

Risk assessment due to various terrestrial radionuclides concentrations scenarios

PURPOSE

The purpose of this paper is to evaluate the morbidity excess cancer risk (ECR) due to internal and external exposure to three category levels of natural radionuclides in soil like ²³⁸U, ²³²Th and ⁴⁰K. Although the exposure rate in soil is low but effect this radiation over time can lead to cancer risk and this risk can be calculated.

MATERIALS AND METHODS

Natural activity concentration levels of ⁴⁰K, ²³⁸U and ²³²Th in soil were selected from last reports in three concentration categories including: low, medium and high levels. The excess cancer risks of three concentration levels were calculated by means of RESidual-RADioactivity (RESRAD) code.

RESULTS AND CONCLUSIONS

The calculated average morbidity ECR from ⁴⁰K, ²³⁸U and ²³²Th in three concentration categories levels in soil were 1.40 × 10^-4, 8.56 × 10^-4 and 1.35 × 10^-3, respectively. This calculation shows that the excess cancer risk value is the highest value in 100 years' time in all categories. Overall ECR from ⁴⁰K radionuclide was maximal and the highest exposure pathways was through plant pathway; however, these pathway changes over 60 years to the drinking water pathway. The results of this study may be useful to risk assessment and for decision making for public health protection against high-level radiation.

RADON EXHALATION FROM BUILDING MATERIALS USED IN YEMEN

The present article seeks to determine the annual effective doses of 222Rn exposure, effective radium content and radon exhalation rates in some building materials from the local market of Ibb province, Yemen. A total of 33 samples of building materials were collected from the target area. The radon exhalation rate and effective radium content in these samples were measured using solid-state nuclear track detector, which has become an important tool in every investigation of the radon levels in the surrounding environment. Surface exhalation rate has been found to vary from 178.90 to 1267.6 mBq m-2 h-1, whereas mass exhalation rate has been found to vary from 5.51 to 33.25 mBq kg-1 h-1. All the values of effective radium content in all samples under test were found to be quite lower than the permissible value of 370 Bq kg-1 recommended by Organization for Economic Cooperation and Development. Annual effective doses have also been estimated.

Influence of grain size on radionuclide activity concentrations and radiological hazard of building material samples

The knowledge of radioactivity content in various radionuclides in building materials plays an important role in health physics; therefore, we measured the amount of naturally occurring radionuclides in building material (sand, granite, marble, and limestone) samples of different grain sizes by using NaI (Tl) and MCA1024 gamma-ray spectrometers. Data analyses were performed to determine ²²⁶Ra, ²³²Th, and ⁴°K activity concentrations. The results revealed an inverse relationship between activity concentration and grain size of the samples. The radium equivalent activity (Ra_eq), representative level index I, and annual absorbed dose rate were calculated.