Assessment of natural radioactivity and its radiological hazards in several types of cement used in Senegal

Abstract

In this study, the activity concentrations of 226 Ra, 232 Th and 40 K in twenty cement samples of four types (CEM, CEM II, CEM III, and CEM IV) collected from building material suppliers in Senegal were measured using a low-background digital gamma-ray spectrometer equipped with broad energy germanium detector. The activity concentrations of 226 Ra, 232 Th and 40 K varied from 7.1-150.3 Bq kg −1 , 3.7-16.1 Bq kg −1 , and 48.7-133.9 Bq kg −1 , respectively. Also, possible radiological risks from the usage of these materials were assessed by estimating external and internal index, indoor absorbed gamma dose rate and the corresponding annual effective dose, effective dose rate to different body organs and tissus, and excess lifetime cancer risk. The estimated radiological hazard indices were revised in light of the relevant national and international legislation and guidance. The values of the radiological hazard indices were found to be within relevant all limit values for structural building materials.

Assessment of Natural Radioactivity in Cements Used as Building Materials in Poland

“…First one is the geological origin, the second one—production technology. One should notice that among the sparse data of small 40 K concentration and high 226 Ra concentration are those from Senegal [ 35 ], and samples are of CEM-II, CEM-III, and CEM-IV types, thus with fly ash or slag or other materials, which may possess specific geological origin or specific production technology. The above-mentioned main branch reflects the almost-linear relationship: the higher radium concentration, the higher potassium and thorium concentration.…”

“…For this reason, samples were tested only when the secular equilibrium between 214 Bi and 226 Ra and 208 Tl and 232 Th has been settled, hence after a period of at least 4 weeks. The 4-week maturing time is sometimes questioned (as too short for settling the secular equilibrium) and in some newest articles the authors use 45-day (or 6-week) time for aging their samples, e.g., [ 35 ]. Since the approach to this issue is different in various articles, the authors decided to study cement samples for both 30-day maturing and 45-day maturing, to verify whether there is a statistically significant difference in concentration activity.…”

“…The obtained results were then compared with international standard values defined by the European Commission [ 4 ], and values recommended by the United Nations Committee on the Effects of Ionizing Radiation [ 1 , 24 ]. The results were also compared with results of studies performed by other authors from various countries all over the world [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ].…”

Health risk assessment and statistical analysis of natural radioactivity in the uranium exploration area of Zabili, Chad

“…where ATRa , ATTh and ATK are the specific activities of 226 Ra, 232 Th and 40 K, respectively. The permissible maximum value of the radium equivalent activity is 370 Bq/kg (Krisiuk et al, 1971) which corresponds to an effective dose of 1 mSv for the general public (Ndour et al, 2020).…”

“…Effective dose rate to different organs and tissues (𝐸 𝑜𝑟𝑔 ) was estimated using the following formula (Darwish et al, 2015;Ndour et al, 2020):…”