Evaluation of excess life time cancer risk from gamma dose rates in Jhelum valley

Radiological assessment of the disposal of bulk oil NORM waste: Case study from Brazil

The oil and gas industries are the largest producers of NORM wastes that are continuously generated during production and extraction activities. In addition, an increasing trend is observed in waste production worldwide due to the decommissioning of oil platforms. The problem is that most of these wastes are in activity concentration levels above the exemption and the clearance limits and are being accumulated in storage sites because no repositories exist in Brazil for NORM wastes generated by oil industries. There are regulations for radioactive wastes and for the licensing of repositories for managing wastes with low and intermediate levels of radiation but the current regulations apply only to packaged wastes. Therefore an initial radiological assessment was carried out with the RESRAD-OFFSITE code to show that bulk NORM wastes (not packaged wastes) could be disposed of in repositories near the surface without causing additional risk to the public above the criteria used. The results can also support decision-making by the Regulatory Authority to change the current regulations and allow for the disposal of wastes in bulk form.

Radiogeochemistry, mineralogy, lithology, radiogenic heat production, and health implication using airborne radiometric data of Ilesha and its surroundings

The current study analyzed and interpreted airborne radiometric data from Ilesha's basement complex rock and its surroundings. At the surface, the concentrations of the most frequent primordial radionuclides notably K, elemental concentration of uranium eU, and elemental concentration of thorium eTh were measured. The weighted mean elemental and activity concentrations were 0.85%, 2.75 ppm, 10.22 ppm, and 267.54 Bq kg^-1, 34.41 Bq kg^-1, 41.51 Bq kg^-1 for ⁴⁰ K, ²³⁸U, and ²³²Th, respectively. The low concentration of ⁴⁰ K was certainly due to the effects of weathering, kaolinization of granites, and pedogenesis activities. The abundance of uranium was ascribed to the availability of uranium minerals such as allanite, apatite, and sphene with accessories minerals, while that of thorium was due to minerals such as cheralite, thorite, uranothorite, thorianite, and uranothorianite with accessories minerals. The RPHR weighted mean 1.48 µWm^-3 compared to the earth's crust mean between 0.8 and1.2 µWm^-3 was higher due to significant presence of gneiss rocks in all the studied profiles. Radiological hazard, in particular, dose rates, external hazard index, internal hazard index, radium equivalent, annual gonadal dose, effective dose dispensed to various organs of the body were computed to determine the deleterious effects of rocks in the area. The weighted means of annual gonadal dose of 363.98 µSv y^-1 and outdoor 0.91 × 10^×3 and indoor 1.65 × 10^-3 excessive life cancer risks were more than the global average 300 µSv y^-1, 0.29 × 10^-3 and 1.16 × 10^-3. As a result, proper surveillance is required in the area in order to prevent epidemics occurrence in future.

DETERMINATION OF RA-226, TH-232, K-40 AND CS-137 ACTIVITIES IN SOILS AND BEACH SANDS AND RELATED EXTERNAL GAMMA DOSES IN ARIKLI MINERALIZATION AREA (AYVACIK/TURKEY)

Uranium mineralization areas may jeopardize public health and surrounding natural life. In the current study for radioactivity and geochemical analyses, 43 soil, 5 rock and 10 beach sand samples were collected in and around Arıklı (Ayvacık, Turkey) uranium mineralization area. Radioactivity levels in the soils (up to Ra-226: 629, Th-232: 240, K-40: 3669 Bq/kg) were found higher than the that of beach sands. Besides, radioactivity of the beach sand samples is found at normal levels (avg: Ra-226: 31, Th-232: 31, K-40: 542 Bq/kg) when compared to worldwide average soil. Dose values indicate that the region have ~three times higher average gamma radioactivity than the corresponding world average although measured gamma doses ranged up to 687 nGy/h. The high measured values are related to uranium mineralization, alteration zones, faults and Arıklı tuff.

AT HIGH BACKGROUND RADIATION AREAS THE RELATIONSHIP BETWEEN IN SITU INDOOR GAMMA DOSE RATES AND BUILDING MATERIALS: A CASE STUDY FROM ARIKLI VILLAGE (AYVACIK/ÇANAKKALE/TURKEY)

This study measured in situ indoor gamma dose rates in Arıklı village situated near a uranium mineralisation region, evaluated the risks of radiological health hazards and established a hypothetical relationship between these values and building materials using statistical tools. Eberline brand portable type ESP-2 model Na (I) scintillation probe connected detector was used for the measurements in 45 dwellings. Statistics revealed two groups. The first group consists of the dwellings made of bricks or mixed materials both plastered by cement, while the second group represented the dwellings made of Arıklı tuff plastered with soil (modified Arıklı tuff) or cement. For the first and second groups, respectively, the medians of the indoor gamma dose rates were 188.79 and 261.87 nGy/h; for indoor Annual Effective Dose Equivalents (AEDEin) they were 0.93 and 1.28 mSv/h; and for Excess Lifetime Cancer Risks (ELCRin) they were 3.69 and 5.12, respectively. All the values were higher than those of the world averages.

PRE-ANTHROPIC AND PRESENT OUTDOOR GAMMA EQUIVALENT DOSE RATE OF THE HISTORIC CENTER OF ROME (ITALY)

The outdoor gamma background of the historic center of Rome was studied by in situ measurements and average values of the outcropping geological formations. The survey resulted in two maps of dose equivalent rate, related to pre-anthropic and present conditions. Presently, the average of the dose equivalent rate from outdoor gamma-ray field is equal to 0.31 μSv h-1, corresponding to an outdoor annual effective dose equivalent of 0.548 mSv a-1 and to an outdoor excess lifetime cancer risk [International Commission on Radiological Protection (ICRP). Recommendations of the ICRP, 21, 1/3, Publication 60, 1990] of 2.56 × 10-3. The originary radioactivity was enhanced by anthropic action up to a level of health risk comparable to that one deriving by fine particulate matter. The assessment of the evolution and dispersion of the outdoor gamma background offers a new perspective to study the urban architectural evolution. Such a mapping allows us to individuate mitigation actions and neighborhoods in which the monitoring of illicit trafficking of radioactive material can be efficiently tested.

Determination of natural radiation levels and lifetime cancer risk in Kırıkkale, Turkey

The aim of this study is to determine the levels of background radiation in nine districts of Kırıkkale, Turkey. The outdoor gamma dose rate in the air was measured using a portable digital environmental radiation detector at 170 locations. The mean outdoor gamma dose rate in the air was determined as 121 nGy h−1 with a range between 23 and 320 nGy h−1. The annual effective dose for districts was between 0.04 and 0.59 mSv year−1 with a mean value of 0.23 mSv year−1. Excess lifetime cancer risk values for districts ranged from 0.14×10−3 to 2.07×10−3 with a mean of 0.80×10−3. The activity concentrations of 226Ra, 232Th, 40K and 137Cs in 84 soil samples were determined using HPGe detector. The mean activity values (ranges) of 226Ra, 232Th, 40K and 137Cs in soil samples were found to be 20.4 (4.9±3.0–53.0±0.8) Bq kg−1, 38.8 (3.7±0.2–163.5±1.8) Bq kg−1, 598.0 (108.5±70.2–1500.5±38.7) Bq kg−1 and 3.9 (0.2±0.1–11.9±0.7) Bq kg−1, respectively. The mean activity concentration of 232Th and 40K was higher than the world’s mean value. The mean radium equivalent activity was 119.76 Bq kg−1 which is lower than the recommended maximum value of 370 Bq kg−1. The mean external terrestrial gamma dose rate was found to be 56.71 nGy h−1. This mean value was lower than the world mean of 60 nGy h−1. The calculated external hazard value was 0.32 and within the acceptable limit which is less than unity (Hex≤1). The indoor radon concentration in 150 houses for the summer and winter seasons was determined using solid state nuclear track detector (CR-39). The mean indoor concentration for the summer season was found to be 63.27 Bq m−3 ranging from 14.0±1.5 to 288.0±21.9 Bq m−3. On the other hand, the mean indoor concentration in the winter season was found to be 86.94 Bq m−3 ranging from 17.0±4.5 to 484.0±26.9 Bq m−3. The present results showed that the radon activity concentrations in winter were 42.3% higher than in the summer. The mean annual effective dose equivalent and lifetime cancer risk were also calculated.

Dose rate estimates and spatial interpolation maps of outdoor gamma dose rate with geostatistical methods; A case study from Artvin, Turkey

In this study, compliance of geostatistical estimation methods is compared to ensure investigation and imaging natural Fon radiation using the minimum number of data. Artvin province, which has a quite hilly terrain and wide variety of soil and located in the north-east of Turkey, is selected as the study area. Outdoor gamma dose rate (OGDR), which is an important determinant of environmental radioactivity level, is measured in 204 stations. Spatial structure of OGDR is determined by anisotropic, isotropic and residual variograms. Ordinary kriging (OK) and universal kriging (UK) interpolation estimations were calculated with the help of model parameters obtained from these variograms. In OK, although calculations are made based on positions of points where samples are taken, in the UK technique, general soil groups and altitude values directly affecting OGDR are included in the calculations. When two methods are evaluated based on their performances, it has been determined that UK model (r = 0.88, p < 0.001) gives quite better results than OK model (r = 0.64, p < 0.001). In addition, as a result of the maps created at the end of the study, it was illustrated that local changes are better reflected by UK method compared to OK method and its error variance is found to be lower.