Benchmarking PHITS for radiation dose assessment from fly ash-blended concrete using MCNP6 and ResRad-Build.

Activity concentrations of 234U, 238U and 226Ra in mineral waters were determined on the basis of nine water bottling facilities using alpha particle spectrometry. The mineral water samples were collected from three geographic regions of Turkey. The radiochemical separation used in the uranium analysis is based on the isolation of uranium radioisotopes from other radionuclides such as Th, Am, Pu and Np using UTEVA resin. Alpha sources were prepared using electrodeposition method. The activity concentration of 226Ra was determined after deposition on a membrane using BaSO4 co-precipitation method. The activity concentrations (mBq L−1) of 226Ra, 238U and 234U ranged from <0.56 to 165, from <0.42 to 439 and from <0.42 to 464, respectively. The measured activity concentrations were used for the calculation of the average total annual effective ingestion doses for children and adults. The committed effective doses were calculated for three different scenarios according to mineral water consumption rate. In the most extreme scenario (for age group 12–17), all water samples except MW1 and MW2 cause annual committed effective doses below the reference level (0.1 mSv year−1) recommended by World Health Organization (WHO).

Over the last few decades, the global production of building materials has increased. Concrete is one of the highly used construction materials and in recent year different types of concretes are prevailing. Fly ash blended concrete with galvanized iron (GI) fiber is a type of concrete in which the cement can be partially or fully replaced by fly ash. This study investigates the influence of fly ash and GI fiber on the engineering properties of concrete by replacing different percentages of cement (5, 10 and 15 by weight) with fly ash and by adding 0.5% (by volume) GI fiber into the concrete. Workability, compressive strength, splitting tensile strength, flexural strength, stress strain response under axial compression, durability at high temperature are the engineering properties that have been investigated. It was found that concrete up to 15% fly ash and fiber showed better result of compressive strength than concrete without fly ash and fiber. The splitting tensile strength was also found to be highest in concrete with 15% fly ash and 0.5% fiber. The flexural strength of fiber reinforced concrete with fly ash has been examined by loading concrete beams. According to the findings, increasing the percentage of fly ash and adding GI fiber improved flexural strength and changed the stress strain response of fly ash blended concrete with GI fiber from brittle to ductile. The durability test results showed that higher percentages of fly ash decreased the strength reduction between compressive stresses at high temperature (500 °C) and room temperature (25 °C).KeywordsFly ashGalvanized iron fiberCompressive strengthFlexural strengthStress–strain behavior

The aim of this study was to provide baseline radioecological data for the temperate forest ecosystem in Plitvice Lakes National Park. Emphasis was placed on the determination of naturally occurring radionuclides since there is an acknowledged lack of data for these radionuclides in non-accident conditions in wildlife, even for bioindicator organisms. Activity concentrations of 238U, 226Ra, 210Pb, 232Th, 40K, 134Cs, and 137Cs were measured by gamma spectrometry in soil and bioindicators: earthworms, conifer needles, mosses, and lichens. From the measured activity concentrations, concentration ratios were calculated to quantify the transfer of these radionuclides from soil to bioindicators. Our results show that soil activity concentrations are biased toward results from other studies conducted within the Dinaric mountain region. However, in moss and lichen samples, we measured higher activity concentrations of 226Ra and lower activity concentrations of 40K and 137Cs in comparison to similar studies. Also, we estimated lower concentration ratios for all radionuclides from soil to these organisms, except for 210Pb, in comparison to generic values. The transfer of 238U was generally low for all of the bioindicator organisms. For conifer needles, a correlation was found between activity concentrations of 226Ra and 137Cs in soil and related concentration ratios. Correlation was also found between the activity concentration of 40K in soil and transfer of 40K and 137Cs to mosses and lichens. A comparison with literature data highlighted the lack of 226Ra related concentration ratios for conifer trees and especially for earthworms. Therefore, the results of this study could supplement the sparse data currently available on radionuclide background data in similar ecosystems and related soil-to-wildlife transfer of radionuclides. Dose rate assessments, performed by the ERICA Tool, estimated that 96% of the overall exposure of wildlife in the Park area is due to the background dose rates, while 0.06μGyh-1 on average can be attributed as an incremental dose rate from 134Cs and 137Cs.

Alkali-activated concrete with Serbian fly ash and its radiological impact

Two samples collected from the phosphogypsum deposits of the chemical products industry Elixir Prahovo (Serbia) were subjected to a recrystallization experiment performed over several repeated cycles. In these tests, phosphogypsum was separated into recrystallized (purified) gypsum, insoluble residue and supernatant. Both raw phosphogypsum and recrystallized gypsum were examined using inductively coupled plasma optical emission spectrometry, X-ray diffraction and scanning electron microscopy with energy-dispersive spectrometry. The activity concentrations of 238U, 235U, 226Ra, 210Pb, 232Th and 40K were investigated using γ-ray spectrometry. Based on the activity concentration results, a number of radiometric parameters were calculated for the original and recrystallized phosphogypsum (i.e. radium equivalent activity, γ indices for construction materials, α index and external and internal hazard indices). Raw phosphogypsum samples showed greater mean activity concentration levels of 238U and 226Ra than the international recommended limits, while the recrystallized gypsum demonstrated notably lower activity concentrations for these two isotopes. The activity concentration of 226Ra in recrystallized gypsum is ~6 times lower than in raw phosphogypsum. Therefore, recrystallized gypsum does not present a radiation hazard when used as a building material, while raw phosphogypsum meets the requirements only for road construction materials.

This study assesses the results of environmental radioactivity measurementsfor Bayburt Province in the Eastern Black Sea area of Turkey. Usingγ-ray spectrometry, activity concentrations of the natural radionuclides 226Ra,232Th and 40K and a fissionproduct 137Cs were investigated in soil samples. The activity concentrations of 226Ra,232Th and 40K in various building materials such as sand, cement and marble and indrinking waters were determined. The activity concentrations vary from 16 to54 Bq kg−1 for 226Ra, from 10to 21 Bq kg−1 for 232Th and from113 to 542 Bq kg−1 for 40K in building materials. The mean specific activity concentrations of 226Ra,232Th and 40K in drinking waterswere 93, 30 and 504 mBq l−1, respectively. The concentrations of grossα andβ radioactivity in drinking water samples collected from four differentsampling stations have been determined. The results show that the grossα andβ activities are lower than the screening levels given by the World HealthOrganization (WHO), which are a maximum contaminant level of0.5 Bq l−1 and1.0 Bq l−1 grossα andβ radioactivity, respectively, in drinking water. Indoor radon measurements were made in 44 dwellingsin Bayburt by using Cr-39 detectors. Radon concentrations in dwellings in Bayburt varied from 17 to125 Bq m−3 and the averagevalue was 56 Bq m−3. The results obtained in this study indicate that the region has a background radiationlevel that is within the typical natural range and shows no significant departures from otherparts of the country.

Indoor radon (222Rn) and thoron (220Rn) are the most important natural sources of ionizing radiation to the public. Radiological studies that assess simultaneously 222Rn and 220Rn, and their controlling factors are particularly scarce in African countries. Hence, we conducted a survey of indoor 222Rn and 220Rn in buildings located in the SW region of Angola. Bedrock samples were also collected, and a borehole was executed to assess 226Ra and 224Ra activity concentration, 222Rn and 220Rn exhalation and emanation potential in the surface and at depth. The aim of this study was to determine the factors (geological and anthropogenic) that may influence the annual inhalation dose (AID) received by the population. Overall, the sum of indoor radon and indoor thoron concentrations, labelled the total indoor radon concentration (TIRC), was higher than 300Bq/m3 in only 5% of the buildings studied. The contribution of 220Rn to the TIRC averaged 35% but may reach 95%, demonstrating the relevance of discriminating radon and thoron in indoor radon surveys. Indoor 222Rn and 220Rn were not correlated, indicating both must be estimated to properly assess the AID. Indoor 220Rn concentrations were statistically different according to the building materials and type of usage. Higher 222Rn and 220Rn concentrations were observed in dwellings compared to workplaces. The median AID estimated for dwellings was 1.50mSv/y compared to 0.26mSv/y for workplaces, which are lower than the estimated average radiation exposure due to natural sources of 2.4mSv/y. AID values higher than 1mSv/y effective dose threshold established in the Council Directive 2013/59/EURATOM for the purpose of radiation protection in workplaces were observed in 12% of the workplaces studied suggesting the need for mitigation measures in those buildings. The analysis of bedrock samples revealed statistically significant correlations between 224 and 226Ra activity concentration, and 220Rn and 222Rn exhalation and emanation potential. The borehole samples indicated a strong influence of weathering processes in the distribution of radioisotopes. The highest 226Ra and 224Ra activity concentration, and 222Rn and 220Rn exhaled per unit mass, TIRC and AID were observed in association with A-type red granites and porphyries. We conclude that both geological and anthropic factors, such as the type of building usage and building materials, must be considered in dose assessment studies and for the development of risk maps.

Radioactivity of some building and raw materials used in Croatia In the present study, the activity concentrations of 226Ra, 232Th, 40K in some building and raw materials used in Croatia were measured by using a gamma-ray spectrometer with the HPGe detector. The average activity concentrations of the studied different building and raw materials ranged from 11.6 ± 1.7 (concrete) to 251.2 ± 25.7 Bqkg-1 (GBFS), 14.0 ± 2.7 (concrete) to 54.4 ± 8.3 (coal fly ash) and 147.2 ± 19.0 (concrete) to 773.7 ± 82.0 Bqkg-1 (tuff) for 226Ra, 232Th and 40K, respectively. Radium equivalent activity, activity concentration index, absorbed gamma dose rate indoor due to the external exposure and corresponding annual effective dose were determined to estimate the exposure risk arising due to the use of these building and raw materials.

In this study, the activity concentrations of 226Ra, 232Th, 222Rn, and 40K, emanation fractions (P), equilibrium equivalent concentration (EEC), and mass exhalation rates (Em) of radon released from building materials used in Malaysia were studied using gamma-ray spectrometer with HPGe detector. Radiological parameters [activity concentration index (ACI), indoor air-absorbed dose rate (Din), annual effective dose (AEDin) from external and internal (ERn), soft tissues (HST) and lung (HL), and effective dose equivalent (Heff)] were estimated to evaluate radiological hazards due to the use of these building materials: sand, cement, gravel, bricks, tiles, fly ash, white cement, and ceramic raw materials. The measured P, EEC, and Em vary from 10 to 30%, 0.9 to 22 Bq m−3, and 33 to 674 mBq h−1 kg−1, respectively, while the calculated ACI and AEDin vary from 0.1 ± 0.01 to 2.1 ± 0.1 and 0.1 ± 0.01 to 2.4 ± 0.6 mSv y−1, respectively. On the other hand, the internal annual effective dose ranges from 0.1 to 1.4 mSv y−1. The estimated radiological risk parameters were below the recommended maximum values, and radiological hazards associated with building materials under investigation are therefore negligible.

Radiometric measurement of building materials is very important to assess the internal and external exposure caused by the ionizing radiation emitted from terrestrial radionuclides in building materials. The activity concentrations of 226Ra, 232Th, and 40K in fifty-eight samples of fifteen different structural and covering building materials commonly used in Osmaniye province located in the Mediterranean region of Turkey were measured by using gamma-ray spectroscopy. The activity concentrations of 226Ra, 232Th, and 40K varied from 2.5 ± 0.1 (marble) to 145.7 ± 4.4 (clay brick), 1.3 ± 0.1 (marble) to 154.3 ± 4.1 (marble), and 8.6 ± 0.2 (sand) to 1044.1 ± 70.3 (granite), respectively. Radiological parameters (activity concentration index, alpha index, indoor absorbed gamma dose rate and the corresponding annual effective dose rate, and excess lifetime cancer risk) were estimated to evaluate the health hazards associated with these building materials. Since the estimated values of these parameters are within the recommended safety limits or criteria values, the use of the studied building materials in the construction of dwellings can be considered to be safe for the residents of the region.

Predictions of radionuclide dose rates to freshwater organisms can be used to evaluate the radiological environmental impacts of releases from uranium mining and milling projects. These predictions help inform decisions on the implementation of mitigation measures. The objective of this study was to identify how dose rate modelling could be improved to reduce uncertainty in predictions to non-human biota. For this purpose, we modelled the activity concentrations of 210Pb, 210Po, 226Ra, 230Th, and 238U downstream of uranium mines and mills in northern Saskatchewan, Canada, together with associated weighted absorbed dose rates for a freshwater food chain using measured activity concentrations in water and sediments. Differences in predictions of radionuclide activity concentrations occurred mainly from the different default partition coefficient and concentration ratio values from one model to another and including all or only some 238U decay daughters in the dose rate assessments. Consequently, we recommend a standardized best-practice approach to calculate weighted absorbed dose rates to freshwater biota whether a facility is at the planning, operating or decommissioned stage. At the initial planning stage, the best-practice approach recommend using conservative site-specific baseline activity concentrations in water, sediments and organisms and predict conservative incremental activity concentrations in these media by selecting concentration ratios based on species similarity and similar water quality conditions to reduce the uncertainty in dose rate calculations. At the operating and decommissioned stages, the best-practice approach recommends relying on measured activity concentrations in water, sediment, fish tissue and whole-body of small organisms to further reduce uncertainty in dose rate estimates. This approach would allow for more realistic but still conservative dose assessments when evaluating impacts from uranium mining projects and making decision on adequate controls of releases.

A retrofit of the San Francisco Oakland Bay Bridge involves more than 30 different concrete mixes, each of which confers specific advantages.For instance, according to the U.S. EPA, concrete containing more than 50% fly ash resists the cracking and corrosion associated with seawater.

Activity concentrations of 226Ra, 228Ra, 210Pb, 40K and 7Be and their temporal variations in surface air

Graphical Abstract Highlight Research 226Ra and 232Th were determined in sediments and seawater of Cirebon waters. The activity of natural radionuclides varies in Cirebon waters. Natural radioactivity in sediment is relatively higher than in seawater. Natural radioactivity in sediment and seawater is comparable to other regions' levels. Abstract 226Ra and 232Th are natural radionuclides with long half-lives, and they have a dangerous radiation exposure effect on marine biota and even humankind. This study investigates the activity concentration and horizontal distribution of natural radionuclides 226Ra and 232Th in sediments and seawater from the coastal waters of Cirebon, Indonesia, directly adjacent to the Cirebon Coal-Fired Power Station (CFPS). The activity concentrations of 226Ra and 232Th radioactivity were measured using gamma-ray spectrometry. Radioactivity analysis of 226Ra and 232Th was conducted on sediment and seawater columns. Furthermore, Ocean Data View (ODV) version 5.8.2 software was used to analyse the horizontal distribution pattern. The results showed that the highest concentrations of 226Ra and 232Th radioactivity were found in the sediment rather than the water column, even though they varied by location. The concentration activity of 226Ra and 232Th radioactivity was found to be a linear function of distance from the potential pollution source. Higher activity was detected at stations closer to the pollution source (CFPS). There was no significant effect of the depth of radionuclide distribution. Further monitoring activities at Cirebon’s CFPS should be conducted to predict and manage the impact on biota and human life.

Radiometric monitoring of construction materials is required for estimating the interior and exterior exposure to ionizing radiation emitted by terrestrial radioactive elements in building materials. Using gamma-ray spectroscopy, the activity concentrations of 226Ra, 232Th, and 40K in fifty-two samples from eighteen different building materials commonly used in Erbil city, Kurdistan region, Iraq, were evaluated to assess possible radioactive dangers to human health. The activity concentrations of 226Ra, 232Th and 40K ranged from 1 ± 0.1 (gypsum board) to 130 ± 11 (granite), 1.3 ± 0.2 (gypsum) to 66 ± 8 (ceramic sample), and 18.74 ± 4 (gypsum) to 1061.708 ± 40 (granite) with an average of 28 ± 5, 20.7 ± 4, and 340.8 ± 18 (average ± standard deviation), respectively. Radiological indicators (activity concentration index, alpha and gamma index, hazard indices, interior absorbed gamma dose rate and the corresponding yearly effective dosage rate, and excess lifetime cancer risk) were computed to assess the health risks associated with these building materials. Consideration was given to the indoor annual effective dosage for common construction materials, the radon surface expiration rate, and the indoor radon concentration. The mean values of activity concentration were then inputted into the RESRAD-BUILD computer software to calculate a resident's long-term radiation exposure. The dosages were measured over a range of 0 to 70years. From 0 to 30years, there was a significant change in dosages; however, from 30 to 70years, the dosages were reasonably consistent. This research demonstrates that granite samples are not safe for dwellings with poor ventilation (especially those without windows). In general, other investigated construction materials in the buildings are deemed safe for the population, since the computed values for these parameters fall within the well-being restrictions or criterion values.