Radionuclides In Sediments Research Articles

Activity concentration of natural radionuclides in sediments of Bree, Klein-Brak, Bakens, and uMngeni rivers and their associated radiation hazard indices

A hyper-pure germanium (HPGe) detector was used to measure the activity concentrations in sediment samples of rivers in South Africa, and the associated radiological hazard indices were evaluated. The results of the study indicated that the mean activity concentrations of 226Ra, 232Th and 40K in the sediment samples from the oil-rich areas are 11.13, 7.57, 22.5 ; 5.51, 4.62, 125.02 and 7.60, 5.32, 24.12 for the Bree, Klein-Brak and Bakens Rivers, respectively. In contrast, the control site (UMngeni River) values were 4.13, 3.28, and 13.04 for 226Ra, 232Th, and 40K. The average excess lifetime cancer risks are 0.394 × , 0.393 × , 0.277 × and 0.163 × for sediment samples at Bree, Klein-Brak, Bakens, and uMngeni rivers. All obtained values indicated a significant difference between the natural radionuclide concentrations in the samples from the rivers in oil-rich areas compared to those of the non-oil-rich area. The values reported for the activity concentrations and radiological hazard indices were below the average world values; hence, the risk of radiation health hazard was negligible in all study areas.

Distribution of 40K, 238U and 232Th and associated radiological risks in river sand sediments across Enugu East, Nigeria

The distributions of 40K, 238U and 232Th in sand sediments of rivers in Enugu east, Southeastern, Nigeria have been studied and measured using NaI(TI) gamma-ray spectrometry detector. The average activity concentrations of 40K, 238U and 232Th across the studied locations were found to range from 13.18 (at Emene river) to 109.64 Bqkg–1 (at Trans-Ekulu river), 8.52 (at Abakpa river) to 15.45 Bqkg–1 (Eke express river) and 10.67 (at Emene river) to 16.94 Bqkg–1(at Abakpa river), respectively. The overall averages were found to be 60.55, 12.07 and 13.02 Bqkg–1 for 40K, 238U and 232Th, respectively. The activity concentrations of the radionuclides in sediments of the study areas were found to be lower than their world average of 400, 35, and 30 Bqkg–1, respectively. Radium equivalent activity, external hazard index, internal hazard index, absorbed dose rate, total Annual effective dose, excess lifetime cancer risk and gamma representative index were calculated. The purpose was to assess the radiological suitability of the use of the sediments as building material. The overall average values of the radiological indices were 35.35 Bqkg–1, 0.10, 0.13, 15.96 nGyh–1, 0.10 mSvy–1, 0.34 × 10–3 and 0.25, respectively, which are lower than their respective recommended worldwide limits. The results of the study have shown that the radiation hazard associated with the use of these sediments is insignificant and therefore can be used for building construction purposes without restriction.

ОСОБЕННОСТИ РАСПРЕДЕЛЕНИЯ БЕНТОСНЫХ ФОРАМИНИФЕР И ЕСТЕСТВЕННЫХ РАДИОНУКЛИДОВ В ДОННЫХ ОСАДКАХ СЕВЕРНОЙ АТЛАНТИКИ

The analysis of the relationship of benthic foraminifera and of natural radionuclides (232Th, 238U and 226Ra) distribution in the deep-water sediments of the North Atlantic in the section of 60○N crossing the arctic front is fulfilled. A oppositely directed correlation between the distribution of natural radionuclides in sediments and Alabaminella Weddellensis (Rs = 0.8) and Cibicidoides wuellerstorfi (Schwager, 1866) (Rs = –0.68) species occupying different ecological niches was revealed. The weighted radiation dose is calculated. The dose values obtained are in the range of 0.63–2.16 μGr/hour. It is assumed that under the conditions of measured background radiation, the effect of radiation hormesis in foraminifera manifests itself, stimulating their development.

Radiological Hazard Assessment of Radionuclides in Sediment and Water Samples of International Meighan Wetland in Arak, Iran

Introduction: There are natural and artificial radioactive nuclei in our environment, as well as in the structure of the living organism. Currently, industrial and municipal pollution has also an impact on increasing the level of radiation. The present study investigated the effect of inlet water from Arak Wastewater Treatment Plant on international Meighan Wetland and assessed the radiological indicators of sediments and water samples in this area. Material and Methods: In this study, the specific activity of radionuclides in water and sediment samples taken from the water entry areas of the international Meighan wetland was determined using a high purity germanium detector (Baltic Scientific Instrument LTD, 005- Latvia). Radiological indices for collected samples were calculated, and the topographical maps of radiation dose distribution were plotted using Surfer software (version 13). Results: Specific activities of 226Ra, 232Th, 40K, and 137Cs in sediment samples were in the range of 14.44-26.58, 22.78-34.56, 360.84-447.79, and 0.7-13.03 , respectively. The average values ​​of the external hazard index for sediment samples were calculated at 0.25. Conclusion: According to the obtained results, it can be concluded that pollution is more embedded in the Treatment Plant's basin, and a small amount goes to the wetlands. Radioactivity in the research area is normal, and topographic maps show that the distance from the entrance reduces the activity of radium and increases the activity of cesium. Assessment of hazard indicators showed that radiation levels in this area are not dangerous to human health.

Long-lived radionuclides in marine sediments from the Beibu Gulf, South China Sea: Spatial distribution, controlling factors, and proxy for transport pathway

The source and transport process of sediments are of great concern in marine sedimentology. In this study, naturally occurring radionuclides (238U, 226Ra, 228Ra, and 40K) in surface sediments and sediment cores were comprehensively analysed using high-purity germanium (HPGe) γ spectrometry in order to explore radionuclide fingerprints as novel proxies for tracking the source and transport pathway of sediments in the Beibu Gulf. We found that the radioactivity level of sediments in the Beibu Gulf was lower than that in other Chinese seas, following a comprehensive compilation and comparison of radioactivity in the region, indicating the Beibu Gulf is a high-quality marine environment. An interesting “butterfly pattern” was exhibited in the horizontal distribution of radionuclides in surface sediments from the Beibu Gulf, mainly attributable to the controlling factors of the non-linear negative regulation of sediment grain size and positive role of total organic carbon in sediment. Furthermore, the vertical distribution of radionuclides in sediment cores was affected by the redox state and a physical/biological disturbance, which were demonstrated by the simultaneous analysis of redox-sensitive element Mn and 210Pb, respectively. Additionally, the 226Ra238U endmember model and 232Th238U endmember model were proposed for quantifying local input (85%) and trans-region input (15%) of marine sediments in the Beibu Gulf in the context of the Guangdong-Qiongzhou Strait-Guangxi framework. We inferred that the Beibu Gulf was at risk of contamination by artificial radionuclides derived from nearby Guangdong Province, which has the highest number of nuclear power plants in China, through a trans-region input by ocean currents. Our study not only provided spatiotemporal distributions of radionuclides in the Beibu Gulf and their controlling factors (sediment grain size, total organic carbon, redox state, physical/biological disturbance, and ocean currents) but also indicated the radionuclide fingerprints (226Ra/238U and 232Th/238U) as potential geochemical proxies for quantifying the distinct sources of radionuclides and other associated chemicals (e.g., heavy metals, organic pollutants) in sediments.

Natural radioactivity and external dose rates in tailing samples from Rosterman gold mine, Kakamega county, Kenya

In this article, documented results of natural radionuclide concentrations in tailings at Rosterman gold mine, Kakamega county, Kenya were evaluated. Thirty tailing samples from Rosterman gold mine were collected as per standard sampling procedures and were analyzed for 238U, 232Th and 40K by NaI (TI) gamma-ray spectroscopy. The activities of 238U, 232Th and 40K was found to vary from 39 ± 1.63 Bq/Kg to 118 ± 4.43 Bq/Kg, 72 ± 2.24 Bq/Kg to 223 ± 8.36 Bq/Kg and 85 ± 3.6 Bq/Kg to 362 ± 10.65 Bq/Kg respectively. Radium equivalent activities were found below 370 Bq/Kg in all the collected samples. External gamma dose rates estimated from the levels of radionuclides in sediments had a range of 32 ± 3.4 nGy/h to 68 ± 5.83 nGy/h. Hence, mining of gold at Rosterman has minimal significant health implications to the general population and the miners.

Estimation of radiological parameters from seasonal observations of primordial natural radionuclides in sediments of Darbandikhan Lake water resources at Kurdistan region, Northeastern Iraq

In this study, sediments from different resources of Darbandikhan Lake were studied through 100 samples taken from spring, stream, and lake during the four seasons. The specific activity of (238U, 232Th and 40K) natural radionuclides have been measured using the Gamma Spectrometry analysis with HPGe detector. The measured average activity concentration of these radionuclides in the studied samples were (11.9 ± 1.00, 7.80 ± 1.08 and 211 ± 3.41) Bq/kg in spring; (9.23 ± 1.19, 7.66 ± 0.977 and 181 ± 3.06) Bq/kg in summer; (12.7 ± 1.52, 8.16 ± 1.04 and 188 ± 3.10) Bq/kg in autumn; (11.91 ± 1.55, 9.13 ± 1.03 and 219 ± 3.04) Bq/kg in winter. The radiological hazard indices of radium equivalent activities (Raeq), outdoor absorbed dose rate (Dout), outdoor annual effective dose equivalent (Eout), activity utilization index (AUI), external hazard index (Hex), internal hazard index (Hin), annual gonadal dose equivalent (AGDE), and excess life time cancer (ELCR) were calculated. All of these radiological parameters were below the international recommended values, and hence the usage of these sediments is considered safe regarding their radioactivity.

Distribution of natural radionuclides and radon concentration in the riverine environs of Cauvery, South India.

Systematic studies were carried out to understand the distribution of natural radionuclides in sediments and radon in water in the riverine environs of Cauvery, one of the major rivers of South India. The activity of radionuclides in the sediment was measured by gamma ray spectrometry. The radon emanation from the sediment was measured by the sealed 'can technique' and the radon in the water was measured using the RAD-7 instrument. The mean values of 40 K, 226Ra, and 232Th in the sediment samples were found to be 297.3 ± 4.16 Bq kg-1, 75.1 ± 2.64 Bq kg-1, and 85.5 ± 2.62 Bq kg-1, respectively. The mean activity of radon, radon exhalation rate, and radium content were found to be 135.68 Bq m-3, 327.1 mBq m-1 h-1, and 133.03 mBq kg-1, respectively. The radon in the water ranged from 0.19 kBq m-3 to 1.40 kBq m-3. The hyper pure germanium gamma spectroscopy measured via 226Ra activity and the radon activity measured by the passive can technique showed good correlation. The mean value of radon in the water was within the internationally recommended level. The sediment was considered safe for the purpose of construction, except for some extreme values, and the water was deemed safe for drinking.

Deposition of artificial radionuclides in sediments of Loch Etive, Scotland

The nuclear fuel reprocessing plants on the Sellafield site (UK) have released low-level effluents into the Irish Sea under authorisation since 1952. This has led to the labelling of nearby offshore sediments with a range of artificial radionuclides. In turn, these sediments act as a long-term secondary source of both soluble and particle-associated radionuclides to coastal areas. These radionuclides are of interest both in assessing possible environmental impacts and as tracers for marine processes. Here we present results from a study of the geochemistry of natural (234, 238U) and artificial (137Cs, 241Am, 238Pu, 239+240Pu, and 236U) radionuclides and their accumulation in sediments from Loch Etive, Scotland. The data are interpreted in the context of the historical radioactive discharges to the Irish Sea and biogeochemical processes in marine sediments. Loch Etive is divided into two basins; a lower, seaward basin where the sedimentation rate (∼0.6 cm/yr) is about twice that of the more isolated upper basin (∼0.3 cm/yr). These accumulation rates are consistent with the broad distribution of 137Cs in the sediment profiles which can be related to the maximum Sellafield discharges of 137Cs in the mid-1970s and suggest that 137Cs was mainly transported in solution to Loch Etive during that period. Enrichments of Mn, Fe, and Mo in sediment and porewater from both Loch Etive basins result from contemporary biogeochemical redox processes. Enrichments of 238U and 234U in the lower basin may be a result of the cycling of natural U. By contrast, the Sellafield-derived artificial isotope 236U does not seem to be affected by the redox-driven reactions in the lower basin. The 238Pu/239,240Pu ratios suggest contributions from both historical Sellafield discharges and global fallout Pu. The uniform sediment distributions of Pu and Am, which do not reflect Sellafield historical discharges, suggest the existence of a homogenous secondary source. This could be the offshore ‘mud patch’ in the vicinity of Sellafield from which the supply of radionuclides reflects time-integrated Sellafield discharges. This source could also account for the continuing supply of Cs to Loch Etive, even after substantial reductions in discharge from the Sellafield site.

Comportamento de Cs e Co em Sedimentos Marinhos da Enseada de Piraquara de Fora - Angra dos Reis

As a result of discharging of liquid effluents of the Angra dos Reis power plants, 137 Cs and 60 Co radionuclides are the greatest contributors to increasing of radioactivity level in the sediments of the Saco de Piraquara de Fora (SPF) inlet. The thermodynamic and kinetic of sorption of the two radionuclides in sediments of the impact area from the effluent liquid discharge were study to investigate their role in the radionuclide distribution patterns and trends. Cobalt sorption is slightly higher than the cesium one, but mostly both distribution coefficient values were lower than the literature data, which could be ascribed to the predominance of the kaolinite clay in the sediments. For both metals the sorption was higher onto the sediment with the highest cation exchange capacity. Although the velocities of sorption are slow for both metals, both may accumulate in considerable amount in sediments and their sorption is irreversible: 60 Co and 137 Cs accumulate in orders of magnitude of 10 10 and 10 9 Bq g -1 sediment , respectively, which shows the ability of the sediments to adsorb much of the radionuclides released by the power plants. In the range of SPF water temperature, as much the sorption as the desorption of the two metals increase with temperature; however, in general, the retention rate of the metals in the sediments remain constant. The sorption sites are heterogeneous as the sorption data could be fitted by the Langmuir and Freundlich isotherms. The process of sorption of Co and Cs is endothermic, which is spontaneous at low temperature.

Methodology for determination of correction factors in direct gamma spectrometric measurement of radionuclides in sediments

In this study, the practical methodologies are described for the determination of the factors for the self-absorption effect (Fs), spectral interferences (Fcsi), and true coincidence summing effects (Fcoi), which are used in direct gamma-spectrometric measurement of radionuclides such as 210Pb, 238U, 234Th, 226Ra, 214Pb, 228Ac, 208Tl, 214Bi, 137Cs and 40K in samples. To validate the applied methods, certified reference materials (CRMs) of lake and stream sediments were measured with an n-type Germanium (Ge) detector-calibrated using a multinuclide reference source. The highest self-absorption correction factors ranged from Fs = 1.44–2.10 for 46.5keV peak (210Pb) and Fs = 1.25–1.60 for 63.3keV peak (234Th) lying in the low energy region of the spectrum. The systematic influence was observed for 186.2keV (226Ra) peak due to spectral interferences with the 235U contribution. For this peak, Fcsi is changed from 0.921 to 0.955. Additionally, the present study suggests that true coincidence summing (TCS) effects are not dominant, except for 208Tl and 214Bi for which Fcoi ranged from 1.179 to 1.192 an ranged from 1.140 to 1.151, respectively.

Distribution of natural and anthropogenic radionuclides in northwest Mediterranean coastal sediments

The distribution of radionuclides in NW Mediterranean coastal sediments, and the processes controlling their abundance were investigated in three cores taken near the island of Porquerolles and one offshore Monaco. The sediments collected near Porquerolles were strongly anoxic due to diagenetic processes involved in the decomposition of organic matter, whereas they transitioned from oxic to anoxic at a depth of 4 cm beneath the seawater interface at Monaco. Organic carbon (OC) was more abundant in sediments at Porquerolles (by about a factor of 3–5) than at Monaco and elsewhere in the coastal NW Mediterranean. Sediment cores collected NE of Porquerolles also possessed elevated uranium concentrations that correlated with high OC content and strong reducing conditions. The 239,240Pu and 241Am activities in surficial sediments ranged from 1 to 5.7 Bq kg−1 and 0.3 to 1 Bq kg−1, respectively, while the 137Cs activity ranged from 0.3 to 6.2 Bq kg−1. The mean activity ratios of 241Am/239,240Pu and 238Pu/239,240Pu in Porquerolles and Monaco sediments were similar to the global fallout ratios. Sediment inventories of global fallout 239,240Pu (430–800 Bq m−2) and 241Am (150–285 Bq m−2) were by about a factor of 5–10 higher at Porquerolles, whereas the inventory of 137Cs (430–1000 Bq m−2) was substantially lower at the investigated stations than have been reported elsewhere at similar latitudes. Specific local conditions characterised by high OC sediment loads due to the growth and mortality of Posidonia oceanica have been responsible for deposition of large amounts of seagrass tissues at the NE corner of Porquerolles, which have had a profound effect on the distribution of radionuclides in the sediments.

Erratum to: Occurrence of heavy metals and radionuclides in sediments and seawater in mangrove ecosystems in Pattani Bay, Thailand.

Mangrove ecosystems in Pattani Bay, Thailand are considered representatives for monitoring the occurrence of anthropogenic and natural pollution due to metal and radionuclide contamination. Sediments and seawater were collected from five locations to determine metal (Cd, Cr, Cu, Mn, Ni, Zn, and Pb) and radionuclide (226Ra, 232Th, and 40K) concentrations. Spatial variations in metal and radionuclide concentrations were determined among the sampling sites. A geoaccumulation index (I geo ) and enrichment factor (EF) were used to classify the impacts of metals from anthropogenic point sources. Significant values for I geo and EF were measured for Pb in site 4 (I geo 0.65; EF 28.2) and Cd in site 1 (I geo 1.48; EF 46.2). EF values in almost all sampling sites were >1 which indicates anthropogenic pollution. To assess the potential public hazard of radioactivity, the average radium equivalent activity (Raeq), the external hazard index (H ex), the internal hazard index (H in), the absorbed dose rate in air (D), and the annual effective outdoor dose rate (E) were determined. Based on these measurements, it is concluded that the probability of human health risk from radionuclides is low. However, the absorbed dose in air (D) values in sites 4 and 5 were greater than the global average value of 55 nGy h-1, indicating that sediments in these locations pose a radiological hazard. The data obtained in this study provides useful information on metal and radionuclide background levels in mangrove sediments and seawater, and can be applied toward human health risk assessment and metal and radionuclide mapping.

Seasonal measurement and dose assessment of natural radionuclides in sediments of Darbandikhan Lake in Kurdistan-Iraq

A total of 100 sediment samples were collected from Darbandikhan Lake and its different resources (spring, stream, and lake) during the four seasons. Spectrometry analysis of HPGe detector was used for measuring the specific activity. The seasonally measured mean activity concentration of 238U, 232Th and40K for sediment samples were 11.9±1.0, 7.8±1.0 and 213.4±3.4Bq/kg in spring; 9.2±1.1, 7.9±1.0 and 205.8±3.0Bq/kg in summer; 12.7±1.5, 8.2±1.0 and 188.1±3.1Bq/kg in autumn; 11.9±1.6, 9.1±1.0 and 218.7±3.0Bq/kg in winter, respectively. The obtained activity concentrations of 238U, 232Th and 40K are all below the recommended values suggested by UNSCEAR (2000) for sediment 35, 30 and 400Bq/kg, respectively.The ordinary kriging method was used to draw the contour maps using the surfer digital program.RESRAD-BUILD simulation code was used to determine the indoor dose, annual dose rate and cancer risks received and exposed to individuals in the dwellings, which show an increase over a period of 50 years. Two scenario descriptions of changing wall thickness and room dimension were, studied and they shows that the indoor dose and cancer risks increase with wall thicknesses until 50cm and over a period of 50 years, as well as the increase of room size increases the internal dose and cancer risks inside the buildings. From the analyzed results it was concluded that the sediments in the Darbandikhan Lake has no risks when used in building construction.

Occurrence of heavy metals and radionuclides in sediments and seawater in mangrove ecosystems in Pattani Bay, Thailand.

Mangrove ecosystems in Pattani Bay, Thailand are considered representatives for monitoring the occurrence of anthropogenic and natural pollution due to metal and radionuclide contamination. Sediments and seawater were collected from five locations to determine metal (Cd, Cr, Cu, Mn, Ni, Zn, and Pb) and radionuclide (226Ra, 232Th, and 40K) concentrations. Spatial variations in metal and radionuclide concentrations were determined among the sampling sites. A geoaccumulation index (I geo ) and enrichment factor (EF) were used to classify the impacts of metals from anthropogenic point sources. Significant values for I geo and EF were measured for Pb in site 4 (I geo 0.65; EF 28.2) and Cd in site 1 (I geo 1.48; EF 46.2). EF values in almost all sampling sites were >1 which indicates anthropogenic pollution. To assess the potential public hazard of radioactivity, the average radium equivalent activity (Raeq), the external hazard index (H ex), the internal hazard index (H in), the absorbed dose rate in air (D), and the annual effective outdoor dose rate (E) were determined. Based on these measurements, it is concluded that the probability of human health risk from radionuclides is low. However, the absorbed dose in air (D) values in sites 4 and 5 were greater than the global average value of 55 nGy h-1, indicating that sediments in these locations pose a radiological hazard. The data obtained in this study provides useful information on metal and radionuclide background levels in mangrove sediments and seawater, and can be applied toward human health risk assessment and metal and radionuclide mapping.

Assessment of environmental and radiological health hazards due to heavy metals and radionuclides contents in utility water reservoirs' sediments

Heavy metals and natural radionuclides in sediments of Awara and Osse reservoirs, Ondo State, Nigeria have been measured using X-ray fluorescence and γ-ray spectrometry techniques. Heavy metals detected in the two reservoirs include K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Ba, Pb and Th. The average concentrations of the measured heavy and trace metals in the sediment of Awara dam vary as Fe>K>Ca>Mn>Ti> Sr>Cr>V>Rb>Zn>Ni>Cu while those of Osse dam vary as Ba>K>Fe>Ca> Mn>Sr>Ti>V>Rb>Cr>Zn>Ni>Th>Pb>Cu. Geoaccumulation index and enrichment factor evaluation of potentially toxic heavy metal contents in both reservoirs revealed that the two reservoirs are uncontaminated with hazardous heavy metals. Naturally occurring radionuclides (40K and 232Th) detected in the two reservoirs show values that are higher than their mean crustal value, while 226Ra is lower than the world mean crustal value. There is little or no ecological or radiological risk associated with the sediment of the two reservoirs.

Natural and man-made radionuclides in sediments of an inlet in Rio de Janeiro State, Brazil

The distribution of natural radionuclides 226Ra, 228Ra, 40K and man-made radionuclides (54Mn, 60Co and 137 Cs) in the surface sediments of an inlet of Ribeira Bay were investigated. Sediment samples were collected and analyzed for radionuclides, organic matter, carbonate, sulfate, cationic exchange capacity and grain size composition. The natural radionuclide concentrations ranged from 4.4 to 45, from 10 to 93, from 66 to 1347Bq·kg−1 dry weight for 226Ra, 228Ra and 40K, respectively. Natural radionuclide concentrations tend to be higher in the silt fraction, which determines their pattern distributions. Only one sample presented measurable concentration for 137Cs, while 54Mn was detected in two samples and 60Co in four sediment samples. Man-made radionuclides present a maximum value of dose external four times lower than the normal background and the potential risk due to the presence of man-made radionuclides in sediments is lower than the risk provided by the natural radionuclides.

Certified reference materials for radionuclides in Bikini Atoll sediment (IAEA-410) and Pacific Ocean sediment (IAEA-412)

The preparation and characterization of certified reference materials (CRMs) for radionuclide content in sediments collected offshore of Bikini Atoll (IAEA-410) and in the open northwest Pacific Ocean (IAEA-412) are described and the results of the certification process are presented. The certified radionuclides include: 40K, 210Pb (210Po), 226Ra, 228Ra, 228Th, 232Th, 234U, 238U, 239Pu, 239+240Pu and 241Am for IAEA-410 and 40K, 137Cs, 210Pb (210Po), 226Ra, 228Ra, 228Th, 232Th, 235U, 238U, 239Pu, 240Pu and 239+240Pu for IAEA-412. The CRMs can be used for quality assurance and quality control purposes in the analysis of radionuclides in sediments, for development and validation of analytical methods and for staff training.

Fukushima-derived radionuclides in sediments of the Japanese Pacific Ocean coast and various Japanese water samples (seawater, tap water, and coolant water of Fukushima Daiichi reactor unit 5).

We investigated Ocean sediments and seawater from inside the Fukushima exclusion zone and found radiocesium (134Cs and 137Cs) up to 800 Bq kg−1 as well as 90Sr up to 5.6 Bq kg−1. This is one of the first reports on radiostrontium in sea sediments from the Fukushima exclusion zone. Seawater exhibited contamination levels up to 5.3 Bq kg−1 radiocesium. Tap water from Tokyo from weeks after the accident exhibited detectable but harmless activities of radiocesium (well below the regulatory limit). Analysis of the Unit 5 reactor coolant (finding only 3H and even low 129I) leads to the conclusion that the purification techniques for reactor coolant employed at Fukushima Daiichi are very effective.

External Gamma Dose Levels In The Soil Samples of HBRAs of Kerala and Tamil Nadu, India

Knowledge on the distribution of these radionuclides in soil is of great importance for radiation protection and measurement. A systematic radiological survey has been carried out in the region of HBRAs in Kollam district of Kerala and Manavalakurichi in Tamilnadu in India to compare the natural gamma-radiation levels. 180 soil samples collected and were analyzed for 238U, 232Th and 40K by NaI(Tl) gamma-ray spectrometry. Heterogeneous distribution of radionuclides in the region may be attributed to the deposition phenomenon of soil in the region. The result of gamma dose rate measured at the sampling sites using survey meter showed an excellent correlation with dose rates computed from the natural radionuclides estimated from the soil samples. From these radioactivity levels, the radium equivalent activity and the external hazard index which resulted from the natural radionuclides in sediments are also tabulated for the analyzed samples and compared with internationally recommended values.