Comparison of analytical methods used to determine <Superscript>235</Superscript>U, <Superscript>238</Superscript>U and <Superscript>210</Superscript>Pb from sediment samples by alpha,beta and gamma spectrometry

An intercomparison of the methodology (alpha, beta and gamma spectrometry) used for ²³⁸U, ²³⁵U and ²¹⁰Pb determination was carried out based on 38 sediment samples. The activity range of the samples varied from 10–700 Bq/kg for ²¹⁰Pb, 1–35 Bq/kg for ²³⁵U and 10–800 Bq/kg for ²³⁸U. Results obtained using the three methods were not statistically different at high activity levels, but agreement between the results decreased at lower sample activity levels. For ²¹⁰Pb, the smallest difference was found between alpha and gamma spectrometry. A good correlation between results from alpha and gamma spectrometry was observed over the whole activity range. In beta spectrometry, the results were slightly higher than those obtained by alpha or gamma spectrometry due to the impurity of ²²⁸Ra. In ²³⁸U analysis, good correspondence was observed between ²³⁸U determined by gamma and alpha spectrometry, particularly at higher ²³⁸U activity concentrations over 100 Bq/kg. In ²³⁵U analysis, attention needs to be paid to interference from ²²⁶Ra and its reduction.     

Alpha and gamma spectrometry for determination of natural and artificial radionuclides in tea, herbal tea and camomile marketed in Italy

Several kinds of tea, camomile and herbal tea were analysed to determine natural and artificial radioactivity. The radionuclides were determined by alpha (²¹⁰Po) and gamma (²²⁸Ac, ²¹⁴Pb, ²¹⁴Bi, ²¹⁰Pb, ⁴⁰K and ¹³⁷Cs) spectrometry. ²²⁸Ac ranged between 0.6 and 9.0 Bq kg⁻¹_dry; ²¹⁰Po between 1.90 and 36.1 Bq kg⁻¹_dry; ²¹⁴Pb and ²¹⁴Bi between 0.7 and 4.9 Bq kg⁻¹_dry; ²¹⁰Pb between < 10.0 and 58.9 Bq kg⁻¹_dry; ⁴⁰K between 463 and 936 Bq kg⁻¹_dry; ¹³⁷Cs between < 0.3 and 2.6 Bq kg⁻¹_dry. The percentage of ²¹⁰Po extraction in infusion was also determined; the arithmetical mean value of percentage of ²¹⁰Po extraction resulted 20.7 ± 7.50.     

Radioactivity of coals and fly ashes

The level and the behavior of the naturally occurring primordial radionuclides ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²³²Th, ²²⁸Ra and ⁴⁰K in coals and fly ashes are described. The activity concentrations of the examined coals and originated from coal mines in Greece ranged from 117 to 435 Bq·kg⁻¹ for ²³⁸U, from 44 to 255 Bq·kg⁻¹ for ²²⁶Ra, from 59 to 205 Bq·kg⁻¹ for ²¹⁰Pb, from 9 to 41 Bq·kg⁻¹ for ²²⁸Ra and from 59 to 227 Bq·kg⁻¹ for ⁴⁰K. These levels are comparable to those appeared in coals of different countries worldwide. The activity concentrations of the examined fly ashes and produced in coal-fired power plants in Greece ranged from 263 to 950 Bq·kg⁻¹ for ²³⁸U, from 142 to 605 Bq·kg⁻¹ for ²²⁶Ra, from 133 to 428 Bq·kg⁻¹ for ²¹⁰Pb, from 27 to 68 Bq·kg⁻¹ for ²²⁸Ra and from 204 to 382 Bq·kg⁻¹ for ⁴⁰K. The results showed that there is an enrichment of the radionuclides in fly ash relative to the input coal during the combustion process. The enrichment factors (EF) ranged from 0.60 to 0.76 for ²³⁸U, from 0.69 to 1.07 for ²²⁶Ra, from 0.57 to 0.75 for ²¹⁰Pb, from 0.86 to 1.11 for ²²⁸Ra and from 0.95 to 1.10 for ⁴⁰K.     

Accurate determination of naturally occurring radionuclides in Philippine coal-fired thermal power plants using inductively coupled plasma mass spectrometry and γ-spectroscopy

There is an increased interest in measuring naturally occurring radioactive materials (NORM) like coal, fly ash considering health hazards caused by naturally occurring radionuclides. This paper presents activity concentration (AC) of ²²⁶Ra, ²²⁸Ra, ²³²Th, ²³⁸U and ⁴⁰K in feed coal, bottom and fly ash samples from Philippines coal-fired thermal power plants using inductively coupled plasma mass spectrometry (ICP-MS) and high-purity germanium gamma spectroscopy (HPGe γ-spectroscopy). Coal, bottom and fly ash samples were digested using a microwave oven with a mixture of HNO₃, HClO₄ and HF. Uranium (²³⁸U) and thorium (²³²Th) ACs were also analyzed from samples using ICP-MS. A good correlation was found for the measurement of U and Th using both techniques (R² = 0.97 and 0.94 respectively). ICP-MS measurements showed the highest AC of ²³²Th and ²³⁸U in fly ash and lowest for feed coal samples. With HPGe γ-spectroscopy measurements, highest AC (in Bq kg^{− 1}) of ²²⁶Ra, ²²⁸Ra, ²²⁸Th and ⁴⁰K, were noticed in fly ash followed by bottom ash and feed coal. ICP-MS method is rapid for the measurement of uranium and thorium in comparison to γ-spectroscopy as secular equilibrium is not required. Activity concentrations of bottom and fly ash samples were found to be within the reported values worldwide and below the International Atomic Energy Agency recommended values for regulatory control.     

Preliminary studies on 226Ra, 228Ra, 228Th and 40K concentrations in foodstuffs consumed by inhabitants of Accra metropolitan area, Ghana

Knowledge of radioactivity levels in human diet is of particular concern for the estimation of possible radiological hazards to human health. However, very few surveys of radioactivity in food have been conducted in Ghana. The natural radionuclides ²²⁶Ra, ²²⁸Ra, ²²⁸Th and ⁴⁰K were measured in the foodstuffs using gamma ray spectrometry. All samples were found to contain high ⁴⁰K content in the range 87.77?C368.50?Bq?kg^?1. The maximum concentration of ²²⁸Th and ⁴⁰K were found in cassava to be 14.93?±?3.86 and 368.50?±?19.20?Bq?kg^?1, respectively. The total annual committed effective dose was estimated to be 4.64?mSv. The daily intake of radionuclides from food consumption reveals that cassava and plantain are the highest contributors, while millet is the lowest. The daily radionuclide intake from the foodstuffs consumed by the general public was 411.32?Bq and the daily internal dose resulting from ingestion of the radionuclides in the foodstuffs was 0.01?mSv. The radionuclide concentrations were comparable with those reported from other countries.     

Measurement of natural radioactivity and radiation hazard assessment in the soil samples of Visakhapatnam,Andhra Pradesh,India

The present work aims to measure and estimate radioactivity and hazardous radiation indices of the soil. Soil samples were collected from various locations in the Visakhapatnam district in Andhra Pradesh, India. The measurement of specific activity of ²²⁶Ra, ²³²Th, and ⁴⁰K radionuclides is carried out with the help of HP-Ge based gamma spectrometer system. Activity concentration of radionuclides in the samples ²²⁶Ra, ²³²Th and ⁴⁰K ranged from 20 ± 2 to 91 ± 2 Bq.kg^-1, 45 ± 3 to 365 ± 3 Bq.kg^-1, and 400 ± 9 to 607 ± 8 Bq.kg^-1, and the respective mean values are 53.36 Bq.kg^-1, 203.74 Bq.kg^-1 and 479.19 Bq.kg^-1. The measured mean value of the absorbed dose rate is 171.41 nGy.h^-1, which was beyond the worldwide mean outdoor value of 60 nGy.h^-1. Thus, the annual effective dose estimated from the above value is 1.04 mSv.y^-1. The correlation was done among the measured ²²⁶Ra, ²³²Th, and ⁴⁰K activity concentrations. The estimated radium equivalent dose is 381.60Bq.kg^-1. The estimated health hazard index and annual effective dose rates of dwellers of Visakhapatnam were studied and compared to Indian average values. The study will help to generate the baseline data for assessing hazard indices to the public and geological mapping of natural radiation in India.     

Radiochemical determination of uranium and radium isotope in natural water using liquid scintillation counter

²³⁴U, ²³⁸U, ²²⁶Ra, and ²²⁸Ra were analyzed in 14 Korean hot spring waters. Uranium was extracted with mixture of extractive scintillation cocktail containing HDEHP and ²³⁴U, ²³⁸U were analyzed with LSC. Radium isotopes were separated using Ba coprecipitation method and counted with LSC and ²²⁸Ra was also analyzed its daughter ²²⁸Ac with HPGe γ-detector. Among them ²²⁶Ra was ranged <0.01–0.155 Bq/L and ²²⁸Ra is below detection limit <0.1 Bq/L. And also, uranium content was ranged <0.01–49.7 μg/L and ²³⁴U/²³⁸U ratio was ranged 0.69–1.17.     

Radiochemical characterization of spring waters in Balaton Upland, Hungary, estimation of radiation dose to members of public

Hungary is rich in spring waters. A survey studying the naturally occurring alpha emitter radionuclides in 30 frequently visited and regularly consumed spring waters was conducted out in the Balaton Upland region of Hungary.²²⁶Ra, ²²⁴Ra, ²³⁴U, ²³⁸U and ²¹⁰Po activity concentrations were determined by using alpha spectrometry after separation from matrix elements. Average concentration (mBq L^{− 1}) of ²²⁶Ra, ²²⁴Ra, ²³⁴U, ²³⁸U and ²¹⁰Po in the spring waters is varied from 2.1 to 601, from < 1.1 to 65.4, from 3.9 to 741.9, from < 0.44 to 274.3 and from 2 to 15.2 respectively. In most cases radioactive disequilibrium was observed between uranium and radium isotopes. The doses for the analyzed samples of spring water are in the range 3.59–166.73 μSv y^{− 1} with an average 18.2 μSv y^{− 1} .This is well below the 100 μSv y^{− 1} reference level of the committed effective dose recommended by WHO. Only one water sample had a dose higher than 100 μSv y^{− 1}, mainly due to the contribution from radium (²²⁶Ra, ²²⁴Ra) and ²¹⁰Po isotopes. This study provides important information for consumers and authorities about their internal radiological exposure risk from spring water intake.     

NORM activity concentration in sediment cores from the Peninsular Malaysia East Coast Exclusive Economic Zone

Study for distribution of Naturally Occurring Radioactive Materials (NORM) i.e. ²²⁶Ra, ²²⁸Ra and ⁴⁰K in the east coast of Peninsular Malaysia Exclusive Economic Zone (EEZ) was carried out as part of the national marine environment project. Sixteen marine sediment cores from selected locations within the EEZ were collected for determination of NORM activity concentrations using high-purity germanium (HPGe) gamma spectrometer. From the measurement, the activity concentration of ²²⁶Ra, ²²⁸Ra and ⁴⁰K is ranged from 16 ± 4 Bq/kg to 46 ± 6 Bq/kg (total mean 30), 28 ± 7 Bq/kg to 87 ± 11 Bq/kg (total mean 56) and 171 ± 33 Bq/kg to 690 ± 89 Bq/kg (total mean 420), dry wt., respectively. The activity concentrations of radionuclides in most of the core were quite uniform suggesting that there were thorough vertical mixed of sediment throughout the core. The results obtained were also in good agreement with those previous reported from other countries in the region and therefore can be used to enhance present radioactivity database. The calculated external hazard values were ranged from 0.25 to 0.51 with the mean of 0.38 (less than unity) showed little risk of external hazard to the workers handling the sediments and it was likely low level of the mainland natural gamma-radiation in the east coast of Peninsular Malaysia.     

Marine radioactivity concentration in the Exclusive Economic Zone of Peninsular Malaysia: 226Ra, 228Ra and 228Ra/226Ra

The present occurrence of ²²⁶Ra and ²²⁸Ra in marine sediment core and fish from the Exclusive Economic Zone in the east coast of Peninsular Malaysia were studied. Sediment core and biota in respectively was collected using multicorer device and purchased from local fishermen at identified stations during the cruise expedition conducted in 2008. The purpose of this study was to determine and to make available an inventory of activity concentration levels and activity ratio for these radionuclides in this region. The activity concentrations of ²²⁶Ra and ²²⁸Ra in sediment core and edible part of fish were ranged between 15.9–46.5 and 27.7–87.1 Bq/kg dry wt and; 0.80–2.13 and <0.95–3.57 Bq/kg fresh wt, respectively. Meanwhile, the activity ratios of ²²⁸Ra/²²⁶Ra in sediment core and fish were varied with the range between 1.63–2.09 and 0.45–2.38, respectively. Refer to those ranges the activity concentrations of radium isotopes were comparable with other region. Thus, it can be concluded that the occurrence of radium isotopes mainly supplied from terrestrial sources and the factors of assimilation efficiency and transfer coefficient of radium may probably effect to the variation activity concentration of ²²⁶Ra and ²²⁸Ra and its activity ratio in edible part of pelagic and demersal fish obtained in this study.     

Radiological characterization of drinking waters in Central Italy

Due to the importance of water in human life, its quality must be strictly controlled; for this purpose, simple and reliable analytical methods must be available. In this study, a monitoring of radioactivity content was performed in tap waters collected in a region of Central Italy to check the compliance with recent European and Italian regulations. Gross alpha and beta activities, ²³⁸U, ²³⁴U, ²²⁶Ra, ²²²Rn, and ³H concentrations were measured. Gross alpha and beta activities were determined by standard ISO 9696 and ISO 9697; for ²²⁶Ra, ²²²Rn and ³H determination, liquid scintillation was used. ²³⁸U and ²³⁴U concentrations were determined by alpha spectrometry after separation from the matrix by extraction chromatography and electroplating. The results revealed that the tritium concentration was always lower than 6.75 Bq l^− 1. The concentrations (mBq l^− 1) of ²²⁶Ra, ²²²Rn, ²³⁸U, and ²³⁴U ranged from < 1.70 to 15.31, from 0.69 to 20.3, from 0.65 to 48.77, and from 0.78 to 51.50, respectively.²³⁴U/²³⁸U ratios were higher than 1 in most cases. The results obtained revealed that, in most samples, gross alpha and gross beta were lower than the parameter value indicated in the international regulations. An attempt was also made to find a correlation between these results and the chemical parameters of waters.     

Natural radionuclides in Italian diet and their annual intake

This study was dedicated to the evaluation of the background activity concentration of natural radionuclides as ²²⁸Ra and ²²⁸Th of ²³²Th family, ²²⁶Ra of ²³⁸U family and ⁴⁰K in the Italian daily diet. These radionuclides were determined by gamma spectrometry. ⁴⁰K activity concentration, in the samples taken into account in the present paper, ranged between 70.5 (milk) and 181.1 Bq kg _ww ^?1 (pasta), ²²⁶Ra activity concentration ranged between 1.1 (milk) and 5.7 Bq kg _ww ^?1 (pasta), ²²⁸Ra and ²²⁸Th activity concentration, in the same samples, ranged between 0.7 (milk) and 3.7 Bq kg _ww ^?1 (pasta) and between 1.4 (milk) and 6.1 Bq kg _ww ^?1 (flours) respectively. The annual intake of every radionuclide from foodstuffs ingestion was also calculated. The 94–95 % of the total intake comes from ⁴⁰K. For adults and children, the highest activity intake of all radioisotopes was from grain products, for infants it was from milk products.     

Determination of226Ra and uranium in fish samples from waters of the Grand Canyon by alpha spectroscopy without electrodeposition

A previous paper reported the application of a method for determining²²⁶Ra by -spectroscopy. This paper presents important improvements which permit the determination of²²⁶Ra in the presence of large amounts of Ca. The method was applied to the analysis of²²⁶Ra and U isotopes in fish samples from the waters of the Grand Canyon.²²⁶Ra ranged from 0.05 Bq kg^–1 /1.4 pCi kg^–1/ to 0.17 Bq k^–1 /4.7 pCi kg^–1/.²³⁸U values ranged from 0.13 Bq kg^–1 /3.5 pCi kg^–1/ to 0.52 Bq kg^–1 /14 pCi kg^–1/ and²³⁴U values were between 0.23 Bq kg^–1 /6.2 pCi kg^–1/ and 12 Bq kg^–1/ /326. pCi kg^–1/.     

Measurement of <Superscript>228</Superscript>Ra in the Yellow Sea and East China Sea using the radon emanation method

²²⁸Ra levels in the Yellow Sea and East China Sea were determined using the emanation method. The seawater radium was concentrated using an Mn-fiber and the ²²⁴Ra ingrowth was measured after about half a year when the initial ²²⁴Ra in the sample would have decayed. The ²²⁴Ra activity in the sample was evaluated using the decay dynamics relationship between parent ²²⁸Ra and daughter ²²⁸Th. The concentration and distribution feature of ²²⁸Ra in the Yellow Sea and East China Sea were studied and the ²²⁸Ra concentrations in the surface seawater of the Yellow Sea and the East China Sea were in the range 0.09–15.0 Bq/m³ with an average of 6.84 Bq/m³ during the summer cruise, and in the range 0.09–16.9 Bq/m³ with an average of 6.37 Bq/m³ during the winter cruise. The ²²⁸Ra distribution in the northern Yellow Sea was different from the southern Yellow Sea and East China Sea. The highest ²²⁸Ra activity of surface water was located in the middle of the northern Yellow Sea, but for the southern Yellow Sea and East China Sea, it decreased with increasing distance from China continent.     

Hokutolite collected from riverbed at Peitou Hot Spring in Taiwan: With emphasis on radiochemical studies

Summary Hokutolite, and hot spring water and river water collected recently at Peitou Hot Spring in Taiwan were analyzed for U, Th, Ra and ²¹⁰Pb isotopes. Concentrations of major chemical elements were also measured. Hokutolite had its typical chemical composition make-up for this area. The concentrations of ²³⁸U, ²³⁴U, ²³² Th, ²³⁰ Th, ²²⁸ Th, ²²⁶Ra, ²²⁸Ra and ²¹⁰Pb in samples scrapped into 7 layers from the surface to the bottom of a hokutolite specimen were 0.0021-0.0068, 0.0022-0.0075, 1.47-2.07, 1.00-1.29, 1.56-1.97, 56.7-68.6, 1.46-2.06 and 25.9-36.0 Bq/g, respectively. All the radionuclides exhibited a relatively uniform distribution, and radioequilibrium was confirmed among ²³² Th, ²²⁸Ra and ²²⁸ Th. From the relationship between the decay and growth of Th-series nuclides it was considered that the hokutolite studied was isolated from the stream water at least 70-80 years ago. The U/Th-series radionuclides in the hot spring water were in rather high concentrations and the enrichment of ²²⁸Ra and ²²⁸ Th to ²³² Th was the most prominent feature. Evaluation of the distribution coefficients (K_d) using the data on hot spring water or river water and hokutolite indicated that Th (K_d = 10⁴-10⁵) in water was likely to be precipitated (and/or co-precipitated) with BaSO₄ as Th(SO₄)₂ with a relatively high concentration into hokutolite, together with Ra (K_d = 10⁶-10⁷).     

Distribution of137Cs and228Ra in the sediments of Aswan High Dam lake

Sediment samples of the High Dam lake were investigated for their¹³⁷Cs,²²⁶Ra,²²⁸Th, and⁴⁰K content, using low-level -spectroscopy. The results show that at the begining of the lake (500 km from the High Dam), where sediments consist mostly of sand, the level of¹³⁷Cs is very low (0.1 Bq kg^–1). The maximum value (22.3 Bq kg^–1) was found 40 km from the wall of the High Dam, where the composition of the sediments is nearly 50% clays. The distribution of the natural nuclides²²⁶Ra,²²⁸Th, and⁴⁰K shows a different trend.     

Advantages of low-background liquid scintillation alpha-spectrometry and pulse shape analysis in measuring222Rn, uranium and226Ra in groundwater samples

Liquid scintillation counting (LSC) and pulse shape analysis (PSA) was used in measuring radon and gross alpha- and beta-activities in groundwater. We used conventional LSC counters for the measurement of radon in water, but low-background LSC spectrometers for the gross activity measurements. The lower limit of detection (LLD) for radon in water is 0.6 Bq/l for a 60 min count with a conventional counter, but 0.1 or 0.2 Bq/l, with the two types of low-background LSC spectrometers equipped with a pulse shape analyser (PSA). The gross alpha and beta activity measurements are made using a simple sample preparation method, PSA of a low background LSC and spectrum analysis. The LLD recorded for gross alpha and beta with the two spectrometers are 0.02 and 0.03 Bq/l and 0.2 and 0.4 Bq/l, respectively, for a 180 minutes count and a 38 ml sample volume. The method also enable the calculation of the U and²²⁶Ra contents in water and indicates the presence of some other long-lived radionuclides (²¹⁰Pb,²²⁸Ra or⁴⁰K). The LLD for U recorded with both spectrometers is 0.02 Bq^–1 and for²²⁶Ra 0.01 Bq·1^–1. The LLDs attained by this LSC method are two orders of magnitude lower than the maximum permissible concentrations set for U and²²⁶Ra.     

Radiological assessment of natural and fallout radioactivity in the soil of Chamba and Dharamshala areas of Himachal Pradesh,India

This paper presents the results of measurement of natural and fallout radioactivity in soil samples of Chamba and Dharamshala areas in Himachal Pradesh, India. Spatial distribution of ²³⁸U, ²²⁶Ra, ²³²Th, ⁴⁰K, ¹³⁷Cs was determined using High resolution gamma-ray spectrometry. The mean activity concentration in Chamba region due to ²³⁸U, ²³²Th, ⁴⁰K and ¹³⁷Cs was 32.3, 58.4, 588.3, and 10.9 Bq kg⁻¹, respectively, whereas in Dharamshala it was 35.7, 61.3, 594.9, 10.0 Bq kg⁻¹, respectively. Absorbed gamma dose rate (D) in air was calculated using appropriate dose conversion factors, which was varying from 45 to 103 nGy h⁻¹. To control the radiation exposure due to natural radioactivity in soil, if it is used as building materials, radium equivalent activity (Ra_eq) and activity index were also evaluated. Radium equivalent activity calculated for the soil ranged from 95.5 to 234.2 Bq kg⁻¹ with average of 171.0 Bq kg⁻¹.The calculated Activity concentration index was ranged from 0.34 to 0.85 with an average value of 0.64. The natural and fallout radioactivity in soil of this region is comparable with Indian average and other parts of the world. The percentage contribution of ²³⁸U, ²³²Th and ⁴⁰K and ¹³⁷Cs to the average external gamma dose rate was 22, 46, 32, 2%, respectively. This shows that the dose contribution due to fallout radioactivity is negligible as compared to the natural radioactivity.     

Radioactivity measurements and radiation dose assessments due to natural radiation in Karabük (Turkey)

In this work, the radionuclide activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in surface soils and radon levels in dwellings of Karabük, Turkey were determined in order to evaluate the environmental radioactivity. Concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K radionuclides were determined using gamma spectrometry with using HPGe detector. The etch track detectors (CR-39) were used to determine the distribution of radon concentrations. The average activity concentrations for ²²⁶Ra, ²³²Th and ⁴⁰K were found as 21.0, 23.5 and 363.5 Bq kg⁻¹, respectively. The calculated average annual effective dose equivalent from the outdoor terrestrial gamma radiation from ²²⁶Ra, ²³²Th and ⁴⁰K is 53.5 μSv y⁻¹. The average radon concentration and annual effective dose equivalent of ²²²Rn in Karabük dwellings were obtained 131.6 Bqm⁻³ and 3.32 mSv y⁻¹, respectively. The evaluated data were compared with the data obtained from different countries.     

Radioactivity of coal and ashes from Figueira coal power plant in Brazil

Summary The Figueira coal-fired power plant (CFPP) is among the Brazilian CFPP which presents higher uranium concentration. Gamma-ray spectrometry was used to determine ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²³² Th and ⁴⁰K contents in pulverized coal, furnace bottom ash and fly ash samples. The natural radionuclide concentrations in pulverized coal ranged from 813 to 2609 Bq ^. kg^-1 for U series and from 22 to 40 Bq ^. kg^-1 for ²³² Th. The fly ash fraction gave concentrations ranging from 1442 to 14641 Bq ^. kg^-1, for uranium series. The same enrichment factor was observed for ²³⁸U, ²²⁶Ra and ²³² Th. Only ²¹⁰Pb and stable Pb presented a high enrichment factor for the last stage filter fly ash. The concentration of the uranium series found in the ashes is close to the limit adopted by the Brazilian guideline (CNEN-NN-4.01).²² Therefore, it is advisable to evaluate the environmental impact of the installation.