Radioactivity measurements in the environment of the Udhampur area,Jammu and Kashmir Himalayas,India

LR-115 plastic track detectors have been used for the measurement of radon exhalation rate and radium concentration in soil samples collected from some villages of the Udhampur district, Jammu and Kashmir, India. Uranium concentration has also been determined in these soil samples using the fission track registration technique. Radium concentration in soil samples varies from 5.46 to 19.17 Bqkg^?1, whereas uranium concentration varies from 2.53 to 3.65 ppm. The radon exhalation rate in these samples has been found to vary from 6.42 to 22.47 mB kg^?1 hr^?1. The work is undertaken for health risk assessments due to uranium and radium in the study area. A positive correlation has been observed between uranium and radium, as well as uranium and radon exhalation rate in soil samples.     

Uranium, radium and radon exhalation studies in some soil samples using plastic track detectors

Radium concentration and radon exhalation rate have been measured in soil samples collected from some areas belonging to upper Siwaliks of Kala Amb, Nahan and Morni Hills of Haryana and Himachal Pradesh states, India using LR-115 type II plastic track detectors. Uranium concentration has also been determined in these soil samples using fission track registration technique. Radium concentration has been found to vary from 5.30 to 31.71 Bq.kg⁻¹, whereas uranium concentration varies from 33.21 to 76.26 Bq.kg⁻¹. The radon exhalation rate in these samples varies from 216.87 to 1298.00 mBq.m⁻²hr⁻¹ (6.15 to 36.80 mBq.kg⁻¹.hr⁻¹). Most of the samples have uranium concentration above the worldwide average concentration of 35 Bq.kg⁻¹. A good correlation (R ² = 0.76) has been observed between uranium concentration and radon exhalation rate in soil. The values of uranium, radium and radon exhalation rate in soil are compared with that from the adjoining areas of Punjab.     

Fast determination of uranium and radium in waters of variable composition

The effects of uranium and its progeny radium are known to be harmful and their measurements in drinking water are necessary for careful monitoring. Fast and accurate methods for determination of uranium and radium in water samples with various salinity and activities concentrations have been developed. High Resolution Inductively Coupled Plasma Mass Spectrometry is used for direct measurement of uranium. Calibration is performed with ²³⁸U standards and ²⁰⁹Bi is used as internal standard to correct the matrix effects and plasma instability. The radium is determined by photon electron rejected alpha liquid spectrometry after a chemical separation procedure that includes co-precipitation of radium with barium sulphate, transformation of the sulphate to carbonate and extraction of radium in the scintillation cocktail. The minimal detectable activities of 3.5×10⁻⁸ Bq kg⁻¹ for uranium and 2.3×10⁻⁴ Bq kg⁻¹ for radium are obtained.     

14C in uranium and thorium minerals: a signature of cluster radioactivity?

Various uranium and thorium minerals have been analysed with accelerator mass spectrometry to determine their ¹⁴C content. It is found that, whenever the contribution from secondary reactions such as the ¹¹B(α,p)¹⁴C is sufficiently low, the ¹⁴C concentration is consistent with that expected from ¹⁴C (spontaneous) cluster radioactivity from radium isotopes of the uranium and thorium natural series. Received: 15 February 1999     

Evaluation of radiation level and radon exhalation rate of rock samples from Mahd Ad Dahab mine in Saudi Arabia

Mahd Ad Dahab mine is the largest and oldest gold mine in the middle East, situated in the western region of Al-Madina Al-Munawara in Saudi Arabia. By using a high-resolution gamma-ray spectroscopy system, various radionuclides in about 20 rock samples, collected from four different locations of the Mahd Ad Dahab mine, have been identified quantitatively based on their characteristic spectral peaks. The activity concentrations of the natural radionuclides uranium (²³⁸U), thorium (²³²Th), and potassium (⁴⁰K) as well as some radiological parameters were measured in the rock samples. The activity concentration of uranium was found to vary from 7.94 to 38.52 Bq/kg, thorium from 3.14 to 17.79 Bq/kg and potassium activity from 93.51 to 175.83 Bq/kg. The radon emanation coefficient of the rock samples was estimated. It ranged between 0.48 and 0.55. Moreover, the radium equivalent activity in the samples ranged between 19.3 and 77.49 Bq/kg, which is lower than the allowed maximum value for worker safety. The external and internal hazard indices and gamma-radiation hazard index were found not to exceed the permissible limits.     

Determination of 226Ra, 224Ra, 223Ra and 228Ra in mineral water samples of the Slovak Republic

The Slovak Republic is very rich in mineral water sources. In recent years, it has been discovered that a number of mineral waters in the Slovak Republic contain high levels of ²²⁶Ra and ²²⁸Ra. Moreover, there is a lack of information on ²²⁴Ra and ²²³Ra concentrations in mineral waters as well. The currently approved techniques for alpha emitting radium isotopes are based on radon emanation methods. Due to the long ingrowth periods required by these techniques, any ²²⁴Ra and ²²³Ra in the sample decay away and go undetected. For this reason, we have used an alpha spectrometric method for the simultaneous determination of ²²⁶Ra, ²²³Ra and ²²⁴Ra. Radium was concentrated by a lead sulphate co-precipitation. The precipitate was dissolved in EDTA and the radium isotopes were separated from possible interfering radionuclides using barium sulphate micro precipitation. The radium-barium precipitate was filtered and counted by alpha spectrometry. ¹³³Ba was used to quantify the yield by gamma spectrometry. In our laboratory, gamma spectrometry was also used for the determination of ²²⁸Ra in mineral water samples. Radium was concentrated by a lead-barium sulphate co-precipitation. ¹³³Ba was used to quantify the yield, found to be 97% on the average, by gamma spectrometry. Furthermore, the committed effective doses for ²²⁶Ra, ²²⁴Ra, ²²³Ra, ²²⁸Ra intake via ingestion of mineral waters for the members of public were calculated.     

Nuclear pears: Recent developments and future prospects

We report studies of examples of reflection-asymmetric nuclei which are difficult to access using compound nucleus reactions. The octupole radium isotopes withN>132 and radon isotopes are not accessible by reactions employing stable targets and beams; we have shown that multinucleon transfer reactions can populate these nuclei with sufficient yield for their structure to be determined. We report high-spin studies in^{218, 220, 222}Rn and^{222, 224, 226, 228, 230}Ra: these show that the Ra isotopes withA<228 have the characteristics of octupole deformed nuclei whereas the Rn isotopes behave like octupole vibrators. Measurements of theB(E1)/B(E2) ratios indicate that the electric dipole moment in these nuclei is constant with spin. The most octupole deformed nuclei are predicted to be uranium isotopes withN≈132; measurements of the very fissile nucleus²²⁶U suggest that it is octupole deformed and has a large intrinsic electric dipole moment. Finally, we speculate that the best examples of pear shapes are the hyperdeformed minima predicted to lie low in uranium isotopes withN≈140; their signature of high-multiplicity low-energyE1 photon cascades should be detectable using present-day high-efficiency germanium arrays.     

Measurement of uranium and its isotopes at trace levels in environmental samples using mass spectrometry

Actinides have widely entered the environment as a result of nuclear accidents and atmospheric weapon testing. These radionuclides, especially uranium, are outstanding radioactive pollutants, due to their high radiotoxicity and long half-lives. In addition to this, since depleted uranium (DU) has been used in the Balkan conflict in 1999, there has been a concern about the possible consequences of its use for the people and environment. Therefore, accurate, precise and simple determination methods are necessary in order to evaluate the human dose and the concentration and effects of these nuclides in the environment. The principal isotopes of uranium e.g. ²³⁵U and ²³⁸U are of primordial origin and ²³⁴U present in radioactive equilibrium with ²³⁸U. ²³⁶U occurs in nature at ultra trace concentrations with a ²³⁶U: ²³⁸U atom ratio of 10⁻¹⁴. Concentrations of uranium in soil samples were determined using inductively coupled plasma mass spectrometry (ICP-MS) and isotope ratios of uranium were measured using a thermal ionisation mass spectrometer. Radioactive dis-equilibrium of ²³⁴/²³⁸U, depletion of ²³⁵/²³⁸U and significant evidence of ²³⁶U/²³⁸U were noticed in soil samples.      

Radon exhalation rate in Chhatrapur beach sand samples of high background radiation area and estimation of its radiological implications

Chhatrapur beach placer deposit, situated in a part of the eastern coast of Orissa, is a newly discovered high natural background radiation area (HBRA) in India. The sand samples containing heavy minerals, were collected from Chhatrapur region by the grab sampling method at an interval of ∼1 Km. Radon exhalation rates were measured by “Sealed Can Technique” using LR-115 type type II in the sand samples containing heavy minerals collected from the beach. Radon activity is found to vary from 1177.1 to 4551.4 Bq m-3 whereas the radon exhalation rate varies from 423.2 to 1636.3 mBq m⁻²h⁻¹ with an average value of 763.9 mBq m⁻²h⁻¹. Effective dose equivalent in sand samples estimated from exhalation rate varies from 49.9 to 193.0 μSv y⁻¹ with an average value of 90.1 μSv y⁻¹. From the activity concentration of ²³⁸U, ²³²Th and ⁴⁰K computed radium equivalent is found to vary from 864.0 to 11471.5 Bq kg⁻¹ with an average value of 3729.0 Bq kg⁻¹. External hazard index, H_ex range from 2.3 to 31.0 with a mean value of 10.1, which is quite high. This value supports the conclusion based on high mean absorbed gamma dose rate in air due to the naturally occurring radionuclides as 1627.5 nGy h⁻¹. A positive correlation has been found between U concentration and radon exhalation rate in the sand samples. The use of sand as construction material may pose a radiation risk to ambient environment.      

238U and total radioactivity in drinking waters in Van province,Turkey

As part of the national survey to evaluate natural radioactivity in the environment, concentration levels of total radioactivity and natural uranium have been analysed in drinking water samples. A survey to study natural radioactivity in drinking waters was carried out in the Van province, East Turkey. Twenty-three samples of drinking water were collected in the Van province and analysed for total α, total β and ²³⁸U activity. The total α and total β activities were counted by using the α/β counter of the multi-detector low background system (PIC MPC-9604), and the ²³⁸U concentrations were determined by inductively coupled plasma-mass spectrometry (Thermo Scientific Element 2). The samples were categorised according to origin: tap, spring or mineral supply. The activity concentrations for total α were found to range from 0.002 to 0.030 Bq L^?1 and for total β from 0.023 to 1.351 Bq L^?1. Uranium concentrations ranging from 0.562 to 14.710 μg L^?1 were observed in drinking waters. Following the World Health Organisation rules, all investigated waters can be used as drinking water.     

Correlation between radon exhalation and radium content in granite samples used as construction material in Saudi Arabia

Measurements of radon exhalation for a total of 205 selected samples of construction materials used in Saudi Arabia were carried out using an active radon gas analyzer with an emanation container. It was found that granite samples were the main source of radon exhalation. The radon exhalation rates per unit area from these granite samples varied from below the minimum detection limit up to with an average of 1.5 . The radium contents of 27 granite samples were measured using an HPGe-based γ spectroscopy setup. The ²²⁶Ra content of the granites varied from below the minimum detection limit up to , with an average of . The linear correlation coefficient between exhaled radon and radium content was found to be 0.90.     

Anomalous ratios of radioisotopes in PM10 as tracer of global fallout impact in the centre of Mexico

The monitoring and evaluation of radioactive content in samples of PM₁₀ aerosols have been investigated. The specific radioactivity concentrations (SRC) of ²³⁴U, ²³⁵U, ²³⁸U and ²³²Th were determined using inductively coupled plasma-sector field mass spectrometry in 13 samples collected in Mexico City and 8 samples collected in Cuernavaca in the centre of Mexico. The SRC of the radioisotopes analysed in PM₁₀ were larger than those reported in PM_2.5. The enrichment factor was greater than 5, indicating anthropogenic influences in both sites. The activity ratios of these isotopes in the samples were determined. The ²³⁵U/²³⁸U ratio showed variations with respect to the natural value, while the ²³⁴U/²³⁸U and ²³²Th/²³⁸U ratios did not show any secular equilibrium in all sites, corroborating that the increase of uranium is not influenced by natural sources. The annual dose results obtained have no impact on health.     

Radon activity measurements around Bakreswar thermal springs

²²²Rn concentrations were measured in the bubble gases, spring waters, soil gases and in ambient air around the thermal springs at Bakreswar in West Bengal, India. This group of springs lies within a geothermal zone having exceptionally high heat flow about 230 mW/m², resembling young oceanic ridges. The spring gas has a high radon activity (～885 kBq/m³) and is rich in helium (～1.4 vol. %) with appreciably large flow rate. The measured radon exhalation rates in the soils of the spring area show extensive variations from 831 to 4550/mBqm² h while ²²²Rn concentrations in the different spring waters vary from 3.18 to 46.9 kBq/m³. Surface air at a radius of 40 m around the springs, within which is situated the Bakreswar temple complex and a group of dwellings, has radon concentration between 450 and 500 Bq/m³. In the present paper we assess the radon activity background in and around the spring area due to the different contributing sources and its possible effect on visiting pilgrims and the people who reside close to the springs.     

Radiation dose-dependent risk on individuals due to ingestion of uranium and radon concentration in drinking water samples of four districts of Haryana,India

Uranium gets into drinking water when the minerals containing uranium are dissolved in groundwater. Uranium and radon concentrations have been measured in drinking water samples from different water sources such as hand pumps, tube wells and bore wells at different depths from various locations of four districts (Jind, Rohtak, Panipat and Sonipat) of Haryana, India, using the LED flourimetry technique and RAD7, electronic silicon solid state detector. The uranium (²³⁸U) and radon (²²²Rn) concentrations in water samples have been found to vary from 1.07 to 40.25?µg?L^?1 with an average of 17.91?µg?L^?1 and 16.06?±?0.97 to 57.35?±?1.28?Bq?L^?1 with an average of 32.98?±?2.45?Bq?L^?1, respectively. The observed value of radon concentration in 43 samples exceeded the recommended limits of 11?Bq?L^?1 (USEPA) and all the values are within the European Commission recommended limit of 100?Bq?L^?1. The average value of uranium concentration is observed to be within the safe limit recommended by World Health Organization (WHO) and Atomic Energy Regulatory Board. The annual effective dose has also been measured in all the water samples and is found to be below the prescribed dose limit of 100?µSv?y^?1 recommended by WHO. Risk assessment of uranium in water is also calculated using life time cancer risk, life time average daily dose and hazard quotient. The high uranium concentration observed in certain areas is due to interaction of ground water with the soil formation of this region and the local subsurface geology of the region.     

Exposure to radon in the radon spa Niška Banja,Serbia

There is a well-known radon spa Ni?ka Banja in south-east of Serbia. In Ni?ka Banja spa there is a medical complex and radon is used for therapeutic purposes for many different diseases. This paper presents elevated radon levels in the Ni?ka Banja spa. Indoor radon and radon in water activity concentration measurements in thermal pools and therapy rooms are presented. There are also results from gamma spectrometry measurements of soil, rock and therapy mud. A special attention is paid to the medical staff exposure to radon around thermal pools. The annual effective doses from radon for staff working around the thermal pools in Ni?ka Banja spa are very high comparing to the maximum recommendation level. The maximal radon concentration of (22.90 ± 0.57) kBq m^?3 was measured in the basement of the hotel-dispensary “Radon”. This hotel is settled on “bigar” rock – travertine, which has high content of ²²⁶Ra.     

Emanations and “induced” radioactivity: From mystery to (mis)use

Radon, Rn; atomic number Z=85; is a (gaseous) chemical element of which no stable but only radioactive isotopes exist. Three of them, namely actinon (²¹⁹Rn), thoron (²²⁰Rn) and radon (²²²Rn) are the decay products of naturally occurring radioisotopes of radium:²²³Ra,²²⁴Ra and²²⁶Ra, respectively. The natural Rn isotopes were discovered within the period 1899–1902 and at that time referred to as emanations because they came out (emanated) of sources/materials containing actinium, thorium and radium, respectively. The (somewhat mysterious) emanations appeared to disintegrate into radioactive decay products which by depositing at solid surfaces gave rise to “induced” radioactivity i.e. radioactive substances with various half-lives. Following the discovery of the emanations the volume of the research involving them and their disintegration products grew steeply. The identity of a number of these radioactive products was soon established. Radium- emanation was soon used as a source of RaD (²¹⁰Pb) to be applied as an “indicator” (radiotracer) for lead in a study on the solubility of lead sulphide and lead chromate. Moreover, radium and its emanation were introduced into the medical practice. Inhaling radon and drinking radon-containing water became an accepted medicinal use (or misuse?) of that gas. Shortly after the turn of the century, the healing (?) action of natural springs (spas) was attributed to their radium emanation i.e. radon. Bathing in radioactive spring water and drinking it became very popular. Even today, bathing in radon-containing water is still a common medical treatment in Jáchymov, Czech Republic.     

Radon exhalation and gamma radioactivity levels in soil and radiation hazard assessment in the surrounding area of National Thermal Power Corporation,Dadri (U.P.), India

In the present study soil samples were collected from the region around a National Thermal Power Corporation (NTPC) at Dadri (U.P.), India. Radon activity and radon exhalation rates were measured by using “sealed can technique” using LR 115-type II nuclear track detectors. Radon activities are found to vary from 177.5 ± 23.1 to 583.4 ± 4.9 Bq m⁻³ with an average value of 330.5 ± 30.4 Bq m⁻³. Surface exhalation rates in these samples vary from 63.9 ± 8.3 to 210.2 ± 15.1 mBq m⁻² h⁻¹ with an average value of 119.1 ± 11.1 mBq m⁻² h⁻¹, whereas mass exhalation rates vary from 2.5 ± 0.3 to 8.1 ± 0.6 mBq kg⁻¹ h⁻¹ with an average of 4.6 ± 0.4 mBq kg⁻¹ h⁻¹.Activity concentrations of naturally occurring radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K) were also measured in these soil samples using high resolution γ–ray spectroscopic system. Activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K vary from 32.2 ± 6.0 to120.9 ± 4.5 Bq kg⁻¹, 19.3 ± 0.9 to 44.6 ± 1.5 Bq kg⁻¹ and 195.4 ± 2.8 to 505.4 ± 6.3 Bq kg⁻¹ with overall mean values of 70.0 ± 8.9 Bq kg⁻¹, 34.8 ± 1.2 Bq kg⁻¹ and 436.1 ± 5.6 Bq kg⁻¹ respectively. From the activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K, radium equivalent activity (Ra_eq) and the external hazard index (H_ex) were calculated and found to vary from 73.4 to 214.7 Bq kg⁻¹ and from 0.2 to 0.6 respectively.     

Soil radon levels measured with SSNTD's and the soil radium content

The source of the radon gas ²²²Rn in the ground air is the soil and the bedrock underneath. The potential radon level in the ground is given by the content of ²²⁶Ra in the ground. The presence of ²²⁶Ra is in turn dependent on the amount of ²³⁸U in the ground, and these two isotopes are not always found to be in equilibrium in a sample of soil or bedrock. Especially if the soil is washed out, the radium content may be reduced. When the soil is the relevant source of the radon gas, it is interesting to look for a possible relation between the radon level and the radium content of the soil.

In this paper we report on measurements of soil radon level carried out with SSNTDs at several European sites. Soil samples were collected at these sites and analysed with gamma spectrometry to determine their radium content. A comparison of the different degree of disequilibrium of radon, defined as the ratio between the actual and the secular equilibrium-with-radium soil radon concentration, found at the different sites and depths is presented. The influence on the result of soil type and climate is briefly discussed.     

Study of radon transport through concrete modified with silica fume

The concentration of radon in soil usually varies between a few kBq/m³ and tens or hundreds of kBq/m³ depending upon the geographical region. This causes the transport of radon from the soil to indoor environments by diffusion and advection through the pore space of concrete. To reduce indoor radon levels, the use of concrete with low porosity and a low radon diffusion coefficient is recommended. A method of reducing the radon diffusion coefficient through concrete and hence the indoor radon concentration by using silica fume to replace an optimum level of cement was studied. The diffusion coefficient of the concrete was reduced from (1.63 ± 0.3) × 10⁻⁷ to (0.65 ± 0.01) × 10⁻⁸ m²/s using 30% substitution of cement with silica fume. The compressive strength of the concrete increased as the silica-fume content increased, while radon exhalation rate and porosity of the concrete decreased. This study suggests a cost-effective method of reducing indoor radon levels.     

The potential health hazard due to elevated radioactivity in old uranium mines in Dolina Białego,Tatra Mountains,Poland

Natural radioactivity is one of the essential components of the environment. Unlike the Sudety mountains area in Poland, the Tatra Mountains were not the subject of wide survey as regards the levels of natural radioactivity. Especially, the concentrations of radon (natural radioactive gas) have not been investigated there in terms of their possible negative health impact. Within the frame of bilateral cooperation between the Institute of Nuclear Physics in Kraków, Poland, and the Jo?ef Stefan Institute in Ljubljana, Slovenia, the measurements of natural radioactive elements in old uranium mines in the Tatra National Park were performed in June 2010. The investigated sites were located in Dolina Bia?ego (The Valley of the White). One of the mines is situated near the tourist path. The paper presents the results of complex measurements of natural radioactivity in both uranium drifts. The concentration of radon gas inside the mining drifts exceeded 28,000 Bq m^?3. Also, very high gamma dose rates were observed (up to 5600 nSv h^?1). The maximum concentrations of natural radioactive elements (potassium ⁴⁰K, radium ²²⁶Ra, thorium ²³²Th) in rock samples amounted to 535, 2137, and 18 Bq kg^?1, respectively. The effective dose rates due to radon and thoron inhalation have been assessed as 0.013 mSv h^?1 (for the lowest concentration) and 0.121 mSv h^?1 (for the highest concentration).