SSNTD Technique Research Articles

Using SSNTD Technique to Assess Radon Flux Density in Liquid Cleaning Materials Samples Available in Iraqi Pharmacies and Markets

In this study, thirty samples of cleaning materials (liquid) were collected from the local pharmacies and markets of Al-Najaf government to assess radium content and radon flux density (radon exhalation rate) using LR-115 Type II technique. These samples were divided into six groups according to country of origin (i.e. Iraq, Turkey, Jordon, Saudi Arabia, Egypt and other countries). The results demonstrate that, the average of radium content in six groups (Iraq, Turkey, Jordon, Saudi Arabia, Egypt and other counties) were 55.22±0.29 Bq/kg, 56.15±0.37 Bq/kg, 32.38±0.37 Bq/kg, 27.28±0.63 Bq/kg, 60.34±0.73 Bq/kg and 41.90±0.23 Bq/kg respectively. The average values of radon flux density were 9.24±0.25 µBq/m2.h, 11.00±0.31 µBq/m2.h, 6.06±0.31 µBq/m2.h, 4.55±0.59 µBq/m2.h,11.17±0.64 µBq/m2.h and 7.33±0.20 µBq/m2.h respectively. All values of radium content and radon flux density in the study samples were found to be less than the allowed the values of 57.600 mBq/m2.h and 370 Bq/kg published by UNSCEAR and OECD.

STUDY OF RADON AND THORON CONCENTRATION IN ENVIRONMENT OF MORADABAD DISTRICT OF UTTAR PRADESH, INDIA

Purpose: A study of indoor radon and thoron has been carried out in the dwelling of Moradabad, Uttar Pradesh, India. Radon is an invisible radioactive gas that occurs naturally in the indoor atmosphere. It comes from the natural breakdown of uranium in soils and rocks. Lung cancer risk depends upon the concentration of radon, thoron and their decay product in the air.
 Methodology: The measurements of radon and thoron concentration were carried out by using LR-115 type II plastic track detectors (SSNTD Technique). 
 Findings: In the present study the value of radon concentration from10.5 Bq/m3to 30Bq/m3 with an average19.9Bq/m3and thoron concentration from 5.6 Bq/m3 to 24 Bq/m3 with an average of 14.9 Bq/m3. It is observed that radon and thoron concentration is maximum in winter and minimum during summer. The maximum concentration in winter is essentially influenced by the intense temperature inversion, which occurs in the winter season when the wind velocity is low.
 The maximum concentration in winter is also the result of decreased ventilation because in this season the houses are closed for a long time and radon/thoron accumulated inside the room and a weak positive correlation was observed between radon and thoron.
 Social Implications: There are some difficulties in assessing the exact risks of radon in the home. Most studies have used data from miners who will have had far more exposure to radon than is likely in any building.
 Originality/ Novelty: This study is done at Moradabad City and Research Lab present in S.S.P. G. College Shajhanapur. Data of radon and thoron concentration has been taken from twin cup radon-thoron Dosimeter and Spark Counter.

Natural radioactivity levels in the soils and human risk assessment in Tiruchirappalli district (Tamil Nadu, India)

The activity concentrations of 226Ra, 232Th and 40K in 91 soil samples collected from proposed housing sites in Tiruchirappalli district were measured using gamma ray spectrometer, 222Rn activity using SSNTD technique and ambient absorbed gamma dose employing hand held scintillometer. The mean activity concentrations of 226Ra, 232Th and 40K were found to be 6.5, 61.7 and 379.8 Bq kg−1, respectively. The mean ambient gamma dose rate was 66.7 nGy h−1 and the mean radon activity 210.8 Bq m−3. The study identified two stations in which Raeq levels exceeded the permissible limit (370 Bq kg−1).

A follow-up study on indoor 222Rn, 220Rn their decay product concentrations in a mineralised zone of Himachal Pradesh, India.

A follow-up study was taken up in a mineralised zone situated in Hamirpur district, Himachal Pradesh, India, to investigate high values of radon concentrations reported in past studies as well to update the old radon data based on bare SSNTD technique. In the present investigation, the concentrations of indoor radon, thoron and their decay products have been measured using the newly developed radon/thoron discriminating diffusion chamber with single entry face, direct radon and thoron progeny sensors (DRPS/DTPS), respectively. The measurements have been carried out in 75 dwellings of 14 different villages where the previous studies were carried out using bare SSNTD technique. It was observed that high values of earlier reported radon concentrations were mainly due to thoron interference in the Solid State Nuclear Track Detector (LR-115 type II) exposed in bare mode. Now, the average concentration values and the estimated annual inhalation dose in these villages have been found to be within the reference level as recommended by the ICRP. The annual average indoor radon and thoron concentrations observed in these dwellings have been found to vary from 44±12 to 157±73 Bq m(-3) and 44±11 to 240±125 Bq m(-3), respectively. The equilibrium equivalent concentrations of radon and thoron decay products have been observed to be in the range of 10 to 63 and 1 to 5 Bq m(-3), respectively.

English

The application of CR-39 SSNTD technique to the determination of radioactive contaminants in different kinds of milk can be very useful. Radon concentrations in animal milk samples collected from different countries were measured using the sealed-can technique based on the CR-39 SSNTDs. The average 222 Rn and 226 Ra concentrations are found to be 20.20 Bq m -3 and 0.15 Bq kg -1 , respectively. The highest radon exhalation rate was found in sample AL-Mudhish, Oman.

Radon exhalation from Libyan soil samples measured with the SSNTD technique

Radon concentrations in soil samples collected from the cities of Benghazi and Al-Marj, located in northeastern Libya, were measured using the sealed-can technique based on the CR-39 SSNTDs. Mass and areal radon exhalation rates, radium content and radon concentration contribute to indoor radon, and annual effective doses were determined. The results indicate mostly normal rates, but there were some higher levels of radon concentration and emanation in samples collected from Al-Marj and one sample from Benghazi.

Measurement of radon permeability through polyethylene membrane using scintillation detector

The permeability of Radon 222 through polyethylene membranes has been studied using activated charcoal technique. The permeability constant of Radon 222 through low-density polyethylene, linear low-density Polyethylene and high density polyethylene samples has been measured. There is a considerable agreement between the values obtained by our method and the method suggested by W. Arafa [2002. Permeability of radon 222 through some materials. Radiat. Meas. 35, 207–211], and SSNTD technique suggested by A. Hafez and G. Somogyi [1986. Determination of radon and thoron permeability through some plastics by track technique. Int. J. Radiat. Appl. Instrum. Nucl. Track Radiat. Meas. 12 (1–6), 697–700]. In this work Radon permeability through different polyethylene membranes has been measured using three different methods, i.e. solid state nuclear track technique, W. Arafa [2002. Permeability of radon 222 through some materials. Radiat. Meas. 35, 207–211] method and our proposed method. In addition to this, in this study, the diffusion coefficient of radon in charcoal as well as solubility of Radon in polyethylene membrane has been taken into consideration.

Angular distribution of photofission fragment of even-even and odd mass nuclei studies using SSNTD technique

Fission fragment angular distribution measurements of even-even (232Th) and odd mass (237Np) nuclei were carried out using bremsstrahlung radiation in the energy range 7.4 to 9.2 MeV from variable energy microtron at Mangalore University. In the present work SSNTD lexan polycarbonate films were used to detect the fission tracks from both even-even (232Th) and odd mass (237Np) nuclei. From the knowledge of track density formed from photofission reaction of 232Th and 237Np, angular distribution of fission fragments was measured. The results obtained are discussed on the basis of Age Bohr theory in this paper.

Radon exhalation rate and uranium estimation study of some soil and rock samples from Tusham ring complex, India using SSNTD technique

Besides uranium and radium, radon exhalation rate is also a crucial factor for radon emanation from ground or building material. In the present study uranium concentration and radon exhalation rate in the wide range of soil and rock samples collected from Tusham ring complex, Haryana, known to be composed of acid volcanics and the associated high heat producing granites, have been estimated. For comparative analysis, the soil samples from some districts of Punjab have also been analysed for uranium estimation and radon exhalation rate. The ‘can’ technique using plastic track detectors LR-115 type-II has been used for radon exhalation rate measurement, whereas the ‘Fission track registration’ technique has been employed for uranium content determination in these samples. The 222Rn exhalation rate in weathered granite area of the Tusham ring complex shows a maximum value of 63.76 Bq kg - 1 h - 1 , whereas the maximum value for uranium content has been found to be around 62.02 ppm. The corresponding values of exhalation rate and uranium content in the soil samples of this region are 11.54 Bq kg - 1 h - 1 and 13.41 ppm, respectively. A positive correlation between radon exhalation rate and uranium concentration has been observed for both soil and rock samples under the present investigation.

Neutron measurements using the SSNTD technique during prototype fast breeder reactor bulk shielding experiments

The in-vessel radial shield configurations for a Prototype Fast Breeder Reactor (PFBR) consist of layers of steel and borated graphite/boron carbide with sodium as coolant. This in-vessel shield is provided to reduce the neutron flux at the intermediate heat exchanger so that secondary sodium activation in the heat exchanger can be kept to an acceptable level. It is necessary to optimise this in-vessel shield because an over design will increase the cost of the reactor and under design will increase secondary sodium activation. Mock up experiments to study neutron transport through various combinations of shield models consisting of layers of steel, sodium, borated graphite and boron carbide were carried out. In these shield model combinations, along with activation detectors, SSNT detectors were also kept to measure the reaction rate by the ( n, f) technique. For this purpose, Lexan ® polycarbonate track detector were used in combination with various fissionable nuclides such as natural uranium, thorium, neptunium, depleted uranium, etc., either in deposition form or foil form. The fission reaction rates per atom in various neutron energy regions were evaluated by counting the induced fission track density. These reaction rates are being interpreted using an appropriate computer code for unfolding the neutron spectrum. The paper describes the results obtained from the fission track data in the various sets of the experiments.

Determination of spatial and energy distributions of neutrons in experiments on transmutation of radioactive waste using relativistic protons

The experiments on transmutation of 129I and 237Np using uranium-lead targets surrounded by a paraffin moderator were performed at the Joint Institute for Nuclear Research (JINR, Russia). The targets were irradiated by 1.5 GeV and 7.4 GeV protons at the Synchrophasotron of JINR. In the frame of present work spatial and energy distributions of neutrons on the surface of the paraffin moderator were measured using SSNTD technique. It is shown that measured values of spetral indices do not pretend on the energy of incident protons but depend on the target composition. The presence of the uranium insertion softens neutron spectra.

Radon exhalation rate and uranium estimation in rock samples from Bihar uranium and copper mines using the SSNTD technique

Widespread uranium mineralization is associated with copper, nickel and other sulphides in the Singhbhum shear zone developed at the northern margin of the Singhbhum craton in the state of Bihar of India. The south-eastern part of the shear zone between Surda-Mosabani-Badia is rich in copper mineralization while the central part between Jaduguda-Bhatin-Nimdih and Narwapahar-Garadih-Turamdih is enriched in uranium. In the present study, trace uranium concentration in geological samples from the Mosabani copper mine and the Narwapahar and Jaduguda uranium mine areas have been determined using fission track registration technique. For the measurement of the radon exhalation rate, the `can technique' using alpha sensitive LR-115 type II plastic track detectors were used. Uranium concentrations were found to vary from 1.5 to 2097.9 ppm whereas the radon exhalation rate varied from 0.2 to 19.2 Bq m −2 h −1. The values of radon exhalation rate from crushed rock and soil samples are found to correspond with the measured values of uranium in the corresponding samples. A positive correlation has been found between radon exhalation rate and uranium concentration in the samples. The linear coefficients are found to be 0.40, 0.98 and 0.95 in the Mosabani, Narwapahar and Jaduguda mine areas respectively. High values of radon exhalation in subsurface mines like Jaduguda (depth∼800 m) and Mosabani (depth>1000 m) seem to emphasize the need for adequate ventilation for the removal of radon and its progenies from the mines.

Neutron flux imaging with nuclear track detectors

The results of an investigation on the spatial variations of neutron flux using neutron-charged particle converter materials and solid state nuclear track detectors in a thermal neutron irradiation site are reported. In this context, three neutron beam maps have been established and analyzed. Neutron flux cartographies performed with the BN1 converter, which has been found to be more sensitive to neutron flux variations than the lithium tetraborate converter, have allowed location of neutron concentration areas. The results of average neutron flux measurements obtained by means of the SSNTD technique are in good agreement with those obtained using the conventional technique of neutron flux measurement by activation of foils.

Determination of radon and radium content of water samples by SSNTD technique

We have developed a method to determine the dissolved radon and radium content of water samples using etch track type radon monitors. In two measurements the radon exposures in a freshly sealed and in a degassed water sample are determined. From the measured exposures the radon and radium content of water is calculated.

Alpha activity measurements of biological samples from areas around the site of the Chernobyl nuclear disaster using the SSNTD technique

A set a five human hair and lung samples from supposedly contaminated and non-contaminated regions around the site of the Chernobyl nuclear accident of April 1986 have been analysed using the SSNTD technique. Only one of the samples displayed an alpha activity significantly greater than what might be expected in a normal healthy specimen. The results, thus, support the conclusions of the IAEA International Chernobyl Project meeting, held at Vienna in May 1991, indicating that many of the ill effects found in the area are primarily due to factors other than high environmental radiation levels.

Application of CR-39 solid-state nuclear track detectors to radon survey in the mine cities of inner Mongolia

The measurement of the indoor Rn concentration was performed in the main cities of the Inner Mongolia houses form Jan.1991 to Jun.1991 with the SSNTD technique. The average of indoor and outdoor Rn concentration has been found to be 33.0 Bqm-3 and 8.1 Bqm-3, respectively. The high accumulation of Rn concentration is formed easely in one-story houses with basement.

Radon permeability of foils measured by SSNTD technique (non-equilibrium approach)

Abstract A mathematical approach based on non equilibrium conditions was developed to determine radon permeability coefficient as well as radon/thoron separation factor for different synthetic materials with SSNTD technique. The method allows a reduction of exposure times down to some hours.

Assessment of the radioactivity of environmental samples by SSNTD technique

Plant samples collected from Transdanubia and spring water samples collected from the Highland of Lake Balaton were measured by alpha autoradiography with CR-39 detector. Standards were made in order to examine the influence of the sample matrix on the correlation between the track density and radioactivity concentration. The effective range of uranium alpha particles in grass ash was found to be 1.35×10-3 g/cm2 and that of the dry residues of water 8.26×10-4 g/cm2 The nominal uranium concentration of the spring water samples collected in 1989–1990 was found to be 0.5–3 μg/1 and that of ash samples 0.15–0.25 ppm. For the plant samples collected just after the Chernobyl accident this value was 0.5–2 ppm.

Radon-222 as an indicator of geothermal reservoirs behaviour

Radon-222 concentration in soils at shallow depth was measured at the “Los Azufres” geothermal field, Michoacan State, Mexico, in order to observe possible temporal variations in relation with the peculiar conditions of the area. A four years' survey is reported using the SSNTD technique. The obtained data indicate the feasibility of the technique for this type of investigation and illustrate the role of Radon-222 as a tracer of pore fluids motion in the substratum.

Radon signals related to seismic activity in Ecuador, March 1987

A radon concentration measurement survey was carried out in Ecuador using the SSNTD technique. The data analysis shows a definite radon anomaly prior to March 6, 1987;M=6.9 earthquake. Anomalies found before October 18 and October 28th mild earthquakes in 1986 could be correlated with these events. Other anomalies that we cannot correlate with any geophysical event were also found.