Distribution Of Radioactive Material Research Articles

Testing and results of an open-source radiation epidemiology model using the Goiânia accident

In the event of dispersed radioactive materials, whether from accidental orphan sources or deliberate use of radiological dispersal devices (RDD) or radiological exposure devices (RED), free open-source modelling codes can greatly assist in forecasting the dispersion of the radiation following the event. Several codes are currently available to quickly calculate the progression of radiological dispersion. However, most of these codes can only simulate the evolution of the threat for limited times after the event and over relatively short distances from the location. In order to predict the transport of radioactive material over long distances and for long times, and thus prevent its expected effects on the exposed population, specific epidemiological codes can be used, taking into account the characteristic of the radiation. If it is considered that radioactive material can be deposited on unsuspecting people who continue their daily activities after exposure, it can be assumed that these people unintentionally carry this radioactive material over long distances. This scenario is comparable to viral vectors of a hypothetical virus designed to mimic the physical characteristics of radiation. In this work, the free open-source spatio-temporal epidemiological modeller (STEM) tool is used to simulate the spread of a chimeric viral agent with specific characteristics of Ebola and COVID-19, designed to replicate the biological conditions caused by exposure to a Cs-137 source for an individual unaware of the risk. The goal is to predict the territorial spread of radioactive material caused by a CBRNe event, such as orphan sources or the use of a RDD or a RED, and its possible effects on the affected population. This supports decision-makers in forecasting the consequences of radioactive material spread and thus helps in reducing the risk. The code was tested comparing its results with the real case of the famous 1987 Goiânia radiological accident. The results show that the developed code was indeed able to accurately represent the number of contaminated individuals and the number of casualties within a month of the initial exposure, with a distribution of radioactive material in the territory similar to that actually caused by the Goiânia accident.

Improvement of analysis results from the GAGG scintillator Compton camera operated on an unmanned helicopter by selecting stable flight conditions

ABSTRACT A Compton camera system for use on an unmanned helicopter was previously developed to characterize the distribution of radioactive materials in highly contaminated areas. For this study, a Compton camera system was equipped with a small camera, laser distance meter, an attitude angle sensor, temperature sensors, and real-time monitoring software for better measurement of flight parameters and more precise detection of hot spot locations. To confirm whether the detection results were improved by the modifications, ground-level ambient dose equivalent rate distributions were derived from hovering and programmed flights over a field in Okuma, Fukushima Prefecture (Japan) and compared against readings from survey meters taken at the ground level. For one hovering flight, the correlation between the datasets was improved by selecting a period of stable flight position and attitude and restricting the deviation of the attitude angles. Between 6.0% and 7.6% improvement in the position resolution was achieved using the data from stable flight periods, even when only 1-minute data windows were used. The precision of hot spot detections and ambient dose equivalent rate distributions obtained from the Compton camera were thus improved by the aforementioned modifications to the system.

Simulation Study of a Shield-Free Directional Gamma-Ray Detector Using Small-Angle Compton Scattering

Abstract Gamma-ray imaging is a technique for visualizing the spatial distribution of radioactive materials. Gamma-ray imaging has recently been applied to research on environmental restoration and decommissioning of the Fukushima Daiichi Nuclear Power Station (FDNPS). In this paper, we present an elemental technology study of the gamma-ray imager using small-angle scattering (GISAS), which is intended for application at the FDNPS decommissioning site. GISAS consists of a set of directional gamma-ray detectors that do not require a shield. In this study, we investigated the feasibility of a shield-free directional gamma-ray detector by simulation. The simulation result suggests that by measuring scattered-electron energies of several keV using a scatterer detector, gamma rays with ultrasmall-angle scattering could be selected. Using Compton scattering kinematics, a shield-free detector with a directivity of about 10 deg may be feasible. By arranging the directional gamma-ray detectors in an array, we expect to be able to realize the GISAS, which is small, light, and capable of quantitative measurement.

Unilateral Approval—Is it Working?

MDS Nordion, owned by Canadian based MDS Inc., designs, manufactures and uses transport packages for the distribution of radioactive materials used in the medical, research and sterilisation indust...

The Flow from Fukushima

Ocean Science As engineers continue their efforts to stabilize the Fukushima Daiichi nuclear power plant, marine scientists are studying the amount and distribution of radioactive material released into the ocean. Sources include atmospheric fallout, release of contaminated freshwater and seawater used to cool the reactors, and contaminated groundwater discharges, but the overall magnitude of the contamination is not well documented. Buesseler et al. have analyzed ocean data from TEPCO (Tokyo Electric Power Company) and the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) in comparison to data acquired before the accident. Ocean discharges peaked in early April, 1 month after the accident, but levels of cesium-137 remained more than 10,000 times higher than normal through the end of July, indicating continued release from the reactors or other sources. The impact on marine biota and humans through direct exposure is likely to be minimal, but further study is required to understand the full effects of bioaccumulation and associated implications for seafood and seaweed consumption by humans. Environ. Sci. Technol. 45 , 10.1021/es202816c (2011).

Lung counting: Comparison of a four detector array that has either metal or carbon fiber end caps, and the effect on array performance characteristics

Abstract This study described the performance of an array of HPGe detectors, made by ORTEC. In the existing system, a metal end cap was used in the detector construction. In general, the natural metal contains some radioactive materials, create high background noises and signals during in vivo counting. ORTEC proposed a novel carbon fiber to be used in end cap, without any radio active content. This paper described the methodology of developing a model of the given HPGe array-detectors, comparing the detection efficiency and cross talk among the detectors using two end cap materials: either metal or carbon fiber and to provide a recommendation about the end cap material. The detector's counting efficiency were studied using point and plane sources. The cross talk among the array detectors were studied using a homogeneous attenuating medium made of tissue equivalent material. The cross talk was significant when single or multiple point sources (simulated to heterogeneous hot spots) were embedded inside the attenuating medium. With carbon fiber, the cross talk increased about 100% for photon energy at about 100 keV. For a uniform distribution of radioactive material, the cross talk increased about 5–10% when the end cap was made of carbon instead of steel. Metal end cap was recommended for the array of HPGe detectors.

Simulation of a method for determining one-dimensional 137Cs distribution using multiple gamma spectroscopic measurements with an adjustable cylindrical collimator and center shield

With multiple in situ gamma spectroscopic measurements obtained with an adjustable cylindrical collimator and a circular shield, the arbitrary one-dimensional distribution of radioactive material can be determined. The detector responses are theoretically calculated, field measurements obtained, and a system of equations relating detector response to measurement geometry and activity distribution solved to estimate the distribution. This paper demonstrates the method by simulating multiple scenarios and providing analysis of the system conditioning.

Liposomal distribution in malignant glioma: possibilities for therapy.

We investigated the potential of 111In-labelled liposomes to specifically target recurrent high-grade glioma in eight patients, all of whom had clinical and radiological evidence of relapse following prior treatment with surgery and radiotherapy. The phospholipid liposomes were labelled with 74 MBq 111In and injected intravenously. The distribution of radioactive material in the brain was imaged using a dedicated neuro-SPET imager. Images were taken 1 h post-injection and repeated at 24, 48 and 72 h. In addition, whole-body images were performed with a gamma camera and blood taken for radioactivity determination. At 72 h post-injection, excellent tumour demarcation could be seen in seven of eight patients. The images obtained correlated well with the corresponding computed tomography images. Blood radioactivity levels gradually declined over the 72 h. Tumour uptake continued to rise throughout this time and, together with the steady fall in normal brain tissue, the tumour-to-brain contrast gradually increased (maximum 7:5). Whole-body images indicate that the liver is the major organ of uptake with up to 50% of the injected dose. No toxicity could be attributed to the injected liposomes. Although the total percentage uptake was low (1.1%), the tumour-to-brain contrast ratios, together with the SPET images, suggest the potential for tumour-specific targeting.

Transfer of benzo(a)pyrene into mouse embryos and fetuses.

The distribution of radioactive material within maternal and embryonic/fetal mouse tissue was studied over a period of 2 days following a single dose of 14C-benzo(a)pyrene (B(a)P) orally on days 11, 12, 13 or 18 of pregnancy. B(a)P poorly penetrated into the embryo/fetus, and 14C-radioactivity was found in embryonic tissues at concentrations one to two orders of magnitude lower than in maternal organs. If the compound was administered for 3 consecutive days at the same dose the expected cumulation was compensated for by an accelerated elimination of the substance, which is probably due to enzyme induction.

Electron microscope autoradiographic evidence for specific transneuronal transport in the mouse accessory olfactory bulb

The distribution of radioactive material was examined autoradiographically 8 h after application of [ 3H]proline to the vomeronasal organ in mice. Labelled material was transported along the axons of the vomeronasal nerves to their terminals in the glomerular layer of the accessory olfactory bulb (AOB). A lesser but consistent amount of radioactivity was found in the external plexiform layer (EPL) of the AOB. Electron microscopic autoradiography was used to determine which of the components of the EPL contained this labelled material. The method of proportional grain counts showed that the highest concentration of silver grains lay over the mitral cell dendrites, which are the elements immediately postsynaptic to the vomeronasal nerve axons. However, a fairly high proportion of grains also lay over the peripheral processes of granule cells. By application of a method of ‘crossfire analysis’ (which is explained in detail) it was possible to show that the observed grain distribution is best explained by the assumption that the radioactive material is confined to mitral cells, and the labelling over granule cell processes is due to crossfire from these sources. In one animal at 5 days after [ 3H]proline administration label was found to have extended from mitral cells to granule cells, suggesting that the transsynaptically transported radioactive material, which was confined to the mitral cells at 8 h, may have become further redistributed at longer survivals. In a control experiment, [ 3H]proline was applied directly to the surface of the AOB. This gave rise to a completely different distribution of radioactivity in the EPL: radioactive material was present in all tissue components.

Distribution of radioactive materials in aquatic environments, with consideration of their carcinogenic potential in aquatic animals.

Distribution of radioactive materials in aquatic environments, with consideration of their carcinogenic potential in aquatic animals.

原研東海研究所における放射性固体廃棄物焼却処理装置の排ガス除染性能

The radioactive waste incinerator at Tokai Research Establishment, JAERI was installed in 1966, and has been operated routinely for seven years. In the operation, a lot of inadequate parts of the incinerator such as furnace, spray scrubber, cyclone, and electrostatic precipitator have been improved.This experimental program was carried out to examine the decontaminability of furnace and exhaust-gas system. The decontamination factors (DF) of the incinerator components were determined by obtaining the ratio of activity of 32P in the influent gas to that in the effluent gas. DF of 3.6×10 in the spray scrubber and 7.0×10 in the electrostatic precipitator were obtained. Retention factor in the furnace was 2.3×10. Using the value of 1.0×102 in the cloth filter and 1.0×103 in the HEPA filter obtained in the previous examination (in 1966), the over-all DF of the incinerator was calculated to be 6×109.Also the distribution of radioactive material in each part of incinerator was 93% in the ash, 5% in the spray scrub solution, 0.5% in the electostatic precipitator, 0.02% in the cloth filter and 0.3% in the duct of exhaust-gas.

Cooling rates and thermal histories of iron and stony-iron meteorites

Cooling rates of meteorite parent bodies are calculated on the basis of theoretical thermal models. These calculated cooling rates are compared with meteorite cooling rates derived by diffusion-growth analysis of the metal phase of iron and stony-iron meteorites. Previous thermal calculations are extended to include effects of melting, redistribution of radioactive heat sources, and surface heating. For a range of assumed conditions, the cooling rates depend strongly on the extent of internal redistribution of radioactive elements. Cooling rates calculated for uniform and fractionated parent bodies exceeding 100 km in radius can differ by a factor of more than 3. Since the distribution of radioactive materials is uncertain, size estimates for bodies with a radius exceeding 100 km can only be narrowed to a range of values bounded by the uniform and the fractionated case. This range of body sizes is still compatible with an origin of iron and stony-iron meteorites in asteroidal bodies. The present calculations are not consistent with the development of iron meteorites by surface heating of parent bodies. The core model appears to be appropriate for some iron meteorites. However, the variable cooling rates for iron meteorite groups IIIa and IVa are explained by a model where small iron bodies are distributed throughout a large region of the parent body from the deep interior out to a fractional radius of 0.90 to 0.96. It is proposed that such a distribution of iron meteorites could be produced by a zone melting process

Metabolism of neutral steroids in the human fetus (I) distribution of radioactive material in the previable human fetus after administration of progesterone-4- 14c

Progesterone-4- 14C was injected into three male fetuses after 13 to 22 weeks gestation via the pulsating umbilical vein within a period of 30 seconds. The first fetus was examined 8 minutes after the injection, the second 12 minutes, and the third 18 minutes after the injection. Much radioactivity present in the free form amounted to 85.1%, 78.6% and 73.1% of the total, respectively. Other tissues of the fetuses, such as the kidney and adrenal, were also examined and the results obtained confirm those of other workers. The radioactivity in the liver was analyzed and the following metabolites were isolated and identified: 20α-dihydroprogesterone (49.0%, 30.6% and 35.5% of the total free steroid, respectively); 17α-hydroxyprogesterone (1.6% 1.5% and 1.5%, respectively); 16α-hydroxyprogesterone (1.8% of the radioactivity in the fetus after 13 weeks gestation); and 5β-pregnane-3α,5α-diol (2.4% in the fetus after 17 weeks, and 2.4% in the fetus after 22 weeks gestation).

Autoradiographic distribution studies of 3h-labeled prostaglandin e 1 in mice. prostaglandins and related factors 31

3H-labeled prostaglandin E 1 (2–7 μg) was injected intravenously into mice and the distribution of radioactive material was studied by autoradiography. Autoradiograms obtained from sagittal sections of the whole body showed high concentration of 3H in the kidney, liver and connective tissue. Lower but significant uptakes were also observed in the lungs and in the myometrium of uterus. The results were discussed in relation to current concepts of metabolism and biological effects of prosta- glandin E 1, and also in relation to possible new sites of action.

AUTORADIOGRAPHIC STUDIES ON PREVIABLE HUMAN FOETUSES PERFUSED WITH RADIOACTIVE STEROIDS. 1. DISTRIBUTION OF RADIOACTIVE MATERIAL FOLLOWING PERFUSION OF PROGESTERONE-4-14C.

ABSTRACT Using the technique of whole-body autoradiography, the distribution of radioactive material was studied in two previable foetuses following perfusion with progesterone-4-14C. The uptake of radioactivity was by far the highest in the adrenal cortex. A specific accumulation of radioactive material was also demonstrated in the pituitary gland, testicles, thyroid and thymus. The liver, intestinal mucosa, kidneys and certain structures of the developing eye and central nervous system also showed an increased uptake. The possible physiological significance of the findings is discussed.

The behaviour of recoil atoms in ionic solids

The rate of escape of thoron from solids containing radiothorium depends upon both recoil and diffusion, and is steady at any temperature if the distribution of radioactive material remains unchanged. At very high temperatures the emanating power of ThO 2 (and other indexed oxides) increases with time at constant temperature; the emanating power-temperature characteristics eventually resemble those of a solid with a surface source of thoron. The enhancement of emanating power decays with time in such a way as to prove that Th X is no longer uniformly distributed, although the distribution of the parent Rd Th is unchanged; the Th X atoms, formed by recoil from Rd Th, migrate during their lifetime to trapping sites which, in this case, are on the surface. Similar effects are found with BaThO 3 and BaF 2 , even though Th X (= Ea) can replace Ba isomorphously; these compounds are anionic conductors and have only a low concentration of vacant cation sites at high temperatures. If (e.g. in BaO) vacant sites capable of accepting large cations are present in high concentration, the recoil atoms are trapped and retained in uniform distribution.

Significance of Radioactivity in Water Supply and Treatment

This article begins by providing a brief overview of the biologic effects of radioactivity. Variables that affect the extent of health effects of radiation include: quantity of material absorbed; distribution of radioactive material in the body; the half‐life of the material; and, the rate at which the material is excreted from the body. Various forms of potential sources of radioactive contamination of water supplies are discussed, along with methods for removal of radioactive materials from the water supply that include: natural processes of riverbed sedimentation, ion exchange capabilities of silts, the biologic processes of both plants and animals including some forms of algae, the natural filtration of water percolating down through the earth to an aquifer, and the ion exhange properties of minerals and clays; conventional treatment plant processes of coagulation and sedimentation, filtration, lime soda ash softening, and ion exchange; and, beds of steel, clay pellets, activated carbon, and cation‐anion‐exchange resins in series. Distillation units are also mentioned as capable of removing nonvolatile materials, but are expensive and limited in capacity.

CLOSE-IN FALLOUT

Abstract The phenomenon of radioactive fallout from an atomic explosion is described, and a quantitative technique for determining the distribution of radioactive material on the ground is developed. The primary factors which must be considered are wind field, yield and height of burst, and particle-size distribution. Certain parameters which enter directly into a fallout determination are given quantitatively, such as the altitude and size of the atomic cloud (as a function of explosion yield and atmospheric stability) and particle fall-rates (as a function of altitude and particle size). Two hypothetical fallout patterns for a one-megaton explosion, computed on a high-speed digital computer are presented, showing the large effect which the wind has in determining the character of the fallout. The meteorological problems associated with a fallout prediction are discussed.

A device to determine the distribution of radioactive material in a source.

A device is described, incorporating lead screens and a Geiger counter, which offers an alternative method to that of autoradiography for determination of the distribution of radioactive materials.