Radioactive Decontamination Research Articles

Adsorption of radioactive substances by an electrically activated natural adsorbent

Processes of radioactive decontamination of water with application of an electrical discharge effect are investigated. It is shown that use of electrical discharge of the torch type considerably increases the efficiency of the adsorption decontamination of water. By the method of thermally stimulated relaxation, it is revealed that accumulation of surface and space charges takes place in adsorbents. The method of X-ray structural analysis is shown to be a tool allowing qualitative investigation of the processes in the adsorbent structure.

The Chinese nuclear tests, 1964–1996

A combination of intellectual rigor, technical sophistication, hard work, and intelligence gathering brought China into the world’s nuclear club in record-shattering time.

Comparison of Different Types of Plasma in Radioactive Surface Decontamination Process

Comparison of Different Types of Plasma in Radioactive Surface Decontamination Process

Radiation protection in humans: extending the concept of as low as reasonably achievable (ALARA) from dose to biological damage.

Ionizing radiation has proven to be a double-edged sword since its discovery by Dr Roentgen in 1895. Radiation is a potent mutagen and carcinogen; however, it is also used in the diagnosis and treatment of human diseases. Background radiation consists of cosmic radiation and radiation emitted from radioactive substances present in the ground or commercial sources. Thus, all living organisms have been exposed to background radiation since their appearance on Earth. The appearance of oxygen some 4.5 billion years ago, allowed the appearance of aerobic organisms that used oxygen for their survival. The usage of oxygen generated toxic chemical species, free radicals, as byproducts. The interaction of radiation with oxygen may have caused increased production of free radicals. In order to cope with these adverse conditions, aerobic organisms that survived have antioxidant defence systems to quench excessive levels of free radicals and repair systems that can correct mutagenic changes. Today, humans, well equipped with antioxidant systems (from dietary and endogenous sources) and efficient repair mechanisms, are constantly exposed to varying levels of background radiation, depending upon the region and altitude where they live. In the USA, the average annual effective dose equivalent from natural sources to a member in the population is about 3.0 mSv (2.0 mSv from radon and 1 mSv from cosmic, terrestrial and internal) [1]. Medical exposure, consumer products, occupational, fallout, nuclear fuel cycle and miscellaneous contribute to about 0.6 mSv [1]. Patients can receive medical radiation exposure of varying levels up to 100 mSv, generally about 20 mSv or less, for diagnostic purposes. The use of radiation in medicine has always been rationalized on the basis of risk vs benefit. Owing to the growing use of nuclear energy in the world, especially in developed countries for civilian and military purposes, the concept of risk was applied to all personnel involved with radiation. In order to further safeguard against potential radiation damage, the concept of maximum permissible dose (MPD) was developed for the two major population groups. The annual MPD value for the general population for stochasticeffects, where the probability of the biological effect is proportional to the dose (linear no-threshold effect) is about 50 times less (1 mSv) than that recommended for radiation workers (50 mSv). In the UK, the radiation worker standard is 20 mSv as effective dose [2]. Although the value of MPD for radiation workers for the above effect has remained fairly constant during the last several decades, this value for the US population was recommended to be reduced by a factor of 5 in 1991 [3] and made law in 1993. This is due to the emergence of new data on low doses of radiation on somatic and heritable mutations in mammals and in mammalian cells in culture [4–7], the synergistic effect of the interaction of radiation with other chemical and biological carcinogens and tumour promoters on cancer incidence and mutations, and epidemiological studies in humans. To address the growing concerns of radiation-induced somatic and heritable mutations, the concept of ALARA (as low as reasonably achievable) with respect to dose was recommended by national and international radiation protection agencies for radiation workers [2, 3]. Efforts to protect normal tissues were started soon after the discovery of X-rays. However, the observation by Dr Muller of Columbia University in 1927, that radiation causes gene mutations inDrosophila melanogaster (common fruit fly) provided new impetus to reduce exposures [5]. The initial concept of radiation protection involved three physical principles: (a) shielding (usually by lead) of unexposed areas, especially radiosensitive organs such as bone marrow, gonads and thyroid; (b) increased distance between the radiation source and radiation workers or patients; and (c) reduction of exposure time. Each of these factors has been very useful, but they have limitations. For example, during fluoroscopy, it may not be possible to protect the gastrointestinal tract (one of the most radiosensitive organs) against radiation damage by lead shielding. Increasing the distance between the radiation source and exposed individuals may not be practical for many radiation workers, patients, civilian or military personnel. Reducing exposure time may also not be pertinent to all populations, except those that are involved in taking care of patients who have received gammaemitting radioisotopes for medical purposes or who are responsible for radioactive decontamination as a result of accidents or attack. Nevertheless, radiation protection based on physical factors has served a useful purpose and has been successful in reducing the level of unnecessary medical exposure to patients and to radiation workers. In order to protect normal tissues from potential radiation Received 31 March 2003 and in final form 1 September 2003, accepted 22 September 2003. The British Journal of Radiology, 77 (2004), 97–99 E 2004 The British Institute of Radiology DOI: 10.1259/bjr/88081058

Surface decontamination studies using polyvinyl acetate based strippable polymer

Polyvinyl acetate based strippable polymer has been developed for surface decontamination. Stainless steel, mild steel, polyvinyl chloride and rubber have been selected as candidate materials for the radioactive decontamination studies. The ease of strippability and homogeneity of the polymer coating has been studied using infrared spectrophotometer. Decontamination of used radioactive respirator has been carried out and the peels obtained have been subjected to leaching and incineration studies. The infrared spectrophotometric studies also have been counducted to study the interaction between polyvinyl acetate and ions, like cesium, strontium and cobalt.

An attemp to use a pulsed CO2 laser for decontamination of radioactive metal surfaces

There is a growing interest in laser radioactive decontamination of metal surfaces. It offers advantages over conventional methods: improved safety, reduction of secondary waste, reduced waste volume, acceptable cost. The main mechanism of cleaning by lasers is ablation. Apulsed TEACO2 laser was used in this work for surface cleaning in order to show that ablation of metal surfaces is possible even at relatively low pulse energies, and to suggest that it could be competitive with other lasers because of much higher energy efficiencies. A brief theoretical analysis was made before the experiments. The laser beam was focused using a KBr-lens onto a surface contaminated with 137 Cs (b-, t1/2 = 30.17 y). Three different metals were used: stainless steel, copper and aluminium. The ablated material was pumped out in an air atmosphere and transferred to a filter. The presence of activity on the filter was shown by a germanium detector-multichannel analyzer. The activity levels were measured by a GM counter. The calculated decontamination factors and collection factors showed that ablation occurs with a relatively high efficiency of decontamination. This investigation suggests that decontamination using a CO2 laser should be seriously considered.

原子力施設の廃止措置における「放射性廃棄物でない廃棄物」の区分手順 動力試験炉の解体における経験

In the final stage of decommissioning nuclear facilities, building structures are demolished to be green field conditions if dismantling is chosen as a decommissioning strategy. Since building structures are generally made from massive reinforced concrete materials, it is not a rational way to treat all concrete materials arising from its demolition as radioactive waste. Segregation of radioactive parts from building structures and measurement of radioactivity are therefore indispensable before demolishing building structures. The procedure of decontamination and measurement of radioactivity were studied for demolition of building structures in consideration of treating waste as non-radioactive materials, on the basis of the concept published by Nuclear Safety Commission. This procedure was then implemented in the Japan Power Demonstration Reactor dismantling demonstration project. The data obtained in the project relating to decontamination and measurement of radioactivity showed that the procedure was reasnable, and that the experiences will be useful for future decommissioning of nuclear power plants in Japan.This report describes the procedure studied on the segregation of non-radioactive waste related to decommissioning nuclear facilities, and the results of its implementation in the Japan Power Demonstration Reactor dismantling demonstration Project.

Use of electric-arc plasma for radioactive waste immobilization

We analyze the basic trends in the use of electric-arc plasma for radioactive waste decontamination. We present a scheme and performance figures of a process for a shaft-type furnace with fuel-plasma heating. We present the results of numerical and experimental investigations for a 150-kW direct-flow plasma reactor.

The Role of Mushrooms and Berries in the Formation of Internal Exposure Doses to the Population of Russia After the Chernobyl Accident

The present work is devoted to an analysis of the data on the dynamics of 137Cs transfer factors in the current most critical (for the population of Russia) links of food chain: 'soil mushrooms' and 'soil berries'. Data were obtained during 1986 - 1994 in the most contaminated region of Russia - the Bryansk region - and then were used for assessing the contribution of forest products consumed by the population of contaminated territories to internal exposure doses. It was shown in contrast to agricultural food products (where natural decontamination took place quickly) that radioactive decontamination of mushrooms and berries during the eight years after the Chernobyl accident was very slow. Use is made of aggregated radioecological data together with broad assumptions about the consumption of forest products to predict the doses that might arise from consumption of such foodstuffs. These predictions are then compared with values derived from whole-body measurements.

Decontamination of radioactive milk--a review.

The Chernobyl nuclear reactor accident in Russia in 1986 has further revealed the susceptibility of the environment to radioactive contamination. This can have serious implications for the safety of milk as well as other foods. Global fallout and other isotope releases can threaten to increase the radionuclide levels in milk alarmingly, and thus make it unfit for human consumption. Perception of such fears in the past resulted in considerable research efforts being directed towards radioactive decontamination of milk by different means. The holding of milk and milk products long enough to deactivate certain radioisotopes prior to consumption, conversion of milk into butter, and manufacturing cheese by using modified processes are some of the approaches in minimizing the radioactivity risk to consumers. Extensive studies carried out in the USA have shown that though somewhat expensive, ion-exchange treatment of milk in large-scale, automated plants can eliminate 90% or more of the radionuclides of concern, i.e. strontium-90, and iodine-131, and much of caesium-137. Various factors affecting the efficiency of the ion exchange process and properties of the treated milk are reviewed. Other processing techniques such as electrodialysis are also briefly discussed in relation to removal of radionuclides from milk.

High Solute Rejecting Membranes for Reverse Osmosis: Polyetheramide Hydrazide

Abstract Synthesis of benzhydrazide polymers and determination of reverse osmosis properties of their membranes were reported earlier. Although high solute rejections could be achieved, their performance was not adequate for seawater desalination or for high radioactive decontamination factors (DF). In the process of investigation of polymers with improved performance, the same hydrazide polymers modified by incorporation of additional monomers with ether linkages were synthesized by low temperature polycondensation of freshly prepared m−amino benzhydrazide, p−amino benzhydrazide, and 4,4′-diamino diphenyl ether, with isophthaloyl chloride and terephthaloyl chloride in dimethyl acetamide solvent. A series of film-forming polymers prepared by altering the molar ratios of the reacting monomers were characterized in terms of percent moisture regain, inherent viscosity, solubility parameters, and interfacial sorption characteristics. Asymmetric membranes prepared from these polymer samples were characterized ...

Techniques for radioactive decontamination in nuclear medicine

Working with unsealed radioactive sources in nuclear medicine carries the potential risk of contamination. Careful design of a department and its operational procedures will minimize but never completely eliminate the possibility of such incidents occurring. Contingency planning forms as important a part of handling such incidents as the procedures to reduce the hazard once an incident has occurred. It should include anticipating where such incidents are likely to occur, training and exercising staff in the appropriate procedures to deal with these incidents, providing a comprehensive decontamination kit, and implementing a routine contamination monitoring survey. Assessing the magnitude of the radiation hazard and the effect of decontamination efforts, containing the spread of contamination, minimizing the radiation dose to individuals, and continuing to decontaminate to the lowest level possible are principles to follow in managing any incident. Nuclear medicine staff should be familiar with techniques for decontaminating different anatomical sites on the body; for eliminating or reducing the uptake of radioactivity absorbed into the body; and for decontaminating dry and wet surfaces, equipment, clothing, and bedding. Radiopharmaceutical dispensing procedures, ventilation scanning, and decontaminating 131I treatment areas are identified as the most likely causes of body surface and internal contamination of nuclear medicine staff.

Radioactive substances decontamination exercise

Radioactive substances decontamination exercise

Radioactive decontamination of waste oil by filtration, centrifugation, and chelation

Laboratory studies were conducted on select physical and chemical processes for decontamination of a composite waste lubricating oil from a boiling water reactor. Physical treatments included successive filtration through 25, 8 and 1 μm filters to remove particulate matter and centrifugation to remove water. Chemical treatment consisted of mixing the oil with an aqueous solution of the chelating agent ethylenediaminetetraacetic acid (EDTA) and centrifuging the resulting emulsion. The effectiveness of the treatment processes was evaluated by measuring radionuclide concentrations in the oil following each treatment step and calculating decontamination factors. The total activity of the oil was dominated by 60Co, 54Mn, and 137Cs, although 51Cr, 58Co, 59Fe, and 134Cs were also present. Filtration consistently achieved decontamination factors of approximately 200, 100, and 40 for 137Cs, 54Mn, and 60Co, respectively, and reduced concentrations of the other radionuclides below their detection limits. Following filtration, centrifugation reduced 137Cs concentrations below the detection limit and reduced 54Mn and 60Co concentrations by approximately 40% and 20%, respectively. Subsequent chemical treatment with EDTA reduced the 54Mn concentration to below the detection limit and removed approximately 95% of the remaining 60Co activity. The overall decontamination factor for successive filtration, centrifugation, and chelation was in excess of 10,000 for 54Mn and 137Cs and on the order of 1000 for 60Co.

Decontamination of cotton tissues from some radioactive elements

Radioactive decontamination of cotton from some nuclides was investigated. The pH of the medium and concentrations of decontaminating agent and radioelement were principal factors affecting the interaction between the radioelements and cotton tissues. EDTA was found to be an economic and most effective decontaminating agent for radioactive-contaminated cotton tissues.

Electrolytic Decontamination of Stainless Steel Using a Basic Electrolyte

An electrolytic plutonium decontamination process or stainless steel was developed for use as the final step in a proposed radioactive waste handling and decontamination facility to be construced at the Rockwell International Rocky Flats plutonium handling facility. This paper discusses test plan, which was executed to compare the basic electrolyte with phosphoric acid and nitric acid electrolytes. 1 ref.

Radioactive decontamination methods and their effectiveness as a function of terrain.

Radioactive decontamination methods and their effectiveness as a function of terrain.

Propagation of high power helicons in [formula omitted]-indium antimonide crystal

Determining long-lived radionuclide concentrations in radioactive waste has fundamental implications for the long-term management of storage sites. This paper focuses on the measurement of low 129I contents in ion exchange resins used for primary fluid purification in Pressurised Water Reactors (PWR). Iodine-129 concentrations were successfully determined using Accelerator Mass Spectrometry (AMS) following a chemical procedure which included (1) acid digestion of resin samples in HNO3/HClO4, (2) radioactive decontamination by selective iodine extraction using a new chromatographic resin (CL Resin), and (3) AgI precipitation. Measured 129I concentrations ranged from 4 to 12 ng/g, i.e. from 0.03 to 0.08 Bq/g. The calculation of 129I/137Cs activity ratios used for routine waste management produced values in agreement with the few available data for PWR resin samples.

Radioactive decontamination by bacterial growth

Radioactive decontamination by bacterial growth

Radioactive Decontamination by Slurrying With Yazoo and Zilpha Clays

The level of radioactivity of most radionuclides discharged into watercourses must be reduced before the water can be consumed. One of the most practical methods of activity reduction is that of slurrying with clay as described by Lacy. Good results have been obtained by this method and by the addition of clay in conventional water treatment processes such as chemical coagulation and lime‐soda ash softening. The clays chosen for this experiment were Yazoo and Zilpha clays, which are found throughout the state of Mississippi and are easily mined near the surface. It was determined that each particular clay had to be slurried with each radioisotope before the overall effectiveness of the clay could be determined. This study was limited to three radioisotopes – Co60, Sr90, and Cs137 – which were selected because of their presence in most nuclear waste discharges, and the latter two are abundant in fallout from nuclear detonations.