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Decontamination and cleaning of surface-contaminated radioactive waste using laser ablation is a promising new technique being researched. One advantage is the potential to recycle waste and reduce the demand for repository storage. However, prior studies have shown that residual radioactivity can persist after laser decontamination indicating the incorporation of contaminants beneath the surface of metal samples. In this study, a q-switched laser was used to measure the depth of the recast zone at various fluences and simulate a decontamination process using a gold-coated sample. The results showed that surface material was found in the recast zone for fluences ranging from 1 to 10 J/cm2. This suggests that incorporation of surface contaminants after laser ablation is an important issue that must be considered before using this technique for radioactive waste treatment. [ABSTRACT FROM AUTHOR]

Here we present a newly developed two-step oxidative-reductive in-service chemical decontamination process suitable for high temperature and high pressure circuit (HTHPC) decontamination in a pressurized water reactor (PWR). Various process parameters on the corrosion depth and decontamination factor were investigated by employing different kinds of detergents. Under optimal conditions, the average decontamination factor is about 60.0 and the maximum corrosion depth is 0.20 um. Actual decontamination by applying this process to HTHPC, the dose field in most locations decreased by more than 89% and it's proved that the decontamination process is completely suitable for the decontamination of PWRs in service. [ABSTRACT FROM AUTHOR]

Radioactive contamination induced by nuclear leakage accidents, nuclear and radiation terrorism and other radioactive pollution events needs to be controlled and removed urgently, otherwise it will cause a wider range of pollution diffusion and radioactive risk. Strippable coatings have been employed for radioactive contamination removal for a period of time. Since ALARA™ 1146 paved the way, an ever-growing number of developments that aim to bring higher performance and new pattern decontamination process have been conducted. In this article, the composition and decontamination performance of strippable coatings in recent years are reviewed. Some so-called unconventional and new forms of strippable decontamination materials have also been presented. In addition, the direction of growth potential for strippable coatings in the future is also prospected. These directions include (a) paying more attention to optimize the decontamination performance, (b) enabling the strippable coatings multifunctional, (c) improving the environmental friendliness of strippable coatings and (d) improving the decontamination timeliness of strippable coatings. [ABSTRACT FROM AUTHOR]

The feasibility of the chlorination reaction as a decontamination technique for 90Sr-contaminated concrete waste was investigated via thermodynamic and experimental approaches. Thermodynamic calculations suggested that SrO reacts with chlorine prior to CaO, CaCO3, and MgO, while other oxides remain in their oxide forms. It was found experimentally that a temperature of at least 700 °C is required to convert more than 40% of SrO into SrCl2. A set of comparison experiments performed at various temperatures verified that CaO exhibits higher conversion ratios than those of SrO, while significantly lower ratios were observed with CaCO3. [ABSTRACT FROM AUTHOR]

The AP1000 reactor of China would overhaul for the first time. In order to achieve in-service decontamination of AP1000 primary loop equipment, three simulated corrosion oxides of the AP1000 reactor primary loop were prepared by sedimentation-calcination method, and ultrasonic chemical dissolution test was conducted. The analysis of the characteristics of the simulated oxide showed that the addition of zinc resulted in a different composition of the oxides from that of ordinary PWR, and that is smaller particle size and tighter bonding. Suitable decontaminants and decontamination processes were identified by the dissolution laws of the simulated oxides in the experiment. [ABSTRACT FROM AUTHOR]

The SP-HyBRID process, which has a similar performance to commercial technologies for the decontamination of a nuclear reactor coolant system, can reduce the secondary waste generation significantly. However, the process has a problem of discharging decontamination wastewater every cycle. In this study, an improved SP-HyBRID process that can conduct the process cycles continuously without discharging decontamination wastewater every cycle was designed. It was confirmed that the improved process could be effectively applied to equipment for a decontaminating test of contaminated components, and the waste reduction can be close to 15% when compared with the existing SP-HyBRID process. [ABSTRACT FROM AUTHOR]

This study selects microalgae suitable for the decontamination of radioactive cobalt (Co-60) in radioactive solutions based on the decontamination efficiency of Co-60 and Cs-137 by various microalgae. The biosorption rates of Co-60 in the low-level contaminated water have been measured using three different types of microalgae Haematococcus sp., Vacuoliviride crystalliferum, and Chlorella vulgaris, which are known to uptake Cs-137 and Sr-90 effectively. In the comparative experiments, Haematococcus sp. showed the highest decontamination efficiency within 48 h, and it could be a suitable bio-adsorbent out of three types of microalgae for the removal of Co-60. Haematococcus sp. also removed 88.0% of Cs-137 from contaminated water for 48 h. Our findings indicated that the low-level radioactive solution was decontaminated to a very low-level state through the biosorption process of microalgae. [ABSTRACT FROM AUTHOR]

Decontamination processes always generate large volumes of secondary waste. As a result, strong demand for new technologies capable to remove radionuclides and recycle the residue, thus minimizing the amount of waste, is required. In this case, ionic liquids offer reasonable potential of various ways how to separate and concentrate radionuclides directly and with additional recycling option. A model experiment was performed for cobalt extraction from systems simulating selected aspects of spent decontamination solutions by using various ionic liquids and dissolved extractant. Based on the results, a two-step separation method consisting of extraction followed by electrodeposition using an extractant dissolved in ionic liquid phases was suggested, which represents a promising system for recycling of decontamination solutions and thereby reduction of the respective waste. [ABSTRACT FROM AUTHOR]

It is very important to minimize the secondary waste generation for the decontamination of the primary coolant system. The SP-HyBRID process can obtain a similar decontamination performance to the HP CORD UV process. The SP-HyBRID decontamination wastewater can be purified by a precipitation process using Ba(OH)2, and the waste generation can be greatly reduced. For this reason, removal tests of impurities in a SP-HyBRID decontamination wastewater surrogate were conducted using the precipitation process. As the results, the impurities in the surrogate were effectively removed, and the waste generation was reduced by 60% when compared with the HP CORD UV process. [ABSTRACT FROM AUTHOR]

The spontaneous reductive decomposition behavior of HMnO4 in water as a function of the initial HMnO4 concentration and reaction temperature was investigated. The decomposition of HMnO4 was fast in the early stage of the reaction and thereafter slowed down significantly, regardless of the initial HMnO4 concentration. The loss of HMnO4 by spontaneous reductive decomposition increased with increasing reaction temperature. Based on the experimental results and the classical nucleation theory, a mathematical model was developed using a combination of two first-order reactions representing the nucleation and crystal growth of MnO2 to predict the spontaneous reductive decomposition behavior of HMnO4. [ABSTRACT FROM AUTHOR]

Many of the water coolant nuclear reactors are following the zinc ion water chemistry route to mitigate the radioactivity build up in out of core area due to Co. Decontamination of these systems with chromium oxide as a passive layer require redox multi cycle process, and permanganate based formulation is used in this regard. The present article highlights the chemical dissolution behaviour of chromites and also sorption behaviour of released metal ion during the permanganate medium treatment. Chromites, MFeCrO (M = Co, Ni and Zn, x = 0.0, 0.2 and 0.4) were synthesised by combustion process and characterised by XRD and laser Raman spectroscopy and were used for dissolution studies. Cobalt and nickel chromite showed a lower dissolution rate and higher sorption of cobalt on the MnO compared to zinc chromite in HMnO. [ABSTRACT FROM AUTHOR]

Batch experiments were conducted to study the ability of hazelnut shell activated carbon (HSAC) to remove uranium(VI) ions from aqueous solutions. The effects of various operational parameters, such as contact time (0-200 min), pH (2.0-7.0), initial U(VI) concentration (20-240 mg/L) and adsorbent dosage (4.0-50 g/L) were examined. Results showed that the adsorption process was rapid within the first 100 min and then achieved equilibrium at 140 min. The kinetics followed a pseudo-second-order rate equation, and the adsorption process was well fit with the Langmuir model. HSAC exhibited good uranium adsorption capacity (16.3 mg/g) at pH 6.0, 140 min contact time and 8.0 g/L adsorbent dosage. Furthermore, the regeneration efficiency was 96.3 % over five cycles under the optimum operational conditions. These properties revealed that HSAC can be a suitable adsorbent for the fast and convenient removal of U(VI) from contaminated water. [ABSTRACT FROM AUTHOR]

Silica nanoparticles synthesized by using TEOS/CTABr/NHOH/HO were modified with a grafting method using organic amino functional groups. The physical properties of the surface-modified nanoparticles and their sorption behavior with regard to radioactive cobalt and the effect of the surfactant on the sorption were evaluated. The surface-modified nanoparticles had a non-hexagonal structure owing to the partial collapse of the mesopore wall on the surface of the silica nanoparticle. The cobalt sorption capacity increased with the number of amine groups within the organic functional group. An evaluation of the effect of surfactant on cobalt sorption found that the sorption performance was reduced by 0.1 mg/g. [ABSTRACT FROM AUTHOR]

Indoor electrokinetic decontamination equipment was manufactured to treat 1.2 tons of uranium-contaminated soil. For a reduction of waste electrolyte and metal oxide, waste electrolyte was reused and the optimum pH was adjusted to minimize metal oxide volume in the cathode chamber. It was found that the optimum pH of the waste electrolyte in a cathode chamber was below 2.35 at 25 °C. When the initial uranium concentrations in the soils were 7.0-27.0 Bq/g, the reuse periods of waste electrolyte required for uranium concentrations in the soils to reach below 5.0 Bq/g were 5-25 days. In addition, when the initial concentrations in the soils were 7.0-20.0 Bq/g, the periods required to reach below the clearance concentration level were 25-40 days. [ABSTRACT FROM AUTHOR]

Agricultural soil containing radioactive cesium was decontaminated using an extraction method involving aqueous potassium solutions. Results demonstrated that the potassium solution could extract radioactive cesium from soil artificially contaminated with Cs, although extraction rate decreased as time after contamination increased. However, visual examination of radioactivity distribution in soil samples significantly contaminated by the accident at the Fukushima Daiichi nuclear power plant showed that radioactive cesium also existed as insoluble particles. Therefore, reducing the volume of radioactive wastes generated from soil decontamination requires a physical decontamination method combined with chemical treatment. [ABSTRACT FROM AUTHOR]

Practical decontamination procedure and equipments have been developed to decontaminate uranium-contaminated concrete waste generated from a uranium conversion plant. The direct burning of mortar block coated with epoxy and then the mechanical removal of the burned surface reduces the amount of sludge by preventing the dissolution of whole cement paste in concrete block. And the removal of calcium from the concrete washing solution for the use of electrokinetic equipment decreases the volume of waste by a recycling of the solution. This improved decontamination procedure makes more than 70 % of concrete waste be self-disposed and remarkably reduces secondary radioactive waste. [ABSTRACT FROM AUTHOR]

The extraction behavior of Pu(III), Pu(IV), Np(IV) and Np(V) with di(chlorophenyl)-dithiophosphinic acid (DCPDTPA) in toluene from nitric acid solutions was studied systematically. In aqueous solution with high nitric acid concentration, the extraction capability (represented by distribution ratio D) for Pu and Np in different valences with DCPDTPA comes as D > D > D > D. A new radiochemical procedure for Np/Pu separation based on DCPDTPA extraction was proposed and tested with simulated samples. The recoveries of Np and Pu are as high as 80 % after the whole separation procedure, with the decontamination factor of trivalent lanthanide fission product element (e.g. Eu) greater than 1.5 × 10. The decontamination factor of Pu-Np is 2.0 × 10, while the decontamination factor of Np-Pu is greater than 4.8 × 10 after additional purification. [ABSTRACT FROM AUTHOR]

This paper describes the use of molecular recognition technology product AnaLigSr-01 gel from IBC Advanced Technologies, Inc. to effectively and selectively pre-concentrate, separate and recover strontium from evaporator concentrate samples from Nuclear Power Plant Mochovce which belongs to the most difficult matrices to analyze. The method is suitable for analyzing highly contaminated samples of radioactive waste in a relatively short time and with high decontamination factors. Activity of Sr was measured using Cherenkov counting on TRI CARB 2900 TR liquid scintillation counter. [ABSTRACT FROM AUTHOR]

Ground water was collected from a depth of 1,200 m in the Al-Qasim area in mid-Saudi Arabia. This underground water contains minerals, mainly Fe and Mn and radio-nuclides like radium and other ionic materials. This water was filtered through a sand bed, which contains layers of sands of different sizes in order to remove those impurities from water. Mn and Fe were deposited on outer layer of each sand granule during filtration and radium was adsorbed on surfaces of these minerals. Ra was separated from these minerals by dissolving them in various acids such as ascorbic acid, citric acid, tannic acid, salicylic acid, tartaric acid and lactic acid under different experimental conditions like acid concentration, contact time, shaking speed, particle size, temperature and liquid/solid ratio. The effectiveness of these acids on radium removal was found as follows: ascorbic acid ≈ citric acid > tartaric acid > tannic acid > lactic acid > salicylic acid. Various reaction parameters were also optimized. Reaction kinetic and mechanism parameters of dissolution process were studied and compared with other published data. [ABSTRACT FROM AUTHOR]

The chemical precipitation method for radioactive wastewater treatment has the advantages of being simple and cost-effective. However, difficulties with the solid-liquid separation and sludge concentration restrict the application of this method. In this paper, a pellet co-precipitation micro-filtration (PCM) process was studied for treating strontium-containing wastewater on a laboratory scale. The seed was prepared by CaCO powders. Sr and CO were constantly crystallised on the seed surface, with NaCO as the precipitating agent in the pellet reactor. The following membrane separator with the addition of FeCl enhanced the treatment effect. The average strontium concentrations in the raw water and in the effluent were 12.0 and 0.0220 mg/L, respectively. The strontium decontamination factor (DF) increased with the operation time, with an average value of 577. The precipitate particles formed gradually grew larger, with good sedimentation properties. When the experiment was complete, the formed precipitate was separated easily from the liquid phase and directly discharged. The concentration factor (CF) was 1,958. In the PCM process, crystallisation was the main mechanism for strontium removal, with the influent strontium level playing an important role. Membrane pore blockage and cake layer formation could help to further intercept the strontium crystallites. Furthermore, ferric chloride coagulation in the membrane separator also contributed to strontium removal. The PCM process has potential for wider application in the removal of strontium from wastewater. [ABSTRACT FROM AUTHOR]

The source material for the study of X-ray induced γ emission,Hf was obtained as Hf(OH) by a variety of separation methods, such as precipitation, solvent extraction and ion exchange chromatography to isolate Hf from an ytterbium target with a copper substrate, after irradiation in a cyclotron with α particles. The target was prepared by vacuum filtration technology. The overall chemical yield and decontamination factors of this separation process were measured with radioactive tracers. The results show that the chemical yield of the whole process is about 69 % for hafnium and the decontamination factor is very good for Zn (~10) and good for Lu (~10). [ABSTRACT FROM AUTHOR]

A wide variety of materials can become contaminated by radionuclides, either from a terrorist attack or an industrial or nuclear accident. The final disposition of these materials depends, in large part, on the effectiveness of decontamination measures. This study reports on investigations into the decontamination of a selection of building materials. The aim has been to find an effective, easy-to-use and inexpensive decontamination system for radionuclides of cesium and cobalt, considering both the chemical and physical nature of these potential contaminants. The basic method investigated was surface washing, due to its ease and simplicity. In the present study, a basic decontamination formulation was modified by adding isotope-specific sequestering agents, to enhance the removal of cesium(I) and cobalt(II) from such construction materials as concrete, marble, aluminum and painted steel. Spiking solutions contained Cs or Co, which were prepared by neutron activation in the SLOWPOKE-2 nuclear reactor facility at the Royal Military College of Canada. Gamma spectroscopy was used to determine the decontamination efficiency. The results showed that the addition of sequestering agents generally improved the radiological decontamination. Although the washing of both cesium and cobalt from non-porous materials, such as aluminum and painted steel, achieved a 90-95 % removal, the decontamination of concrete and marble was more challenging, due to the porous nature of the materials. Nevertheless, the removal efficiency from 6-year-old concrete increased from 10 % to approximately 50 % for cobalt(II), and from 18 to 55 % for cesium(I), with the use of isotope binding agents, as opposed to a simple water wash. [ABSTRACT FROM AUTHOR]

Technetium decontamination factor as a function of the acidity, flow ratio, scrubbing stage number was investigated by counter-current cascade experiments or mixer-settler batch tests. Results showed that the acidity of the scrubbing acid has little influence on the decontamination factor of technetium when the acidity was kept in the range of 4.5-6 M. The most effective method to increase the decontamination factor is to lower the feed-to-acid flow ratio. Keeping other condition same the factor increased to 10.3 from 3.1 when feed-to-acid ratio changed to 4 from 5.6. The loss of uranium and plutonium can be recovered through a re-extraction technology. [ABSTRACT FROM AUTHOR]

This paper describes a rapid method of Nb pre-concentration, separation and purification by using cation and anion exchange resins. The method is suitable for analyzing highly contaminated radioactive waste samples in a relatively short time and high decontamination factors. The use and effectiveness of the method was successfully tested by analysis of samples from nuclear reactor parts such as control rod drive shaft, shielding cassettes, neutron in-core measurement channels (KNI), pressure vessel construction material and fuel cassette construction material samples. [ABSTRACT FROM AUTHOR]

Decontamination technologies are generally developed to reduce the collective dose of the maintenance and operation personnel at nuclear power plants (NPP). The highest efficiency (i.e., the highest decontamination factors) available without detrimental modification of the treated surface of structural material is the most important goal in the course of the application of a decontamination technology. At the Paks NPP the AP-CITROX procedure has been utilized for the decontamination of the primary coolant circuit's components (e.g., main circulating pump (MCP) and steam generators (SGs)). Our previous studies have revealed that a 'hybrid' structure of the amorphous and crystalline phases was formed in the outermost surface region of the austenitic stainless steel tubes of SGs as an undesired consequence of the industrial application of the AP-CITROX decontamination technology during the period of 1993-2001. In this paper, we report some comparative findings on the corrosion and surface chemical effects of the AP-CITROX procedure and the novel decontamination technology elaborated at our institution. On optimizing the operational parameters the latter technology may become suitable for the effective decontamination of both dismountable (e.g., MCP swivel) and separable (e.g., SGs) equipments. For this purpose experiments were performed. In this laboratory scale experiments, the passivity, morphology and chemical compositions of the treated surfaces of tube specimens were investigated by voltammetry, and SEM-EDX methods, respectively. The SEM-EDX results have revealed that the oxide removal is surprisingly uniform even after 2 or 3 consecutive cycles. The electrochemical studies have provided evidences that no unfavorable tendencies in the general corrosion state of the tube samples can be detected in the course of the chemical treatments. [ABSTRACT FROM AUTHOR]

This study characterized the removal of strontium from an aqueous solution via co-precipitation followed by microfiltration (CPMF) on a lab-scale. Sodium carbonate was used as the precipitating agent. Ferric chloride was added to a settler at a dosage of 20 mg/L to improve strontium removal, and it was added to a membrane separator at a dosage of 10 mg/L to reduce membrane fouling. The concentration of strontium in the raw water used in this study was about 5 mg/L. In two intermittent tests, where dosages of sodium carbonate were 2000 mg/L and 1000 mg/L, the mean decontamination factors (DFs) were 237 and 158 and the mean concentration factors (CFs) were 288 and 462, respectively. Although the mean DF value was lower when the sodium carbonate dosage was 1000 mg/L instead of 2000 mg/L, the rate at which the specific flux (SF) of the membrane declined decreased as the amount of the effluent treated increased. The problem of strontium release at the beginning of the operation was controlled by a continuous test in which the dosage of sodium carbonate still was 1000 mg/L and the other parameters were the same as in the other tests. The results showed that the mean DF and CF were 157 and 480, respectively. [ABSTRACT FROM AUTHOR]

Chlorpyrifos is an organophosphate pesticide commercialized since 1965 and it is now one of the top five commercial insecticides. It is registered for use in over 900 different pesticide formulations in the world. Chlorpyrifos poisoning usually affects many organs of the body, such as the central and peripheral nervous system, eyes, respiratory system, and the digestive tract. Depending on the pesticide formulation and type of application, chlorpyrifos residues may be detectable in water, soil, and on the surfaces from months to years. This paper presents preliminary studies of the removal of chlorpyrifos by exposition to ionizing radiation, to be applied in pesticide container decontamination. Samples containing various concentrations of chlorpyrifos in acetonitrile were irradiated with absorbed doses varying from 5 to 50 kGy, using a 60Co gamma-source with 5,000 Ci activity (Gamma cell type). The chemical analysis of the chlorpyrifos and the by-products resulted from the radiolitic degradation were made using a gas chromatography associated to mass spectrometry (GC-MS) and gas chromatography with flame ionization detector (GC-FID). [ABSTRACT FROM AUTHOR]

This study proposes a method for decontamination of acid drainage water from a uranium mine, as an alternative process to lime treatment. The research embodied the recovery of uranium with an ion-exchange resin, treatment of effluent resin with lime, or with inorganic adsorbents and biosorbents. The uranium decontamination level using the resin process was 94% and allowed the recovery of this element as a commercial product. Among the inorganic adsorbents studied, phosphogypsum was effective for 226Ra, 228Ra, and 210Pb removal. Among the biosorbents, Sargassum sp.was superior in relation to its specific capacity to accumulate and remove 226Ra. [ABSTRACT FROM AUTHOR]

During the period of 1993-2001 chemical decontaminations of 24 SGs in the units 1-3 of the Paks NPP were carried out by a non-regenerative version of AP-CITROX technology, even in two or three consecutive cycles. A comprehensive investigation of the above decontamination method have revealed that the fundamental issues of analytical chemistry and corrosion science were not taken into consideration during the elaboration of AP-CITROX procedure. Therefore, the non-regenerative version of the technology utilized at Paks NPP can be considered to be not an adequate method for the chemical decontamination of any reactor equipments having large steel surfaces (e.g., SGs). As a consequence of the lack of the appropriate decontamination method, initiation of a R&D project focused on the elaboration of the required technology should not be postponed. In this paper, we present a brief overview on the fundamental issues of the technology development . Selected findings obtained in our laboratory on the field of the improvement of the AP-CITROX technology are also reviewed in order to demonstrate the crucial role of some selection criteria. [ABSTRACT FROM AUTHOR]

This paper describes the Syrian experience with respect to naturally occurring radioactive materials (NORM) waste produced by the Syrian oil industry. Three main categories of NORM waste were identified. First, hard scales from decontamination of contaminated equipment and tubings which are considered to contain the highest levels of radium isotopes (226Ra, 228Ra, 224Ra); this type of waste being currently stored in standard barrels in a controlled area. Second, sludge wastes containing low levels of radium isotopes were found in large amounts in each Syrian oilfield; plastic lined disposal pits were constructed in each area for temporary storage. However, disposal criteria for the above two categories of NORM waste are still under discussions. Third, soil contaminated with NORM as a result of uncontrolled disposal of production water was also considered as NORM waste. The Syrian criteria for disposal and clean up of this type of waste has been defined and approved by the Regulatory Office. [ABSTRACT FROM AUTHOR]

A multistage process combining photocatalytic degradation of organic complexes and complexants followed by separation of the radionuclides by ion exchange was developed and tested for the treatment of aqueous waste from chemical or electrochemical decontamination of NPP primary circuit internals. In these solutions, both the oxalic and citric acids could be quantitatively degraded within 10-12 hours of irradiation by 254 nm UV radiation in the presence of TiO2 photocatalyst. For the group radionuclides separation, a standard cation exchanger was found to be preferable to any of the set of the tested inorganic-organic composite absorbers. [ABSTRACT FROM AUTHOR]