Detection of reprocessing activities through stable isotope measurements of atmospheric noble gases

Noble gas stable isotope abundance measurements may provide a tool for detecting reprocessing activities of nuclear fuels. An approach has been made by carrying out blending calculations of released fission xenon and krypton in air using the Isotope Mixture Programs which have been developed at the IRMM. After having obtained a reliable approximation to the expected range of the isotope ratios in the blends and the respective detection limit thereof through these calculations, the potential application of ultra-accurate measurements of the isotopic composition of anthropogenic and atmospheric noble gases is taken into consideration. Also the important role of radiometric measurements of ⁸⁵Kr and ¹³³Xe for the detection of nuclear fuel reprocessing is taken into account. The information provided by such activity measurements is limited, therefore a method to calculate the initial isotopic composition of released fission noble gases, through measuring of their atmospheric mixing ratio, is presented and discussed. Highly accurate stable isotopic measurements of atmospheric noble gases might provide more detailed information on the “history” of the reprocessed nuclear fuel. Therefore they could serve, in combination with radiometric detection techniques, as an excellent tool for the identification of reprocessing activities.     

Microextraction by demixing of two miscible solvents for the determination of phenols in water

A method for the determination of anionic solutes such as phenol, cresols, and xylenols present in industrial effluents has been developed. It is based on microextraction using two miscible phases followed by demixing of the phases by the addition of ammonium sulfate. The extraction properties of 2-propanol were examined and the procedures were optimized. High resolution gas chromatography–mass spectrometry in the selected ion monitoring mode was used as a separation and quantitation technique. This method is rapid and precise and allows detection limits of 1 μg L^?1 to be easily obtainable employing a 50 mL water sample.     

Monitoring chlorophenols in industrial effluents by solid-phase microextraction–gas chromatography–mass spectrometry

A method for the determination of 19 chlorophenols in industrial effluents samples using solid-phase microextraction (SPME) coupled to gas chromatography–mass spectrometry has been developed. Four kinds of different SPME fibres have been studied. Among them, the polyacrylate and carbowax®-divinylbenzene fibres were the most adequate. The extraction process was optimized by means of the experimental design, which allows the study of a large number of factors with a reasonable number of experiments. The optimized method allows the determination of the studied chlorophenols in complex matrices with a high organic content with detection limits down to 0.07?ng?mL^?1 and RSD ranging from 4.4% to 13.8%. The recovery studies with spiked real effluent samples at low levels of chlorophenols ranged from 59.8% to 142.1% for the lowest level (0.5?ng?mL^?1) and from 79.6% to 115.8% for the highest spiked level (2?ng?mL^?1). These results show the suitability of the proposed method to monitor chlorophenols in complex samples. 2,4,5-TCP was detected at concentrations close to its limits of detection in effluents coming from an oil refinery.     

Vertical distribution of uranium concentrations and 235U/238U atom ratios in the coastal water off Aomori, Japan: A survey prior to the operation of a nuclear fuel reprocessing facility

Summary From the viewpoint of environmental radioactivity monitoring, the determination of uranium and its isotope ratio is important for identifying and assessing the environmental impact of any unexpected release from nuclear facilities. In this work, a survey was conducted to determine ²³⁸U concentrations and ²³⁵U/²³⁸U atom ratios in coastal waters off Rokkasho Village, Aomori, Japan, where several uranium-related nuclear facilities have been operating since 1992, and a newly constructed nuclear fuel reprocessing plant is scheduled to be commissioned in 2006. Seawater samples were analyzed directly after a 10-fold dilution using isotope dilution sector-field ICP-MS. Based on the results, we concluded that there is no observable uranium contamination in the investigated sites. In addition, for the first time, a correlation between uranium concentration and salinity was established in coastal waters using the SF-ICP-MS technique.     

Rapid quantification of TBP and TBP degradation product ratios by FTIR-ATR

Tri-n-butyl phosphate (TBP) is the key complexant within the plutonium and uranium reduction extraction process used to extract uranium and plutonium from used nuclear fuel. During reprocessing TBP degrades to dibutyl phosphate (DBP), butyl acid phosphate (MBP), butanol, and phosphoric acid over time. A method for rapidly monitoring TBP degradation is needed for the support of nuclear forensics. Therefore, a Fourier transform infrared spectrometry-attenuated total reflectance (FTIR-ATR) technique was developed to determine approximate peak intensity ratios of TBP and its degradation products. The technique was developed by combining variable concentrations of TBP, DBP, and MBP to simulate TBP degradation. This method is achieved by analyzing selected peak positions and peak intensity ratios of TBP and DBP at different stages of degradation. The developed technique was tested on TBP samples degraded with nitric acid. In mock degradation samples, the 1,235 cm^?1 peak position shifts to 1,220 cm^?1 as the concentration of TBP decreases and DBP increases. Peak intensity ratios of TBP positions at 1,279 and 1,020 cm^?1 relative to DBP positions at 909 and 1,003 cm^?1 demonstrate an increasing trend as the concentration of DBP increases. The same peak intensity ratios were used to analyze DBP relative to MBP whereas a decreasing trend is seen with increasing DBP concentrations. The technique developed from this study may be used as a tool to determine TBP degradation in nuclear reprocessing via a rapid FTIR-ATR measurement without gas chromatography analysis.     

Determination of plutonium and <Superscript>90</Superscript>Sr in air particulate samples

Within the surveillance program of the gaseous effluents coming from the nuclear reprocessing plant EUREX of ENEA (Italian National Agency for New Technologies Energy and Environment, CR Saluggia) in the North of Italy, the content of some radionuclides is continuously monitored. The so-called 1AW high-activity liquid waste (HLLW) is the aqueous raffinate of the first cycle of PUREX extraction process which was the starting point of the reprocessing activity of some MTR and CANDU spent fuel elements. Nowadays, 1AW-HLLW is stored in five tanks placed inside the EUREX plant site. This paper describes the sampling and radioanalytical methods employed to determine the activities of ²⁴¹Am, plutonium isotopes and ⁹⁰Sr in the total suspended particulate material (TSP) of the 1AW tank primary ventilation air circuit.     

Field testing of collection and measurement of radioxenon for the Comprehensive Test Ban Treaty

Pacific Northwest National Laboratory, with guidance and support from the U.S. Department of Energy's NN-20 Comprehensive Test Ban Treaty (CTBT) Research and Development program, has developed and demonstrated a fully automatic sampler-analyzer (ARSA) for the collection and quantitative measurement of the four xenon radionuclides,^131mXe (11.9 d),^133mXe (2.19 d),¹³³Xe (5.24 d), and¹³⁵Xe (9.10 h), in the atmosphere. These radionuclides are important signatures in monitoring for compliance to a CTBT, and may have applications in stack monitoring and other areas where xenon radionuclides are present. The activity ratios between certain of these radionuclides permit discrimination between radioxenon originating from nuclear detonations and that from nuclear reactor operations, nuclear fuel reprocessing, or from medical isotope production and usage. With the ARSA system, xenon is continuously and automatically separated from the atmosphere at flow rates of about 100 lpm by sorption-bed techniques. Samples collected in 8 hours are automatically analyzed by electron-photon coincidence spectrometry to provide detection sensitivities as low as 100 μBq/m³ of air. This sensitivity is about 10-fold better than achieved with reported laboratory-based procedures¹ for the short time collection intervals of interest. Gamma-ray energy spectra and gas analysis data are automatically collected.     

Uranium analysis in urine by inductively coupled plasma dynamic reaction cell mass spectrometry

Urine uranium concentrations are the best biological indicator for identifying exposure to depleted uranium (DU). Internal exposure to DU causes an increased amount of urine uranium and a decreased ratio of ²³⁵U/²³⁸U in urine samples, resulting in measurements that vary between 0.00725 and 0.002 (i.e., natural and depleted uraniums ²³⁵U/²³⁸U ratios, respectively). A method based on inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS) was utilized to identify DU in urine by measuring the quantity of total U and the ²³⁵U/²³⁸U ratio. The quantitative analysis was achieved using ²³³U as an internal standard. The analysis was performed both with and without the reaction gas oxygen. The reaction gas converted ionized ²³⁵U⁺ and ²³⁸U⁺ into ²³⁵UO₂⁺ (m/z=267) and ²³⁸UO₂⁺ (m/z=270). This conversion was determined to be over 90% efficient. A polyatomic interference at m/z 234.8 was successfully removed from the ²³⁵U signal under either DRC operating conditions (with or without oxygen as a reaction gas). The method was validated with 15 urine samples of known uranium compositions. The method detection limit for quantification was determined to be 0.1 pg U mL^–1 urine and an average coefficient of variation (CV) of 1–2% within the sample measurements. The method detection limit for determining ²³⁵U/²³⁸U ratio was 3.0 pg U mL^–1 urine. An additional 21 patient samples were analyzed with no information about medical history. The measured ²³⁵U/²³⁸U ratio within the urine samples correctly identified the presence or absence of internal DU exposure in all 21 patients.The opinions and assertions expressed herein are those of the authors and are not to be construed as official or as representing the views of the Armed Forces Institute of Pathology, the Department of the Army, or the Department of Defense     

Natural and anthropogenic radionuclides in the rivers of Azerbaijan

In the frame of an International Atomic Energy Agency Technical Cooperation project, a radiological survey was performed in the Araks and Kura Rivers (Azerbaijan). Sediment samples, and where available, aquatic plants were collected along these two rivers and their inflow and tributary rivers. ¹³⁷Cs, ²³⁸U, ²³⁴U, ^239+240Pu, ²³⁸Pu, ⁹⁰Sr and ²⁴¹Am activity concentrations were measured. The radionuclide levels measured were relatively low, and in most cases below the detection limit, as compared with those from other areas of the world which have been directly affected by effluents from nuclear installations or influenced by the Chernobyl accident. The results indicated that the radionuclides are of natural origin or attributable to the atmospheric fallout from nuclear weapons tests or to the Chernobyl-derived deposition.     

Dynamic adsorption properties of Kr and Xe isotopes in charcoal

Some batches of²³³U oxide product obtained from the reprocessing treatment of irradiated thorium rods, called J-rods in our plant, have been found to contain thorium as much as 85% and iron above 5% as impurities. This product has to be purified before sending for fabrication of the fuel. The present purification method consists of the following three steps: (1) preferential dissolution of U₃O₈ as compared to thoria, (2) a novel solvent extraction process, and (3) preferential precipitation of Th as oxalate leaving behind the entire U in the filtrate. Development and application of the present purification method to the above²³³U oxide proxduct are presented in this paper.     

A method for quick estimation of129I by low energy photon spectrometry

Methods have been developed for the routine analysis of¹²⁹I in effluents of fuel reprocessing plants using 29.4 keV xenon X-rays. Direct counting methods have been standardized in liquid medium as well as in ion-exchange resin medium. A low energy photon spectrometry Ge detector system and a well-type NaI/Tl/ detector are used for direct counting. Attenuation of xenon X-rays in liquid medium as well as in ion-exchange resin medium have been studied. Sample size is optimized by studying the self attenuation of xenon X-rays in the sample. Activity as low as 1 Bq could be detected with an accuracy of 11% and 30% using LEPS and NaI/Tl/counting systems, respectively.     

Determination of 210Po and uranium in high salinity water samples

A method for the determination of uranium and ²¹⁰Po in high salinity water samples has been elaborated. Both radionuclides are preconcentrated from 0.5 dm³ saline media by co-precipitation with hydrated manganese dioxide, followed by dissolution of the precipitate in 200 mL of 1 M HCl. Uranium isotopes ²³⁵U and ²³⁸U can be directly determined by ICP MS method with a detection limit of 0.01 ppb for ²³⁸U. Prior to a selective determination of ²¹⁰Po, the majority of other naturally occurring α-emitting radionuclides (uranium, thorium and protactinium) can be stripped from this solution by their extraction with a 50% solution of HDEHP in toluene. Finally, ²¹⁰Po is simply separated by direct transfer to an extractive scintillator containing 5% of trioctylphosphine oxide in Ultima Gold F cocktail and determined by an α/β separation liquid scintillation technique with detection limit below 0.1 mBq/dm³.     

Quantification of human pharmaceuticals in water samples by high performance liquid chromatography-tandem mass spectrometry

An improved analytical method for determination of human pharmaceuticals in natural and wastewaters with ng L⁻¹ sensitivity is presented. The method is applicable to pharmaceuticals from a wide range of therapeutic classes including antibiotics, analgesics, anti-inflammatories and anti-cancer compounds. Pharmaceuticals were extracted from waters using solid-phase extraction, and after concentration, analysed by high performance liquid chromatography with tandem mass spectrometric detection (HPLC-MS/MS). Identification of each compound was secured using retention time and by the selected reaction monitoring of two transitions, one of which was additionally used for quantification. Limits of detection ranged from 0.03 to 0.96 ng L⁻¹ and were up to two orders of magnitude lower than those of previously published methods. The method was validated using spiked samples prepared from tap, river and sea water as well as wastewater effluents, collected from the North of Scotland. Analysis of wastewater effluents revealed the presence of mefenamic acid, ibuprofen, erythromycin, diclofenac and trimethoprim. None of the selected pharmaceuticals were detected in river, tap or sea water samples.     

High performance liquid chromatographic separation of <Superscript>228,229</Superscript>Th and <Superscript>232,233</Superscript>U and their estimation by α- and γ-ray spectrometry

The activities of ^228,229Th and ^232,233U from an irradiated ThO₂ sample were radiochemicaly separated by using high performance liquid chromatography. Plancheted sources of the separated samples were made and the amount of ^232,233U and ^228,229Th were estimated by using alpha and gamma-ray spectrometric techniques. These estimations are important for the Th–U fuel reprocessing cycle of advanced heavy water reactor and accelerator driven sub-critical system.     

Glass capillary gas chromatography with simultaneous flame ionization (FID) and Hall® element-specific (HECD) detection

Two glass capillary gas chromatographic systems were equipped with inert effluent splitters which allowed simultaneous data acquisition using nonspecific and element-specific detectors. Simultaneous detection was achieved using the nonspecific flame ionization detector (FID) and the Hall^® electrolytic conductivity detector (HECD) operated in either the sulfur-or the nitrogen-specific mode. Typical application of the simultaneous detection system as applied to analysis of petroleum residues is briefly described. The Hall electrolytic conductivity detector can be made element specific for halogen-, sulfur-, or nitrogen-containing compounds. Simultaneous detection enhances the information yield from a single sample injection and proves to be a powerful complementary technique when used with computerized gas chromatography/mass spectrometry.     

Nano-scale column partition chromatography

Column chromatography was adapted to natural product isolates in which the components were present in concentrations of the order of 10^?9 g. Use for this technique has been found in purification of nanogram quantities of gas Chromatographic effluents, and in resolution and concentration build-up of compounds which may otherwise be difficult to identify by gas chromatography-mass spectrometry.     

Pesticides Residues Rapid Extraction from Panax Ginseng Using a Modified QuEChERS Method for GC–MS

A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) rapid detection method followed by gas chromatography–tandem mass spectrometry (GC–MS) has been developed for the simultaneous determination of 42 pesticides in Panax ginseng. This method can be different from the other QuEChERS methods in the sense that it uses acetone and n-hexane solution rather than acetonitrile to extract and partition pesticides. This acetone, water and n-hexane solution QuEChERS method consists essentially of two steps: extraction/partitioning and purification. In step 1, P. ginseng was mixed with acetone, water and n-hexane solution, and then partitioned by vortex. In step 2, the top layer (n-hexane) was transferred into a centrifuge tube containing primary secondary amine, activated carbon and C₁₈ for purification. After the centrifuge supernatant was injected into GC–MS. The QuEChERS method was applied in P. ginseng detection and we confirmed that this method can easily extract various types of pesticides from P. ginseng. The rates of recovery for pesticides studied were satisfactory, ranging from 75.3 to 119.4 % for most of the pesticides with a relative standard deviation of less than 13 %. The LOQs ranged between 0.5 and 1.2 µg kg⁻¹. The modified QuEChERS method and GC–MS could enable complex pretreatment in P. ginseng analysis quickly and easily.

     

Application of 129I as an environmental tracer

¹²⁹I is produced naturally by cosmic-ray spallation of Xe and by spontaneous fission of ²³⁸U. In the environment ¹²⁹I is mainly due to nuclear weapon tests and reprocessing plants. The high water solubility of iodine makes ¹²⁹I a good oceanographic tracer. Long residence time and large air releases of ¹²⁹I from reprocessing plants allow ¹²⁹I to be used as a geochemical and metrological tracer. The same chemical and physical properties of ¹²⁹I and ¹³¹I enable one to use ¹²⁹I as a tool for the reconstruction of ¹³¹I doses after a nuclear accident. Some studies using ¹²⁹I as a tracer which were carried out in the author's laboratory, are summarized. This revised version was published online in July 2006 with corrections to the Cover Date.     

Estimation of natural thorium in low level effluents from processing plants

This is a report of simple estimations of natural thorium in low level effluents generated during the reprocessing of irradiated Th/ThO₂ rods for the recovery of²³³U. The method involved co-precipitation of thorium with ceric iodate at pH 1.29±0.01 and subsequent photometric determination. Conditions were optimised to eliminate the interferences of other ions present in the effluent. Approximately 15 mg each of phosphate, fluoride, and sulphate, 10 mg of iron, and 300 g zirconium did not interfere in the estimation of 2–5 g Th/100 ml of the effluent. Average thorium recovery was around 101.9%±2.6% when nearly 10 g of thorium were spiked.     

In-line determination of heavy elements by gamma ray-induced energy-dispersive K-line XRF

In-line determination of heavy elements, especially in nuclear fuel reprocessing solutions by means of XRF analysis and -emitting radionuclides as excitation sources for the K-lines has been investigated.⁵⁷Co,¹³³Ba and¹⁹²Ir are used as radionuclide sources. U, Np, and Pu can be determined from the lower ppm range up to the saturation concentration of about 400 g/l. In case of Pu concentrations >100 mg/l the detection limits for U and Np increase. A matrix effect due to the composition of the solution is observed, which depends only on the density of the solution. At higher activities of fission products in the solution, an increase of the background count rate but no interferences are observed. This allows determination of heavy elements in fission product solutions.