Sequential determination of Am, Cm, Pu, Np and U by extraction chromatography

Environmental contamination by artificial radionuclides and the evaluation of their sources require precise isotopic analysis and accurate determination of actinide elements above all plutonium and americium. These can be achieved by alpha spectrometry or by inductively coupled plasma mass spectrometry (ICP-MS) after chemical separation. In the present work, a simple, rapid method has been developed for the sequential separation of actinide elements from aqueous solutions and their determination by alpha spectrometry. Extraction chromatography was applied to the separation of ²⁴¹Am, ²⁴⁴Cm, ^{239 + 240,238}Pu, ²³⁷Np and ^238,235,234U using microporous polyethylene supporting tri-n-octylamine as the stationary phase and hydrochloric acid with and without reducing agents as the mobile phase. Actinide in 9 M HCl solution is introduced into the anion exchange column; Pu (IV), Np (IV) and U(VI) are retained on the column while Am (III) and Cm passed through. Pu is eluted first, reductively, after which, Np and then U are eluted. The method can be applied to all aqueous solutions which do not contain strong complexing or precipitation agents for the elements considered.     

Determination of Np,Pu and Am in high level radioactive waste with extraction-liquid scintillation counting

A new method for the determination of transuranium elements, Np, Pu and Am with extraction-liquid scintillation counting has been studied systematically. Procedures for the separation of Pu and Am by HDEHP-TRPO extraction and for the separation of Np by TTA-TiOA extraction have been developed, by which the recovery of Np, Pu and Am is 97%, 99% and 99%, respectively, and the decontamination factors for the major fission products (⁹⁰Sr,¹³⁷Cs etc.) are 10⁴–10⁶. Pulse shape discrimination (PSD) technique has been introduced to liquid scintillation counting, by which the counting efficiency of -activity is >99% and the rejection of -counts is >99.95%. This new method, combining extraction and pulse shape discrimination with liquid scintillation technique, has been successfully applied to the assay of Np, Pu and Am in high level radioactive waste.     

Analysis of Th, U, Pu, and Am in radioactive metal waste using extraction chromatography

In order to analyze actinide elements in radioactive metal waste, the dissolution and chemical separation conditions were optimized. The surfaces of a type 304 stainless steel plate and of pipe waste sampled from the prototype advanced thermal reactor (Fugen) were dissolved in mixed acid solution (HNO₃:HCl:H₂O = 1:1:4). The resulting solution was evaporated to dryness and dissolved with 2 mol/dm³ of HNO₃ to prepare sample solutions. In order to analyze trivalent actinide elements in the sample solution containing a large amount of Fe(III) (>0.1 g) using TRU resin, the effect of Fe(III) concentration on the recovery of Am(III) and reduction effect of Fe(III) to Fe(II) with ascorbic acid were studied. On the basis of results of this study, chemical separation scheme was constructed and Pu and Am in the sample solutions were separated. Thorium and U in the sample solutions were separated with UTEVA resin. High recoveries for all experimented elements were obtained from the analysis of spiked sample solutions, the effectiveness of the method was confirmed.     

Measurement of63Ni in highly radioactive Hanford waste by liquid scintillation counting

Characterization of high-activity radioactive waste stored in underground tanks at Hanford requires determining⁶³Ni (100 y). This low-energy -emitter (E_max 67 keV) must be separated with a high degree of radiochemical purity large amounts of other fission and activation products. The method to be discussed involves multiple precipitation steps with several holdback carriers added, followed by precipitations with dimethylglyoxime, ion exchange, and electrodeposition. The⁵⁹Ni activity is determined by low-energy photon spectrometry. The sample is then stripped from the counting disk with HNO₃, converted to the chloride form, and the⁶³Ni -spectrum is measured with high efficiency by liquid scintillation counting.Pacific Northwest Laboratory is operated for the U.S. Department of Energy under Contract DE-AC06-76RLO-1830.     

Advanced separation of harmful metals from industrial waste effluents by ion exchange

Advanced separation methods of harmful metals from industrial waste effluents, i.e., radionuclides from nuclear waste solutions, transition metals from metallurgical waste effluents, developed at the Laboratory of Radiochemistry, are discussed.     

Study of the interferences in the determination of Pu, Am and Cm in radioactive waste by extraction chromatography

This paper describes the experimental studies carried out to determine (238)Pu, (239/40)Pu, (241)Pu, (241)Am, (242)Cm and (244)Cm in samples from nuclear power plants (mainly spent ion exchange resins and evaporator concentrates) using an organophosphorus compound immobilized on an inert support. These materials are commercially available under the name TRU Resin (for Transuranium Specific) from Eichrom Industries, Darien, IL. An attempt is made to develop a rapid, accurate method of analysis, with minimum waste generation. Standard solutions of Pu and Am and one sample of spent ion exchange resin that contains fission, activation products, Pu, Am and Cm were analyzed to study the separation factors and interferences in the measurement of Pu, Am and Cm isotopes.     

Fusion and chemical separation of Am,Pu and Sr from barite-concrete

Journal of Radioanalytical and Nuclear Chemistry - The goal of this study was to omit the hazardous hydrofluoric acid for silica removal before fusion of barite-concrete. Furthermore, the goal was...     

Sorption characteristics of237Np,238Pu and241Am in sedimentary materials

Adsorption experiments were performed to measure distribution coefficients of²³⁷Np(V),²³⁸Pu(IV) and²⁴¹Am(III) for sedimentary sequential chemical extraction of the adsorbed radionuclides was carried out with water, CaCl₂, KCl, NH₂OH−HCl, K-oxalate and H₂O₂ solutions, to elucidate their dominant sorption mechanisms. The distribution coefficient of²³⁷Np was two orders of magnitude smaller than that of²³⁸Pu and²⁴¹Am. Most of²³⁷Np adsorbed was extracted with CaCl₂ solution and its sorption was controlled by a reversible ion exchange reaction. The adsorbed²³⁸Pu was mainly extracted with NH₂OH−HCl+K-oxalate solution and its sorption was possibly controlled by irreversible reactions.     

Radiochemical separation of Pu, U, Am and Sr isotopes in environmental samples using extraction chromatographic resins

This study presents a rapid and quantitative sequential radiochemical separation method for Pu, U, Am and Sr isotopes in environmental samples with extraction chromatographic resins. After radionuclides were leached from the samples with 6 M HNO₃, Pu and U isotopes were adsorbed onto the UTEVA column and Am isotopes were adsorbed onto the TRU column connected with the UTEVA column. Also, ⁹⁰Sr was adsorbed onto the Sr column connected with the TRU column. Pu and U isotopes were purified from other nuclides through the UTEVA column. In addition, Am isotopes were separated from other nuclides with the TRU column. Finally, ⁹⁰Sr was purified with the Sr resin. After α source preparation for the purified Pu, U and Am isotopes with micro-coprecipitation method, Pu, U and Am isotopes were measured using alpha spectrometry. On the other hand, ⁹⁰Sr was measured using a low level liquid scintillation counter. The radiochemical procedure for Pu, U, Am and Sr nuclides investigated in this study has been applied to environmental samples after validating the simulated samples.     

Low level Pu and Am estimation in liquid waste from nuclear reactor

Estimation of very low amount up to pico-gram of Am and Pu in the liquid waste of U–Pu fuel cycle of the irradiated U fuel from the nuclear reactor has been carried out using combined method of α- and γ-ray spectrometric techniques. ²⁴¹Am was estimated by γ-ray spectrometry from a plancheted source. In spite of the same α energy of 5.49 MeV for ²⁴¹Am and ²³⁸Pu, the amount ²³⁸Pu was estimated by α spectrometry from the same plancheted source after subtracting amount of the ²⁴¹Am obtained from γ-ray spectrometry. The amount of Am and Pu obtained by this technique is found to be superior compared to other techniques even in the presence of Th, U and fission products.     

Determination of 94Nb in radioactive waste using ion exchange chromatography

This paper describes a rapid method of ⁹⁴Nb 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.     

Recent developments in the analysis of transuranics (Np,Pu, Am) in seawater

Summary A procedure is described to extend the current radiochemical method of seawater analysis for Pu and Am including Np. Short-lived ²³⁹Np tracer was prepared by separation from its ²⁴³Am parent. Irish Sea Water reference material (IAEA-381) containing known concentrations of ²³⁷Np, Pu isotopes and ²⁴¹Am was used to test the procedure for small water volumes. Inductively-coupled plasma mass spectrometry (ICP-MS) was used in addition to alpha spectrometry for measurement of ²³⁷Np in the purified final Np fractions.     

The separation of mercury from gold by ion exchange

Mixtures containing large amounts of gold and small amounts of mercury (50:1) can be quantitatively separated by passing a 2N hydrochloric acid solution of the chlorides through Dowex 50 resin. Mercury behaves as a cation and is quantitatively retained. Gold behaves as an union and is not retained by the resin. The gold is obtained spcctrobcopically free from all metals. The capacity of the resin is approximately 10 nig of mercury per gram of rebin. The rcyin is freed from mercury by washing with 2N liydroclonc acid and may be used over again.     

Distribution of global fallout237Np,Pu isotopes,and241Am in lake and sea sediments

In order to investigate the sedimentary behaviour of neptunium,²³⁷Np together with Pu isotopes and²⁴¹Am have been measured for the sediment cores collected from Lake Mikata (freshwater) and from Lake Kugushi (brakish water) both belonging to the Mikata Five Lakes, and from Nyu Bay (sea water). In all sediment core samples²³⁷Np was detected, and its concentrations were far below those of^239,240Pu and²⁴¹Am measured for the same samples. Inventories of²³⁷Np in Lake Mikata, Lake Kugushi and Nyu Bay were estimated to be 0.53, 0.29 and 0.34 MBq/km², respectively. The activity ratio of²³⁷Np/^239,240Pu calculted from the inventories in each sediment core was 0.29% for Lake Mikata, 0.15% for Lake Kugushi and 0.10% for Nyu Bay. These values except for the value for Lake Mikata are two or three times lower than the value of 0.3–0.4% observed for surface soils of 0–20 cm depth, suggesting that Np is more soluble compared with Pu.     

A separation procedure for the analysis of90Sr,154Eu, and the actinides237Np,239Pu,241Am and244Cm

A procedure for the analysis of⁹⁰Sr,¹⁵⁴Eu,²³⁷Np,²³⁹Pu,²⁴¹Am and^242−244Cm was developed. Separation was done with the separating agent, di-2(ethyl hexyl)-phosphoric acid (HDEHP), and results in fractions containing the different elements to be analysed.⁹⁰Sr analysis was done by analysing its daughter nuclide⁹⁰Y, detected through the Cherenkov radiation emitted by this high energy β⁻-emitter.¹⁵⁴Eu was detected using γ-spectrometry with a lower Compton background as a result of the removal of other fission products.²⁴¹Am could also be detected with γ-spectrometry or together with^242−244Cm with α-spectrometry. The long-lived radionuclides²³⁷Np and²³⁹Pu were detected using inductively coupled plasma mass spectrometry (ICP-MS).     

On-line separation of Pu(III) and Am(III) using extraction and ion chromatography

An on-line method developed for separating plutonium and americium was developed. The method is based on the use of HPLC pump with three analytical chromatographic columns. Plutonium is reduced throughout the procedure to trivalent oxidation state, and is recovered in the various separation steps together with americium. Light lanthanides and trivalent actinides are separated with TEVA resin in thiocyanate/formic acid media. Trivalent plutonium and americium are pre-concentrated in a TCC-II cation-exchange column, after which the separation is performed in CS5A ion chromatography column by using two different eluents. Pu(III) is eluted with a dipicolinic acid eluent, and Am(III) with oxalic acid eluent. Radiochemical and chemical purity of the eluted plutonium and americium fractions were ensured with alpha-spectrometry.     

Study on a stable destruction method of radioactive waste ion exchange resins

This paper is a study on a stable destruction method of radioactive waste ion exchange resins. According to the resin TGA results, its decomposition occurred through three stages. And a sufficient retention time of the resins and an effective retention capacity of SO₂ gases and the doped metal compounds were required to destruct resins doped with radioactive metals stably. The resins doped with radioactive metal surrogates were effectively destructed in the lab-scale MCO system. CO and SO₂ emissions were below 100 and 1 ppm, respectively. And the surrogates were collected more than 99.9% in the molten carbonate. Thus, the resins can be destructed stably in the MCO process.     

Polymeric structure of oxalato-bridged complexes of tetravalent actinides Th, U, Np and Pu

A series of isostructural oxalates of Th, U, Np, and Pu have been synthesized. The crystal structure of {C(NH(2))(3)}(4)[An(C(2)O(4))(4)]·2H(2)O comprises infinite [An(C(2)O(4))(4)](4n-) chains, guanidinium cations and water molecules. Each An atom is connected to five oxalate anions, two of which act as bridging tetradentate ligands, while the other three function as terminating bidentate ligands. Electron and IR spectra of the compounds as well as the results of thermal analysis correlate with their structure. An actinide contraction effect is demonstrated by a decrease in the An-O interatomic distances and the volumes of An atom coordination polyhedra and Voronoi-Dirichlet polyhedra. Ten-coordinate An oxalates are discussed in terms of continuous shape measures approach.     

The determination of U,Np and Pu in urine by sequential extraction with ALAMINE-336 from hydrochloric acid medium

A method has been developed for the extraction of uranium, neptunium and plutonium from human urine using the comparatively cheap technical amine ALAMINE-336. These elements are coprecipitated with a calcium phosphate carrier, which is then subjected to a wet-ashing procedure with NHO₃/H₂O₂ and HCl/H₂O₂. The residue is dissolved in 10M hydrochloric acid and U, Np and Pu are extracted with a 10% ALAMINE-336/xylene solution, followed by subsequent back-extraction with 10M HCl/NH₄I (Pu), 4M HCl/HF (Np) and 0.1M HCl (U), respectively. The average recoveries are around 95%.