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1.
This paper reports an analytical method for rapid determination of neptunium ( 237Np) in environmental solid samples exploiting automated sequential injection (SI)-based anion exchange separation. Pivotal issues on analytical method performance were investigated including sorption behavior of 237Np onto various AG 1-type anion exchangers; suitability of 242Pu as a tracer for 237Np determination in environmental solid samples; and long-term chemical stability of tetravalent Np. Experimental results revealed that the degree of resin cross-linking has a significant influence on the separation efficiency in terms of chemical yields of 237Np and removal of interfering nuclides. Although ca. 30% of sorbed Np onto AG 1-×4 was stripped out during HCl rinsing step for the removal of Th, chemical yield ratios of 237Np to 242Pu were proven steady with an average value of 0.67 ± 0.04 ( n = 15) under selected experimental conditions. Disulfite-8 M HNO 3 was selected as a redox pair for valence adjustment to Np(IV) and the tetravalent Np in the sample solution was demonstrated to be stabilized for up to 5 days under 3 °C. The analytical results for reference materials showed a good agreement with the expected values, thereby demonstrating the usefulness of 242Pu as a non-isotopic tracer for 237Np chemical yield monitoring. The on-column separation procedure fosters rapid analysis as required in emergency situations since each individual sample can be handled within 2.5 h, and leads to a significant decrease in labor intensity compared to conventional batch-wise protocols. 相似文献
2.
Neptunium is sorbed, together with plutonium, uranium and iron on Bio Rad AG 1×4 anion exchange resin from 9 mol/1 HCl, eluted with 7 mol/l HNO 3 and 1.2 mol/l HCl, purified on a second, identical column and electrodeposited on stainless steel discs. 237Np is determined by -spectrometry, 239Np by -spectrometry with a Ge detector, or via its 14.3 keV L X-rays in a Si(Li) measurement. The neptunium yield is determined from the count rate of the 13.6 keV L X rays of the tracer 235Np in a later Si(Li) measurement. The average chemical yield is 78±11%. The detection limit for 237Np is 1 mBq. The procedure allows the sequential determination of neptunium, together with plutonium, strontium, uranium and iron from one sample. The method was applied to air and total deposition samples from Munich-Neuherberg and to sediment samples from the Irish sea. 相似文献
3.
This paper describes the analytical methods for the determination of 237Np, Pu isotopes, and 241Am, with particular emphasis on 237Np by alpha-ray spectrometry and 241Pu by liquid scintillation technique. Results are also presented for the sediment cores collected from Mikata Five Lakes in Fukui Prefecture, Japan. 相似文献
4.
An accurate and reliable method has been developed and routinely carried out for the sequential determination of 239,240Pu and 241Am in environmental samples. After suitable pretreatment. 239,240Pu and 241Am are separated from other elements by means of the anion exchange resin method. Americium-241 is purified by coprecipitation with calcium oxalate and then ion exchanged in mixed media of the mineral acid-methanol. In the analysis, 242Pu (or 236Pu) and 244Cm are used as chemical yield monitors. The recoveries of the yield monitors in the analyses of some kinds of environmental samples were 7080% for plutonium and 7686% for curium. The concentration of 239,240Pu in the coastal sea water were 7.022 Bq/l and that of 241Am was 1.26.3 Bq/l. The mean concentrations of 239,240Pu in the edible parts of the marine products ranged from 0.22 to 7.4 mBq/kg · fresh and those of 241Am ranged from 0.11 to 2.6 mBq/kg · fresh. 相似文献
5.
The photoluminescence of crystallophosphors, activated by neptunium and plutonium has been studied in connection with the necessity of discovering and elaborating on new analytical methods for actinides determination. Crystallophosphors on the base of fluorides, molybdates and tungstates have been prepared by introducing neptunium and plutonium solutions into the powder matrix, further drying and blend calcination. Luminescence spectra at room temperature have been found to have some broad bands in the near i.r. region independently of the method of crystallophosphor preparation, the oxidation state of introduced elements and the conditions of u.v. irradiation. The effect of matrix nature, flux content and concentration of quenching elements in analyzed solution on crystallophosphors luminescence has been studied. The methods of neptunium and plutonium 相似文献
6.
Accelerator mass spectrometry (AMS) was used to measure 237Np in environmental water samples extracted from Irish Sea sediments. The samples were of limited volume (approximately 700 ml) and of low activity (0.06-0.79 mBq l-1; 2.30-30.3 pg l-1). AMS proved to have the required sensitivity for measuring these samples, and was in principle capable of measuring much smaller amounts, as low as 0.4 microBq (3.9 x 10(7) atoms). However, the background level in the procedural blanks showed that there was a systematic low level 237Np contamination of each sample, arising from the 239Np yield monitor used in the separations procedure, which effectively increased the detection limit of these analyses. 相似文献
7.
In order to deliver reliable results for a multitude of different scenarios, e.g. emergency preparedness, environmental monitoring, nuclear decommissioning and waste management, there is a constant process of method development in the field of radioanalytical chemistry. This work presents the results of a method comparison exercise aimed at quantifying 90Sr and 239,240Pu in environmental soil samples, with the intention of evaluating the performance and applicability of different methods. From the methods examined in this work, recommendations are given in order to find a radioanalytical measurement procedure, for 90Sr and 239,240Pu analysis, which is fit-for-purpose for a particular scenario. 相似文献
8.
Several samples of 237Np and 242Pu were irradiated in the guided cold neutron beam of the prompt gamma activation analysis facility at the Budapest Research Reactor. The thermal neutron capture cross sections of 237 Np and 242Pu were evaluated from the obtained prompt and delayed gamma ray data. The thermal neutron capture cross sections for 237Np( n,γ) 238Np was found to be $ \sigma_{0} ({}^{237}{\text{Np}}) = 170.4 \pm 7.4\,{\text{b}} $ and for 242Pu(n,γ) 243Pu to be $ \sigma_{0} ({}^{242}{\text{Pu}}) = 19.6 \pm 3.9\,{\text{b}} $ . 相似文献
9.
研究了以242Pu为稀释剂时,电感耦合等离子质谱(ICP-MS)定量分析237 Np的理论可行性。研究结果表明:237 Np和242Pu灵敏度的差异主要是由两者电离度的差异和质量歧视效应引起的。在等离子体温度为7 000~10 000K和样品提升率为50~1 000μL/mL时,经过质量岐视校正后,237 Np和242Pu灵敏度的差异只在于两者电离度的差异,且两者相对差异<1%。以242Pu为稀释剂ICP-MS定量分析237 Np的方法在理论上是可行的。 相似文献
10.
Ammonium uranates (AU) obtained by the addition of aqueous NH 4 OH to a solution of UO 2 (NO 3) 2 or the equilibrium reaction of UO 3 · 2H 2 O with the vapour over concentrated NH 4 OH have been studied by X-ray diffraction (XRD) analysis, diffuse reflectance Fourier transform infrared spectrometry (DR-FTIR) and chemical analysis. Ammonia can be present as either NH 3 or NH
4
+
. For precipitates obtained at a pH of 3.7, ammonia in the form of NH 3 is predominant. For ammonium uranate obtained by reaction over concentrated NH 4OH, most of the ammonia is bonded as NH
4
+
. The reaction mechanism and structures of the products are also discussed. 相似文献
11.
A new method for the determination of (237)Np and Pu isotopes in large soil samples has been developed that provides enhanced uranium removal to facilitate assay by inductively coupled plasma mass spectrometry (ICP-MS). This method allows rapid preconcentration and separation of plutonium and neptunium in large soil samples for the measurement of (237)Np and Pu isotopes by ICP-MS. (238)U can interfere with (239)Pu measurement by ICP-MS as (238)UH(+) mass overlap and (237)Np via (238)U peak tailing. The method provides enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then transferring Pu to DGA resin for additional purification. The decontamination factor for removal of uranium from plutonium for this method is greater than 1×10(6). Alpha spectrometry can also be applied so that the shorter-lived (238)Pu isotope can be measured successfully. (239) Pu, (242)Pu and (237)Np were measured by ICP-MS, while (236)Pu and (238)Pu were measured by alpha spectrometry. 相似文献
12.
Journal of Radioanalytical and Nuclear Chemistry - In the original article, the LOD assigned to method Sr-B in Table 1 was published incorrectly as 24 Bq/kg, the correct LOD for... 相似文献
13.
A simple method is described for the isolation and determination of plutonium isotopes in sediments. The method involves leaching of sample with nitric acid and subsequent separation of plutonium on an anion-exchange column. Major matrix elements and several potential radiochemical interferences are removed during 8M HNO 3 sample loading on the column. Thorium is removed by thorough washing with 10M HCl. Plutonium (IV) is eluted with 4M HCl. Source for alpha-particle spectrometry is prepared by LaF 3 coprecipitation technique at which stage a complete separation from uranium(VI) is also achieved. The entire analytical procedure is completed in about two days. 相似文献
14.
A procedure for determining Pu in environmental soil using 238Pu as a yield tracer is described. The method involves radiochemical separation and electrodeposition onto a stainless steel disc followed by alpha-spectrometric measurement with a solid-state detector. In order to eliminate error in calculation caused by 238Pu contained in original samples, a new calculating method is introduced in this paper. By using this method, the activity of 238Pu contained in original samples can be substracted from the total activity of samples, to which the 238Pu tracer is added. This procedure has been applied satisfactorily to the determination of Pu in a soil reference sample, which was supplied by the Institute of Metrological Science of China. 相似文献
15.
Intertidal coastal and estuarine sediments from 24 sites in the Irish Sea have been analyzed for 99Tc, 237Np, 238Pu, 239,240Pu and 241Am. The 237Np activity and 239Pu/ 240Pu ratio were measured simultaneously by ICP-MS, and 99Tc was determined by HR-ICP-MS which is ten times more sensitive than Q-ICP-MS.The activities of 99Tc, 237Np, 239,240Pu and 241Am were distributed over a wide range of 1.5–70.5, 0.01–13.3, 2.3–1589, 2.6–1894 Bq/kg, respectively. Activities of these radionuclides decreased exponentially with distance from the Sellafield source. The 241Am/ 239,240Pu and 237Np/ 239,240Pu ratios were almost constant with distance from the Sellafield. This result suggests that the distribution and behavior of Np and Pu are controlled by complicated factors such as the influence of transport, the variation with time of Np/Pu ratio in the Sellafield discharges and sedimentary mixing processes in the Irish Sea. 相似文献
16.
A new method that allows rapid preconcentration and separation of plutonium and neptunium in water samples was developed for the measurement of 237Np and Pu isotopes by inductively-coupled plasma mass spectrometry (ICP-MS) and alpha spectrometry. 238U can interfere with 239Pu measurement by ICP-MS as 238UH + mass overlap and 237Np via peak tailing. The method provide enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then moving Pu to DGA resin for additional removal of uranium. The decontamination factor for uranium from Pu is almost 100,000 and the decontamination factor for U from Np is greater than 10,000. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration is performed using a streamlined calcium phosphate precipitation method. Purified solutions are split between ICP-MS and alpha spectrometry so that long and short-lived Pu isotopes can be measured successfully. The method allows for simultaneous extraction of 20 samples (including QC samples) in 4?C6 h, and can also be used for emergency response. 239Pu, 242Pu and 237Np were measured by ICP-MS, while 236Pu, 238Pu, and 239Pu were measured by alpha spectrometry. 相似文献
18.
Adsorption experiments were performed to measure distribution coefficients of 237Np(V), 238Pu(IV) and 241Am(III) for sedimentary sequential chemical extraction of the adsorbed radionuclides was carried out with water, CaCl 2, KCl, NH 2OH−HCl, K-oxalate and H 2O 2 solutions, to elucidate their dominant sorption mechanisms. The distribution coefficient of 237Np was two orders of magnitude smaller than that of 238Pu and 241Am. Most of 237Np adsorbed was extracted with CaCl 2 solution and its sorption was controlled by a reversible ion exchange reaction. The adsorbed 238Pu was mainly extracted with NH 2OH−HCl+K-oxalate solution and its sorption was possibly controlled by irreversible reactions. 相似文献
19.
A radiochemical procedure is developed for the determination of 237Np in soil with multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS) and gamma-spectrometry. 239Np (milked from 243Am) was used as an isotopic tracer for chemical yield determination. The neptunium in the soil is separated by thenoyl-trifluoracetone extraction from 1 M HNO 3 solution after reducing Np to Np(IV) with ferrous sulfamate, and then purified with Dowex 1 × 2 anion exchange resin. 239Np in the resulting solution is measured with gamma-spectrometry for chemical yield determination while the 237Np is measured with MC-ICP-MS. Measurement results for soil samples are presented together with those for two reference samples. By comparing the determined value with the reference value of the 237Np activity concentration, the feasibility of the procedure was validated. 相似文献
20.
A simple, rapid, cost-efficient, and robust method for separation of 237Np with an extraction chromatographic column (TOA: tri-n-octylamine on Teflon powder) is outlined in detail and further improved for direct ICP-MS analysis. The column efficiently retained 237Np in 2 mol L(-1) HNO3 medium and all of the 237Np was easily eluted with 0.02 mol L(-1) oxalic acid in 0.16 mol L(-1) HNO3 at 95 degrees C. The separated solutions were free from most matrix elements and were aspirated into the ICP-MS directly. The decontamination factor for 238U is more than 10(4). The instrumental detection limit for 237Np was 0.46 pg mL(-1), which corresponds to 1.2 x 10(-5) Bq mL(-1). The method is more rapid than traditional radiometric techniques. It is also considered to be more suitable for environmental monitoring than existing methods based on TOA. 相似文献
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