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1.
Nak Bae Kim Keung-Shik Park Hyung Joo Woo Kil Yong Lee Yoon Yeol Yoon Duk Kyung Kim 《Journal of Radioanalytical and Nuclear Chemistry》1992,160(2):539-548
A radiochemical separation method using an anion exchange resin has been applied to 4N grade tungsten for determining U, Th and 4 other elements. While tungsten remained in the resin, Na, K and As were separated with 0.05M HCl and 1M HF and then U, Th and Cr were eluted with 1M HCl and 1M HF. The separation yield of neptunium (U) was influenced largely by the amount of thorium, but this influence could be neglected as the concentration of the thorium was below 0.5g/ml. The content of these elements were calculated by a single comparator method using monitors, gold and cobalt. The detection limits of U and Th are 4.0 and 1.2 ppb, respectively. 相似文献
2.
《Journal of Inorganic and Nuclear Chemistry》1981,43(11):2629-2631
Independent yields of 92mNb were measured in the thermal neutron-induced fission of 233U, 235U, and 239Pu, using radiochemical techniques. Upper limits of < 2.2 × 10−8% and < 4.6 × 10−8% were found for 233U and 235U, respectively. The independent yield for 239Pu was determined to be (11 ± 6) × 10−8%. This yield is much higher than values predicted from models of charge and isotopic distributions. It probably reflects the influence of the nearby closed 50 neutron shell. 相似文献
3.
《Journal of Inorganic and Nuclear Chemistry》1981,43(12):3067-3069
Absolute yields of 10 fission products in the reactor neutron induced fission of 232Th and 17 fission products in the thermal neutron induced fission of 233U have been determined using track etch-cum γ-ray spectrometric technique. The number of fissions occurring in the target is obtained by recording the fission events in a mica track detector. The fission product atoms are determined by the direct counting of the irradiated target on a 60 cm3 Ge(Li) detector coupled to a 4096 channel analyser. A one step radiochemical separation was done, before gamma ray counting, for few fission products in the reactor neutron induced fission of 232Th. The measured yield values are compared with the available literature data and an analysis of the possible errors are done. The overall uncertainty in the measurements is estimated to be 4–5%. 相似文献
4.
Keung Shik Park Nak Bae Kim Young Suk Kim Kil Yong Lee Han Woo Choi Yoon Yeol Yoon 《Journal of Radioanalytical and Nuclear Chemistry》1988,123(2):585-592
A radiochemical separation method has been applied for determining uranium, thorium and other impurities in molybdenum metallic powder. The impurities of Na, K, Sm, Cr, Zr, Cs, Rb, Zn, Fe, Co and La were separated with a cation exchange resin, and uranium and thorium were, then, separated with an anion exchange resin. The content of impurities were determined by a single comparator method using two monitors, gold and cobalt. 相似文献
5.
A method for simultaneous determination of uranium and thorium based on the deviation of their fission cross-section curves has been developed. Using a D-T neutron generator two different neutron spectra were produced with and without moderator around the target. The detection limits were found to be 0.044 mg and 0.25 mg in the presence of a moderator, while for fast neutrons 0.017 mg and 0.037 mg for uranium and thorium, respectively.This work was supported in part by the Ministry of Higher Education and the Hungarian Academy of Sciences. 相似文献
6.
《Journal of Inorganic and Nuclear Chemistry》1978,40(3):377-379
The independent yields of 96Nb and 51 min 98Nb were determined in the thermal neutron-induced fission of 233U, 235U and 239Pu using radiochemical techniques. The results for these fissionable nuclides are as follows for 96Nb: (5.3±0.3) × 10−3%, (5.2±0.2) × 10−4% and (3.6±0.1) × 10−3%, respectively, and for 51 min 98Nb: (0.13± 0.03)%, (0.034±0.015)% and (0.16±0.03)%, respectively. 相似文献
7.
K. S. Park N. B. Kim H. J. Woo K. Y. Lee Y. Y. Yoon J. H. Lee 《Journal of Radioanalytical and Nuclear Chemistry》1993,168(1):153-161
Interferences by uranium fission for95Zr,99Mo,103Ru,140La,141Ce and147Nd have been studied using a single comparator method with two monitors. The effect of the neutron energy spectrum on the interference factor was examined by using the effective activation cross section. All the activities of140La produced during neutron irradiation of uranium were included in the calculation of the factor for lanthanum. The calculated and experimental interference factors are in good agreement within 10% deviation. The results have been applied for the analysis of several rock samples containing uranium in a wide concentration range. 相似文献
8.
Determination of Th and U at ppt levels in a neutral hot spring water by neutron activation analysis
Y. Kikawada T. Honda T. Oi T. Ossaka H. Kakihana 《Journal of Radioanalytical and Nuclear Chemistry》1991,153(5):357-364
Neutron activation analysis was successfully applied to the determination of Th and U at ppt levels in a neutral hot spring water. Blank test corrections were found to be essential to reach the final determined values. Normal NAA is a better method for the Th determination than epithermal NAA, while both NAAs are nearly equally effective for U determination. 相似文献
9.
Instrumental and radiochemical neutron activation analysis has been applied to a comprehensive trace characterization of AlSiCu sputter targets. By instrumental neutron activation analysis via long-lived indicator radionuclides, up to 33 elements were assayed with detection limits between 0.01 and 200 ng·g–1. The high activity of64Cu and24Na produced from the matrix significantly limits the instrumental performance via short- and medium-lived indicator dionuclides. For this reason, a radiochemical separation was developed based on adsorption of24Na on hydrated antimony pentoxide and extraction of64Cu by diethylammonium diethyldithiocarbamate from HCl medium. By this radiochemical method, As, Ga, K, La, Mn, Mo, Re, Sb, U and W could be assayed via medium-lived radionuclides and the achievable limits of detection were between 0.1 and 25 ng·g–1. Further improvement of detection limits for U and Th was achieved by a selective radiochemical separation of239Np and233Pa on a Dowex 1×8 column in HF and HF/NH4F medium providing limits of detection for U and Th of 0.06 and 0.02 ng·g–1, respectively. These techniques were applied to the analysis of two AlSiCu sputter target materials. Results are compared with those of glow discharge mass spectrometry. 相似文献
10.
The determination of235U/238U ratios by activation analysis utilizing high resolution γ-spectrometry
The application of high resolution γ-spectrometry to the direct determination of235U/238U isotopic ratios in small uranium samples after neutron activation is reported. The consistency obtained relative to mass
spectrometrically determined isotopic ratios is better than 5% for isotopic ratios between 0.06885 and 1.095. The method is
not subject to the main disadvantages of the known radiochemical methods for235U/238U isotopic ratio determinations, and should be appreciably more rapid compared to the solid-source mass spectrometric method
giving the same precision. 相似文献
11.
M. N. Nadkarni P. C. Mayankutty N. S. Pillai 《Journal of Radioanalytical and Nuclear Chemistry》1984,86(5):275-280
Application of extraction chromatographic technique to the analytical separation of Th/IV/ and U/VI/ has been investigated. The stationary phase was a macroporous resin Amberlite XE-270 impregnated with undiluted trin-n-butylphosphate /TBP/ and the mobile phase was either 5.OM HNO3 or 6M HCl. Separation of traces of Th/IV/ from large quantities of U/VI/ was achieved on a laboratory column by elution of the absorbed Th/IV/ with 6M HCl. 相似文献
12.
E. Martinho 《Journal of Radioanalytical and Nuclear Chemistry》1999,241(2):271-276
The purpose of the present paper is to suggest a method for determining the235U abundance in uranium samples (compounds, metallic alloys or other uranium materials, where this element may be natural or
not) through a particular application of neutron activation analysis, based on the fission interference by molybdenum. The
method lies on an a priori calibration with natural uranium, thus it does not require235U certified standards. 相似文献
13.
14.
The rapid industrial development in regions of Mexico during recent years has had the side effect of introducing toxic metals, fertilizers, and pesticides into the ecosystem. Sediment cores were collected from eight locations around the Julian Adame-Alatorre dam located in the Municipality of Villanueva in the State of Zacatecas, México. The cores were analyzed for 32 major, trace, and rare earth elements (As, La, Lu, Nd, Sm, U, Yb, Ce, Co, Cr, Cs, Eu, Fe, Hf, Rb, Sb, Sc, Sr, Ta, Tb, Th, Zn, Zr, Al, Ba, Ca, Dy, K, Mn, Na, Ti, and V) in order to estimate the health risk. The samples were analyzed by instrument neutron activation analysis (INAA) using thermal neutron fluxes of 8 × 1013 and 5 × 1013 n cm−2 s−1 for short and long irradiations, respectively. The results of the contamination levels for elements such as As, Ba, Cr, Fe, Mn, Ta, V, and Zn were compared with the Mexican regulations and the guidelines of USEPA. Enrichment factors for quantified elements identified high As, Sb, Hf, and Cs contents using Fe as a crustal reference. 相似文献
15.
László Szentmiklósi Tamás Belgya Zsolt Révay Zoltán Kis 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(2):501-505
The Budapest Research Reactor’s Prompt Gamma Activation Analysis (PGAA) and Neutron-Induced Prompt gamma Spectroscopy (NIPS) facilities were significantly upgraded during the last few years. The higher neutron flux, achieved by the partial replacement and realignment of the neutron guides, made feasible the automation and specialization of the two experimental stations. A new neutron flux monitor, computer-controlled beam shutters and a low-level counting chamber have been put into operation to assist with in-beam activation experiments. An automatic sample changer has been installed at the PGAA station, while the NIPS station was redesigned and upgraded with a Compton suppressor to use for the non-destructive analysis of bulky samples. In the near future the latter setup will be completed with a neutron tomograph and a moving table, to turn it into a Neutron Radiography/Tomography-driven PGAA equipment. 相似文献
16.
S. E. Glover R. H. Filby S. B. Clark 《Journal of Radioanalytical and Nuclear Chemistry》1998,234(1-2):65-70
The accurate and precise determination of232Th in biological samples is very important for the development of biokinetic models for thorium and for improving our knowledge
on its distribution in human tissues. Radiochemical neutron activation analysis has long been one of the most sensitive methods
for the determination of232Th. However, these determinations suffer in reliability because recovery information following the separation is not typically
available. This information is particularly important for difficult matrices such as human bone where recoveries may be significantly
less than unity. Also, the separation of difficult matrices following neutron activation may involve relatively high personal
dose from the co-activated matrix. A novel approach for the determination of radiochemical yield has been developed which
employs the use of a readily available, gamma-emitting isotope of thorium,227Th.227Th, obtained by radiochemical separation from227Ac, is added to each, dissolved sample prior to separation and the chemical yield determined by gamma-ray spectrometry following
the separation. This pre-concentration step is then followed by neutron activation and the232Th determined via233Pa using gamma-ray spectrometry. Detection limits were approximately an order of magnitude lower than obtained by alpha-spectrometry. 相似文献
17.
M. Â. B. C. Menezes E. C. P. Maia C. C. B. Albinati Â. M. Amaral 《Journal of Radioanalytical and Nuclear Chemistry》2007,271(1):119-123
Gold is not included in the current list of elements considered essential to humans and there are many controversies related to its toxicity. According to the chemical characteristics of the element, Au1+ is favored for binding at sites with S donor, such as sulfhydryl group (-SH) in proteins in biological systems. This tendency raises the possibility of health-related risk, mainly linked to a long-term exposure to high and low levels of gold. This paper highlights the determination of gold by instrumental neutron activation analysis (INAA) during the assessment of exposure levels to metals and possible workers’ contamination in three galvanizing factories applying the same processes. This assessment is aimed at giving support to Worker’s Health Awareness Program of the Municipal Department of Health of Belo Horizonte, Minas Gerais, Brazil. INAA, mix of k 0 and monostandard methods was applied to air filter, hair and toenail samples, and to urine samples. Solvent extraction of gold was carried out followed by comparative INAA. The results revealed that gold was present in all matrixes, indicating the exposure in the workplace and suggesting endogenous contamination. Is gold playing a role as a toxic element? 相似文献
18.
J. H. Augustson J. W. Haynes T. W. Sanders 《Journal of Radioanalytical and Nuclear Chemistry》1980,60(2):373-383
A method for the determination of uranium based on235U thermal neutron fission, has been developed and employed on samples of ashed fish tissue and seaweed. The method involves
a post-irradiation ion exchange separation of iodine isotopes. The 884 keV photopeak of134I is used for measurement. Uranium detection limits in the samples concerned have been estimated to be 1·10−8g in terms of natural uranium. The precision achieved in analysing several series of 3–5 samples was 4–10 per cent. The accuracy
of the method was tested by employing an independent neutron activation procedure based on239U measurement. The accuracy of both methods was checked by analysing NBS SRM 1571 ‘Orchard Leaves’. 相似文献
19.
J. Al-Jundi K. Randle L. G. Earwaker 《Journal of Radioanalytical and Nuclear Chemistry》1993,174(1):145-151
Two fairly recent sediment reference materials (MESS-1, PACS-1) have been analyzed by INAA in order to determine the concentration of their elements and to ascertain the homogeneity of each standard. Two rock samples (USGS-GSP-1 and JG-1) were used as standards for the determination of element concentrations, for inter-calibration purposes and also to assess the precision of the technique used. Eighteen elements were determined in these sediments. Comparison of the certified values with our results, where this is possible, indicates the accuracy of the method for environmental studies. These materials were shown to be very homogeneous and hence useful as sediment standards. The data presented here extend the range of useful element concentrations in these reference materials. 相似文献
20.
K. K. S. Pillay R. J. Meyer R. P. Larsen 《Journal of Radioanalytical and Nuclear Chemistry》1969,3(3-4):233-243
A method is described for the determination of the fission yield of141Pr. This method was developed to determine the fast fission yield of141Pr in the Mark III loading (enriched uranium with about 2% zirconium) of the fast fission breeder reactor, EBR-1. The burnup
of the fuel sample was determined using the previously reported fission yield of137Cs. Praseodymium was separated from uranium, plutonium and other fission products by a combination of precipitation and ion
exchange stages. Thereafter,55Mn was added to serve as an internal flux monitor and praseodymium determined by neutron activation analysis. A precision
of ±2% was obtained.
Presented at the 15th Annual Meeting of the American Chemical Society, Miami Beach, Florida (USA), April 1967. 相似文献