共查询到20条相似文献,搜索用时 15 毫秒
1.
Matthias J. Brunnermeier Stefanie A. K. Schmied Robert Schupfner 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(3):1285-1290
The period of date of death of an elephant can be assessed by analyzing four different radionuclides, 14C, 90Sr, 228Th and 232Th in its ivory. These nuclides are supposed to have variing concentrations at different parts of a tusk. The reason is the
procedure of growth which takes place at the butt-site of a tusk. Therefore the site of sampling could have a big influence
on the assessed date of death. However, to find out if the position of sampling is important a complete tusk was analyzed
regarding the distribution of these nuclides. Results show that the concentration activity of 14C and 228Th varies in different parts of a tusk. The activity concentration of 90Sr is very similar in all analyzed parts. The conclusion is that sampling at the butt of a tusk is recommended for age assessment. 相似文献
2.
J. H. Park K. B. Lee C. S. Lee Y. K. Kwon J. H. Lee J. Y. Kim W. Hong 《Journal of Radioanalytical and Nuclear Chemistry》2008,275(3):627-631
A (D3C)2O (d6-acetone) target was irradiated with semi-monoenergetic neutrons generated from 9Be(p,n)9B reaction with 20 MeV protons to convert 13C and oxygen nuclides in the target into 14C. With both liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS) we measured the (D3C)2O (d6-acetone) liquid targets, which were combustible and easy to afford CO2 for the AMS measurements. The 14C yield measured by the LSC method turned out to be 80 times larger than that by the AMS method. This large discrepancy may
be attributed to the loss of 14C atoms during the sample pretreatment in the AMS method such as combustion and cryogenic trapping of CO2. It means that 14C newly produced by nuclear reactions can exist in various chemical forms, i.e., C3D6O, CO, CO2, hydrocarbons, etc., and a simple sample pretreatment right after production can cause serious isotopic fractionation. Therefore,
using the AMS method, extreme caution in sample pretreatment should be exercised when the 14C yield produced immediately by nuclear reaction is measured. 相似文献
3.
L. Popov G. Mihailova I. Naidenov 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(2):223-237
The origins of different artificial radionuclides found in soils from Northern and Southern Bulgaria was determined by measurements
of their actual concentrations and respective ratios. On the basis of the measured mobility and concentrations of the investigated
radionuclides in soils, it was estimated that after the Chernobyl accident the mean depositions of fresh 137Cs were 3.0 ± 2.5 kBq/m2 for Northern Bulgaria and 15 ± 7 kBq/m2 for Southern Bulgaria. As a result of global fallout following atmospheric nuclear weapon tests in the 1950s, mean depositions
(corrected to 1965) were calculated for Northern and Southern Bulgaria as follows: for 90Sr—1.0 ± 0.5 and 2.3 ± 1.3 kBq/m2, 238Pu—1.3 ± 0.8 and 2.8 ± 1.6 Bq/m2, 239+240Pu—15 ± 14 and 47 ± 38 Bq/m2, and 241Pu—520 ± 200 and 760 ± 260 Bq/m2. 相似文献
4.
Tongke Zhao Lei Zhang Qiuju Guo Wenbin Dong 《Journal of Radioanalytical and Nuclear Chemistry》2017,313(2):379-384
The activity concentrations of 218Po, 214Pb and 214Bi [i.e. C(218Po), C(214Pb), and C(214Bi)] and the calculated concentration ratios [i.e. 1:C(214Pb)/C(218Po):C(214Bi)/C(218Po)] are necessary for assessing radon and its progenies exposure. In this study, a measurement method of radon progenies concentrations with both high sensitivity and low uncertainty, was developed based on the Kerr method. The field measurement results of radon progeny concentrations and calculated concentration ratios in both typical indoor and outdoor environments in Beijing, China, were reported. The effects of air exchange rate on concentration ratios of radon progenies in indoor environments were discussed. 相似文献
5.
S. P. Patil D. B. Kalgutkar N. Jayachandran V. K. P. Unny 《Journal of Radioanalytical and Nuclear Chemistry》2005,266(1):75-78
Summary An attractive and simple method has been developed for the preparation of ammonium [14C]thiocyanate from [14C]thiourea which eliminates the necessity of handling highly hazardous potassium [14C] cyanide. [14C]thiourea was isomerized to ammonium [14C]thiocyanate by heating the aqueous solution of thiourea (12%) in a sealed tube at 160 °C for 24 hours. The product formed was purified by silica-gel column chromatography. A radiochemical yield of 92.7% was obtained based on [14C]thiourea. The specific activity of the product obtained was 53.3 mCi/mmol (1.97 GBq/mmol) and the radiochemical purity was greater than 99%. This method has not been reported so far for the production of this labeled compound. 相似文献
6.
N. Momoshima M. Sayad M. Yamada M. Takamura H. Kawamura 《Journal of Radioanalytical and Nuclear Chemistry》2005,266(3):455-460
Summary Global fallout levels of 99Tc and 137Cs of surface seawater in the Pacific Ocean were measured. The 99Tc concentrations ranged from 0.62 to 3.33 mBq. m-3and 5 of 6 samples showed less than 1 mBq. m-3except one sample taken in the Great Barrier Reef, Australia. The 137Cs concentrations ranged from 2.13 to 3.14 Bq. m-3, showing a gradual decrease in the North Pacific toward the equator and a constant level in the South Pacific. The 99Tc/137Cs activity ratios ranged from 2.5. 10-4to 2.9. 10-4, which is very close to that calculated theoretically from the fission yield. 相似文献
7.
S. D. Park J. S. Kim S. H. Han K. Y. Jee 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(3):503-511
It is regarded that the spent resins from the water purification systems of moderator (MOD) and the primary coolant of the
Canada deuterium uranium-pressurized heavy water reactor (CANDU-PHWR) are a unique waste, owing to their high 14C and gamma-emitting nuclides. In this work, 14C and 3H contents, anion and cation fractions and the predominant gamma-emitting nuclides of the spent resins from 4 units of CANDUPHWRs,
were investigated. Also the chemical species of 14C of the spent resins were determined. For a simultaneous separation of 14C and 3H from the spent resins, the wet oxidation-16 wt% H2SO4 stripping process was utilized. The 14C and 3H activity concentration range of the spent resins of the nuclear power plant (NPP), 4 units of all CANDU-PHWR types, was
2.48E5 Bq/g ∼5.33E6 Bq/g, 1.29E5 Bq/g and ∼2.33E5 Bq/g, respectively. Among the analyzed spent resins, the highest 14C and 3H activity concentration was detected in units 4 and 3, respectively. It was found that more than 92% of the 14C activity concentration was retained on the anion resin and the predominant chemical species was inorganic 14C. It was revealed that the anion resin fraction of the spent resins from unit 1 and unit 2, was about 40% and that of unit
3 and unit 4 was around 60%. More than 80% of the total gamma-radioactivity concentration was associated with the cation fraction
of the spent resin. The predominant gamma-emitting nuclide of the spent resin for unit 2 was 137Cs, a fission product, and that for unit 4 was 60Co, a corrosion product. 相似文献
8.
M. Yamamoto A. Sakaguchi J. Tomita T. Imanaka K. Shiraishi 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(1):93-103
To estimate the dietary intakes of 210Pb and 210Po for the Japanese adults and their annual effective doses, 210Pb and 210Po were measured for 240 daily diet samples collected at two locations of Ishikawa Prefecture in Japan over three years by
duplicate portion studies. No appreciable differences in intake rates of 210Pb and 210Po and their 210Po/210Pb ratios were seen among the years in each district, and between the two districts. The intake rates evaluated using 240
diet samples were 0.20 Bq/d/p for 210Pb and 0.61 Bq/d/p for 210Po as a median, respectively. Annual effective doses of 210Pb and 210Po for Japanese adults were estimated to be 0.050 and 0.053 mSv/y, respectively. 相似文献
9.
Possibility of using a low-temperature magnesium-potassium phosphate matrix to solve the problem of immobilizing the radioactive wastes containing radioactive carbon (14C) in the form of calcium carbonate was examined. The physicochemical characteristics of the compounds obtained were determined. Large values of the ultimate compression strength (22 ± 5 MPa), which satisfy the technical requirements for cemented radioactive wastes (no less than 4.9 MPa), were obtained. The minimum carryover of carbon dioxide into the atmosphere in the course of synthesis and in keeping of samples for 14 days was noted: not more than 3 wt % relative to the starting CaCO3. The leaching rate of carbonate ions from magnesium-potassium compounds by 28th day of contact with air does not exceed 10?9 g cm?2 day?1, with this value for the rest of the compound components not exceeding 10?4 g cm?2 day?1. Thus, it was found that the magnesium?potassium phosphate matrix is an alternative to the cementation for solidification of radioactive wastes containing 14C. 相似文献
10.
Matías Ezequiel Carranza 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(2):787-799
In this work, the optimization of a segregation method of 129I and 14C, two long-living radionuclides, main constituents of nuclear radioactive waste, has been developed. To be able to carry out this project, a fractional factorial experimental design was applied using 5 factors and 2 levels by factor (25–2). Only 8 experiments were necessary to identify the variables affecting the process, and very good recoveries of both radionuclides were obtained: (94?±?2)% for 129I, and (99?±?1)% for 14C. The segregation of 129I was influenced by flow (Q), volume of H2SO4 (VH+), and carriers (CR), while VH+ and time (t) played a major role in the segregation of 14C. 相似文献
11.
T. Nakanishi M. Kusakabe T. Aono M. Yamada 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(3):769-776
A technique to determine concentrations of 32P, 33P and 7Be in dissolved and particulate forms, in the upper ocean was developed. By using a large volume in situ filtration and concentration
system (LV-FiCS), several tons of seawater at different depths were filtered concurrently through two kinds of filters. The
dissolved radionuclides were concentrated onto adsorbents in the LV-FiCS. The radionuclides obtained were further purified
by precipitation and ion-exchange chromatography, and quantified by gamma-spectrometry and ultra-low level liquid scintillation
counter measurements. The technique was used with good results in a coastal area of Ibaraki, Japan. 相似文献
12.
P. Vesterbacka S. Klemola K. Salahel-Din M. Saman 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(3):441-448
An intercomparison of the methodology (alpha, beta and gamma spectrometry) used for 238U, 235U and 210Pb determination was carried out based on 38 sediment samples. The activity range of the samples varied from 10–700 Bq/kg
for 210Pb, 1–35 Bq/kg for 235U and 10–800 Bq/kg for 238U. Results obtained using the three methods were not statistically different at high activity levels, but agreement between
the results decreased at lower sample activity levels. For 210Pb, the smallest difference was found between alpha and gamma spectrometry. A good correlation between results from alpha
and gamma spectrometry was observed over the whole activity range. In beta spectrometry, the results were slightly higher
than those obtained by alpha or gamma spectrometry due to the impurity of 228Ra. In 238U analysis, good correspondence was observed between 238U determined by gamma and alpha spectrometry, particularly at higher 238U activity concentrations over 100 Bq/kg. In 235U analysis, attention needs to be paid to interference from 226Ra and its reduction. 相似文献
13.
Emily K. Mace Craig E. Aalseth Anthony R. Day Eric W. Hoppe Justin I. McIntyre Allen Seifert Richard M. Williams 《Journal of Radioanalytical and Nuclear Chemistry》2018,318(1):125-129
A radiotracer gas with a blend of 37Ar and 127Xe was created for a gas migration experiment and was characterized at Pacific Northwest National Laboratory using ultra-low-background proportional counters. This paper describes the direct low-energy measurement of 37Ar and 127Xe in a dual-isotope sample. Using this low-energy technique, the dual-isotope radiotracer gas was determined to have activity concentrations of 483 Bq/cc and 1435 Bq/cc for 37Ar and 127Xe, respectively, and a ratio of 1:3 on the reference date of 7/11/2016. 相似文献
14.
S. Salminen J. Paatero P. Roos K. Helariutta 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(3):405-413
Activity concentrations of 237Np in peat and lichen samples in Finland were determined and contributions from nuclear weapons testing in 1950–1960s and
the Chernobyl accident were estimated. 237Np was determined with ICP-MS using 235Np as a tracer. Activity concentrations of 237Np in peat samples varied between 1.98 ± 0.05 and 14.1 ± 0.3 mBq/m2. The contribution from the Chernobyl accident to the total 237Np deposition in peat was 0.1–13%, the Chernobyl-derived fraction of total 237Np in peat being much lower than the previously determined corresponding Chernobyl-derived fractions of 239+240Pu, 241Pu, 241Am and 244Cm. 相似文献
15.
Ho-Yeon Yang Ji-Hoon Lee Jung-Jin Lee 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(2):177-186
The removal characteristics of H14CO3
− ions from IRN-150 mixed resin contaminated with 14C radionuclide and the gasification effects of 14C radionuclide on 14CO2 are investigated in this study. The stripping solutions used for the removal of 14C from spent resin are NaNO3, Na3PO4, NH4H2PO4, and H3PO4. The influence of the stripping solution concentration on the desorption characteristics of an inactive HCO3 ion into a stripping solution from IRN-150 mixed resin and the gasification of this ion to CO2 is analyzed. The gasification behavior to CO2 using NaOH, HNO3, and HCl was also compared to that of phosphate solution. Spent resin stored in Wolsong nuclear power plant is used to evaluate
the gasification characteristics of 14C radionuclide to 14CO2. Gamma radionuclides such as 137Cs and 60Co in residual striping solutions after desorption experiments are analyzed. 相似文献
16.
Chang Heon Lee Moo Yul Suh Kwang Yong Jee Won Ho Kim 《Journal of Radioanalytical and Nuclear Chemistry》2007,272(1):187-194
A sequential separation procedure has been developed for the determination of 99Tc, 94Nb, 55Fe, 90Sr and 59/63Ni in various radioactive wastes generated from nuclear power plants. Ion exchange and extraction chromatography were adopted
for individual separation of the radionuclides. Precipitation was supplementarily utilized for both purification of the individual
radionuclides and preparation of the radionuclide sources for use in a radioactivity measurement. The chromatographic separation
behavior of the radionuclides both from the sample matrix metals and from one another was investigated using stable metals,
Re (as a surrogate of 99Tc), Nb, Fe, Sr and Ni. The validity of the procedure for reliability and applicability was evaluated by measuring the recovery
of the metal carriers added to synthetic radioactive waste solutions. The recoveries by the chromatographic separation were
in the range of 84.8 to 102.2% with 2s of less than 8.6%, the recoveries by the precipitation being in the range of 84.3 to 97.3% with 2s of less than 10.9%. 相似文献
17.
A. V. Il’yasov N. K. Gaisin B. I. Buzykin R. B. Zaripov 《Russian Chemical Bulletin》2010,59(8):1506-1511
The 1H spin-lattice relaxation times of the proton-bearing groups and the 31P spin-lattice relaxation times in C-phosphorylated oximes R1C(=NOH)P(=O)R2R3 (R1 = Ph, R2 = R3 = OMe; R1 = Ph, R2 = OMe, R3 = OCH2CH2Br; R1 = PhCH2, R2 = R3 = OCHMe2) and dioxime R2P(=O)C(=NOH)(CH2)4C(=NOH)P(=O)R2 (R = OMe) in DMSO-d6 were measured. The characteristic reorientation times of the whole molecules were estimated using the measured values of
the 1H relaxation times and the results of semiempirical PM3 quantum chemical calculations of the molecular geometries. The reorientation
times were used to identify the contributions of different relaxation mechanisms to the rate of 31P spin-lattice relaxation. The anisotropy of the chemical shielding of 31P nuclei was evaluated from the difference between the 31P relaxation rates measured at 101.27 and 161.92 MHz. 相似文献
18.
Activity concentrations of 238U, 235U and 234U were determined in different sources of drinking water at the Obuasi gold mines and its surrounding areas in Ghana. Water
samples collected from the mines and its surrounding areas were analyzed using direct gamma-ray spectrometry and neutron activation
analysis. The 234U/238U and 235U/238U ratios were calculated and the mean values range from 1.27 to 1.38 and from 0.044 to 0.045 respectively. The average 234U/238U ratio was from 1.27 for groundwater to 1.38 for treated water, demonstrating the lack of equilibrium. The average 235U/238U activity ratio is 0.045, indicating that only natural uranium was detected in the samples investigated. 相似文献
19.
Liquid state, high resolution 13C NMR spectroscopy and mass spectrometry were used to study the composition and structure of soil organic matter (SOM) using
soil extracts from two long-term experiments at the Rothamsted Experimental Station. Both one- and two-dimensional NMR techniques
were applied. 13C NMR sub-spectra of the CH
n
(n=0...3) groups, obtained by the Distortionless Enhancement by Polarisation Transfer (DEPT) technique, were used for the
elucidation of the qualitative and quantitative composition of humic and fulvic acids in the soils. The chemical structure
of SOM was further analysed at the molecular level through Fast Atom Bombardment Mass Spectrometry (FABMS) and Gas Chromatography-Mass
Spectrometry (GC/MS). Humic and fulvic extract results were not only compared to each other, but also to the solid state 13C NMR results for the complete soil sample. 相似文献
20.
Scott J. Tumey Thomas A. Brown Bruce A. Buchholz Terry F. Hamilton Ian D. Hutcheon Ross W. Williams 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):721-724
By making modifications to our previously established measurement setup, we increased our abundance sensitivity for 233U by three orders of magnitude and can now measure 233U/238U ratios as low as 10−13. Because 233U has separate production pathways than 236U, it can provide valuable information on the particular source of anthropogenic uranium in a sample. We demonstrated the
utility of our improved capability by using 233U to distinguish separate sources of anthropogenic uranium in a set of samples collected from a contaminated site. In the
future, we plan to apply our new capability to characterizing 233U in a wide range of uranium materials. 相似文献