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1.
Simultaneous
measurement of gamma-rays and neutron fluences</p>
using
a HPGE detector</o:p></p>
</p>
Z. B. Alfassi T. Zlatin U. German 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):237-241
Summary A
simultaneous determination of gamma and neutron fluences in a mixed neutron +
gamma field can be achieved by gamma-ray spectrometry, optimizing the
moderator-converter-detector assembly and measuring both the direct gamma-lines
and the neutron induced prompt gammas. For the prompt gamma-lines a combination
of high efficiency and low background is the goal, and it can be best achieved
if the gamma-energy is in the range above about 1 MeV up to 2.5 MeV. The
optimal moderator-converter thickness can be determined experimentally. Most
converter elements produce gamma-rays in the low energy range. If chlorine is
used as a converter, the 1164.7 keV peak and the 1950-1960 keV peaks seems to
be a good choice. A very practical material containing chlorine is PVC. It is
an efficient moderator, it is solid, common, and can be handled easily.</p>
</p> 相似文献
2.
Shuddhodan P. Mishra Diwakar Tiwari Shailesh Kumar Prasad R. S. Dubey Manisha Mishra 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):191-199
Summary The
uptake of indigenously synthesized amorphous stannic and zirconium phosphate
was assessed for, one of the important fission fragment, cesium from aqueous
solutions using a radiotracer technique. A virtual increase in sorptive
concentration (from 1.0 . 10-8 to 1.0 . 10-2
mol . dm-3) and pH (from 2.4 to 10.2) and temperature
(from 303 to 333 K) enhanced the uptake of cesium on stannic phosphate.
However, the extremely high degree of uptake of cesium on zirconium phosphate
was almost unaffected with the dilution beyond 10-5 mol .
dm-3 and pH (i.e., from 2.4 to 10.2) and temperature (from 303 to
323 K). Irreversible uptake occurring for these solids follow the Freundlich
adsorption isotherm and the presence of several complexing agents viz.,
sulphate, phosphate, glycine and EDTA did not affect appreciably the uptake of
cesium on zirconium phosphate but it did affect for stannic phosphate system.
Both these solids showed good radiation stability towards a 11.1 GBq Ra-Be
neutron source having neutron flux ca. 3.2 . 106 n .
cm-2 . s-1 and associated with a nominalg-dose of ca.
1.72 Gy/h, at least for the uptake of cesium.</p>
</p> 相似文献
3.
Chien C. Lin C. F. Wang Y.C. Sun J. H. Chao C. L. Tseng 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):419-424
Summary Exploratory
experiments have been carried out to investigate the effects of gamma-radiation
on iodine aerosols under various chemical conditions. The results indicate that
iodide ions (I-) in aerosol can be readily oxidized to I2
and HIO, and some iodide ions may be converted to organic iodine when organic
additives are present in the KI solution from which the aerosol is generated.
The results also suggest that the chemical transformation of irradiated iodine
aerosol depends on the chemical environment both carrier gas and iodide
solution.</p>
</p> 相似文献
4.
A. Arias A. Arias M. Oddone M. Oddone G. Bigazzi G. Bigazzi A. Di Muro A. Di Muro C. Principe C. Principe P. Norelli P. Norelli 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):371-386
Summary Newly
produced fission track (FT), instrumental neutron activation analysis (INAA)
and micro-Raman spectrometry data have been used to characterize the classical
source areas of the Milos obsidians better and to check the provenance of
obsidian artefacts. The Bombarda-Adhamas and Demenegaki obsidians yielded
indistinguishable FT ages 1.57±0.12 and 1.60±0.06 My, respectively, in agreement with previous FT data. By
INAA analyses it was possible to discriminate between the three obsidian
sources on Milos: Bombarda-Adhamas, Demenegaki and A. Ioannes. Raman
spectroscopy has been found to be a valuable technique to gain a
chemico-structural characterization of a given obsidian population in terms of
dissolved water content and microlite distribution/composition.</p>
</p> 相似文献
5.
H. J. Ding Y. N. Niu Y. B. Xu W. F. Yang S. G. Yuan Z. Qin X. H. Zhou 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):433-436
Summary The
extraction of protactinium with Aliquat 336 (methyl-tri-caprylyl ammonium
chloride) in toluene, cyclohexane and chloroform from HCl, HNO3, H2SO4,
HClO4, HF and mixed HCl-HF media was investigated by radioactive
tracer technique. Distribution ratios of protactinium between the aqueous
solution and the organic phase were determined as a function of shaking time,
concentrations of acid in aqueous solution phase, extractant concentration and
type of diluents in the organic phase. Aliquat 336 can almost quantitatively
extract protactinium from strong HCl solution. At the same time, small amounts
of HF in HCl solutions have a strong effect on Pa distribution.</p>
</p> 相似文献
6.
A. S. Al-Hobaib K. M. Al-Sulaiman D. M. Al-Dhayan A. A. Al-Suhybani 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):425-431
Summary Sand
filters are used in water treatment stations to remove particulate matter from
underground water, where iron and manganese are collected forming thin oxide
films. These oxides of iron and manganese adsorb radium from underground water.
Radium concentration increases in time on the filters, and consequently the
level of radioactivity increases in the station. The removal of adsorbed radium
on sand using inorganic acids was studied. Good efficiency of radium removal
was obtained by controlling different parameters like temperature, time, pH,
addition of competitive cations and anions. It was found that hydrochloric acid
is the best for radium removal from sand filters. Maximum removal obtained was
about 60% at 5M BaCl2 and 2M HCl at 50 °C for 180-minute contact
time. Kinetic parameters of the removal process were studied and compared with
literature data.</p>
</p> 相似文献
7.
A. Bhattacharyya P. K. Mohapatra P. N. Pathak V. K. Manchanda 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):323-328
Summary Sorption
behavior of Th and U on cation-exchange resins was investigated from nitric
acid medium by both batch and column methods. The cation-exchange studies
involved the sorption of UO22+ and Th4+ and
their cationic complexes onto Dowex 50Wx8 and Dowex 50Wx4 resins (50-100 mesh).
The batch data yielded a separation factor (Kd,Th/Kd,U)
value of >100 for the cation-exchanger, Dowex 50Wx4 at 1-2M HNO3.
Separation of uranium from thorium was also carried out by column method in
nitric acid medium using cation-exchangers, Dowex 50Wx4 as well as Dowex 50Wx8.
While uranium elution was possible at 1M HNO3, Th could be eluted
only at higher concentration of nitric acid (>6M). The stripped solution
emanating from a mixer settler employing di-2-ethyl hexyl isobutyramide as
extractant and feed solution similar to THOREX process comprising 350 mg/l U
and 380 mg/l Th in 0.75M HNO3 was loaded on the column and the
decontamination factor value for U in the product was >1000.</p>
</p> 相似文献
8.
D. Nayak M. Nag S. Banerjee R. Pal S. Laskar S. Lahiri 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):337-340
Summary The
bioaccumulation of 198Au radionuclide, by Rhizoclonium riparium
a member of Chlorophyceae has been studied. It has been observed that
accumulation of gold on Rhizoclonium is almost pH independent and
slightly higher at basic pH. Accumulation of gold was studied with 198Au
radiotracer, 0.1, 1 and 5 ppm concentrations of gold. It has been concluded
from the biochemical analysis that the gold accumulation is due to adsorption
in the cellulose and not in protein, fat and carbohydrate. Accumulated gold was
recovered when washed with conc. HNO3.</p>
</p> 相似文献
9.
S. R. Kayasth K. K. Swain T. Mukherjee 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):393-395
Summary A
simple pre-irradiation separation approach has been worked out for the
determination of traces of tellurium in high purity selenium followed by
neutron activation analysis (NAA) for the end determination of the analyte/s.
The difference in volatilities of these elements has been utilized for the
separation of the analyte from the matrix. The complete volatility of selenium
at ~600 °C was established using neutron activation analysis and selenium
radiotracer. Standard addition was used to validate the results. The proposed
method of separation of selenium prior to irradiation could make the
determination of tellurium possible and also improved the detection limit by
several folds.</p>
</p> 相似文献
10.
E. A. A. El-Shazly R. R. Sheha H. H. Someda 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):255-260
Summary 8-Hydroxyquinoline
in benzene, xylene, chloroform and toluene diluents was used to modify silica
gel as a solid phase extractant (SPE) for the sorption of Eu(III) in batch
extraction techniques. Influences of solid/liquid ratio, pH, metal ion
concentration, particle size and temperature were studied. The optimum initial
pH is 4.2, while the maximum sorption capacities for the prepared impregnated
resins in benzene, xylene, chloroform and toluene diluents are 18.52, 14.98,
14.79 and 5.94 mg . g-1, respectively. The sorption
process is found to be affected by both metal ion concentration and particle
size of the impregnated resin. Thermodynamic parameters for the sorption of
Eu(III) were determined and the reaction is found to be exothermic and spontaneous
with enthalpy-14.23
and-23.71
kJ . mol-1 for benzene and xylene as diluents. Release of
the element from the loaded solid particles into 0.01M HNO3 is@85% and@53% from
8-HQ/benzene/silica gel and 8-HQ/xylene/silica gel.</p>
</p> 相似文献
11.
D. Bontea C. Mita D. Humelnicu 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):305-311
Summary Three
silylcellulosic derivatives with different substitution degree were examined as
sorbents for uranyl ions. The adsorption rate and capacity of cellulose and
modified cellulose were investigated in aqueous media, at various pH and
temperature values. The polymer - metal complexes of UO22+
were characterized by infrared and electronic spectra, and thermogravimetry.
The thermal behavior of cellulose (C), trimethylsilyl - cellulose (tmsc, SD=
2.85) and triphenylsilyl - cellulose (TPSC1, SD=2.89 and TPSC2, SD
=2.70) and their complexes with
uranyl ions in atmospheric air has been studied between room temperature and
600 °C. The Coats-Redfern method was applied to estimate the kinetic
parameters. The results revealed that the complexation of C and TMSC with UO22+
increases the thermal stability.</p>
</p> 相似文献
12.
H. Kazemian H. Zakeri M. S. Rabbani 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):231-236
Summary Potassium
nickel hexacyanoferrate, KNiFC, was incorporated in the porous matrix of
zeolites by successive impregnation with Ni(NO3)2 and</o:p></p>
K4Fe
(CN)6.1 CFC and PFC exchangers were first prepared by
impregnating the potassium nickel hexacyanoferrate into the clinoptilolite and
the synthetic P zeolite, respectively. Ion-exchange isotherms and breakthrough
curves were plotted. Results showed that the CFC sorbent is suitable for
removal of Cs+ where PFC is more suitable for Sr2+.
Negative effect of Na+ as a competing ion in these exchangers was
less than in the parent zeolites. Isotherm plots fitted the Langmuir equation.</p>
</p> 相似文献
13.
Adel M. El-Menshawy M. E. Khalifa 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):341-348
Summary Duolite
C20 resin modified with trimethylammonium acetosalycoylhydrazone has been
developed, for the selective separation and/or preconcentration of uranium. The
modified resin was characterized by elemental analysis and infrared spectra.
Batch and column modes were applied. The newly designed resin quantitatively
sorbs uranium ion at pH 3 when the flow rate equals to 2 ml . min
-1 . The sorption capacity was 0.750 mmol . g-1 for
uranium ion, whereas its preconcentration factor was 200. The lower limit of
detection was 5 ng . ml-1 and its desorption was
effective with 5 ml of 3 mol . l-1 HCl or HNO3
prior to detection spectrophotometry. The modified resin was highly
ion-selective in nature even in the presence of large concentrations of
electrolyte or organic media, with a preconcentrating ability for uranium ion.
The modified resin was tested on its utility with synthetic, real and certified
ore samples, showed RSD values of <2% reflecting the accuracy and
reproducibility of the newly modified resin.</p>
</p> 相似文献
14.
15.
K. Radó Z. Németh K. Varga J. Schunk F. Kőrösi 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):313-322
Summary During
the period of 1993-2001 chemical decontaminations of 24 SGs in the units 1-3 of
the Paks NPP were carried out by a non-regenerative version of AP-CITROX
technology, even in two or three consecutive cycles. A comprehensive
investigation of the above decontamination method have revealed that the
fundamental issues of analytical chemistry and corrosion science were not taken
into consideration during the elaboration of AP-CITROX procedure. Therefore,
the non-regenerative version of the technology utilized at Paks NPP can be
considered to be not an adequate method for the chemical decontamination of any
reactor equipments having large steel surfaces (e.g., SGs). As a consequence of
the lack of the appropriate decontamination method, initiation of a R&D project
focused on the elaboration of the required technology should not be postponed.
In this paper, we present a brief overview on the fundamental issues of the
technology development. Selected findings obtained in our laboratory on
the field of the improvement of the AP-CITROX technology are also reviewed in
order to demonstrate the crucial role of some selection criteria.</p>
</p> 相似文献
16.
A. Abbady 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):243-246
Summary Samples
of limestone, sand, marble, clay brick, red brick, gypsum, Portland cement and
white cement collected from upper Egypt used in building manufacturing have
been analyzed for the natural radionuclides 226Ra, 232Th and 40K usingg-ray
spectrometry. The specific concentrations for 226Ra, 232Th and 40K, ranged from 20-88,
13-115 and 54-304 Bq/kg, respectively. The average specific activities of these
radionuclides were compared. Higher values of 226Ra and 232Th could be noticed in marble while that of 40K
was in red bricks. Radium equivalent activities, dose rate and the annual
gonadal dose equivalents AGDE were calculated for the measured samples to
assess the radiation hazard arising from using those materials in the
construction of dwellings. The radioactive heat production values of the
selected materials have also been determined. They vary from a minimum of 0.41
for white cement to a maximum of 5.52mW/m3 for
marble samples. The calculated heat-production values are quite similar to
those estimated in Corsica.</p>
</p> 相似文献
17.
Summary A
tail-made polymer matrix is proposed to remove strontium ions from aqueous
solutions. The removal behavior of strontium ions on a crosslinked copolymer
containing methacrylic acid as functional groups was investigated as a function
of sorptive concentration, time, temperature and pH. It was observed that an
increase of these parameters enhanced the removal of Sr(II) ions from aqueous
solution. It is found that a maximum adsorption of Sr(II) ions can be obtained
on the crosslinked copolymer after 30 minutes and at pH 8. The increase of
Sr(II) ion concentration in the solution resulted in an increase in the amount
of Sr(II) ions adsorbed on the crosslinked copolymer containing methacrylic
acid as functional groups. However, after a maximum of Sr(II) concentration in
the solution, the percentage of adsorbed Sr(II) ions decreased. The adsorption
data are well represented by the Freundlich, Langmuir and Dubinin-Radushkevich
(D-R) isotherms. The adsorption capacity of the copolymer and the free energy
change were calculated by using the D-R isotherm. For the adsorption of Sr(II)
ions on the crosslinked copolymer the thermodynamic parameters (DH°,DS° andDG°) were
calculated.</p>
</p> 相似文献
18.
Strontium
isolation from natural samples with Sr resin and subsequent determination of 90Sr</p>
</p>
Ž. Grahek K. Košutić M. Rožmarić-Mačefat 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):179-190
The
reliability of an 90Sr determination method was tested using an Sr
extraction chromatographic resin for strontium isolation. The 90Sr-content
in samples of vegetables, soil and water (obtained from Environmental
Measurement Laboratory, USA) were determined and the results were controlled by
classical methods and by using an anion-exchanger and an alcohol solution of
nitric acid for the strontium isolation. These methods were previously tested
by determining 90Sr in IAEA 326 and 327 samples of soil. It is shown
that the isolation process with Sr resin is simpler and faster than the
classical and mixed solvent anion-exchange methods. The efficiency of isolation
on a Sr column depends on the resin quantity and separation conditions; and is
the highest with a Sr column, compared to the classical and anion-exchange
methods. Experimental data and theoretical models were used to calculate the
parameters that enable the estimation of optimum dimensions of the column for
isolation. A simple relation is proposed for the calculation of breakthrough
volume, which defines the sample and eluent volumes for an optimal strontium
isolation.</p>
</p> 相似文献
19.
Summary Macroporous
methyl methacrylate polymeric resin (XAD-7) was investigated incorporating both
acidic organophosphorous extractant (cyanex-301) and one neutral extractant
from the followings: dibenzo 18 crown 6 (DB18C6), 18 crown 6 (18C6) and 15
crown 5 (15C5). The sorption behavior of the solvent impregnated resin (SIR)
towards thorium ion, including batch equilibrium, and kinetic operation are
described. Different factors affecting the uptake of metal ions and hence, the
separation efficiency of the impregnated resins were investigated. The maximum
uptakes of Th4+ were found to be 62.9, 66.7 and 92.6% for DB18C6,
18C6 and 15C5, respectively. Synergistic extraction of various CE towards
thorium ion was tested with cyanex-301 to enhance the sorption capacity as well
as the selective separation efficiency. A relatively high capacity of the
chelating resin towards tetravalent thorium was found. The capacities of the
co-impregnated resins were found to be 2.11, 2.42 and 3.85 mmol/g for DB18C6,
18C6 and 15C5, respectively. The impregnated resin containing cyanex-301 and
15C5 can be utilized for selective separation and pre-concentration of thorium
ion from nitrate medium in the presence of several interfering metal ions.</p>
</p> 相似文献
20.
M. S. Al-Masri A. Nashawati Y. Amin B. Al-Akel 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):289-295
Summary Transfer
of 226Ra, 85Sr and 137Cs from cow and sheep
milk to various Syrian dairy products has been evaluated. Dairy products
include Kashkivan cheese, braided cheese, Haloom cheese, Sircassian cheese,
liquid cheese, native cheese, cottage, thick yogurt, butter and milk cream. The
results showed that the percentage of 226Ra, 85Sr and 137Cs
transferred from cow milk to milk cream (Pt=food
processing retention factor′processing efficiency′100%) has reached 32%, 16% and 7%,
respectively. Butter and liquid cheese were found to have the lowest percentage
of transferred 226Ra, 85Sr and 137Cs.
Most of the obtained Pt values of the studied radionuclides
in thick yogurt were relatively low in spite of the high processing
efficiencies of thick yogurt. Moreover, the transfer, Pt, of
the studied radionuclides from cow milk to the prepared cheese was higher than
those values determined for sheep milk. This is due to differences in chemical
compositions of each type of milk. On the other hand, the treatment of Native
cheese, most commonly consumed cheese in Syria, with different concentrations
of NaCl solutions showed that 137Cs was completely removed from
cheese soaking in 5% NaCl solution (soaking time of 48 hours), while 40% of 226Ra
and 80% of 85Sr were also decontaminated using 0-2.5% NaCl solutions
and soaking time of 48 hours. Based on the obtained results, industrialization
processes of the dairy products that resulted the removal of radionuclides have
been identified.</p>
</p> 相似文献