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The application and development of k 0 -standardization method of neutron activation analysis at Dalat research reactor
Abstract
In recent years the k
0-NAA method has been applied and developed at the 500 kW Dalat research reactor, which includes (1) the establishment of a PC database of k
0-NAA-related nuclear parameters, e.g., radionuclide produced, half-lives, k
0-factors, Q
0, r, E
g, etc; the access to the database is able by a k
0-NAA software or by manual; (2) the detection efficiency calibration of gamma spectrometers used in k
0-NAA, (3) the determination of reactor neutron spectrum parameters such as a and f factors and neutron fluxes in the irradiation channels, and (4) the validation of the developed k
0-NAA procedure by analysing some SRMs, namely Coal Fly Ash (NIST-1633b), Bovine Liver (NIST-1577b) and IAEA-Soil7. The analytical results showed the deviations between experimental and certified values were mostly less than 15% with most Z-scores lower than 2. The k
0-NAA procedure established at the Dalat research reactor has been regarded as a reliable standardization method of NAA and as available for practical applications, in particularly for airborne particulate and crude oil samples.
... The k0-NAA method was used to analyze the moss samples. This method was developed at the Dalat Nuclear Research Institute and has been officially applied since 2002 as the standard method (Ho & Pham 2003;Ho et al. 2016a). ...
In this paper, two multielement analysis techniques, Neutron Activation Analysis (NAA) and Total Reflection X-ray Fluorescence (TXRF), are combined to detect elemental concentrations in Barbula indica moss collected at Dalat, Vietnam. Combining these two techniques has improved the qualitative detection of elements due to atmospheric deposition on moss samples. The concentrations of 40 elements, including Na, Mg, Al, Si, P, S, Cl, K, Ar, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Kr, Rb, Y, Sb, I, Cs, Ba, La, Ce, Sm, Eu, Tb, Dy, Yb, Hf, Ta, Pb, Th, and U in the Barbula indicamoss samples collected at 19 locations at Dalat have been determined. It is shown that the air in Dalat is suspected of contamination by Na, Mg, Si, P, S, V, Mn, Cu, Se, Br, and U; slightly contaminated by Mg, Cl, K, Cr, Ni, S, and Ni; moderately contaminated by Sc, Fe, Co, Zn, As, Kr, Rb, Y, Sb, Cs, Ba, La, Ce, Sm, Eu, Dy, Yb, Ta, Pb, and Th; and seriously contaminated by Tb. Factor analysis has been used to explain the contamination sources of these elements, including V, As, Fe, Zn, Se, Rb, Sb, Cs, Al, Cu, and Pb in the investigated area. Four factors have been extracted that can explain 86% of the total variance, and the results suggest that the main sources of atmospheric pollution in Dalat originate from traffic and windblown dust.
... Diện tích đỉnh năng lượng tia gamma thu được nhờ phần mềm Genie 2k. Hàm lượng nguyên tố Se trong các mẫu được tính bằng phương pháp chuẩn hóa k 0 trong phân tích kích hoạt neutron dụng cụ 28,29 . Các số liệu hạt nhân liên quan phản ứng 74 Se(n, γ) 75 Se dùng tính toán hàm lượng được tham khảo từ tài liệu 28 . ...
Selenium (Se) is a trace element that plays an important role in the biological functions of the human body. Toenails are considered as suitable materials for finding the relationship between trace element content with human diseases. The goal of this study is to analyze and evaluate the Se content in the toenails of colorectal cancer patients in order to find out the risk of cancer in human. The Se content in the toenails of 60 colorectal cancer patients (63.3% for men) and 22 healthy persons (54.5% for men) was analyzed by the k0-standardization method of the instrumental neutron activation analysis technique. The results of the analysis showed that Se contents ib healthy persons were 1.13 mg/g and 1.32 mg/g for men and women, respectively; for colon cancer patients were 0.70 mg/g and 0.84 mg/g for men and women, respectively; for rectal cancer patients 0.86 mg/g and 0.82 mg/g for men and women, respectively. By the statistical analysis, it showed that the Se content was significantly different between the patients and the normal patients (p<0.05), but there was no significant difference between women and men. The conclusion of this study was that the Se content in the toenails of colorectal cancer patients is lower than that of normal patients.
... The concentration of trace elements in each sample were calculated using the k 0 -standardization method of neutron activation analysis 53,54 . This method can be brie y described as follows, a sample with weight w is irradiated by a neutron source at thermal neutron position, after irradiation the activities of sample are counted with gamma-ray spectroscopy, then the concentration r a of an analytic "a" is obtained from its measured isotope/gamma ray as where, "Au" refers to the co-irradiated gold monitor [ 197 Au(n, g) 198 Au, E g = 411.8 ...
Nails are considered as suitable biological materials for the diagnosis of diseases by measuring trace element levels. This study aimed to evaluate the role of trace elements in detecting the risk of colorectal cancer. Evaluating the effects of cancer treatment with chemotherapy or radiotherapy was also the aim of this study. The levels of trace elements in the nails of 104 patients with colorectal cancer and 112 healthy subjects were analyzed using the k0-standardization method of neutron activation analysis. The results showed that there were significant differences of the following elements, As, Fe, Hg, Sc, Se, and Zn between the control and the patient groups, while it was not the case for the elements Br, Co, and Cr. Furthermore, this study showed that there was no significant difference in the levels of the obtained trace elements in both colon and rectal cancer patient groups between untreated and treated subjects. We conclude that the levels of As, Hg, Fe, Se, and Zn in integrated samples of the fingernail and toenails may be used to evaluate the colorectal cancer risk, and they were not affected by chemotherapy or radiotherapy.
... The SRMs, brick and ceramic samples were loaded in the aluminum can and irradiated for 10 h at the rotary specimen rack of 500 kW Dalat research reactor. The thermal neutron flux ϕ th , α parameter and f value determined by a "bare triple-monitor" method were (3.61 ± 0.11) × 10 12 n cm −2 s −1 , 0.073 ± 0.005 and 35.7 ± 3.1, respectively [18]. After an appropriate decay time, irradiated samples were then counted on a gamma spectrometer using an HPGe detector with 30% relative efficiency and 2.1 keV resolution at 1332.5 keV of 60 Co. ...
The k0-based internal monostandard INAA method (IM-NAA) has been investigated for the determination of elemental concentrations in non-standard geometry samples at the Dalat research reactor (DRR). The experiments were implemented at the rotary specimen rack of the DRR which the thermal neutron flux was (3.61 ± 0.11) × 1012 n cm−2 s−1. In this work, the concentration analysis of Montana II Soil (SRM 2711a) and Brick Clay (SRM 679) have been used to validate the method. The elemental concentrations of Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Rb, Sb, Sm, Ta, Th, Yb, Zn have been analysed and to be in good agreement with certified values. The IM-NAA method has been applied to determine elemental concentrations in clay bricks and ceramics at the Cat Tien archaeological site.
... However, as shown inFig. 2 (solid lines), detection efficiency curve has a knee at about 150 keV. Drastically decrease of detection efficiency below the knee can be attributed to the absorption of low-energy photos by the detector covering materials [18]. Moreover,Fig. ...
A simple, sensitive and fast procedure for analysis of liquid samples called flowing sample neutron activation analysis has been established based on measurement of short-lived radionuclides. This newly developed method involves continuous flowing of sample between an irradiation cell and measurement station. This arrangement makes it easy to analyze a large volume of sample and thus preconcentration steps can be avoided. Moreover, flowing sample technique feeds detector with fresh irradiated material, which maintains constant dead time during whole time of measurement; hence improves accuracy of the method. The method was tested for its repeatability, detection limits and sensitivity. Obtained limits of detection are favorably comparable with those already published in literature.
... In addition, the (epithermal) spectral index (r) modified by a, is needed so that in k 0 , the excitation function for non-1/v nuclides is parameterized by the term (gðT n Þ þ rðaÞ ffiffiffiffiffiffiffiffiffiffiffiffi T n =T 0 p s 0 ðaÞ), where rðaÞ ffiffiffiffiffiffiffiffiffiffiffiffi T n =T 0 p is the modified spectral index, and s 0 (a) is the reduced resonance integral[10]. Comprehensive reviews of k 0-INAA application at various facilities can be found in references[3,[11][12][13][14][15][16][17][18][19][20]. A common conclusion that is highlighted in reference[20], is that success in implementing k 0-INAA is very sensitive to the reactor's configuration at the time of measurement. ...
A new parametric approach to single-comparator instrumental neutron activation analysis (INAA) at the University of Missouri
Research Reactor (MURR) was investigated. A detailed MCNP steady-state model of the MURR core was developed using the latest
neutron data libraries to compute the continuous-energy neutron flux distribution. Intrinsic reaction rates were predicted
by coupling the computed local flux distribution to the isotopic (n, γ) excitation functions for a range of elements present
in standard reference materials (SRM). Using the predicted (n, γ) reaction-rates, the concentrations for the various elements
were determined. The method worked well for all nuclides tested, including those with cross sections that are not proportional
to 1/v such as Lu and Eu with agreements for most elements within 5% of the reference value.
This study presents a dual method for neutron flux self-monitoring and quality control in the k0-based neutron activation analysis (k0-NAA) using the Synthetic Multi-Element Standards (SMELS). SMELS comprise three distinct types, designated as Type I for short-lived, Type II for medium-lived, and Type III for long-lived radionuclides, all of which are employed for validating the k0-NAA. Each SMELS type incorporates assigned amounts of gold (Au) and can serve as a neutron flux monitor. The Au concentration was automatically integrated into k0-DALAT—a home made software to calculate the gold specific activity (Asp,Au), thereby derivating of mass fractions of elements of interest in the k0-NAA. Additionally, the assigned concentrations of other elements within SMELS were used for k0-NAA quality control purpose. Replicate analyses of NIST-SRM-1633b (Coal Fly Ash) and NIST-SRM-679 (Brick Clay) by k0-NAA showed determination up to 29 and 25 elements, respectively with deviations within 7%, of which u-scores were almost less than ∣2.58∣, except only for Na and Fe of all 2.99. It revealed that the dual method using SMELS for both neutron flux self-monitoring and quality control considered convenient and consistent in comparison with the results obtained by the conventional independent comparator method biased within 1%.
Epithermal Neutron Activation Analysis (ENAA) in which the resonance reactions are utilised by using a cadmium filter to remove thermal neutrons from the reactor spectrum and measuring decay gamma rays leads to an improved detection limit for a number of elements with the resonance integrals higher than the thermal cross-sections. A computer program for data processing of the k0-based ENAA has been developed at the Dalat research reactor. The program allows to choose one of the two options of the k0-based conventional NAA or ENAA methods, according to the bare or Cd-covered irradiations, respectively. The NIST SRM 1633b (Constituent Elements in Coal Fly Ash) was used to check the results of the k0-ENAA program in which the samples along with the comparators were packed in Cd boxes for irradiations. The results show that the elements: As, Br, Cd, Ga, Gd, Ho, Na, Sm, Ba, Cs, Eu, Rb, Sc, Se, Sr, Ta, Tb, Th and U, in the NIST SRM 1633b have been determined by the k0-ENAA. The precision of the analytical results obtained using k0-ENAA for the above mentioned SRM is also discussed. The k0-ENAA program has been developed to assist users of the k0-method in NAA to exploit the advantages of ENAA.
In this study, new method for NAA purposes at 30 kW Isfahan MNSR is suggested. An algorithm based on ANN is proposed to quantitatively predict the unknown elements with no need standard sample. A three-layer feed-forward ANN with back-propagation algorithm has been used to determine concentration of selenium and fluorine in Multiple Sclerosis patients and healthy people blood samples. Predicted concentration of elements show good agreement between new method and experiment results. The correlation coefficient between the experimentally determined and predicted values are 0.99104 and 0.99364, respectively. This method is a rapid and precise approach for elemental analysis.
The aim of this study was to evaluate the effects of cancer treatment with chemotherapy for the trace elements in nails of patients with colorectal cancer. The contents of trace elements in the nails of 102 patients with colorectal cancer (including treated and untreated) and 60 healthy subjects were analyzed using k0-standardization method of neutron activation analysis. All participants aged between 32 and 76. Result of this study showed that the contents of nine trace elements (As, Br, Co, Cr, Hg, Fe, Sc, Se, and Zn) in the nails were measured. Furthermore, this study showed that there was significant difference in the contents of the elements Fe, Se, and Zn in both colon and rectal cancer patient groups between untreated and treated subjects with chemotherapy. We conclude that the contents of Fe, Se, and Zn in the nail samples may be used to evaluate of the colorectal cancer risk, and they may be affected by chemotherapy.
The aim of this study was to find trace elements that increase risk of breast cancer based on the deviation of the concentration of trace elements in the fingernail collected from the women with breast cancer and the normal women. The study was conducted with 10 elements (As, Au, Br, Co, Cr, Fe, Sb, Sc, Se, and Zn) using k0-INAA and statistical analysis method. Significant differences (P < 0.05) were found for Cr, Fe, Sc and Zn between the case and the control groups. A significant correlation between Fe and Zn has found for the normal women, but this disappears in the women with breast cancer. On the contrary, a significant correlation between As and Cr has found in the case group, but no such correlation has noticed for the control group. The elements Cr, Fe, and Zn may be associated to the risk of breast cancer.
The γ - MnO2 nanomaterial has been used to adsorb cobalt in the seawater at Phan Thiet City, Binh Thuan Province, Vietnam. Its concentration is determined by using the neutron activation analysis (NAA) method at the Dalat nuclear research reactor. Factors affecting the uptake of cobalt on the γ - MnO2 material such as the pH, adsorption time, and initial cobalt(II) concentration are investigated. The irradiated experiment data are calculated using the K0-Dalat program. The results obtained show that the trace dissolved cobalt in Phan Thiet seawater is found equal to 0.25 ± 0.04 μ g/L ( n=5 , P=95 %) with the adsorption efficiency being higher than 95% ( n=4 , P=95 %).
The cyclic neutron activation analysis (CNAA) facility based on a pneumatic transfer system for short irradiation and rapid counting has recently been upgraded at the Dalat research reactor. The original facility was only designed for single irradiation. Therefore, this work has aimed to upgrade both hardware and software for the cyclic irradiation. In this paper, the upgrading of the facility for CNAA was described. Irradiation time of the facility were calibrated, thereby reducing irradiation time to seconds with precision. The accuracy and sensitivity of CNAA based-on the upgraded facility were assessed by determination of some short-lived nuclides.
Relevance of the research consists in implementation of comparator method k0-standardization of instrumental neutron activation analysis (k0-INAA) when studying at the reactor IVG.1M that will expand the scope of its application. The k0-INAA method is characterized by durability and technological effectiveness at all stages of analysis. When carrying out the investigations the unique experience to adapt the application techniques will be acquired. The main aim of the study is to adapt the k0-INAA to elemental analysis of various materials based on the IVG.1M reactor taking into account the conditions of exposure, physical and technical features of the reactor. The methods used in the study: comparator method of k0-INAA; characterization of irradiation site in experimental channel of IVG.1M reactor; determination of the parameters α and f; selection of optimal irradiation regimes of standard rock samples; preparation and irradiation of rock samples in the experimental channel of IVG.1M reactor; processing and analysis of the experimental data. Scientific novelty. The authors have implemented the comparator method and determined the features of neutron field in the experimental channel of IVG.1M reactor for calculating the concentration of elements by k0-INAA method. The results. The authors determined the concentration of analyte-elements in standard rock sample by k0-INAA method and investigated the fields of thermal and resonance neutrons in IVG.1M reactor. The values of α and f parameters were determined for calculation of concentration by k0-INAA method. The authors defined the content of analyte-elements standard rock samples. The paper introduces the ratios between the calculated and the certified values of element concentrations. The accuracy of analysis is expressed as Z-criterion and evaluated for analyte-elements. For the majority of analytical results Z-criterion values range from 0 to 2. Thus, the results of elemental analysis showed good agreement between the analytical and the certified values of concentration of analyte-elements.
INAA, ICP-AES and ICP-MS were utilised to elementally characterise four environmental reference materials (NIST SRM 1646a (Estuarine Sediment), NIST SRM 1400 (Bone Ash), IAEA-395 (Urban Dust) and IAEA-450 (Algae)). An analytical scheme consisting of the three analytical methods was first applied to NIST SRM 1646a to validate the methodology because it has been extensively analysed and has certified values for many elements. With repeated analyses of NIST SRM 1646a, the accuracy and repeatability of the data obtained were evaluated based on two statistical calculations (zeta-score and Horwitz ratio), and were observed to be good enough for the analytical scheme to be applied to similar sorts of environmental/geochemical samples. Applying the same approach to NIST SRM 1400, IAEA-395 and IAEA-450, enabled mass fractions of 29, 38 and 28 elements to be determined, respectively. Among these results, the data for rare earth elements (REEs) are of particular interest, not only for IAEA-450 but also for the other three reference samples. The data for Pr, Gd, Dy, Ho, Er, and Tm in NIST SRM 1646a are newly reported in this study. By using small sample amounts (less than 100 mg) for NIST SRM 1646a and IAEA-395, and recommended minimum sample amounts for NIST SRM 1400 and IAEA-450, sample homogeneity was evaluated. This article is protected by copyright. All rights reserved.
Quality evaluation of the k
0-standardized neutron activation analysis (k
0-NAA) at Dalat research reactor (DRR) has been implemented by analyzing the SMELS, a synthetic multi-element standard material as well as the certified reference materials for purposes of validation and verification of the method. The results revealed that the k
0-NAA established at DRR has met the requirements of multi-element analysis for the intended applications with about 42 elements: Al, As, Au, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Cu, Dy, Eu, Fe, Hf, I, In, K, La, Mg, Mn, Mo, Na, Nd, Pr, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, Ti, U, V, W, Yb, Zn and Zr in matrices of environment, geology and biology among others. Evaluation criteria for the laboratory quality used in this work are the statistical analysis parameters namely: u-scores, laboratory result/certified value ratios and relative biases as well as the control charts those are shown in the paper.
The k
0-standardized neutron activation analysis (k
0-NAA) has been applied for determination of multiple elements (25 elements: Al, As, Ba, Br, Ca, Cl, Co, Cr, Cs, Cu, Eu, Fe, Hg, K, La, Mg, Na, Rb, Sc, Se, Sm, Th, Ti, V and Zn) in marine sediment and tuna fish. About 50 marine sediment and 9 tuna fish samples were collected in two coastal areas of Vietnam. The health risk index (HRI) values of As and Br were higher than 1.0 for the tuna fish. Also, HRI value of Hg was 8.92 × 10−1 indicating a relatively high potential health risk, whiles Co and Mn with HRIs = 1.56 × 10−4 and 8.56 × 10−4, respectively, have the lowest potential health risks. Average enrichment factors using Al as a reference element (EF
Al) were higher than 1.5 for Eu, La, Zn, Th, Cs and As in which the highest EF
Al value for As was higher than 10. This study showed that the HRI value of As in the tuna fish correlated positively with the EF
Al value for the element in the marine sediment.
k
0-Standardization method was applied in clinical investigation to evaluate the whole blood correlation factor of Na and K, Fe and Zn of 21 patients suffering from Alzheimer pathology and 5 normal controls. Samples were irradiated at Es-Salam research reactor. However, the concept (QC/QA) is considered to evaluate the accuracy of the method. NIST 1566b (Oyster tissue) and IAEA A13 (animal blood) were analyzed simultaneously with the samples. Three statistical parameters Z-score, U-score and bias were determined and discussed.
Instrumental Neutron
Activation Analysis (INAA) is often used to determine and calculate the elemental concentrations of a sample at The National University of Malaysia (UKM) typically in Nuclear Science Programme, Faculty of Science and Technology. The objective of this study was to develop a database code-system based on Microsoft Access 2010 which could help the INAA users to choose either comparator method, k0-method or absolute method for calculating the elemental concentrations of a sample. This study also integrated k0data, Com-INAA, k0Concent, k0-Westcott and Abs-INAA to execute and complete the ECC-UKM database code-system. After the integration, a study was conducted to test the effectiveness of the ECC-UKM database code-system by comparing the concentrations between the experiments and the code-systems. 'Triple Bare Monitor' Zr-Au and Cr-Mo-Au were used in k0Concent, k0-Westcott and Abs-INAA code-systems as monitors to determine the thermal to epithermal neutron flux ratio (f). Calculations involved in determining the concentration were net peak area (Np
), measurement time (tm
), irradiation time (tirr
), k-factor (k), thermal to epithermal neutron flux ratio (f), parameters of the neutron flux distribution epithermal (α) and detection efficiency (ε
p
). For Com-INAA code-system, certified reference material IAEA-375 Soil was used to calculate the concentrations of elements in a sample. Other CRM and SRM were also used in this database codesystem. Later, a verification process to examine the effectiveness of the Abs-INAA code-system was carried out by comparing the sample concentrations between the code-system and the experiment. The results of the experimental concentration values of ECC-UKM database code-system were performed with good accuracy.
The modified spectral index r(α) √T n; the Westcott g Lu(T n) factor and absolute neutron temperature Tn were determined for the handling of non-1/ν (n, γ) reaction based on the Westcott formalism using k 0-neutron activation analysis (k 0-NAA) method at the Malaysian Nuclear Agency (MNA) research reactor. The r(α) √T n was determined by the bare bi-isotopic monitor method using measurement of radionuclides of 97Zr and 95Zr. The 176Lu as non-1/ν and 197Au as 1/ν monitors were utilized for determination of gLu(Tn). The r(α) √T n and g Lu (T n) values ranged from 0.0715 to 0.1417 with a RSD of 15.24% and from 1.7832 to 2.0149 with a RSD of 3.58%, respectively. The accuracy of the method was evaluated based on the calculated absolute neutron temperature (T n) value. The calculated average value of T n was 40.56±9.32°C while the value reported by MNA was 40°C, which represents an acceptable level of consistency.
This work is concerned with the calibration of
the HPGe detector used in flowing sample neutron activation
analysis technique. The optimum counting configuration
and half-life based correction factors have been
estimated using Monte Carlo computer simulations.
Depending on detection efficiency, sample volume and
flow type around the detector, the optimum geometry was
achieved using 4 mm diameter hose rolled in spiral shape
around the detector. The derived results showed that the
half-life based efficiency correction factors are strongly
dependent on sample flow rate and the isotope half-life.
As a part of the food analysis program executed at Es-Salam research reactor by neutron activation analysis laboratory, the concentration of As, Ba, Br, Ca, Fe, K, La, Rb and Zn in baby formulas milk have been determined by using INAA and k 0-NAA techniques. It was found that the concentration of all elements obtained by both techniques was relatively identical for the three brands of the 0–6 and 6–12 months of analyzed samples. In addition, the analytical results have been compared with those given by producers.
A comparison of the analytical data obtained by three -NAA software programs was carried out using both the airborne particulate matter collected from an urban site and the certified reference materials of the air filter and urban dust to evaluate the performance of the analysis. The individual -NAA standardization methods of three countries, Korea, China and Vietnam which had been modified from the well established -program were used for the comparative analysis. The measured concentrations of 30 elements from the two kinds of air samples based on this software were in agreement with each other within about 20% analytical error except for a few elements. By contrast, the results of China and Vietnam were moderately higher than that of Korea due to a systematic error associated with the detection efficiency, gamma peak analysis and geometric effect.
The present work shows the development of k0-instrumental neutron activation analysis (k0-INAA) method at the Malaysian Nuclear Agency research reactor. To use the k0-INAA method, two formalisms were regulated according to 1/ν and non-1/ν (n, γ) reaction nuclides. The reactor neutron spectrum parameters, the thermal to epithermal neutron flux ratio (f), the epithermal neutron flux shape factor (α) were measured using the bare bi-isotopic monitor and bare triple monitor methods, respectively, based on the Høgdahl convention. In addition, the modified spectral index , the Westcott factor and the absolute neutron temperature T
n
parameters were determined using the Westcott formalism. 176Lu was used as non- 1/ν monitor while 197Au, 96Zr and 94Zr were used as 1/ν monitors. The average values of and T
n
were determined to be 0.1795 ± 0.0044, 1.9729 ± 0.0234 and 50.12 ± 3.21°C, respectively. The accuracy of the method was evaluated by analysing IAEA-Soil 7, IAEA-SL 1, NBS SRM 1633A-1 and IAEA-Soil 375 as reference materials. The results show an acceptable level of consistency.
The Algerian research reactor (Es-Salam) is a 15 MW heavy water reactor type, operating since 1992. It became essential to characterize the neutron field in the most useful irradiation positions, in order to guarantee the accuracy in the application of k
0-neutron activation analysis (k
0-NAA). Experimental value of the thermal to epithermal neutron flux ratio (f) and of the deviation of the epithermal neutron spectrum from 1/E shape (α) were determined using different methods. This work focuses the verification of Monte Carlo neutron flux calculation in typical irradiation channel. Comparison of the results for parameter f obtained experimentally and by Monte Carlo simulations shows good agreement in the irradiation channel studied. The difference between both results is about 2.08%.
A new Compton suppression system (CSS) for the gamma-ray spectrometer portion of the neutron activation analysis (NAA) was
set up at the RPI/ITN. The pneumatic transfer system, SIPRA, for short-lived nuclides and cyclic irradiations was improved.
A full calibration procedure of the CSS and SIPRA systems was performed. Two certified reference materials, NIST-SRM-1572
(Citrus Leaves) and NIST-SRM-1633a (Coal Fly Ash) were analyzed using the calibration factors. The CSS was instrumental in
lowering the detection limits of Cr, Fe, Hg, Rb, Sr, Th and Zn by reducing background and/or spectral interference considerably.
The analytical results were evaluated by comparison to the NIST certified values with deviations ranging from 2% to 8% for
the above mentioned elements, except Zn ranging from 10% to 15% for biological and environmental samples, respectively.
In recent years the k0-NAA method has been applied and developed at the 15MW Es-Salam research reactor, which includes: (1) the detection efficiency calibration of g-spectrometer used in k0-NAA, (2) the determination of reactor neutron spectrum parameters such as a and f factors in the irradiation channel, and (3) the validation of the developed k0-NAA procedure by analysing SRM, namely AIEASoil7 and CRM, namely IGGE-GSV4. The analysis results obtained by k0-NAA with 27 elements of Soil-7 standard and 14 elements of GSV-4 standard were compared with certified values. The analysis results showed that the deviations between experimental and certified values were mostly less than 10%. The k0-NAA procedure established at Es-Salam research reactor has been regarded as a reliable standardization method of NAA and as available for practical applications.
For the general applicability of the k 0 -NAA method two formalisms were carried out to deal with “1/ ν and non-l/ ν ((n,γ)” reaction nuclides, respectively. In the Høgdahl-formalism the reactor neutron spectrum parameters, such as α and f were measured using three methods: Cd-ratio, Cdcovered and bare triple monitors. In addition, bare bi-isotopic method using Zr is also utilized for the calculation of f . According to the Westcottformalism the modified spectral index r ( α )√ T n / T 0 and g ( T n ) factor for monitoring neutron temperature T n , were measured employing Lu as non “1/ v ” monitor and 197 Au, 96 Zr and 94 Zr as “1/ v ” monitors. The reduced resonance integral of lutetium s 0,Lu was also calculated. To evaluate the applicability of k 0 -NAA in our analytical system, the analysis of two kinds of SRMs was executed. The analytical results showed that the relative error of most of the elements was less than 10%.
The Malaysian Nuclear Agency (MNA) research reactor, commissioned in 1982, is a TRIGA Mark II swimming pool type reactor. When the core configuration changed in June 2009, it became essential to re-determine such neutron flux parameters as thermal to epithermal neutron flux ratio (ƒ), epithermal neutron flux shape factor (α), thermal neutron flux (φth) and epithermal neutron flux (φepi) in the irradiation positions of MNA research reactor in order to guarantee accuracy in the application of k0-neutron activation analysis (k0-NAA).The ƒ and α were determined using the bare bi-isotopic monitor and bare triple monitor methods, respectively; Au and Zr monitors were utilized in present study. The results for four irradiation positions are presented and discussed in the present work. The calculated values of ƒ and α ranged from 33.49 to 47.33 and −0.07 to −0.14, respectively. The φth and the φepi were measured as 2.03 × 1012 (cm−2 s−1) and 6.05 × 1010 (cm−2 s−1) respectively. These results were compared to those of previous studies at this reactor as well as to those of reactors in other countries. The results indicate a good conformity with other findings.
In recent years the k0-NAA method has been applied and developed at the 15 MW Es-Salam research reactor, which includes: (1) the detection efficiency calibration of γ-spectrometer used in k0-NAA, (2) the determination of reactor neutron spectrum parameters such as α and f factors in the irradiation channel, and (3) the validation of the developed k0-NAA procedure by analysing SRM, namely AIEA-Soil7 and CRM, namely IGGE-GSV4.The analysis results obtained by k0-NAA with 27 elements of Soil-7 standard and 14 elements of GSV-4 standard were compared with certified values. The analysis results showed that the deviations between experimental and certified values were mostly less than 10%.The k0-NAA procedure established at Es-Salam research reactor has been regarded as a reliable standardization method of NAA and as available for practical applications.
The Analytical Chemistry Laboratory at MINT is using the NAA technique since 1980s and is the only laboratory in Malaysia equipped with a research reactor, namely the TRIGA MARK II. Throughout the years the development of NAA technique has been very encouraging and was made applicable to a wide range of samples. At present, the k0 method has become the preferred standardization method of NAA (k0-NAA) due to its multi-elemental analysis capability without using standards. Additionally, the k0 method describes NAA in physically and mathematically understandable definitions and is very suitable for computer evaluation. Eventually, the k0-NAA method has been adopted by MINT in 2003, in collaboration with the Nuclear Research Institute (NRI), Vietnam. The reactor neutron parameters (α and f) for the pneumatic transfer system and for the rotary rack at various locations, as well as the detector efficiencies were determined. After calibration of the reactor and the detectors, the implemented k0 method was validated by analyzing some certified reference materials (including IAEA Soil 7, NIST 1633a, NIST 1632c, NIST 1646a and IAEA 140/TM). The analysis results of the CRMs showed an average u score well below the threshold value of 2 with a precision of better than ±10% for most of the elemental concentrations obtained, validating herewith the introduction of the k0-NAA method at the MINT.
Participation in inter-comparison programs is an important process to enhance the accuracy and precision of the analytical
techniques. The Instrumental Neutron Activation Analysis laboratory (INAA) at Egypt Second Research Reactor (ETRR-2), ETRR-2
INAA Laboratory, was participated in three inter-comparison tests organized by AFRA Research Reactor Project for Socio-economic
development. AFRAIV-12 Inter-laboratory Analysis Test 2007 is the third inter-laboratory analysis test within that project.
The laboratories were asked to analyze for 43 essential and toxic elements using nuclear and related analytical techniques,
with neutron activation analysis as the common technique. Five materials were distributed to the participants representing
foodstuff, medicinal plants and aquatic biomonitors according to the focus of the AFRA IV-12 2006–2010 project. In this paper
the ETRR-2 INAA Laboratory results is evaluated.
KeywordsINAA ETRR-2 laboratory results evaluation-AFRA IV-12 inter-laboratory analysis test 2007
The NAA#3 irradiation hole in the 30 MW HANARO research reactor of the Korea Atomic Energy Research Institute (KAERI), with a thermal neutron flux of 1.26×1014 cm−2 s−1, has been regarded as suitable for the application of k0-based neutron activation analysis (k0-NAA). The objectives of the present work were: (a) to characterize the NAA#3 irradiation hole via the determination of the neutron spectrum parameters required for the method, (b) to calibrate the HPGe gamma-ray spectrometer system via establishing the detection efficiency curves and (c) to assess the quality of the k0-NAA method by the analysis of six certified reference materials, three of which were of biological nature and three of environmental origin. The results obtained indicated that, by using the k0-NAA method, approximately 25 or 35 elements could be quantitatively determined in the biological and environmental samples, respectively. The deviations between the experimental and the certified values for the determined elements were generally within 12% with u-scores mostly below 2. The results prove that the k0-NAA method, implemented in the HANARO research reactor, is applicable for multi-element analysis in biological and environmental samples with a rather high analytical performance and that the method is available for further practical applications.
はじめに / 久保庭眞彰 日本の自動車製造業におけるエコ・エフィシェンシーの動向分析 : ミクロデータによる試論 / ゾルタン・デーニッシュ 環境再生の課題と費用負担問題 / 除本理史 家電リサイクル法における料金制度と処理責任の数量効果 / 小出秀雄 「環境用水」確保の経済分析 / 野田浩二 ドイツの環境犯罪と廃棄物処理違反 / 阿部新 環境経営の質とその決定要因 : 環境報告書から見た環境配慮型経営 / 中谷勇介
A critical evaluation of different comparator methods is given. The method based on experimentally-determined and convertible comparison factors (k) is considered to be the most suitable for general use. An alternative method is proposed, introducing generalized k0 factors which are independent of irradiation and measuring conditions. This approach combines the simplicity of the absolute methods with nearly the same accuracy attained by the relative ones. It is suggested that k0 factors be compiled in all cases when using single-comparator methods, to allow a continuous re-evaluation.
This paper reports on the contribution made by some cooperating laboratories to the further development of the k0-method. As to the extensions and improvements, emphasis is put on the availability of an Al–0.1% Au reference material for the k0-standardization of NAA, on the counting of large-diameter samples, on the use of a low-energy photon detector, and on the introduction of the Westcott formalism for the handling of non-1/v (n, ) reactions. A survey is given of a large variety of scientific and industrial applications, including the analysis of biological, geological and geochronological samples, various kinds of reference materials, high-purity products and ceramics, and a number of environmental pollution indicators. As shown, the advantage of the k0-standardization will be fully exploited with an increasing level of automation in NAA laboratories. Eventually, new measurements and evaluations of k0-factors and related nuclear data are given in an Appendix.
A new technique is outlined for the calculation of the full-energy peak efficiency of cylindrical gamma-detectors, including coaxial Ge(Li) detectors. Different source geometries are considered, i.e. point, disk and cylindrically shaped sources. Full account is taken of gamma attenuation in the source and in any interjacent absorbing layer. No simplifying mathematical model is adopted and no Monte Carlo calculations are required. Although this method is to be qualified as semi-empirical, the experimental work involved in it is simple and of common practice in most nuclear laboratories. For the calculations a FORTRAN IV + computer program is presented on a VAX 11/780 machine.
The k0 Standardization Method-A Move to the Optimization of NAA”, Rijksuniversiteit Gent
- F De Corte
- F De Corte
- A Simonits
- A De Wispelaere
- A Elek
- F. De Corte