Non-conventional measurement techniques for the determination of some long-lived radionuclides produced in nuclear fuel a literature survey

The results of a literature survey on non-radiometric analytical techniques for the determination of long-lived radionuclides are described. The methods which have been considered are accelerator mass spectrometry, inductively coupled plasma mass spectrometry, thermal ionization mass spectrometry, resonance ionization spectrometry, resonance ionization mas spectrometry and neutron activation analysis. Neutron activation analysis has been commonly used for the determination of¹²⁹I and²³⁷Np in environmental samples. Inductively coupled mass spectrometry seems likely to become the method of choice for the determination of⁹⁹Tc,²³⁷Np and Pu-isotopes. The methods are discussed and the chemical separation methods described.     

A method for correction of matrix effects in activation analysis based on characteristic X-ray measurements

The empirical coefficient method represents the absorption and enhancement effect of each element on each other by parameters independent of mass concentrations. This method is used together with the internal standard method for the determination of cadmium, bromine and selenium by 14 MeV neutron activation followed by X-ray spectrometry. The results of analysis show a relative error not more than ±5%.     

Determination of trace elements in cloud water and aerosols using instrumental neutron activation analysis and hydride generation with atomic absorption spectrometry

Cloud water and aerosol samples were collected at Whiteface Mountain, NY using the ASRC omnidirectional cloud water collector and high volume samples respectively. Trace element concentrations in cloud water samples were determined by neutron activation analysis and hydride generation with atomic absorption spectrometry. Agreement between the two methods for Se concentration was excellent (0.98±0.05). Aerosol samples were also analyzed for trace elements by neutron activation. Elemental analysis of cloud water and aerosols provide information useful to the study of microphysical and chemical interactions in cloud systems.     

Evaluation of methods for the separation of trimethylselenonium ion as a major,minor or general metabolite using neutron activation analysis

Trinethylselenonium (TMSe) ion was separated by dual-column ion-exchange chromatography and assayed by neutron activation analysis. The TMSe content of the selenium in human urine was found to be (14±2)%, consistent with literature values. An altemate, published, multi-step procedure employing Reineckate precipitation followed by decomposition/volatilization conversion of selenium into dimethylselenide, perchloric acid digestion into selenite and subsequent analysis employing inductively coupled plasma mass spectrometry (ICP-MS) was evaluated. A maximum recovery of TMSe was estimated at 32%. It has been suggested that losses in each step of a multi-step procedure yield low recoveries as reported in the literature.     

Neutron spectrum parameters in irradiation channels of the Nigeria Research Reactor-1 (NIRR-1) for the <Emphasis Type="Italic">k</Emphasis><Subscript>0</Subscript>-NAA standardization

Summary The first nuclear research reactor in Nigeria has been commissioned for neutron activation analysis and limited radioisotope production. In order to extend its utilization to include the k₀-standardization method, the following neutron spectrum parameters in inner and outer irradiation channels were determined by the “Cd-ratio for multi-monitor method”: the thermal-to-epithermal flux ratio, f, and the epithermal flux shape factor, α. Neutron spectrum parameters determined in the inner irradiation channel B2, are: α = -0.052±0.002 and f = 19.2±0.5. For the outer irradiation channel B4, the neutron spectrum parameters were found to be α = +0.029±0.003 and f = 48.3±3.3. The results are compared with the neutron spectrum parameters of other reactor facilities with similar core configuration such as the Slowpoke and Miniature Neutron Source Reactor facilities available in the literature.     

Determination of boron in borosilicate glasses by neutron capture prompt gamma-ray activation analysis

Major levels of boron in borosilicate glasses have been determined nondestructively by neutron activation analysis. In contrast to chemical methods for determining boron as a major component, the described nuclear method has few interferences and does not require chemical separation of boron prior to its quantitation. The effects of neutron self-shielding by boron (1 to 8% by weight) are examined, minimized by dilution of powdered samples with high purity graphite, and circumvented by comparative analyses. Results of the analysis of a series of glasses with increasing boron composition are 1.150±.005% and 7.766±.035% for the low and high members of the series. Accuracy of these results depends upon comparative analyses with the certified Standard Reference Material, SRM 93a (3.89±0.02% B). Once analyzed, the glasses are useful as secondary standards for alpha track counting, and also ion and electron microprobe analyses of glasses.     

Neutron activation and mass spectrometric measurement of129I

An integrated procedure has been developed for measurement of¹²⁹I by neutron activation analysis and mass spectrometry. An iodine isolation procedure previously used for neutron activation has been modified to provide separated iodine suitable for mass spectrometric measurement as well. Agreement between both methods has been achieved within error limits. The measurement limit by each method is about 10⁷ atoms /2 fg/ of¹²⁹I.Operated for the U.S. Department of Energy by Battelle Memorial Institute under contract DE-AC06-76RL0 1830.     

Prompt gamma neutron activation analysis of boron with a 241Am-Be neutron source

A prompt gamma neutron activation analysis (PGAA) setup installed at ANRTC has been used to analyze boron. It consists of a 22.6% REGe detector and a 740 GBq ²⁴¹Am-Be neutron source moderated with water and paraffin. At the sample irradiation position, the thermal neutron fluence rate measured was 2.36·10⁴ n·m^–2· s^–1 and the corresponding Cd-ratio was 22 for gold monitor. The absolute detection efficiency in the range of 120–1500 keV was determined using ¹⁵²Eu standard solution. The sensitivity and detection limit for standard boric acid samples has been determined. The boron content in boric acid prepared from Turkish borate ores is measured to be 15.91±0.46% wt.     

Prompt gamma neutron activation analysis of boron with a 241Am-Be neutron source

A prompt gamma neutron activation analysis (PGAA) setup installed at ANRTC has been used to analyze boron. It consists of a 22.6% REGe detector and a 740 GBq ²⁴¹Am-Be neutron source moderated with water and paraffin. At the sample irradiation position, the thermal neutron fluence rate measured was 2.36·10⁴ n·m^–2· s^–1 and the corresponding Cd-ratio was 22 for gold monitor. The absolute detection efficiency in the range of 120–1500 keV was determined using ¹⁵²Eu standard solution. The sensitivity and detection limit for standard boric acid samples has been determined. The boron content in boric acid prepared from Turkish borate ores is measured to be 15.91±0.46% wt.     

Newer trace elements in Iranian diets

The intake of some “newer” trace elements via the daily diet by Iranian population groups was determined. The total mixed diets were prepared on the basis of dietary recording. Aluminium and nickel have been measured via atomic absorption spectrometry, vanadium and tin via radiochemical neutron activation analysis, and scandium via instrumental neutron activation analysis. The results for the Iranian diets are discussed and compared with corresponding data from other countries. The project has been performed in the frame of a co-ordinated research project of the International Atomic Energy Agency with participants from various countries. This revised version was published online in July 2006 with corrections to the Cover Date.     

Characterization of InxGa1−xAs crystals by 14 MeV neutron activation analysis

Indium doped GaAs crystals are analyzed quantitatively for indium by non-destructive 14 MeV neutron activation analysis. Experimental conditions are optimized to provide a precision of ±5% and a practical sensitivity of 50 ppm, by weight. The accuracy of the neutron activation method is established by comparison with the results obtained by atomic absorption and Rutherford back-scattering techniques. The method has been applied for determining the homogeneity of indium distribution of wafers by sectional analysis and is demonstrated as a reference method for calibrating the low temperature photoluminescence technique.     

Determination of vanadium in high grade carbons by radioanalytical methods

The present work deals with the determination of vanadium in high grade carbons by three radioanalytical methods, viz. thermal neutron activation analysis with an accelerator, thermal neutron activation analysis with a reactor and proton induced X-ray emission analysis with an accelerator. It is cleared from this study that thermal neutron activation with an accelerator is more convenient for the rapid and non-destructive analysis of ppm-level vanadium in bulk carbons than thermal neutron activation analysis with a reactor. Proton induced X-ray emission is less useful for the analysis of bulk samples.     

Multielement analysis by total reflection X-ray fluorescence spectrometry for the certification of lichen research material

 Total reflection X-ray fluorescence spectrometry was applied for the certification of IAEA lichen-336. The elements Ca, Mn, Fe, Cu, Zn, Rb, Sr and Pb were determined simultaneously. The concentrations range from 1.8 mg/kg for Rb to 2360 mg/kg for Ca. The results were compared with those of other methods and laboratories having participated in this certification for the International Atomic Energy Agency (IAEA): emission spectrometry, mass spectrometry, atomic absorption spectrometry, X-ray spectrometry, neutron activation analysis and voltammetry. The results determined by TXRF are in good agreement with the overall means of accepted values and differ from the means by 1 to 10%. Received: 1 September 1996/Revised: 15 October 1996/Accepted: 22 October 1996     

Elemental analysis of special materials by X-ray fluorescence spectrometry

The special materials like phosphor bronze for P, Fe, Ni, Cu, Zn, Sn and Pb; mild steel for P, S, V, Cr, Mn, Co, Ni, Cu, As, Nb, Sb and W; special alloys for Ti and Mo, zircaloy and zirconium oxide for Hf; and zircon ore for Zr have been analyzed by X-ray fluorescence spectrometry (XRFS). The measured values along with certified values, precision and accuracy have been given for all the elements analyzed. Some of these materials have also been analyzed by atomic absorption spectrometry (AAS), neutron activation analysis (NAA) and inductively coupled plasma emission spectrometry (ICP-ES). The analytical data of XRFS are in agreement with the results obtained by AAS-ICP-ES and NAA. In most cases the precision is within ±2% and accuracy is ±4%. The precision and accuracy for S, P, Ni and Hf are poor at low concentrations. Practical low detection limit of about 40 g/g of Hf in zirconium matrix has been achieved. It is established that precise and accurate determination of Ti and Mo in special alloys is possible using XRFS.     

Determination of tin in soil by continuous hydride generation and inductively coupled plasma mass spectrometry

A method was investigated for the determination of Sn in soil samples by KOH fusion followed by continuous hydride generation coupled with inductively coupled plasma mass spectrometry (HG-ICP-MS). Sample solutions in 3.0 M HCl were mixed in line with a solution of 2.4% NaBH₄ and 0.25 M KOH to generate stannane gas. The mixture was delivered continuously to a gas/liquid separator and the stannane gas was introduced into a Perkin-Elmer Sciex Elan 6000 ICP-MS for concentration measurements. A method detection limit of 0.45 mg/kg was sufficient for Sn levels commonly found in soil samples. Sn concentrations as low as 2.5 mg/kg were reproducibly measured in soil samples. Sample results by HG-ICP-MS agreed within ±17% relative difference to results by instrumental neutron activation analysis (INAA) and within ±6% relative difference to results by KOH fusion followed by inductively coupled plasma optical emission spectroscopy (ICP-OES).     

Isotope dilution-thermal ionisation mass spectrometric analysis for tin in a fly ash material

Isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) analysis has been applied to the determination of tin in a fly ash sample supplied by the EC Joint Research Centre (Ispra, Italy). The proposed procedure includes the silica gel/phosphoric acid technique for tin thermal ionisation activation and a strict heating protocol for isotope ratio measurements. Instrumental mass discrimination factor has been previously determined measuring a natural tin standard solution. Spike solution has been prepared from ¹¹²Sn-enriched metal and quantified by reverse isotope dilution analysis. Two sample aliquots were spiked and tin was extracted with 4.5 M HCl during 25 min ultrasound exposure time. Due to the complex matrix of this fly ash material, a two-step purification stage using ion-exchange chromatography was required prior TIMS analysis. Obtained results for the two sample-spike blends (10.11 ± 0.55 and 10.50 ± 0.64 μmol g⁻¹) are comparable, both value and uncertainty. Also a good reproducibility is observed between measurements. The proposed ID-TIMS procedure, as a primary method and due to the lack of fly ash reference materials certified for tin content, can be used to validate more routine methodologies applied to tin determination in this kind of samples.     

U determination in environmental samples by delayed neutron activation analysis in Korea

A delayed neutron counting system has been implemented at the HANARO research reactor in 2007. Thermal neutron flux measured at the NAA #2 irradiation hole coupled to the delayed counting system, was higher than 3 × 10¹³ n cm⁻² s⁻¹. The delayed neutron counting system is composed of 18 ³He detectors which are divided into three groups with six detectors and the collected signals of each group are processed to a digital signal. The count numbers were measured with the uranium mass by using NIST SRMs under fixed analytical condition and their correlation could be determined. Finally, delayed neutron activation analysis has been carried out for the determination of uranium mass fraction in the collected environmental samples.     

Determination of trace amounts of chlorine in hydraulic fluid by Instrumental Neutron Activation Analysis

A procedure has been developed for the determination by thermal neutron activation analysis of trace amounts of total chlorine in the Electro-Hydraulic-Control /EHC/ fluid used by the Hadera Power Station in various hydraulic systems. Irradiation for 1 min near the core of a nuclear reactor is followed by high resolution gamma-ray spectrometry using a Ge/Li/ detector. Chlorine amount is quantitatively determined by measuring the gamma-ray photopeaks of the radioactive nuclide³⁸Cl. The system response is linear in the concentration ranges investigated. Chlorine concentration in a fresh hydraulic fluid sample was found to be 17.6±0.5 ppm. The limit of detection, when assaying a 1 cm³ sample of fluid under the present experimental conditions, is 1 g of chlorine and the corresponding concentration is 1 ppm.     

A combined method of neutron activation analysis and radiometric measurements for <Superscript>234</Superscript>U and <Superscript>238</Superscript>U determination in soil samples of low uranium concentration

A method that combines the use of non-destructive neutron activation analysis and high-resolution α spectrometry has been developed for determination of the activities of ²³⁴U and ²³⁸U in geological samples of low uranium content. The ²³⁸U content is determined by k₀-based neutron activation analysis, whereas the ²³⁴U/²³⁸U relationship is measured by α spectrometry after isolation and electrodeposition of the uranium extracted from a lixiviation with 6 M HCl. The main advantage of the method is the simplicity of the chemical operations, including the fact that the steps destined to assure similar chemical state for the tracer and the uranium species present in the sample are not necessary. The method was applied to soil samples from sites of the North Peru Coast. Uranium concentration range 3–40 mg/kg and the isotopic composition correspond to natural uranium, with about 10% uncertainty.     

Sensitivity improvements in the determination of mercury in biological tissues by neutron activation analysis

The possible association of dental amalgam surface exposure, brain mercury (Hg) levels, and pathological markers of Alzheimer's disease (AD) in the brain is the subject of an on-going study in our laboratory. Two radiochemical neutron activation analysis methods and the use of instrumental neutron activation analysis (INAA) with Compton suppression spectrometry have been evaluated for improving our INAA Hg detection limit (2.8±0.6 ng/g, wet-weight basis) in human tissue. Large numbers of samples dictated the use of a purely instrumental method or rapid, simple radiochemical separations. Human brain tissues and NIST biological standards were analyzed using a precipitation of Hg₂Cl₂, a solvent extraction utilizing sodium diethyldithiocarbomate, conventional INAA, and INAA with Compton suppression. The radiochemical precipitation of Hg₂Cl₂ proved to be the most useful method for use in our study because it provided a simultaneous, quantitative determination of silver (Ag) and a Hg detection limit in brain tissue of 1.6±0.1 ng/g (wet-weight basis).