Investigation of the impurity concentrations and product activities of some targets used in radioisotope production: a neutron activation analysis study

Neutron activation analysis using the k ₀ standardization method (k ₀-NAA) and fast neutron activation analysis using reactor fission neutrons, were used to determine the impurity concentrations in WO₃, MoO₃, SnO₂ and TeO₂ targets. The radioimpurities ¹²⁴Sb, ¹³⁴Cs, ⁶⁰Co, ⁸⁷Rb, ¹⁸²Ta, ²³³Pa, ⁶⁵Zn, ⁵⁹Fe, ^110mAg, ⁵¹Cr, ⁹⁵Zr, ⁷⁵Se and ^114mIn were found in the irradiated targets and their origin either neutron capture reactions, or threshold reactions or both were identified. The specific activities of ¹⁸⁷W, ¹⁸⁸Re, ^99mTc, ^113mIn, ^117mSn and ¹³¹I radioisotopes were determined. It is shown that the epithermal neutron flux significantly contributes to the isotopes characterized with high Q₀ values. It is shown that the ^117mSn isotope can be produced with a high specific activity using the fast neutron component of the reactor neutron spectrum.     

An example for activation analysis by low-level radioisotope neutron soruce

A 1 Ci Pu−Be neutron source and a low-background beta-spectrometer were used to activate and to measure the beta-rays of low-activity. The main characteristics of this method can be given as follow: The determined S/N ratio increases because the background beta-rays are lower than the gamma-rays. For example, the sensitivity obtained for quantitative analysis of sulphur in silicon is 100 ppm in case of S/N=1.0.     

An entropy production analysis for electroosmotic flow and convective heat transfer: a numerical investigation

Journal of Thermal Analysis and Calorimetry - In the current numerical study, an entropy production analysis is conducted for the electroosmotic flow and convective heat transfer in the microduct....     

In-vivo neutron activation analysis for medical applications

This paper describes the design of the system and the uses of in-vivo neutron activation analysis (IVNAA) for the determination of total body calcium (TBCa) and total body nitrogen (TBN) in humans. TBCa and TBN assay are useful in a variety of clinical situations dealing with the diagnosis and management of patients with osteopenia, nutritional deficiency, renal dysfunction, transplantation, cancer, thyroid dysfunction and many others. The system can be put together with readily available nuclear components and within a reasonable cost. This paper examines the present status of IVNAA for medical applications in a hospital setting.     

Examination of some binary mixtures by inelastic neutron scattering with a radioisotope neutron source

Magnesium, almuinium and iron have been determined in sand at levels of >1% by inelastic neutron scattering. Neutrons were obtained from a 1 Ci polonium-beryllium neutron source and analytical determination was based on measurement of the characteristic γ-lines emitted during nuclear de-excitation.     

Gas chemical methods for the separation of elements in radioisotope production and activation analysis

Summary Liquid-liquid extraction is used for one-atom-at-a-time separations of transactinide elements from heavy-ion reaction product mixtures. It is suitable for this purpose because it is fast, provided that a chemical system with negligible kinetics is used, and it can be used for continuous separations. It is, however, not quite easy to determine the uncertainties of the measured distribution coefficients or complex formation constants. In this paper methods for such estimates will be discussed.     

Multi-geometry241AmBe neutron irradiator: Design and calibration for total-body neutron activation analysis

Neutron activation analysis provides an accurate elemental assessment of body compositional compartments; the analytical technique identifies skeletal, muscle, protein, and fat masses. Our irradiator system uses 56²⁴¹AmBe sources (4.4·10⁷ n/s each) which can be arranged in four basic geometries to examine body sizes from a preterm infant (500 g, 30 cm) to a very large adult (120 kg, 2m). Both in vivo and human cadaver studies have been performed. Precisions of 1 to 2% for total body Ca, P, Na, and Cl have been obtained.     

Design and construction of a facility for neutron activation analysis using the 14 MeV neutron generator at HMS Sultan

The potential for using a small, sealed tube, DT neutron generator for neutron activation analysis has been well documented but not well demonstrated, except for 14 MeV activation analysis. This paper describes the design, construction and characterization of a neutron irradiation facility incorporating a small sealed tube DT neutron generator producing 14 MeV neutrons with fluence rates of 2·10⁸ s⁻¹ in 4π (steady state) and 10¹¹ s⁻¹ in 4π (pulsed). Monte Carlo modeling using MCNP4c and McBend9 has been used to optimize the design of this facility, including the location of a thermal irradiation facility for conventional neutron activation analysis. A significant factor in designing the facility has been the requirement to conform with Ionising Radiation Regulations and the design has been optimized to keep potential radiation doses to less that 1 μSv/h at the external walls of the facility. Activation of gold foils has been used for flux characterization and the experimental results agree well with the modeling.     

Chemical separation of enriched cadmium target from copper backing in cyclotron production of radioisotope 111In

A radiochemical purification procedure was developed for the separation of enriched cadmium (¹¹¹Cd and ¹¹²Cd) from natural copper that used as backing; and was based upon the chromatographic adsorption. The separation of copper from cadmium was studied in this work. The ions were selectively separated from aqueous solution. Ion-exchange chromatography was employed as a column (1.5 cm i.d. and 15 cm length) with AG1-X8 resin (chloride form, 100–200 mesh) and a flow rate of 1–2 ml/min throughout the separation. 6 M HCl media was used for the adsorption of Cd and Cu on the resin. Then, Cu was eluted by 2 M HCl and Cd by 100 ml 0.5 M HNO₃. The amount of Cu and Cd ions in the final solution (0.5 M HNO₃) were measured by pulse polarographic method and the concentration of Cu was found to be <0.1 ppm. The Cd was quantitatively recovered and the recovery yield from ion-exchange chromatography was greater than 96 %.     

Quantitative aspects of neutron activation analysis and isotope production with a small reactor

The use of “small” research reactors with applicable thermal neutron fluxes of ≤10^12.cm^−2.s⁻¹ in (instrumental) activation analysis based on γ-spectrometry, and in isotope production for radiotracer experiments is surveyed on the absis of the experience at ECN, Petten, The Netherlands and elsewhere. The aim is to provide a practical guideline for the application of “small” reactors in both fields. Reproducibility and knowledge of the physical parameters of irradiation and counting are essential and thus the first task of the radioanalyst. Emphasis is laid on the use of short-lived radionuclides. This implies the elimination of an additional source of bias in γ-spectrometry. Some suggestions are made on eventual projects of current interest.     

Determination of trace elements in semiconductor materials by neutron activation analysis using the radioisotope addition technique

The determination of trace elements in highly activated matrix components was carried out by neutron activation analysis using the radioisotope addition technique. The method is based on the addition to the irradiated test sample of a radioisotope which is a diffeent nuclide of the element to be determined. After separation, the chemical yield is calculated from the radioactivity added and the element is determined by an ordinary technique. Twelve elements in indium phosphide and eight elements in gallium arsenide could be determined by the method.     

Instrumental neutron activation analysis of pottery for provenience study

A scheme for INAA of pottery is proposed. The combination of 3 irradiations-epithermal and pile (short and long time) and 6 measurements (2 times after each irradiation) enables the determination of Al, As, Au, Ba, Br, Ce, Co, Cr, Cs, Dy, Eu, Fe, Hf, K, La, Lu, Mg, Mn, Na, Nd, Rb, Sb, Sc, Si, Sm, Ta, Tb, Th, Ti, U, V and Yb. The accuracy and precision of the method is evaluated by analysis of standard reference materials (USGS-BCR-1, USGS-W-1, ZGI-TB). The applicability of the method is demonstrated by analysis of 15 sgraffito ceramics from XV–XVIII cc. from Tzarevetz, Veliko Tirnovo (Bulgaria). The results from the clustering of the analytical data are presented and discussed.     

Nuclear spallation as a mechanism for radioisotope production: Cross sections for selected nuclides

Proton spallation is a relatively recent method for significant radioisotope production. A detailed discussion of the activation equation for charged-particle reactions is given, and measured values of spallation cross sections for reactions of 800-MeV protons with three target materials are reported.     

Possibility of32Si production as a by-product of32P radioisotope production process

Currently used³²P production process was indicated to be a potential resource of³²Si production. The³²Si yielded by³²S(n, p)³²P(n, p)³²Si reaction was found mainly in³²P product solution rather than sulphur distillation crucible. By using the reported values of cross section of³²P(n, p)³²Si reaction and half-life of³²Si, the yield of³²Si in sulphur target was calculated. A possible ion exchange method was presented for the recovery of³²Si from the³²P production process.     

Quantitative activation analysis of the target assemblies of a medical linear accelerator

Radioactive nuclides with relatively long half-lives in the target assemblies of medical accelerators were investigated. The samples were the target assembly of a 10 MV linear accelerator, a 20 MV microtron and screws of a cyclotron. Gamma-spectroscopy was performed with a high-purity germanium (HPGe) detector. Detected nuclides were ⁵¹Cr, ⁵⁴Mn, ⁵⁹Fe, ⁵⁷Co, ⁵⁸Co, ⁶⁰Co, ⁶⁵Zn, ^108mAg, and ^110mAg. As the half-lives of some generated nuclides are relatively long, it is difficult to adapt to decay-in-storage.