Liquid-Scintillation β–α Spectrometry

An approach permitting the use of liquid scintillation counters as full spectrometers capable of identifying the radionuclide composition of complex samples according to the measured – radiation spectra is presented. The approach is based on simulating the instrumental spectrum of the sample with library spectra of individual radionuclides.Two methods are presented for constructing the radionuclide library – direct measurement of – spectra of each radionuclide and simulation of the spectra using standard mathematical functions. It is shown that the influence of internal conversion on the simulation of the spectra of peaks by asymmetric Gaussian distributions must be taken into account.A comparative analysis is made of modern liquid scintillation counters and of examples of analysis of the spectra of control and real samples.     

Monitoring the radiation conditions in reactors by semiconductor spectrometry methods

Conclusions 1. Semiconductor spectrometry of the radiation facilitates the analysis of the radiation conditions in nuclear reactors for power generation and research:identification of the radiation sources (radionuclides, nuclear reactions); andquantitative determination of the intensity of the radiation from the identified radionuclides and from nuclear reactions in units of H.2. The information makes it possible to determine the origin of the radioactive contamination by man-made radionuclides on industrial sites and the degree of radionuclide migration and allows a comparison of the radiation conditions on inspected objects.3. The total H values of the monoenergetic radiation do not exceed 25% of the maximum admissible amounts in the reactor halls inspected [4].Translated from Atomnaya Energiya, Vol. 68, No. 5, pp. 385–386, May, 1990.     

Computational-Experimental Study of the Heating of Structural Materials by IGRIK Radiation

An experiment measuring the temperature to which small samples of W, Ta, Mo, Cu, Zr, Ni, Fe, Ti, Sn, and Pb are heated by IGRIK radiation is performed. The technology for placing the thermocouples is described, the results of an analysis of the elemental composition of the samples are presented, and the experimental results from measurements of the heating temperature are also presented. The PRIZMA.D and MCNP computer codes are used to calculate the neutron and -ray energy losses in samples irradiated by a reactor pulse. The heat-up temperature is calculated. Discrepancies in calculations performed of the neutron and -ray energy losses in samples of the materials using different nuclear data libraries are shown. It is shown that the heating temperature calculated on the basis of the calculation of the neutron and -ray energy losses in the material of the samples, using the PRIZMA.D program with the BAS nuclear data library, agrees with the experimental value to within 5%. The agreement obtained with the MCNP code using the ENDF-B5 and -B6 libraries is no worse than 10–15%.__________Translated from Atomnaya Energiya, Vol. 98, No. 3, pp. 191–197, March, 2005.     

Back scattering of low-energy gamma radiation

Experimental data regarding the spectral and angular distribution of y quanta back-scattered from various scattering substances are presented for the geometry of an isotropic point source; the scattering substances include paraffin, graphite, aluminum, iron, xinc, cadmium, and lead (semiinfinite media). The energy of the primary ~/radiation was 0.145; 0.190; 0.279; 0.320; 0.396; 0.661 and 0. 765 MeV. The numerical and energetic albedos (A and A_E) determined experimentally agree closely with the values calculated by the Monte-Carlo method. The results are presented in the form of tables and graphical relationships for A, A_E, and A/A_E as functions of Z and E.Translated from Atomnaya Énergiya, Vol. 20, No. 4, pp. 317–323, April, 1966.     

Comparison of measured and calculated neutron and gamma ray energy spectra behind an in-line shielded duct

Integral experiments that measure the transport of 14 MeV neutrons through a 0.30-m-diameter duct having a length-to-diameter ratio of 2.83 that is partially plugged with a 0.15 m diameter, 0.51 m long shield comprised of alternating layers of stainless steel type 304 and borated polyethylene have been carried out at the Oak Ridge National Laboratory. Measured and calculated neutron and gamma ray energy spectra are compared at several locations relative to the mouth of the duct. The measured spectra were obtained using an NE-213 liquid scintillator detector with pulse shape discrimination methods used to simultaneously resolve neutron and gamma ray events. The calculated spectra were obtained using a computer code network that incorporates two radiation transport methods: discrete ordinates (with P₃ multigroup cross sections) and Monte Carlo (with continuous point cross sections). The two radiation transport methods are required to account for neutrons that singly scatter from the duct to the detectors. The calculated and measured neutron energy spectra above 850 keV agree within 5–50% depending on detector location and neutron energy. The calculated and measured gamma ray energy spectra above 750 keV are also in favorable agreement, 5–50%, depending on detector location and gamma ray energy.     

Background Levels of the Radiation Parameters of Soil

A method is proposed for determining the background levels of the radiation parameters of soil: exposure dose rate of the sample and the count rate in radiometry of a thick-layered preparation. Comparing an actually detected radiation parameter of a soil sample and the background level of the same parameter makes it possible to establish the presence and degree of radioactive contamination of the soil and to determine the predominant composition ( or emitters) of the radionuclides present in the soil. The method can be used to perform radiation monitoring of land to be used for a particular purpose.     

Radar–Spectrometric Method for Determining the Characteristics of Radioactive Emission

The uncertainty of the measurement geometry – absence of information about shape, dimensions, activity distribution, and spatial position of the radioactive cloud relative to the detector location – makes it difficult to perform spectrometry of radioactive emissions, for example, from nuclear power plants. The combined use of spectrometer and radar-tracer method, which visualizes a radioactive cloud, makes it possible to switch from qualitative analysis of spectra to determination of quantitative content of radionuclides in the emission. Schemes for radar-spectrometric probing and the basic computational relations for determining the activity of radionuclides are examined.     

Calculation of γ-ray energy absorption in heterogeneous macro-systems

By means of the Monte-Carlo method, a determination was made of the fraction of -ray energy absorbed in the elements of a complex heterogeneous system formed by a cylindrical, irradiated water-equivalent mass, cylindrical -ray sources located inside or outside the mass, and units of auxiliary equipment. From the results, various energy efficiencies (e.e) were determined depending on the radiation from particular systems which were models of radiochemical equipment. Results from corresponding experiments were in good agreement with the calculated data. The program enabled one to find the e.e. for arbitrary macro-systems of a similar type.Translated from Atomnaya Énergiya, Vol. 15, No. 5, pp. 382–286, November, 1963.     

Radiation γ annealing of Silicon Carbide irradiated in a BOR-60 reactor

The results of irradiating at 400–800°C silicon carbide, having the -SiC cubic modification, in different channels of the BOR-60 reactor, where the radiation composition factor was varied over the range 2.3–6.5, are discussed. The expansion of the crystal lattice of -SiC in the saturation stage is taken as the measure of damage. Data on isochronous annealing are used to investigate the energy spectrum for activation of annealing of defects - the smearing at high and low energy under the influence of radiation. The results are compared with data from similar irradiation of silicon carbide in MR and BR-10 and with data on the influence of radiation on other materials and their properties.Translated from Atomnaya Ènergiya, Vol. 97, No. 4, pp. 275–280, October, 2004.     

Application of Extracting Agents in Liquid-Scintillation α Spectrometry

A method is proposed for decreasing the quenching of the lsc sample and improving the resolution of the peaks to 9–10% in liquid-scintillation spectrometers. The method uses liquid chromatography based on extraction-scintillation cocktails containing bis-(2-ethylhexyl)phosphoric acid. A technology is developed for selective extraction, making it possible to obtain lsc samples of different isotopes (U, Pu, Th, Am/Cm).An approach which makes it possible to determine, using in an internal standard (¹⁴⁸Gd), the quenching of an lsc sample and to correct the spectral shifts, which, as a rule, are present in complex mixtures of -emitting radionuclides, is proposed.Examples where extraction chromatography and liquid-scintillation spectrometry are used together to analyze samples extracted from ecological and technological systems are presented.     

Detection of Explosives by Neutron-Radiation Analysis

The possibility of using in practice the analytical methods of computational efficiency and minimization of the directed discrepancy in the algorithm of the working program for a setup for detecting explosives by neutron-radiation analysis is discussed. The captured-radiation spectra, which are recorded on a model of a real setup, and the computed response functions for -ray energies 6 and 10.9 MeV taking account of the energy resolution of the detector are presented. The possibility of applying these methods to the problem of detecting explosives is briefly described. Difficulties arising in the practical implementation of the methods are noted.__________Translated from Atomnaya Energiya, Vol. 98, No. 3, pp. 220–225, March, 2005.     

REIDAC—A Software Package for Retrospective Dose Assessment in Internal Contamination with Radionuclides

For cases of internal contamination with radionuclides, it is necessary to perform an internal dose assessment to facilitate radiation protection. For this purpose, the ICRP has supplied the dose coefficients and the retention and excretion rates for various radionuclides. However, these dosimetric quantities are calculated under typical conditions and are not necessarily detailed enough for dose assessment situations in which specific information on the incident or/and individual biokinetic characteristics could or should be taken into account retrospectively. This paper describes a newly developed PC-based software package called Retrospective Internal Dose Assessment Code (REIDAC) that meets the needs of retrospective dose assessment. REIDAC is made up of a series of calculation programs and a package of software. The former calculates the dosimetric quantities for any radionuclide being assessed and the latter provides a user with the graphical user interface (GUI) for executing the programs, editing parameter values and displaying results. The accuracy of REIDAC was verified by comparisons with dosimetric quantities given in the ICRP publications. This paper presents the basic structure of REIDAC and its calculation methods. Sensitivity analysis of the aerosol size for ²³⁹Pu compounds and provisional calculations for wound contamination with ²⁴¹Am were performed as examples of the practical application of REIDAC.     

Degradation of elastomer by heat and/or radiation

This article studied various problems on the degradation of elastomers by heat and/or radiation. Three kinds of elastomers were irradiated and evaluated by the radiation resistant property using the measurement of tensile test. The fluorine containing elastomer, which has excellent heat resistant properties, was found to be less durable for irradiation than ethylene-propylene-diene (EPDM) elastomer. Ten kinds of different compounding formulas of EPDM were prepared to investigate whether the compounding for heat resistant has durability for irradiation. The thermal exposure was performed in an air oven. The duration of thermal exposure at 140 °C was 384 h. The irradiation condition was 5.0 kGy/h at 70 °C, and the total dose was 0.9 MGy. Elongation retained was taken for the evaluation of the stability. It was found that the formulas for improving the thermal stability did not bring radiation resistant of samples in the experiment.The rate constant of the increase in CO concentration by heat and radiation was measured and defined as k_c(h) and k_c(r), respectively. The rate constant of that under the combined addition of the heat and the radiation is expressed as k_c(h + r). Eq. (1) was obtained by the experiment and it was found that there is a synergistic relationship between heat and radiation on the increase in CO concentration

(1)     

Computational-theoretical model of a wave multiplying pulsed reactor

A computational-theoretical model is proposed for an innovative zero power wave multiplying pulsed reactor (WMPR) for studying the development of a nuclear fission chain reaction near the upper critical state of the system, i.e., in the region where calculations are difficult to perform and on which nuclear explosion-safety of critical systems depends. A scenario of possible accidents is presented.The novelty and special features of the physical scheme of the WMPR required the use of new computational methods. These methods can be used, for example, to calculate conventional pulsed nuclear reactors.Translated from Atomnaya Énergiya, Vol. 97, No. 6, pp. 414–422, December, 2004.Deceased.This revised version was published online in April 2005 with a corrected cover date.     

Albedo of Co60 and Au198 γ-rays from various substances

Absolute values are obtained in the present investigation for the energy albedo of the -radiation of Co⁶⁰ (1.17, 1.33 Mev) and Au¹⁹⁸ (0.410 Mev) from various substances, at angles of 0 °, 45 °, and 60 ° from the original beam.The dependence of the magnitude of the albedo on the effective atomic number and thickness of the scattering material was investigated; in addition, the angular distribution of the intensity of the scattered radiation and its spectral composition were determined.The energy flux of the primary radiation was determined by use of an ionization chamber and Roentgen KH-5 photographic film. The intensity of the scattered radiation was measured with a gas-filled counter with a practically constant sensitivity to -quanta of different energies. The spectral composition of the scattered radiation was determined by the method of absorption in lead.This work was performed at the suggestion of Professor O. I. Leipunskii, whom the authors sincerely thank for his scientific guidance. The authors are deeply grateful to N. Ia. Buben and A. S. Strelkov for help in the work and a discussion of the results.     

Study of annealing induced redistribution of implanted Au in Si: Fluence dependence

One hour 500 °C air annealing induced movement of implanted Au in Si have been studied for 32 keV Au implantation in Si, in the fluence range of . Samples were characterized using Rutherford backscattering spectrometry and cross-sectional transmission electron microscopy. The results indicate that, depending on the initial state of Au in the matrix, there is a clear difference in the diffusion behaviour of Au in Si. When Au is precipitated as gold-silicide nanoclusters inside the Si matrix, annealing is found to cause diffusion of Au into the bulk Si. Compared to this, for a random atomic distribution of Au in an amorphous Si matrix, annealing is found to result in out-diffusion of Au towards the surface.     

Third-Generation Synchrotron Radiation Source at the Joint Institute of Nuclear Research

An accelerator complex DÉLSI (Dubnen Electron Synchrotron) is planned for constuction as source of synchrotron radiation with high brightness in a wide spectral range – from far infrared (100 m) up to high-energy x-ray (50 keV). This will make it possible to perform a wide range of research at the Joint Institute of Nuclear Research. The DÉLSI complex includes a linear electron accelerator up to energy 800 MeV and a storage ring with a 136 m perimeter at 1.2 GeV, in which a 10 T wiggler and an undulator (0.75 T, 150 periods) are built-in. The linear electron accelerator of the DÉLSI complex will be used for injection and for producing free-electron lasers. The parameters of synchrotron radiation from the bending magnets and built-in devices of the DÉLSI complex, the magnetic structure of the storage ring with the wiggler and undulator switched off, the effect of built-in devices on the ring optics, and the effect of errors on the closed orbit are examined; the synchrotron radiation parameters are briefly described.     

Interrelation between the grain orientation and the radiation growth of uranium rods

The results obtained in radiation tests of -heat-treated uranium rods at temperatures of 200–300; 450–470; 480 C are given. Dependences of the radiation-growth coefficients G_i on the growth index GI characterizing the grain orientation of the tested specimens were plotted. The elongation component resulting from the radiation growth due to grain orientation was determined. The dependence of the radiation-growth coefficient on the test temperature for weakly-pronounced grain orientations is given. It is shown that the mean values of the linear thermabexpansion coefficient measured in one direction only, do not provide information on the character and degree of the grain orientation if the latter is not uniaxial.Translated from Atomnaya Énergiya, Vol. 18, No. 4, pp. 357–361, April, 1965