Радиационная обработка краев трещины сверхпроводящего слоя при реставрации ВТСП-ленты

Numerically, within the framework of the critical state model, the density of superconducting currents in a second-generation HTSC tape based on GdBa2Cu3O7-x is determined. It is shown that during the restoration of the transverse crack of the superconducting layer by shunting the crack with a piece of defect-free tape, the critical current of the restored area decreases by ~ 8%. It is shown that preliminary irradiation of the crack edges with ions of hydrogen, helium, neon, and oxygen makes it possible to restore the initial value of the critical current. The calculation of the effect of radiation on a superconducting tape was carried out using the SRIM software package

Influence of radiation-stimulated discharges on the contamination of cover glasses of solar batteries of spacecraft

The results of an AFM study of changes in the surface structure of K-208 and CMG cover glasses after electron irradiation and exposure to molecular fluxes are presented. It is shown that contamination of glass surfaces irradiated with electrons at flux densities (φ) from 1010 to 8·1010 cm–2 s–1 occurs during electrostatic discharges accompanied by the release of plasmoids into the surrounding space, the particles of which are deposited on the glass. It has been experimentally established that the effect of preliminary irradiation of glass on the deposition of molecular flow components is most effective immediately after irradiation and decreases with time. This is due to the drainage of the charge injected into the glass and a decrease in the initially high reactivity of the substances in the discharge channels. It was also shown that the combined effect of electrons and molecular flux on glasses significantly increased the discharge frequency at a given value of φ and, as a result, led to an increase in the number of discharge channels on the sample surfaces. In this case, over time, the process of accumulation of molecular flow components begins to dominate the cleaning of the glass surface due to electron-stimulated desorption and mechanical desorption under the action of shock waves accompanying the discharges. To interpret the experimental results, a mathematical model of the deposition of molecular flow components on glass is proposed.

Effect of Neutron Irradiation on the Mechanical Properties of an A508 Cl.2 Forging Irradiated in a BAMI Capsule

The typical operating temperatures of a nuclear reactor pressure vessel in a PWR is typically between ∼290°C and 300°C. However, many BWRs and some PWRs operate at slightly lower temperatures down to 275°C. Most of the literature and neutron irradiation damage is therefore focused on those irradiation temperatures. It is well-known that the lower the irradiation temperature, the more neutron irradiation damage occurs, because no appreciable annealing occurs at approximately 230°C. The NOMAD-0 irradiation campaign at the BR2 was a preliminary irradiation specifically designed to determine the appropriate irradiation conditions that result in specific irradiation damage levels of an A508 Cl.2 grade at lower temperatures than the usual PWR operating temperature window. The BAMI capsules with controlled He gas gap were used for this irradiation. To avoid temperature gradients from the outside to the center of the cylindrical blocks, the latter were limited in size. Only tensile and fracture toughness data could therefore be obtained with mini-tensile and mini-CT specimens. The results show that no influence of the temperature gradient could be found on the tensile and fracture toughness properties. The specimen size and geometry on the fracture toughness results was analyzed and discussed. The effect of irradiation temperature on the tensile properties and the transition temperature as determined by the master curve approach on the mini-CT samples is discussed.

ВЛИЯНИЕ ПРЕДВАРИТЕЛЬНОГО ОБЛУЧЕНИЯ ГАММА-КВАНТАМИ НА ОДИНОЧНЫЕ СБОИ В МИКРОСХЕМАХ ПАМЯТИ, ВОЗНИКАЮЩИЕ ПРИ ВОЗДЕЙСТВИИ НЕЙТРОНОВ ЭНЕРГИИ 14 МЭВ

Исследовано влияние предварительного облучения гамма-квантами на сечение одиночных событий (ОС) в СОЗУ при воздействии нейтронов с энергией 14 МэВ. Показано, что с увеличением уровня предварительного облучения гамма-квантами сечение ОС возрастает. Рост сечения от величины поглощенной дозы обусловлен накоплением зарядов в диэлектрических слоях интегральной микросхемы. The paper explores the influence of a preliminary gamma ray irradiation on single event upsets (SEU) in SRAM at 14 MeV neutrons influence. It has been shown that there is an increase in SEU cross section with an increase of level of preliminary irradiation by gamma rays. The increase of cross section from absorbed dose level depends on accumulation of charges in dielectric layers of integrated microcircuit.

Influence of the Generator in-Growth Time on the Final Radiochemical Purity and Stability of Radiopharmaceuticals

At Legnaro laboratories of the Italian National Institute for Nuclear Physics (INFN), a feasibility study has started since 2011 related to accelerated-based direct production of by the100Mo(p,2n) reaction. Both theoretical investigations and some recent preliminary irradiation tests on100Mo-enriched samples have pointed out that both the / ratio and the specific activity will be basically different in the final accelerator-produced Tc with respect to generator-produced one, which might affect the radiopharmaceutical procedures. The aim of this work was to evaluate the possible impact of different / isomeric ratios on the preparation of different Tc-labeled pharmaceutical kits. A set of measurements with , eluted from a standard99Mo/ generator, was performed, and results on both radiochemical purity and stability studies (following the standard quality control procedures) are reported for a set of widely used pharmaceuticals (i.e., -Sestamibi, -ECD, -MAG3, -DTPA, -MDP, -HMDP, -nanocolloids, and -DMSA). These pharmaceuticals have been all reconstituted with either the first [O4]−eluate obtained from a99Mo/ generator (coming from two different companies) or eluates after 24, 36, 48, and 72 hours from last elution. Results show that the radiochemical purity and stability of these radiopharmaceuticals were not affected up to the value of 11.84 for the / ratio.

Functional activity of NADH-dependent reductase system in liver and guerin’s carcinoma microsomal fraction in rats exposed to preliminary irradiation

The activity of liver and Guerin’s carcinoma microsomal NADH-dependent reductase system has been investigated in tumor-bearing rats exposed to preliminary irradiation. Preliminary irradiation of rats (before transplantation of Guerin’s carcinoma) resulted in the decrease of NADH-cytochrome b reductase activity and contents of cytochrome b in the Guerin’s carcinoma microsomal fraction in the logarithmic phases of oncogenesis compared with the non-irradiated tumor-bearing rats. The effect of irradiation preceding transplantation of the tumor to rats results in the increase of enzymatic activities of liver microsomal NADH-cytochrome b reductase in the latent and logarithmic phases of tumor growth as compared with non-irradiated tumor-bearing rats. At the same time the contents of cytochrome b decreases. During longer periods after irradiation the investigated parameters approached to those in the group of non-irradiated tumor-bearing animals.