USBAS

used to simulate the neutron flux inside IAEA benchmark ADS design of a 1500 MW th reactor. The reactor is found to have the capability of production of the said amount of thermal energy and has high left over neutron fluence. This n -fluence is equivalent to that of a critical reactor for a given input fuel.

S and W parameters corresponding to the positron Doppler broadening technique have been used to study displacement type defects produced in iron samples irradiated by various imparted doses of gamma ranging from 20 Gy to 2kGy. For the logistic support of the experimental observations Monte Carlo simulation of displacements has also been performed. Of the increase of S parameter with dose up to a limit it is revealed that vacancy type defects dominate. From both the experimental observations and the Monte Carlo study it is inferred that on irradiation monovacancies are produced and under the given irradiation conditions there is negligible chance of the atom+atom collision cascade which may give rise to multiple type vacancies.

The parameters S and W corresponding to the positron Doppler broadening technique have been used to study displacement type defects produced in iron samples irradiated by various imparted doses of gamma ranging from 20 Gy to 2kGy. For the logistic support of the experimental observations, Monte Carlo simulation of displacements has also been performed. Of the increase of S parameter with dose up to a limit, it is revealed that vacancy type defects dominate. From both the experimental observations and the Monte Carlo study, it is inferred that on irradiation monovacancies are produced and under the given irradiation conditions there is negligible chance of the atom+atom collision cascade which may give rise to multiple type vacancies.

Highly photocatalytically active Ag nanoparticle decorated ZnO nanospindles were synthesized by a facile wet chemical method. The structural and optical properties of the as-synthesized materials were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and high resolution TEM (HRTEM) with energy dispersive X-ray spectroscopy, UV-visible absorption spectroscopy and Raman spectroscopy. The photocatalytic activity of these nanostructures was evaluated by analyzing sunlight driven degradation of methyl orange (MO) dye and it was observed that Ag nanoparticle modified ZnO nanospindles show significantly enhanced photocatalytic activity for degradation of MO, as compared to ZnO nanospindles. We attribute the observed enhanced photocatalytic activity of Ag nanoparticle decorated ZnO nanospindles to their improved sunlight utilization efficiency and the efficient suppression of recombination of photogenerated charge carriers due to the electron scavenging action of Ag nanoparticles and the interfacial electron transfers due to the Schottky junction between Ag nanoparticles and ZnO nanospindles.

We report the synthesis of Ag-ZnO hybrid plasmonic nanostructures with enhanced photocatalytic activity by a facile wet-chemical method. The structural, optical, plasmonic and photocatalytic properties of the Ag-ZnO hybrid nanostructures were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL) and UV-visible absorption spectroscopy. The effects of citrate concentration and Ag nanoparticle loading on the photocatalytic activity of Ag-ZnO hybrid nanostructures towards sun-light driven degradation of methylene blue (MB) have been investigated. Increase in citrate concentration has been found to result in the formation of nanodisk-like structures, due to citrateassisted oriented attachment of ZnO nanoparticles. The decoration of ZnO nanostructures with Ag nanoparticles resulted in a significant enhancement of the photocatalytic degradation efficiency, which has been found to increase with the extent of Ag nanoparticle loading.