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Within European Partitioning & Transmutation research programs, infrastructures specifically dedicated to the study of fundamental reactor physics and engineering parameters of future fast-neutron-based reactors are very important, being some of these features not available in present zero-power prototypes. This presentation will illustrate the conceptual design of an Accelerator-Driven System with high safety standards, but ample flexibility for measurements. The design assumes as base option a 70 MeV, 0.75 mA proton cyclotron, as the one which will be installed at the INFN National Laboratory in Legnaro, Italy and a Beryllium target, with Helium gas as core coolant. Safety is guaranteed by limiting the thermal power to 200 kW, with a neutron multiplication coefficient around 0.94, loading the core with fuel containing Uranium enriched at 20% inserted in a solid-lead diffuser. The small decay heat can be passively removed by thermal radiation from the vessel. Such a system could be used to study, among others, some specific aspects of neutron diffusion in lead, beam-core coupling, target cooling and could serve as a training facility.

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The thermal neutron radiation shielding effectiveness of polyurethane (PUR) composites loaded with 20.9% by weight of boron carbide or by 20.4% graphite micronized fillers was evaluated. As expected, the former composite was found very effective in thermal neutron radiation shielding, and its performances were compared with those of other PUR composites loaded with about 20% of amorphous boron or 20% boron nitride. On the other hand the PUR composite loaded with graphite was found not suitable for shielding thermal neutrons. FT-IR spectroscopy and DSC were used to demonstrate the excellent neutron radiation resistance of the PUR composites of this study. [ABSTRACT FROM AUTHOR]

Copyright of Giornale Italiano di Medicina del Lavoro ed Ergonomia is the property of Giornale Italiano di Medicina del Lavoro ed Ergonomia Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, evaluation of neutron flux parameters of TRIGA Mark II reactor in Pavia was carried out. For any of the three irradiation positions investigated, this work represented the first experimental evaluation of α. Moreover, in addition to α, values of other parameters such as f, Φ and Φ were also calculated and compared with the existent literature data from other TRIGA Mark II reactors and the Pavia's facility. Results obtained in the present study represent a mandatory step ahead for future application of k -Neutron Activation Analysis method ( k -NAA) at Pavia's facility. [ABSTRACT FROM AUTHOR]

Summary: The radiological risk assessment and the definition of the radioprotection physical surveillance program applied to a 250 kW (thermal power) research nuclear reactor operated by a large Italian public body. Useful elements for the prevention of personnel exposures, classification criteria for workers, risk reduction methods and optimization of exposures, most common criticalities in plant activities. Analysis of the main operations related to the activities of irradiation and scientific research with an eye to the needs of researchers and one to the indications of prevention. Consolidated intervention methods for ordinary activities and for emergency situations. Detailed examination of the possible unforeseen events or accidents initiators, stopping the assessment at the definition of the source terms related to emergencies inside the plant. Nuclear and conventional causes of accidents and analysis of the radiological consequences. Indications for in-depth-defense and long-term monitoring of the safety of workers, individuals of population and the environment., Competing Interests: The authors of this article have no conflict of interests to disclose., (Copyright© by GIMLE.)

Summary: In this article, there will be presented the main aspects of the radiation protection for a site dedicated to the production of radioisotopes by cyclotron for medical use. After analyzing the design parameters of the site for the operation from a point of view of the radiation protection of the operators, the population and the environment (shielding around the accelerator, ventilation system, chimney releases etc.), we will focus our attention to the handling of unsealed sources produced, with particular regard to the operating procedures. The final part will be dedicated to intervention in exceptional operating conditions (entring the bunker due to a machine failure, breaking of a vial during transfer from the hot cell to the transport container and accidental contamination by an operator)., Competing Interests: The authors of this article have no conflict of interests to disclose., (Copyright© by GIMLE.)

The latest determination of the Avogadro constant, carried out by counting the atoms in a pure silicon crystal highly enriched in (28)Si, reached the target 2 × 10(-8) relative uncertainty required for the redefinition of the kilogram based on the Planck constant. The knowledge of the isotopic composition of the enriched silicon material is central; it is measured by isotope dilution mass spectrometry. In this work, an independent estimate of the (30)Si mole fraction was obtained by applying a relative measurement protocol based on Instrumental Neutron Activation Analysis. The amount of (30)Si isotope was determined by counting the 1266.1 keV γ-photons emitted during the radioactive decay of the radioisotope (31)Si produced via the neutron capture reaction (30)Si(n,γ)(31)Si. The x((30)Si) = 1.043(19) × 10(-6) mol mol(-1) is consistent with the value currently adopted by the International Avogadro Coordination.