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We developed a technique for thermal neutron detection not making use of ³He, also suitable for online real time monitoring of CASTOR spent fuel containers. As a neutron converter we used 6LiF, being the neutron capture cross section of 6Li very well known and with only an alpha and a triton in the exit channel. We can deposit thin layers of converter onto several different substrates, to be placed on top of solid state detectors or scintillators capable of efficiently detecting the decay products. [ABSTRACT FROM AUTHOR]

Nuclear activation is the process of production of radionuclides by irradiation. This phenomenon concerns particle accelerators used in various fields, from medical applications to industrial ones, both during operation and at the decommissioning phase. For more than three decades, the possibility of using cyclotrons for nuclear power generation and nuclear waste reduction has also been discussed, i.e. in the case of Accelerator-Driven Systems [1]. The radioprotection and dismantling issues of accelerator facilities, that have been raised recently, is even more potent for such installations. In our study, we are particularly interested in the activation due to secondary neutrons produced by (x,n) reactions, mostly (p,n) occurring in the accelerator's components. This work focuses on the study of the radioactivity induced in various materials (V, Sc, Tb, W, Ta) irradiated by fast and thermal neutrons, in two different scenarios: through direct irradiation -with an AmBe sourceand around an operating cyclotron at the CYRCé facility (Strasbourg). A broad Monte Carlo study including FLUKA, GEANT4, PHITS and MCNP simulation has been performed, with and without a FISPACT-II coupling, to estimate the reaction rates and to trace the induced radioactivity in samples of known composition. The results of the simulations are compared with the values extracted in two dedicated experimental campaigns in which activated samples underwent high resolution gamma-ray spectrometry. [ABSTRACT FROM AUTHOR]

Neutron cross section measurements are often made relative to a neutron cross section standard. Thus, the accuracy of the neutron standards determines the best possible accuracy of the neutron measurements. The 235U(n,f) cross section is widely used as reference, while it is considered a standard at thermal point and between 0.15 to 200 MeV. For this reason, additional cross section data for the 235U(n,f) reaction are useful in order to improve the accuracy and to extend the energy range of the standard. In this work, preliminary results of the measurement of the 235U(n,f) cross-section relative to the standard 10B(n,a) reaction are presented. The high accuracy measurement was performed at the experimental area EAR-1 of the n_TOF facility at CERN, aiming at covering the energy range from the thermal region up to approximately 100 keV. The samples were produced at JRC-Geel in Belgium, while the experimental setup was based on Micromegas detectors. [ABSTRACT FROM AUTHOR]

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 70MeV, 0.75mA 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. [ABSTRACT FROM AUTHOR]