[en] We developed a new technique for thermal neutron detection not making use of ³He, also suitable for online real time monitoring of CASTOR spent fuel containers. The neutron converter we use is ⁶LiF, being ⁶Li well known for its good neutron capture cross section, whose decay does not produce any gamma rays but only a triton and an alpha particle. We can deposit thin layers of converter onto several different substrates, to be placed on top of solid state detectors of scintillators capable of efficiently detecting the decay products. Moreover, we also exploit a new neutron detection technique based on converter and scintillator, capable of achieving high efficiency, good n/gamma discrimination, millimeter space resolution, low cost. In the same framework as our current DMNR project aimed at the online gamma monitoring of individual radwaste drums, we propose a real time online monitoring system based on a large number of small low-cost neutron detectors, to be deployed all around (and associated with) CASTOR containers in storage sites. Acknowledgement: We are grateful to P. Peerani and V. Forcina of JRC Ispra for the invaluable help provided during the tests performed in their lab at JRC. (author)

[en] A low-cost array of modular sensors for online monitoring of radioactive waste was developed at INFN-LNS. We implemented a new kind of gamma counter, based on Silicon PhotoMultipliers and scintillating fibers, that behaves like a cheap scintillating Geiger-Muller counter. It can be placed in shape of a fine grid around each single waste drum in a repository. After simulating the counting response of thin scintillating fibers to gamma radiation, we verified our simulation results with measurements using radioactive sources. Front-end electronics and an FPGA-based counting system were developed to handle the field data, also implementing data transmission, a graphical user interface and a data storage system. A test of four sensors in a real radwaste storage site was performed with promising results. Following the tests an agreement was signed between INFN and Sogin for the joint development and installation of a prototype DMNR (Detector Mesh for Nuclear Repository) system inside the Garigliano radwaste repository in Sessa Aurunca (CE, Italy). Such a development is currently under way, with the installation foreseen within 2013. Acknowledgement: This work was initially supported by INFN and Ansaldo Nucleare S.p.A. Currently it is supported by INFN and SOGIN S.p.A. (author)

[en] A prototype array of modular sensors for online monitoring of radioactive waste was developed at INFN-LNS. We implemented a new kind of gamma mini-sensor, based on Silicon Photomultipliers and scintillating fibers, that behaves like a cheap scintillating Geiger-Muller counter. It can be placed in shape of a fine grid around each single waste drum in a repository. After simulating the counting response of thin scintillating fibers to gamma radiation, we verified our simulation results with measurements using radioactive sources. Front-end electronics and an FPGA-based counting system were developed to handle the field data, also implementing data transmission, a graphical user interface and a data storage system. A test of four sensors in a real radwaste storage site was performed with promising results. (authors)

[en] We propose a system for the on-line monitoring of short and medium term radioactive waste repositories. Such a system is distributed, fine-grained, robust, reliable, and must be based on low-cost components. It could, in principle, open new perspectives on the modality of waste packaging and storage. In particular we propose to employ a new family of cheap and powerful micro sensors to be placed in shape of a fine grid around each single drum. (authors)

[en] In the context of the on-line monitoring of short and medium term for radioactive waste repository, a new system has been planned. Such system makes use a new kind of detector, named Silicon Photomultiplier, coupled to scintillating fibres to be positioned around each waste drum in shape of fine grid. The purpose of this design is evaluate the variations of the radioactivity distribution by counting the gamma radiation.

[en] A prototype demonstrator for the online monitoring of short-medium term radioactive waste repositories is currently under development at INFN-LNS. Such a system is planned to be distributed, fine-grained, robust, reliable, and based on low-cost components. With the main purpose of counting gamma radiation, we implemented a new kind of mini-detector based on silicon photomultipliers and scintillating fibers that behaves like a cheap scintillating Geiger-Muller counter and is suitable to be deployed in the shape of a grid around waste drums.

[en] An experimental technique is described that is able to measure reaction cross-sections at energies around the Coulomb barrier by using low intensity beams and a Si detector as an active target. Set-up optimization was carefully investigated in terms of collimation, detector efficiency and pile-up rejection. The method has been tested by measuring the total reaction cross-section σ_R(E) for the ⁷Li+²⁸Si system in the energy range of E_lab=12-16 MeV. The deduced excitation function σ_R(E) agrees with the data obtained in a previous experiment. The presented technique can also be applied in order to determine total reaction cross-sections for low intensity radioactive beams at energies around the Coulomb barrier.

[en] We developed and tested a simple prototype of thermal neutron detector suitable for inexpensive deployment in the decommissioning and storage of radioactive waste, as well as for mapping the flux in the out-of-core regions of fission reactors. Though the prototype version we tested provides the neutron rate by subtracting the gamma background measured with a twin detector insensitive to neutrons, a simple geometrical improvement can strongly reduce the gamma contribution.