Helned. Helium-3-free low-cost neutron detectors

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)