POCO Type Graphite Radiation Damage of Spiral-2 Neutron Converter Assembly
J. Bermudez 1,2, G. Acosta 1,2, A. Udup 1,3, L. Tecchio 1, L. Sajo-Bohus 2*
1 INFN, Laboratori Nazionali di Legnaro, 35020 Legnaro, Italy
2 Nuclear Physics Laboratory, Universidad Simon Bolivar
3 Horia Hulubei National Institute of Physics and Engineering, Bucharest, Romania, University POLITEHNICA of Bucharest, Romania
In the framework of the collaboration to the construction of the Spiral 2 facility, at Ganil, (France), the Legnaro National Laboratory of INFN of Italy is contributing to the development and construction of the neutron converter assembly. Spiral 2 is a facility aimed to produce high intensity radioactive ion beams (RIB's)) based on fission of uranium nuclei. The fissions are induced by neutrons having a flux of 1x1012 neutrons/s/cm2. A primary beam constituted by deuterons of energy 40 MeV and current 5mA impinging on a graphite target so to provide the mentioned neutron flux. The Graphite target have been selected as the neutron converter material due to its low neutron absorption cross section and its mechanical stability at a relatively high temperature (1850°C), reached under operation conditions. Analysis of the mechanical and physical properties have been carried out over several commercially available brands of graphite to establish the radiation damage over its structure. Studies of this kind often are reported for a relatively low temperatures that does not provide sufficient informaation on its behaviour under operational conditions set by technical requirement of Spiral 2 facility. Calculations have shown that a 50 dpa damage per year induced by deuteron beam may occur, mainly concentrated in the Bragg region and without take into account annealing process. Considering that machanical stress and swelling can take place on the converter, an experimental evaluation would of of advantage. A previous study of radiation damage was done using protons as impinging particles. The results obtained suggest a new experiment using deuteron beam as impinging particles in order to evaluate graphite under conditions that is set for Spiral 2 operational conditions. In this study we present our results of radiation damage induced by deutron beam.
corresponding author: Judilka Bermudez