Résumé du preprint DAPNIA-07-180

DAPNIA-07-180
Neutronic characterization of the MEGAPIE target
S. Panebianco,O. Bringer, P. Bokov, S. Chabod, F. Chartier, E. Dupont, D. Dore, X. Ledoux, A. Letourneau, L. Oriol, A. Prevost, D. Ridikas, J.-C. Toussaint
The MEGAPIE project is one of the key experiments towards the feasibility 
of Accelerator Driven Systems. On-line operation and post-irradiation analysis 
will provide the scientific community with unique data on the behavior of a 
liquid spallation target under realistic irradiation conditions. A good neutronics 
performance of such a target is of primary importance towards an intense neutron 
source, where an extended liquid metal loop requires some dedicated verifications 
related to the delayed neutron activity of the irradiated PbBi. In this paper we report 
on the experimental characterization of the MEGAPIE neutronics in terms of the prompt 
neutron (PN) flux inside the target and the delayed neutron (DN) flux on the top of it. 
For the PN measurements, a complex detector, made of 8 microscopic fission chambers, 
has been built and installed in the central part of the target to measure the absolute 
neutron flux and its spatial distribution. Moreover, integral information on the neutron 
energy distribution as a function of the position along the beam axis could be extracted, 
providing integral constraints on the neutron production models implemented in transport 
codes such as MCNPX. For the DN measurement, we used a standard 3He counter and 
we acquired data during the start-up phase of the target irradiation in order to take 
sufficient statistics at variable beam power. Experimental results obtained on the PN flux 
characteristics and their comparison with MCNPX simulations are presented, together 
with a preliminary analysis of the DN decay time spectrum.

 

Retour en haut