F. Chartier

Incineration of 241Am induced by thermal neutrons

Abstract An experimental study of the 241Am incineration in a high-intensity thermal neutron flux was carried out at the high-flux reactor of the Institut Laue-Langevin in Grenoble. The combination of nuclear γ -ray spectroscopy and off-line mass spectrometry methods made possible the measurement of several parameters of the transmutation chain and the first experimental determination of the unknown 242gsAm thermal neutron capture cross section, which plays an essential role in the 241Am incineration process. During a 19 days irradiation in a thermal neutron flux of 5.6×10 14 n /( s cm 2 ) , (46±5) % of the initial 241Am was transmuted by neutron capture of which (22±8) % was incinerated by nuclear fission. A value of the thermal neutron cross section of 242gsAm( n ,γ ) of (330±50) barns was obtained. We show that this keeps the option open to incinerate 241Am by high-intensity moderated neutron fluxes.

Actinide Fission and Capture Cross Section measurements at ILL: the Mini‐INCA project

Fission cross section of short‐lived minor actinides is of prime importance for the incineration of minor actinides in high and thermal neutron fluxes. But due to the shortness of their half‐lives, measurements are difficult to handle on these isotopes and the existing data present some large discrepancies. An original method has been developed, in the framework of the Mini‐INCA project at ILL, to measure the fission and capture cross sections of minor actinides with low error bars associated even for short‐lived isotopes. This method lies on a quasi on‐line alpha‐ and gamma‐spectroscopy of irradiated samples and on the use of fission micro‐chambers. Coupled to a very powerful Monte‐Carlo simulation, both microscopic information on nuclear reactions (total and partial cross sections for neutron capture and/or fission reactions) and macroscopic information on transmutation and incineration potentials could be gathered. In this paper, the method is explained in its originality and some recent results are gi...

Transmutation of 241Am in a high thermal neutron flux

Amongst the minor actinides issued from the spent nuclear fuel, {sup 241}Am is present in high concentration and contributes significantly to the long-term radiotoxicity of nuclear waste. A major uncertainty was present in the transmutation chain of {sup 241}Am when irradiated by a high intensity thermal neutron flux. This uncertainty was brought about by the poor knowledge of the {sup 242gs}Am neutron capture cross section. A dedicated experiment has been performed at the Institut Laue-Langevin in Grenoble, which gives a definitive experimental answer to this problem.

The Minor Actinide Transmutation‐Incineration Potential Studies in High Intensity Neutron Fluxes

In the framework of nuclear waste transmutation studies, the Mini‐INCA project has been initiated at CEA/DSM with objectives to determine optimal conditions for transmutation and incineration of Minor Actinides (MA) in high intensity neutron fluxes. Our experimental tools based on alpha‐ and gamma‐spectroscopy of irradiated samples and the development of fission micro‐chambers could gather both microscopic information on nuclear reactions (total and partial cross sections for neutron capture and/or fission reactions) and macroscopic information on transmutation and incineration potentials. Cross sections of selected actinides (241Am, 242Am, 242Pu, 237Np, 238Np) have already been measured at ILL, showing some discrepancies when compared to evaluated data libraries but in overall good agreement with recent experimental data.