Cross section measurement of 241Am(n,f) reaction at the Experimental Area 2 of the n_TOF facility at CERN: First Results

Abstract

The condition for the safe design and operation of fast neutron reactors and energy boosters (Generation-IV reactors, ADS systems [1]) is the accuracy of nuclear data. The ²⁴¹Am isotope (T_1/2 = 433 years) is highly present in nuclear waste, accounting for about 1.8% of the actinide mass in PWR UOx nuclear reactors’ waste [2]. In addition, the ²⁴¹Am isotope is further produced by the β decay of the ²⁴¹Pu isotope (T_1/2 = 14.3 years). Given the high production rate of ²⁴¹Am isotope, its incineration with concurrent energy production is considered to be of utmost importance for the design and implementation of the recycling of existing nuclear waste. Sensitivity studies of the proposed systems for energy production showed that high-precision measurements of the cross section of the ²⁴¹Am(n,f) reaction are required. In the present work, the ²⁴¹Am(n,f) reaction cross section was measured in the Second Experimental Area of the n_TOF facility at CERN, using an array of Micromegas detectors. For the measurement, six targets of ²⁴¹Am with average activity of 17 MBq per sample were coupled with an equal number of detectors in a common chamber. Additionally two ²³⁵U and two ²³⁸U samples were coupled with Micromegas detectors utilizing the neutron flux determination. Within this work, an overview of the experimental set-up and the adopted data analysis technique is presented along with preliminary results.