MAESTRO: An ambitious experimental programme for the improvement of nuclear data of structural, detection, moderating and absorbing materials - First results for <sup>nat</sup>V, <sup>55</sup>Mn, <sup>59</sup>Co and <sup>103</sup>Rh

Abstract

The MAESTRO experimental programme has been designed to improve the nuclear data uncertainty on a large range of materials used for detection, absorption, moderation and structures in LWRs. Samples of high purity elements have been manufactured with severe constraints to reach a target accuracy of ±2% (1σ) on the measurement. Experiments are carried out in the MINERVE low-power facility between 2011 and 2014. Neutron activation and pile-oscillation techniques are used to provide complementary information on the capture and scattering cross sections through the measurement of isotopic capture rate and global reactivity-worth for each material. Preliminary results were obtained for <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nat</sup> V, <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">55</sup> Mn, and <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">59</sup> Co in support to the instrumentation of GEN-III reactors, just like for <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">103</sup> Rh due to its major contribution to the reactivity loss in LWR. They show that the JEFF-3.1.1 evaluations are in close agreement with the experiment, especially for <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">103</sup> Rh where consistent results were obtained from microscopic experiments at GELINA.