JRC-Romania collaboration improves nuclear data for lead-based accelerator driven systems and lead shielding

GAINS germanium detectors measuring gammas from neutron inelastic scattering © EU, 2015

In close collaboration with researchers from Romania the JRC- Institute for Reference Materials and Measurements (IRMM) has obtained new results characterising the interaction of neutrons with lead. This was achieved using the electron linear accelerator (GELINA) of the JRC-IRMM.

The outcome of this research study is an important step towards high-performance predictions of lead and lead-bismuth cooled nuclear reactor systems and the shielding they require. A well-known example is MYRRHA, a multifunctional irradiation facility, which is under design at the Belgian research centre SCK•CEN and is an essential precursor for systems geared towards the elimination of high-level nuclear waste.

At the JRC the Germanium Array for Inelastic Neutron Scattering (GAINS) was used to determine cross sections for 206Pb by gamma-ray measurements with the neutron time-of-flight technique at an unprecedented small uncertainty of 3%. GAINS currently combines twelve high-purity germanium detectors with a neutron flight distance of 200m allowing both excellent selectivity and neutron energy resolution. The array was built with many contributions from Romanian scientists to the installation of the hardware and the software for data-acquisition and analysis.

Present-day uncertainties of neutron inelastic scattering on important nuclides of reactor materials are major contributors to uncertainties of reactor criticality and power distribution estimates. Reducing uncertainties for such important nuclear data to a level allowing accurate predictions with a minimum of dedicated expensive tests, mock-ups and prototypes is an important driver for nuclear data research.

Read more in: A. Negret et al.: “Cross section measurements for neutron inelastic scattering and the (n,2nγ) reaction on 206Pb”, Physical Review C vol. 91, p. 064618 (2015), doi: 10.1103/PhysRevC.91.064618.