Nuclear data development at the European Spallation Source

TL;DR

This paper discusses the development and validation of nuclear data and computational tools at the European Spallation Source to improve neutronic design for various moderators and materials.

Contribution

It introduces new thermal scattering kernels for multiple materials and integrates software tools like NCrystal for nuclear data enhancement.

Findings

Development of thermal scattering kernels for moderator, reflector, and structural materials

New kernels for beryllium, nanodiamonds, liquid hydrogen, and deuterium

Use of NCrystal software to improve nuclear data modeling

Abstract

Transport calculations for neutronic design require accurate nuclear data and validated computational tools. In the Spallation Physics Group, at the European Spallation Source, we perform shielding and neutron beam calculations to help the deployment of the instrument suite for the current high brilliance (top) moderator, as well for the design of the high intensity bottom moderator, currently under study for the facility. This work includes providing the best available nuclear data in addition to improving models and tools when necessary. In this paper we present the status of these activities, which include a set of thermal scattering kernels for moderator, reflector, and structural materials, the development of new kernels for beryllium considering crystallite size effects, nanodiamonds, liquid hydrogen and deuterium based on path integral molecular dynamics, and the use of the software package NCrystal to assist the development of nuclear data in the framework of the new HighNESS project.