Zirconium Nuclear Data Campaign: Measurement of ⁹⁰Zr (n, γ) cross section

¹ Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
² Nuclear Physics Unit, EC-JRC-Geel, Retieseweg 111, 2440 Geel, Belgium

^* e-mail: brownjm@ornl.gov
^** e-mail: guberkh@ornl.gov

Published online: 26 May 2023

Abstract

The isotopes of Zr with A = [90, 91, 92, 94] make up more than 97% of naturally occurring Zr and are important to many nuclear applications such as nuclear reactors. One of the attractive qualities of naturally occurring Zr isotopes is that they have a low σ_γ/σ_t ratio at most neutron energies. Thus, they improve the neutron economy in reactors by preferentially scattering neutrons rather than absorbing them. This same quality also presents a challenge to measuring the capture cross section, σ_γ, of Zr isotopes. The ENDF/B-VIII.0 library has a relative uncertainty of approximately 10–20% for incident neutron energies < 0.1 MeV and an uncertainty greater than 20% for energies > 0.1 MeV for the majority of natural Zr isotopes. This motivated the Nuclear Criticality Safety Program to embark on a campaign to accurately measure and evaluate these Zr isotopes. In this work, we demonstrate energy-dependent neutron capture cross section measurements for the first enriched sample to be measured: ⁹⁰Zr.