Advanced Critical and Subcritical Measurements

Research Focus Areas: 3

Ph.D. Students: J. Arthur (Graduated)

Collaborators: R. Bahran (LANL)

measurement machine

Predictive simulations are key to the NNSA’s mission – including DNN (NA-22). Accurate knowledge of the expected outcomes of correlated neutron measurements is often necessary for nuclear nonproliferation and safeguards applications. Validated nuclear data and computational methods are in turn required for accurate knowledge of the expected outcomes of these measurements.

schematic diagram with blue background

This project, being conducted in collaboration with Los Alamos National Laboratory (LANL), focuses on advanced subcritical measurements for code and nuclear data validation. LANL has performed many subcritical measurements with bare and reflected BeRP ball configurations. Measurements on more complex systems, such as research reactors, are the next step in advanced subcritical experiments. The aim of the measurements to be completed over the years of this project is to cover novel energy ranges, multiplication ranges, materials, and neutron reactions, etc. Correlated neutron data from the measurements will be used to validate MCNP predictive simulation capabilities for more diverse subcritical configurations. Nuclear data validation will also help both identify deficiencies and quantify uncertainties in nuclear data related to neutron multiplication inference. This work is expanding upon LANL leadership in subcritical measurements and analysis, as well as predictive Monte Carlo radiation transport simulation capabilities.

The first measurement, the Critical and Subcritical Zero-Power Experiment at Rensselaer (CaSPER), was performed at the Reactor Critical Facility at Rensselaer Polytechnic Institute in July of 2016. Concurrently, both TMC and a comparison of the performance of various Monte Carlo codes taking into account the correlated physics of fission are being investigated as related sub-projects.

Related Conference Proceedings:

  1. J. Arthur, et. al, Comparison of the Performance of Various Correlated Fission Multiplicity Monte Carlo Codes. Las Vegas, NV: ANS Winter Meeting and Nuclear Technology Expo, 2016. LA-UR-16-28532.
  2. R. Bahran, et. al, Development of a Research Reactor Protocol for Neutron Multiplication Measurements. Las Vegas, NV: ANS Winter Meeting and Nuclear Technology Expo, 2016. LA-UR-16-28556.