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National Criticality Experiments Research Center

NCERC is our nation’s only general-purpose critical experiments facility and is one of only a few that remain operational throughout the world

Located at the Nevada National Security Site (NNSS) and operated by the Los Alamos National Laboratory, the National Criticality Experiments Research Center (NCERC) provides a capability for conducting experiments using fissionable material. Experiments conducted at NCERC support many objectives, including training, R&D, and fundamental science. NCERC is our nation’s only general-purpose critical experiments facility and is one of only a few that remain operational throughout the world.

The mission of NCERC is to conduct experiments and training with critical assemblies and fissionable material at or near criticality in order to explore reactivity phenomena, and to operate the assemblies in the regions from subcritical through delayed critical. One critical assembly, Godiva-IV, is designed to operate above prompt critical.

NCERC has the equipment and expertise to conduct experiments on fissionable material at or near critical. This equipment includes 4 critical experiment machines. The capability was formerly housed at the Los Alamos Critical Experiments Facility.

  • Comet is a general purpose, vertical-lift critical assembly. It is used to conduct large size critical experiments. A nearly infinite variety of experiments can be conducted using Comet.

  • Planet is a general-purpose, vertical-lift critical assembly. With fissionable material, reflectors and interstitial materials loaded on a stationary platform and a moveable platen, Planet can be used to support a nearly infinite variety of experiments.

  • Flat-top is a spherical benchmark critical assembly. It is used for sample irradiations and for demonstrating criticality concepts.

  • Godiva IV is a burst assembly. NCERC has the ability to operate this assembly in the prompt critical regime. This assembly is used for sample irradiations, and to demonstrate criticality concepts.

  • Radiation test objects (RTOs) are subcritical configurations of nuclear material constructed by hand for the purposes of training, radiation measurements, providing information for the criticality safety community. The configurations vary in material type, mass, form, and geometry, resulting in a wide range of subcritical neutron multiplications (from near 1 to about 20).