Abstract
The National Criticality Experiments Research Center (NCERC) located at the Device Assembly Facility (DAF) at the Nevada National Security Site (NNSS) and operated by Los Alamos National Laboratory (LANL) is home to four critical assemblies which are used to support of range of missions, including nuclear criticality safety and nuclear nonproliferation. Additionally, subcritical systems can also be assembled at NCERC. NCERC is providing critical and subcritical experiments valuable to the nuclear data community and experiments performed at NCERC are often published as benchmarks in the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Handbook. This manuscript will give a broad overview of recent experiments performed at NCERC, upcoming experiments, and why integral measurements are important and useful to the nuclear data community. The four critical assemblies are GODIVA IV, FLATTOP, COMET, and PLANET. GODIVA IV is a cylindrical metal fast burst reactor, the fourth in the GODIVA series that dates back to the 1950’s. FLATTOP is an highly enriched uranium (HEU) or Pu core reflected by natural uranium. COMET and PLANET are vertical lift assemblies, where one half of the reactor can be lifted to the upper half of the reactor to create a critical system. Some recent experiments include various critical intermediate energy assemblies with lead, and subcritical measurements of plutonium reflected by copper, tungsten, and nickel. Work is also underway to make a better measurement of the critical mass of neptunium, using a neptunium sphere surrounded by nickel shells. Additionally, measurements will be performed next year with HEU shells from Rocky Flats. These HEU shells will be stacked together to make larger systems, allowing for a large range of criticality (from subcritical to delayed critical). Other upcoming measurements include an HEU critical assembly sensitive to intermediate energy neutrons.
Highlights
Integral experiments are vitally important to many areas of nuclear engineering
National Criticality Experiments Research Center (NCERC) is operated by Los Alamos National Laboratory (LANL), and is located at the Device Assembly Facility (DAF) at the Nevada National Security Site (NNSS), previously known as the Nevada Test Site
LANL operated critical experiments in Los Alamos from 1946-2004; after 2004, the critical assemblies and materials were relocated to the DAF at NNSS
Summary
Integral experiments are vitally important to many areas of nuclear engineering. Criticality safety engineers use the data from integral experiments to refine reactivity estimates and calculate bias in their results [1]. NCERC is operated by Los Alamos National Laboratory (LANL), and is located at the Device Assembly Facility (DAF) at the Nevada National Security Site (NNSS), previously known as the Nevada Test Site. LANL operated critical experiments in Los Alamos from 1946-2004 ( known as the Critical Experiments Facility); after 2004, the critical assemblies and materials were relocated to the DAF at NNSS. Measurements performed at NCERC are regularly documented and published as critical benchmarks for the International Criticality Safety Benchmark Evaluation Project Handbook (ICSBEP) [2], allowing international use of these important data
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