Verification of MCNP6.2 with ENDF/B-VIII.0 Nuclear Data for Nuclear Criticality Safety Applications

The ANSI/ANS-8.1 standard, “Safety Standard for Operations with Fissionable Materials Outside Reactors,” has been available since 1964 as ASA N6.1-1964. In 1969, this standard was revised as ANSI N16.1-1969, “Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors.” This version of the standard includes a variety of subcritical limits (SCLs) for uniform aqueous solutions and metals containing fissile nuclides for 233U, 235U, and 239Pu. Furthermore, SCLs are also included for uranium-water lattices. In the 1983 version of ANSI/ANS-8.1 (a revision of ANSI N16.1-1975), the suite of SCLs in the standard expanded to include 235U enrichment limits for homogeneous uranium-water mixtures and dry/damp oxides, uniform aqueous solutions of low-enriched uranium, and uniform aqueous mixtures of Pu(NO3)4 containing 240Pu, in addition to the SCLs included in ANSI N16.1-1969. The SCLs have changed little in subsequent revisions (ANSI/ANS-8.1-1998 and ANSI/ANS-8.1-2014). The ANSI/ANS-8.1-2014 standard is currently being revised to include new SCLs (uranium metal and compounds with enrichments up to 20 wt. % 235U) and possible updates to the current SCLs already in the standard, although these SCLs will not be available to the nuclear criticality safety community for a number of years. The bases for these SCLs were documented in journal articles such as Nuclear Science and Engineering, and the American Nuclear Society’s meeting transactions; however, the bases were ambiguous enough that sites and regulators in the United States are reluctant to endorse them for safety purposes. The purpose of this paper is to present the results of a comparison study for the SCLs in the ANSI/ANS-8.1-2014 standard using modern codes and cross sections (SCALE/ENDF/B-VIII) to provide some assurance about their quality (bias and bias uncertainty) for use in nuclear criticality safety applications.

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Nuclear Data Measurements, Analysis and Evaluation at the Oak Ridge National Laboratory in Support of Nuclear Criticality Safety

Journal of Nuclear Science and Technology ◽

10.1080/00223131.2002.10875372 ◽

2002 ◽

Vol 39 (sup2) ◽

pp. 1422-1426 ◽

Cited By ~ 2

Author(s):

L.C. Leal ◽

H. Derrien ◽

N.M. Larson ◽

K.H. Guber ◽

T.E. Valentine ◽

...

Keyword(s):

National Laboratory ◽

Nuclear Data ◽

Oak Ridge ◽

Analysis And Evaluation ◽

Oak Ridge National Laboratory ◽

Nuclear Criticality Safety ◽

Criticality Safety

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Validation of Continuous-Energy ENDF/B-VIII.0 16O, 56Fe, and 63,65Cu Cross Sections for Nuclear Criticality Safety Applications

Nuclear Science and Engineering ◽

10.1080/00295639.2020.1830621 ◽

2020 ◽

pp. 1-25

Author(s):

Alex Shaw ◽

Farzad Rahnema ◽

Andrew Holcomb ◽

Doug Bowen

Keyword(s):

Cross Sections ◽

Continuous Energy ◽

Nuclear Criticality Safety ◽

Safety Applications ◽

Criticality Safety

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Contributions to integral nuclear data in ICSBEP and IRPhEP since ND2016

EPJ Web of Conferences ◽

10.1051/epjconf/202023918007 ◽

2020 ◽

Vol 239 ◽

pp. 18007

Author(s):

John Darrell Bess ◽

Tatiana Ivanova ◽

J. Blair Briggs

Keyword(s):

Spectral Characteristics ◽

Nuclear Data ◽

Nuclear Facilities ◽

Reactor Physics ◽

Benchmark Experiment ◽

Reactivity Coefficients ◽

Physics Experiment ◽

Safety Applications ◽

Evaluation Project ◽

Criticality Safety

The contributions to the International Criticality Safety Benchmark Evaluation Project (ICSBEP) and the International Reactor Physics Experiment Evaluation Project (IRPhEP) was last presented to the international nuclear data community at ND2016. Since ND2016, integral benchmark data that are available for nuclear data testing has continued to increase. The 2018 edition of the International Handbook of Evaluated Criti-cality Safety Benchmark Experiments (ICSBEP Handbook) now contains 574 evaluations with benchmark specifications for 4,916 critical, near-critical, or subcritical configurations, 45 criticality alarm placement/shielding configuration with multiple dose points apiece, and 215 configurations that have been categorized as fundamental physics measurements that are relevant to criticality safety applications. The 2018 edition of the International Handbook of Evaluated Reactor Physics Benchmark Experiments (IRPhEP Handbook) contains data from 159 different experimental series that were performed at 54 different nuclear facilities. Currently 156 of the 159 evaluations are published as approved benchmarks with the remaining three evaluations published as drafts. Measurements found in the IRPhEP Handbook include criticality, buckling and extrapolation length, spectral characteristics, reactivity effects, reactivity coefficients, kinetics, reaction-rate distributions, power distributions, isotopic compositions, and/or other miscellaneous types of measurements for various types of reactor systems. Additional benchmark evaluations will be included in the 2019 editions of these handbooks. These handbooks continue to represent the standard for neutronics benchmark experiment evaluation.

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National Criticality Experiments Research Center (NCERC) - capabilities and recent measurements

EPJ Web of Conferences ◽

10.1051/epjconf/202023918003 ◽

2020 ◽

Vol 239 ◽

pp. 18003

Author(s):

Nicholas Thompson ◽

Jesson Hutchinson ◽

Rian Bahran ◽

David Hayes ◽

William Myers ◽

...

Keyword(s):

Critical Mass ◽

National Laboratory ◽

Nuclear Data ◽

Intermediate Energy ◽

Natural Uranium ◽

Research Center ◽

Critical System ◽

Nuclear Criticality Safety ◽

Enriched Uranium ◽

Criticality Safety

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.

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