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The agenda was as follows: Discussion of Agenda, membership, Winter Meeting ANS-8 Subcommittee Minutes, ISO TC85/SC5/WG8 Standards Activity Report - D. Bowen, Nuclear Criticality Safety Consensus Committee (NCSCC) Activity Report - L. Wetzel, Reports from Working Group Chairs, and Old/New Business.
This paper provides a high-level comparison between the international and domestic nuclear criticality safety (NCS) standards, as requested by members of the Nuclear Criticality Safety Division. Currently, there are 18 enacted American National Standards Institute (ANSI)/American National Standards (ANS) standards, and 1 ANSI/ANS standard, in progress. There are 11 NCS standards from the International Organization for Standardization (ISO), Technical Committee 85 (TC85) on Nuclear Energy, Subcommittee 5 (SC5) on Nuclear Fuel Cycle, Working Group 8 (WG8). NCS standard revisions are in progress for both standards organizations. The key differences between the ISO TC85/SC5/WG8 and ANSI/ANS-8 consensus NCS standards are summarized. The hard work done by the ANS-8 and WG8 volunteers allows for applicable, high-quality consensus standards for use by the NCS community. This paper defines the current status of each ANSI/ANS and ISO standard, the work in in progress, the revisions/amendments in progress, and WG8/ANS-8 non-standard business in progress. A forthcoming paper will compare the development process for ISO and ANSI/ANS standards.
Shift can run most KENO V.a and KENO-VI inputs, but beware of small geometry fudge factors. Shift is faster than KENO for fast spectrum systems, but has a higher uncertainty per particle. KENO FoM is higher for thermal systems. KENO V.a in MG is significantly faster than KENO V.a in CE, so this may exacerbate Shift difference. Shift generally has greater speedup for parallel calculations. Shift has only IFP available for TSUNAMI-3D, but parallel calculations are enabled.
Topics include: SGGP Array definition basics, what is meant by the "Inner" Boundary of an array, a critical experiment with flux filter, and NRC verification of criticality calculations with UNF-ST&DARDS.
VALID expansion is on-going and should provide coverage over a wider range of systems in the future. Adding additional application types beyond critical experiments can also be used in expanded data testing. Two other test suites have been developed at ORNL for other purposes, but never waste a good test suite. These suites are more likely to be relevant to testing differences in data as compared to assessing accuracy of evaluations.
Researchers noted an unusually large bias for 8-in. nickel reflected HEU sphere in HMF-003 between the 252- group library and the CE library in SCALE 6.2.4. The bias was investigated by reviewing reactions that $k_{eff}$ is sensitive to using TSUNAMI and collecting reaction rate data using tools within SCALE. For this system, bias is primarily due to the elastic scattering in nickel. Researchers compared new multigroup structures in SCALE 6.3. For this system, reduction in CE-to-MG bias seen in the 302-group and further improved in the 1597-group structure. When researchers compared ENDF/B-VIII.0 in SCALE 6.3, library showed improved results with new nickel evaluation. However, the MG-to-CE bias can still be large as large biases can occur in any system. This example highlights the importance of validating results with measured systems.
Abstract not provided.
Sufficient AGN-201M fuel plate material exists at Y-12 to support the development of a new, inherently safe, subcritical assembly for use in NCS training courses at ORNL. Four experiments with the ORNL subcritical assembly are possible and feasible. Future work includes the final design of the core and reflector and split table component design specifications. The ORNL Material Demonstration Facility (MDF) may be used to 3D print ORSA stand/table components and graphite reflector. Researchers will consider fuel coatings for contamination control, rather than an Al can. A visit to Y-12 will be made to determine the location of AGN fuel plates and remaining fuel transportation considerations. Final facility location will be considered
Limited, specific needs exist to support current reactor fleet and fuel cycle. Primarily, MOX experiments representative of low burnup LWR fuel are needed. LEU+ power distribution measurements may also be useful. Advanced reactors present many challenges and opportunities. New fuel forms and associated processes lack validation. Initial core criticality calculations can be validated with appropriate, highly similar experiments. Transportation of LEU+/HALEU material will be essential, and will rely on new experiments to support validation
Abstract not provided.
The history, development and application uses of Monte Carlo particle transport codes at LANL are extensive. Recent and ongoing investments in MCNP modernization are enabling new code developments using modern programming tools and languages. New and challenging applications continue to drive new research and developments beyond the rich set of established MCNP capabilities. The LANL MCNP radiation transport code has been the international gold standard for particle transport applications for over three decades.
VALID continues as a library of high-quality models used for testing SCALE and nuclear data. Recent expansion of VALID was the largest impactful change in a decade. Adding 233 U experiments circa 2017 added more cases. There are a huge number of cases in the pipeline, but a lack of qualified staff and funding to complete reviews. Future plans should simplify the process and increase the availability of models and results for external users.
This presentation provides an overview of ORNL work on the 30” cylinder, including information about the Oak Ridge Critical Experiments Facility (ORCEF) experiments.
Abstract not provided.
This presentation discusses the purpose of the criticality safety validation, decisions that were made during the validation exercise, the motivation that led to the creation of VADER, an explanation of USLSTATS, and an examination of VADER capabilities and interface.
This presentation discusses the programming languages TSUNAMI and TSAR. It also provides a review of experimental designs using sensitivity analysis in regard to 7uPCX fuel design, fission product experiment analysis, MIRTE, and temperature dependent experiments at the Sandia Pulsed Reactor Facility (SPRF).
The mission of the NCSP is to provide sustainable expert leadership, direction, and the technical infrastructure necessary to develop, maintain, and disseminate the essential technical tools, training, and data required to support safe, efficient fissionable material operations within the Department of Energy. The vision of the NCSP is a continually improving, adaptable, and transparent program that communicates and collaborates globally to incorporate technology, practices, and programs to be responsive to the essential technical needs of those responsible for developing, implementing, and maintaining nuclear criticality safety.
This report documents results obtained for revisions made to cases involving Highly Enriched Uranium (HEU), Intermediate Enriched Uranium (IEU), a mixture of Pu and Uranium (MIX), as well as Pu cases. A previous summary of revisions for HEU an Pu cases was reported and additional investigations into four cases originally presented therein uncovered further revisions which led to better agreement with other transport codes, those cases are updated in this report. The summary of all cases reported in Reference 2 is updated in this report. In addition, a previous summary of revisions for LEU and MIX was reported, a summary of those revisions in reproduced in this report for a comprehensive summary of changes to benchmarks beginning in fiscal year 2020 to current date. The report focuses on the changes made to LANL benchmarks modeled with MCNP6 using ENDF/B-VII.1 nuclear data that appeared to have discrepant results when compared with results of other codes. Feedback was used to pinpoint review of benchmark input files and to revise them when necessary. This report documents the results of review and revision of specific benchmarks highlighted as possibly discrepant in the comparison study. In addition, there is an effort tied to this work involving collaboration between LANL XCP and NCS Divisions in the development of a shared review/revision procedure and use of a new benchmark repository. LANL has a benchmark library of critical experiments from the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Handbook modeled for use with MCNP. This collection is now over 1100 benchmarks, referred to as the Whisper-1.1 library because it is used with the sensitivity/uncertainty package, Whisper, which supports nuclear criticality safety validation and is released with MCNP6.2. The collection, originally created several decades ago, is a combination of smaller collections, which has been revised and expanded, by various groups at LANL over the years. The original authors are no longer at the laboratory and little formal documentation of review and revision of these benchmarks exists today. A branch of the benchmark collection was already the subject of a formal review undertaken by the LANL NCS Division and expanded to include XCP Division.