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Modeling Approach for the Design of the NIST Neutron Source



Abdullah Weiss, Osman Celikten, Anil Gurgen, Joy Shen, Dagistan Sahin, Yaniv Shaposhnik


The NIST Neutron Source, or NNS, is a proposed new research reactor at the NIST Center for Neutron Research to replace the currently operational, but aging, National Bureau of Standards Reactor (NBSR). The NNS is currently in the pre-conceptual design stage, which heavily relies on modeling efforts to find an optimal design that fulfills the desired facility goals while ensuring safety and compliance with the United States Nuclear Regulatory Commission (NRC) requirements and other local codes and standards. This work outlines the adopted multi-physics modeling approach for the NNS, which focuses on safety, accuracy, and then simplicity. A paradigm is developed to guide decisions related to any modeling effort, where the safety focus is illustrated via diversified examples. A clear distinction is made between the safety engineering efforts and the regulatory compliance efforts, where the engineering efforts demand higher accuracy while the regulatory efforts favor simplicity and conservatism. This distinction is relevant when preparing the preliminary safety analysis report and provides a level of trust for the engineers proposing the design that goes beyond regulatory concerns. Discussions of the paradigm and the underlying verification & validation processes are the focus of this manuscript, providing a generalized look at the modeling approaches and how they are adopted towards the NNS design.
Conference Dates
April 16-20, 2023
Conference Location
Antwerp, BE
Conference Title
The European Research Reactor Conference


Nuclear, Modeling, Framework, Approach, Verification, Validation


Weiss, A. , Celikten, O. , Gurgen, A. , Shen, J. , Sahin, D. and Shaposhnik, Y. (2023), Modeling Approach for the Design of the NIST Neutron Source, The European Research Reactor Conference, Antwerp, BE, [online], (Accessed May 24, 2024)


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Created April 16, 2023, Updated March 11, 2024