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Pre-Conceptual Design of the NIST Neutron Source



Dagistan Sahin, Osman Celikten, Jeremy Cook, Abdullah Weiss, Thomas Newton, David Diamond, Charles F. Majkrzak, Hubert King, Joy Shen, Anil Gurgen, Lap-Yan Cheng, Peter Kohut, Cihang Lu, Athi Varuttamaseni


The National Bureau of Standards Reactor (NBSR), a 20 MW thermal power Material Test Reactor (MTR), is located at the NIST Center for Neutron Research (NCNR), providing a safe and reliable neutron source for the thousands of visiting U.S. and international researchers annually. The NCNR has a long-standing reputation for scientific productivity, as measured by the abundance of scientific publications and research participants. The measurement facilities are perennially over-subscribed with a continually increasing demand from the scientific community. There are also increasing maintenance demands associated with aging NBSR reactor systems and components. A new state-of-the-art research reactor utilizing high assay low enriched uranium (HALEU), curved, MTR-type fuel plates, is being conceptualized. The proposed reactor is designated as the NIST Neutron Source (NNS). Eventually, the NNS will be constructed adjacent to the NCNR and replace the currently operational, but aging, NBSR. The NNS concept design is a light water-cooled pool-type compact reactor with a heavy water reflector to operate at 20 MW thermal power. The NNS core is primarily optimized to leak neutrons out of the core toward cold neutron sources and thermal neutron beams. This paper provides preconceptual design characteristics for the proposed NNS, a brief description of the user facilities, thermal neutron guides, cold neutron sources, cold neutron guide network, highlights of reactor core neutronics, and recent thermal-hydraulics analysis results. The initial neutronic analysis results imply a total cold neutron current gain at the guide entrances of about 10 when compared to the existing NBSR liquid hydrogen cold source, and at least a factor of two increase in the thermal neutron Maxwellian brightness with respect to the NBSR thermal beam tubes. At the initial startup (commissioning), the NNS would deliver measurement capabilities that are at least equivalent to those existing at the NBSR. However, once at full capacity, the new facility should provide significantly enhanced measurement capabilities, thereby substantially alleviating the current over-subscription of scientific instruments at the NCNR.
Conference Dates
April 16-20, 2023
Conference Location
Antwerp, BE
Conference Title
The European Research Reactor Conference


NNS, Nuclear, Reactor, Design, Neutron


Sahin, D. , Celikten, O. , Cook, J. , Weiss, A. , Newton, T. , Diamond, D. , Majkrzak, C. , King, H. , Shen, J. , Gurgen, A. , Cheng, L. , Kohut, P. , Lu, C. and Varuttamaseni, A. (2023), Pre-Conceptual Design of the NIST Neutron Source, The European Research Reactor Conference, Antwerp, BE, [online], (Accessed April 17, 2024)
Created April 16, 2023, Updated March 11, 2024