Neutronics simulations for the design of neutron flux monitors in SPARC
Name
083560_1_5.0219508.pdf
Description
Published version
Size
6.35 MB
Format
Adobe PDF
Checksum (MD5)
e40cf47280185499f5398fbbd5a5e870
Author(s)
Wang, X
Gocht, R
Ball, J
Mackie, S
Panontin, E
Tinguely, RA
Raj, P
Holmes, I
Saltos, AA
Johnson, A
Date Issued
August 30, 2024
Journal
Review of Scientific Instruments
Publisher
AIP Publishing
Citation
X. Wang, R. Gocht, J. Ball, S. Mackie, E. Panontin, R. A. Tinguely, P. Raj, I. Holmes, A. A. Saltos, A. Johnson, A. Grieve; Neutronics simulations for the design of neutron flux monitors in SPARC. Rev. Sci. Instrum. 1 August 2024; 95 (8): 083560.
Version
Final published version
Abstract
This paper presents the development and application of high-fidelity neutronic models of the SPARC tokamak for the design of neutron flux monitors (NFM) for application during plasma operations. NFMs measure the neutron flux in the tokamak hall, which is related to fusion power via calibration. We have explored Boron-10 gamma-compensated ionization chambers (ICs) and parallel-plate Uranium-238 fission chambers (FCs). We plan for all NFMs to be located by the wall in the tokamak hall and directly exposed to neutrons streaming through a shielded opening in a midplane port. Our simulations primarily use a constructive solid geometry-based OpenMC model based on the true SPARC geometry. The OpenMC model is benchmarked against a detailed CAD-based MCNP6 model. The B10 ICs are equipped with high-density polyethylene (HDPE) sleeves, borated HDPE housings, and borated aluminum covers to shield out scattered neutrons, optimize detector response levels, and make calibration robust against changes in the tokamak hall. The B10 neutron absorption branching ratio may cause the detectors’ responses to be non-linear to neutron flux >200 keV. However, our simulations unveil that, in the SPARC environment and with the proposed housings and sleeves, >99% of the detector responses are induced by <100 keV neutrons. U238’s insensitivity to slow neutrons makes this FC a promising candidate for direct fusion neutron measurements. Along with a borated HDPE sleeve, about 60% of the FCs’ responses are induced by direct neutrons.
MIT Department
Massachusetts Institute of Technology. Plasma Science and Fusion Center
Terms of Use
Creative Commons Attribution
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1063/5.0219508
