View in EDS

An OpenMC model of the SPARC tokamak for the diagnostic scoping studies.

Saved in:
Bibliographic Details
Title: An OpenMC model of the SPARC tokamak for the diagnostic scoping studies.
Authors: Wang, X.1 (AUTHOR) wxinyan@mit.edu, Gocht, R.1,2 (AUTHOR), Ball, J.1 (AUTHOR), Mackie, S.1 (AUTHOR), Panontin, E.1 (AUTHOR), Peterson, E.1 (AUTHOR), Raj, P.1,2 (AUTHOR), Holmes, I.1,2 (AUTHOR), Saltos, A.A.1,2 (AUTHOR), Johnson, A.1,2 (AUTHOR), Grieve, A.1,2 (AUTHOR), Tinguely, R.A.1 (AUTHOR)
Source: Fusion Engineering & Design. Dec2025, Vol. 221, pN.PAG-N.PAG. 1p.
Subjects: Tokamaks, Neutron flux, Monte Carlo method, Diagnostic examinations, Neutron counters, Parametric modeling, Solid geometry
Abstract: This paper presents an OpenMC model for Monte Carlo neutronics simulations supporting the design scoping studies for various diagnostics for the SPARC tokamak. This constructive solid geometry (CSG) model uses realistic SPARC dimensions. Key components are modeled as a collection of homogenized cells of similar shapes with material composition preserved. A midplane port with a shielded opening, which allows a high flux of direct plasma neutrons reaching the tokamak hall and diagnostic hall neutron detectors, is modeled in greater detail for higher fidelity of neutron diagnostics simulations. The OpenMC model is verified with a CAD-based MCNP model for SPARC built by Commonwealth Fusion Systems, and it is found that the two models produce consistent tokamak hall neutron flux spectra. Compared to the CAD-based MCNP model, the CSG-based OpenMC model is easier to modify for parametric analyses to support rapid design iterations needed in a project like SPARC, which demands speedy engineering and physics design convergence. Multiple neutron diagnostics components are conceptualized and scoped using this model including the fast neutron collimators for the neutron camera and magnetic proton recoil neutron spectrometer, moderation and shielding for neutron flux monitors, and irradiation ends for the activation foil system. The uncollided neutron fluxes at detectors with collimated fields of view are verified using the optical code ToFu. The 14.1 MeV neutron peaks behind the collimators, which are planned to be 1–3 cm in diameter and 280 cm in length, are dominated by uncollided DT fusion neutrons. Activation foils have the best signal strength and uncollided/total neutron ratio at the plasma end of the foil channel in the port shielding. • A CSG-based OpenMC model is built based on realistic SPARC tokamak configurations. • CSG's flexibility allows easy scoping of SPARC neutron diagnostics. • The model is verified with a CAD-based MCNP model and the optical code ToFu. • SPARC's neutron diagnostics are scoped using the model. • 14.1 MeV neutrons peaks behind all collimators are dominated by uncollided neutrons. [ABSTRACT FROM AUTHOR]
Copyright of Fusion Engineering & Design is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
Description
Abstract:This paper presents an OpenMC model for Monte Carlo neutronics simulations supporting the design scoping studies for various diagnostics for the SPARC tokamak. This constructive solid geometry (CSG) model uses realistic SPARC dimensions. Key components are modeled as a collection of homogenized cells of similar shapes with material composition preserved. A midplane port with a shielded opening, which allows a high flux of direct plasma neutrons reaching the tokamak hall and diagnostic hall neutron detectors, is modeled in greater detail for higher fidelity of neutron diagnostics simulations. The OpenMC model is verified with a CAD-based MCNP model for SPARC built by Commonwealth Fusion Systems, and it is found that the two models produce consistent tokamak hall neutron flux spectra. Compared to the CAD-based MCNP model, the CSG-based OpenMC model is easier to modify for parametric analyses to support rapid design iterations needed in a project like SPARC, which demands speedy engineering and physics design convergence. Multiple neutron diagnostics components are conceptualized and scoped using this model including the fast neutron collimators for the neutron camera and magnetic proton recoil neutron spectrometer, moderation and shielding for neutron flux monitors, and irradiation ends for the activation foil system. The uncollided neutron fluxes at detectors with collimated fields of view are verified using the optical code ToFu. The 14.1 MeV neutron peaks behind the collimators, which are planned to be 1–3 cm in diameter and 280 cm in length, are dominated by uncollided DT fusion neutrons. Activation foils have the best signal strength and uncollided/total neutron ratio at the plasma end of the foil channel in the port shielding. • A CSG-based OpenMC model is built based on realistic SPARC tokamak configurations. • CSG's flexibility allows easy scoping of SPARC neutron diagnostics. • The model is verified with a CAD-based MCNP model and the optical code ToFu. • SPARC's neutron diagnostics are scoped using the model. • 14.1 MeV neutrons peaks behind all collimators are dominated by uncollided neutrons. [ABSTRACT FROM AUTHOR]
ISSN:09203796
DOI:10.1016/j.fusengdes.2025.115390