Transient Thermal Analyses of the MPEX Upstream Dump for Loss-of-Coolant Events

Vimal Ramanuj; Adam Aaron; Aftab Hussain

doi:10.1109/TPS.2026.3678114

Transient Thermal Analyses of the MPEX Upstream Dump for Loss-of-Coolant Events

Research output: Contribution to journal › Article › peer-review

Abstract

The Materials Plasma Exposure eXperiment (MPEX) is a facility enabling the study of the effects of fusion reactor-like plasma conditions on materials. The system experiences high heat flux primarily by radiation from the plasma, which makes the design of plasma-facing components (PFC) critical. Upstream dump is a heat exchanger intercepting the plasma, which is designed considering its thermo-mechanical stability under steady-state operation. In this work, we focus on the thermal response of the component in a loss-of-coolant event. Thermal analyses have been performed considering two major scenarios: 1) plug on the downstream side of the cooling system leading to loss of flow and 2) break in the inlet pipe resulting in pressure loss. The key objective of the analyses is to estimate the equilibrium state of the upstream dump and the response times under both these loss-of-coolant events. Multiphase computational fluid dynamics (CFD) simulations are performed to elucidate the coolant characteristics namely, its temperature and phase-change evolution to identify the limiting timescales in each event.

Original language	English
Pages (from-to)	2281-2288
Number of pages	8
Journal	IEEE Transactions on Plasma Science
Volume	54
Issue number	5
DOIs	https://doi.org/10.1109/TPS.2026.3678114
State	Published - May 1 2026

Funding

Received 28 August 2025; revised 26 January 2026; accepted 12 March 2026. Date of publication 14 April 2026; date of current version 12 May 2026. This work was supported by the Office of Fusion Energy Sciences through UT-Battelle, LLC, through U.S. Department of Energy (DOE) under Contract DE-AC05-00OR22725. The U.S. Government retains, and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this article, or allow others to do so, for U.S. Government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). The review of this article was arranged by Senior Editor E. Schamiloglu. (Corresponding author: Vimal Ramanuj.) The authors are with Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA (e-mail: [email protected]). Office of Fusion Energy Sciences through UT-Battelle, LLC, through U.S. Department of Energy (DOE) DE-AC05-00OR22725, U.S. Government retains, and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this article, or allow others to do so, for U.S. Government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan)

Keywords

Materials Plasma Exposure eXperiment (MPEX)
multiphase
thermal analyses
volume of fluid (VOF)

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10.1109/TPS.2026.3678114

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title = "Transient Thermal Analyses of the MPEX Upstream Dump for Loss-of-Coolant Events",

abstract = "The Materials Plasma Exposure eXperiment (MPEX) is a facility enabling the study of the effects of fusion reactor-like plasma conditions on materials. The system experiences high heat flux primarily by radiation from the plasma, which makes the design of plasma-facing components (PFC) critical. Upstream dump is a heat exchanger intercepting the plasma, which is designed considering its thermo-mechanical stability under steady-state operation. In this work, we focus on the thermal response of the component in a loss-of-coolant event. Thermal analyses have been performed considering two major scenarios: 1) plug on the downstream side of the cooling system leading to loss of flow and 2) break in the inlet pipe resulting in pressure loss. The key objective of the analyses is to estimate the equilibrium state of the upstream dump and the response times under both these loss-of-coolant events. Multiphase computational fluid dynamics (CFD) simulations are performed to elucidate the coolant characteristics namely, its temperature and phase-change evolution to identify the limiting timescales in each event.",

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author = "Vimal Ramanuj and Adam Aaron and Aftab Hussain",

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N2 - The Materials Plasma Exposure eXperiment (MPEX) is a facility enabling the study of the effects of fusion reactor-like plasma conditions on materials. The system experiences high heat flux primarily by radiation from the plasma, which makes the design of plasma-facing components (PFC) critical. Upstream dump is a heat exchanger intercepting the plasma, which is designed considering its thermo-mechanical stability under steady-state operation. In this work, we focus on the thermal response of the component in a loss-of-coolant event. Thermal analyses have been performed considering two major scenarios: 1) plug on the downstream side of the cooling system leading to loss of flow and 2) break in the inlet pipe resulting in pressure loss. The key objective of the analyses is to estimate the equilibrium state of the upstream dump and the response times under both these loss-of-coolant events. Multiphase computational fluid dynamics (CFD) simulations are performed to elucidate the coolant characteristics namely, its temperature and phase-change evolution to identify the limiting timescales in each event.

AB - The Materials Plasma Exposure eXperiment (MPEX) is a facility enabling the study of the effects of fusion reactor-like plasma conditions on materials. The system experiences high heat flux primarily by radiation from the plasma, which makes the design of plasma-facing components (PFC) critical. Upstream dump is a heat exchanger intercepting the plasma, which is designed considering its thermo-mechanical stability under steady-state operation. In this work, we focus on the thermal response of the component in a loss-of-coolant event. Thermal analyses have been performed considering two major scenarios: 1) plug on the downstream side of the cooling system leading to loss of flow and 2) break in the inlet pipe resulting in pressure loss. The key objective of the analyses is to estimate the equilibrium state of the upstream dump and the response times under both these loss-of-coolant events. Multiphase computational fluid dynamics (CFD) simulations are performed to elucidate the coolant characteristics namely, its temperature and phase-change evolution to identify the limiting timescales in each event.

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Transient Thermal Analyses of the MPEX Upstream Dump for Loss-of-Coolant Events

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