High heat flux limits of the fusion reactor water-cooled first wall

Zácha, Pavel; Entler, Slavomír

doi:10.1016/j.net.2019.03.013

Cited by 11 publications

(5 citation statements)

References 23 publications

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“…However, heat loads will be more demanding in future commercial fusion reactors. Thus, power requirements are expected to increase [42] as faster flows would be needed to avoid overheating of LMs. If higher flow speeds during operation are desired, not only power requirements would increase, but attempting to thrust a flow with j × B-thrust could generate the same instabilities described in section 3.2.…”

Section: Power Requirements For the Implementation Of J × Bthrustmentioning

confidence: 99%

Experimental, numerical and analytical evaluation of j × B -thrust for fast-liquid-metal-flow divertor systems of nuclear fusion devices

Castro¹,

Fisher²,

Al-Salami³

et al. 2023

Nucl. Fusion

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Divertor systems of fusion devices exhaust intense heat loads from the plasma, which degrades solid plasma-facing components (PFCs). Fast liquid metal (LM) flow divertors may be more advantageous for this purpose. However, LMs have risk of piling due to intense magnetohydrodynamic (MHD) drag. Despite this, severe deceleration of the flow could be countered with the injection of currents that are transverse to external magnetic fields, allowing to thrust the flow with jxB forces. The injection of currents as an approach to propel LM-divertor flows has remained experimentally understudied. This article focuses on the evaluation of jxB-thrust and finding its drawbacks. This paper evidences that the simple operation of a LM-flow divertor with jxB-thrust, without any of the instabilities caused from reactor plasmas or parasitic currents, already presents intrinsic challenges.jxB-thrust was experimentally tested with free-surface-LM flows, a vertical magnetic field and and externally applied current. Experiments were reviewed with a theoretical model, showing agreement in the trends of theory and experiments. Full 3D-MHD-free-surface flow simulations were also performed with FreeMHD and confirmed the sensitivity to unstable flow behavior in LM systems when applying external currents. Furthermore, excessive power requirements are expected for the implementation of jxB-thrust at the reactor scale, making these systems inefficient for commercial devices.

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Section: Power Requirements For the Implementation Of J × Bthrustmentioning

confidence: 99%

Experimental, numerical and analytical evaluation of j × B -thrust for fast-liquid-metal-flow divertor systems of nuclear fusion devices

Castro¹,

Fisher²,

Al-Salami³

et al. 2023

Nucl. Fusion

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“…As is evident from these overplots, an SHPD device with major radius approximately 1/3 to 1/2 the major radius of an FPP will tend to have lower pressure and edge parallel heat flux and higher surface-average heat flux than an FPP. High core radiation fraction will likely be relied upon to reduce the divertor heat load, and given the challenges of managing steady-state firstwall heat fluxes exceeding 0.75-2 MW m −2 [49,50], lower-A and larger-R SHPD device configurations are better suited to matching FPP P heat /S values. Further, as discussed in section 2, FPP studies indicate that exploring aspect ratio range A = 1.9 to 2.3 could inform any potential confinement benefit or disadvantage relative to the Petty08 and/or ITER 98y2 projected confinement.…”

Section: Systems Studies Analysis For Shpdmentioning

confidence: 99%

Fusion pilot plant performance and the role of a sustained high power density tokamak

et al. 2022

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Recent U.S. fusion development strategy reports all recommend that the U.S. should pursue innovative science and technology to enable construction of a Fusion Pilot Plant (FPP) that produces net electricity from fusion at low capital cost. Compact tokamaks have been proposed as a means of potentially reducing the capital cost of a fusion pilot plant. However, compact steady-state tokamak FPPs face the challenge of integrating a high fraction of self-driven current with high core confinement, plasma pressure, and high divertor parallel heat flux. This integration is sufficiently challenging that a dedicated sustained-high-power-density (SHPD) tokamak facility is proposed by the U.S. community as the optimal way to close this integration gap. Performance projections for the steady-state tokamak FPP regime are presented and a preliminary SHPD device with substantial flexibility in lower aspect ratio (A=2-2.5), shaping, and divertor configuration to narrow gaps to a FPP is described.

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“…The latter is instead thought to assess the technical and economic benefits of a continuous hydrogen production from fusion electricity, in contrast to the uneven hydrogen production from over generation events. The option of hydrogen production from nuclear fusion heat is not considered here because of the temperatures required for the chemical process to happen (around 900°C in the sulphur-iodine cycle [21]), well above those of the coolants in fusion power plants (300-500°C) [22] that are indeed limited by technical requirements of the structural materials [23].…”

Section: Introductionmentioning

confidence: 99%

The Fusion to Hydrogen Option in a Carbon Free Energy System

Giuliani,

Agostini,

Bustreo

et al. 2023

IEEE Access

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To address climate change and keep the global temperature increase within 1.5°C above pre-industrial levels in the long term, ambitious climate policies are required. Achieving the decarbonization of all sectors of the economy implies a shift towards electrification. As a consequence, in order to generate high amount of carbon free electricity, the share of electricity generated by solar and wind power will considerably increase in the years to come. However, the inherent intermittency and variability of both solar and wind power require actions in order to increase the resilience and the flexibility of the power systems and assure the security of supply. To this scope, dispatchable capacity and energy storage systems acting on both short and long terms, will play a pivotal role. The paper discusses various scenarios developed with the COMESE code to investigate the affordability and viability of future possible carbon-free Italian power system configurations, based on both existing and under development energy technologies. The 100% renewable generation option is compared to "nuclear scenarios" where a relevant base-load generation is provided by nuclear fusion power plants. Also, besides the conventional storage systems based on electrochemical devices and pumped hydroelectricity, the deployment of long term storage systems based on hydrogen production, storage and utilization (power-to-hydrogen-to-power, P2H2P) is also investigated. Specifically, excess generation from renewables is used to power electrolysers for hydrogen production. The affordability of this option is evaluated in contrast to the "fusion to hydrogen" strategy, where a continuous hydrogen production for long term storage is provided by fusion electricity. The study proves that the average system cost of electricity of any least-cost 100% renewable power system configuration exceeds that of the corresponding alternative scenario with base-load generation from nuclear power plants. If available, P2H2P works along with batteries as short/medium term storage with benefits on the total system costs, that slightly lowers. Neither converting the whole excess energy into hydrogen in order to avoid curtailment nor operating fusion power plants for a continuous hydrogen production are cost-effective strategies. Indeed, the high costs of the large tank system required for storing hydrogen and the low overall efficiency of the P2H2P process are the primary challenge.INDEX TERMS Power system model, energy scenarios, nuclear fusion, system cost of electricity, hydrogen, P2H2P, renewable integration;

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High heat flux limits of the fusion reactor water-cooled first wall

Cited by 11 publications

References 23 publications

Experimental, numerical and analytical evaluation of j × B -thrust for fast-liquid-metal-flow divertor systems of nuclear fusion devices

Experimental, numerical and analytical evaluation of j × B -thrust for fast-liquid-metal-flow divertor systems of nuclear fusion devices

Fusion pilot plant performance and the role of a sustained high power density tokamak

The Fusion to Hydrogen Option in a Carbon Free Energy System

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