Zhang Le1，2， Zhao Ning1，2， Chu Haoran1，2， Zheng Bowen1，2， Chen Yunfa3，4
1.China Institute for Radiation Protection， Taiyuan 030006， China； 2.Shanxi Province Technology Innovation Center of Nuclear Facility Decommissioning and Radioactive Waste Management， Taiyuan 030006， China； 3.Institute of Process Engineering， Chinese Academy of Sciences， Beijing 100190， China； 4.University of Chinese Academy of Sciences， Beijing 100049， China
Abstract
Significance Controlled nuclear fusion， particularly magnetic confinement tokamak deuterium-tritium fusion， has attracted substantial scientific and technological interest worldwide as a promising approach to addressing global energy challenges and achieving carbon neutrality goals. It not only offers abundant fuel resources derived from seawater， but also features inherent safety advantages， negligible greenhouse gas emissions， and limited generation of long-lived high-level radioactive waste. Specifically， the construction of the International Thermonuclear Experimental Reactor （ITER） and the rapid development of Chinese devices such as EAST and HL-3 have created increasing demands for comprehensive safety assessment， operational reliability optimization， and radioactive waste management. Research on dust in fusion devices has been conducted for nearly four decades. The transition of tokamak devices from carbon-based to all-metal plasma-facing components （PFCs） and the construction of large-scale experimental facilities provide an ideal platform for in-depth investigation into dust generation， transport， and interaction mechanisms. Numerous studies have reported dust characterization in individual tokamaks based on post-shutdown sampling and post-mortem analysis. However， such fragmented studies cannot provide a unified understanding of dust behavior across different device configurations and operating conditions because they lack systematic cross-machine comparisons and real-time in situ measurements under the extreme high-temperature， high-vacuum， and high-radiation conditions inside fusion vacuum vessels. As an alternative， comprehensive review articles that integrate scattered experimental data， theoretical models， and safety assessments have become important tools for identifying research gaps and guiding future directions， thereby becoming an active research focus in the fusion safety community over the past decade.
Progress So far， the main dust generation mechanisms in magnetic confinement fusion devices， including plasma sputtering， deposition layer peeling， thermal splashing under abnormal plasma conditions， unipolar arcing， and gas-phase nucleation in edge plasmas， have been investigated. Sharpe et al. published a review on fusion dust， summarizing the early research results from JET and TFTR with carbon-based PFCs and reporting a dust median diameter of 0.76—100 μm and a tritium specific activity of up to 4.0×10¹⁰ Bq/g （Tab.1）. This marks the first systematic recognition of dust as a critical safety hazard that affects both operational performance and nuclear safety in fusion devices. Subsequently， different sampling techniques including vacuum sweeping， filter collection， and surface wiping have been applied in various tokamaks to investigate the influence of PFC materials， plasma parameters， and device geometry on dust properties. However， these early studies， limited by the carbon-based wall configurations characterized by extremely high dust production rates and severe tritium retention， cannot provide practical guidance for next-generation all-metal fusion reactors. The transition to metal-walled devices highlights the magnetic properties of metal dust and their profound implications for dust transport and collection （Fig.3）. Then， considerable efforts have been made to improve the understanding of dust-wall interaction mechanisms， including elastic-plastic collision dynamics， liquid metal droplet impacts， and hypervelocity impacts induced by runaway electrons. Ultra-high-resolution camera observations are used to capture three typical dust-wall collision trajectories and quantify energy dissipation coefficients under magnetized plasma conditions as shown in Fig.4（a）—（d）. Comprehensive characterization of dust generation in JET with the ITER-like wall （JET-ILW） demonstrates that the dust production rate decreases by two orders of magnitude compared to the previous carbon-based JET-C configuration， representing a major advance in source control of fusion dust. Subsequently， the cross-machine comparison approach is applied in multiple metal-walled devices to establish a universal database of dust properties.
Conclusions and Prospects The past four decades have witnessed significant progress in fusion device dust research， enabling the establishment of basic safety standards and dust inventory limits for ITER and other next-generation fusion reactors. Different mechanisms， including plasma sputtering， thermal splashing under edge-localized modes， and unipolar arcing， have been introduced into fusion safety analysis to demonstrate the source-term characteristics of radioactive dust. However， most existing studies have inherent limitations， such as heavy reliance on post-shutdown offline sampling， lack of real-time in situ monitoring data， and incomplete understanding of multi-field coupling evolution under extreme accident conditions. These limitations reduce the accuracy of probabilistic safety assessment and hinder the development of effective dust control and removal technologies as fusion devices move toward long-pulse， high-power operation， especially at the commercial reactor scale. Therefore， the development of integrated in situ dust monitoring systems and real-time active control strategies is expected to become an important direction for future research. In addition， the performance of current dust decontamination and treatment technologies remains insufficient to meet the stringent requirements of commercial fusion reactors and needs to be improved through the application of new materials and innovative designs. Parallel to the fundamental research on dust physics and plasma interactions， further extending the safety evaluation system to cover multi-component mixed dust and severe accident scenarios such as loss-of-coolant accident （LOCA） is also an important research direction.
Keywords： nuclear fusion； Tokamak device； radioactive dust； plasma； nuclear safety
Get Citation：Zhang Le， Zhao Ning， Chu Haoran， et al. Research progress on radioactive dust in magnetic confinement fusion devices［J］. China Powder Science and Technology， 2027， 33（1）： 1-14.
Received：2026-06-07， Revised： 2026-07-18， Online： 2026-09-08。
Funding： The research was supported by the National Key R&D Program of China (Grant No. 2022YFC3702800).
CLC No.：TL69； TB44
Type Code：A
Serial No.：1008-5548（2027）01-0001-14
