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2025 ANS Annual Conference
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Fusion Science and Technology
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Smarter waste strategies: Helping deliver on the promise of advanced nuclear
At COP28, held in Dubai in 2023, a clear consensus emerged: Nuclear energy must be a cornerstone of the global clean energy transition. With electricity demand projected to soar as we decarbonize not just power but also industry, transport, and heat, the case for new nuclear is compelling. More than 20 countries committed to tripling global nuclear capacity by 2050. In the United States alone, the Department of Energy forecasts that the country’s current nuclear capacity could more than triple, adding 200 GW of new nuclear to the existing 95 GW by mid-century.
Takashi Mutoh, Ryuhei Kumazawa, Tetsuo Seki, Fujio Simpo, Goro Nomura, Tsuyoshi Ido, Tetsuo Watari, Jean-Marie Noterdaeme, Yanping Zhao
Fusion Science and Technology | Volume 35 | Number 3 | May 1999 | Pages 297-308
Technical Paper | doi.org/10.13182/FST35-297
Articles are hosted by Taylor and Francis Online.
Steady-state ion cyclotron range of frequency (ICRF) heating technologies have been developed to heat plasma for >30 min in the Large Helical Device (LHD). Steady-state-operation tests of high voltages up to 40 kV0p for >30 min were carried out on radio-frequency (rf) vacuum feedthroughs and a coaxial transmission line in a test set. Four types of ceramic feedthroughs, each having a 240-mm diameter, were tested. Cone-type alumina ceramic and cylinder-type silicon nitride composite-ceramic feedthroughs produced good performances of 40 kV/30 min and 50 kV/10 s. The others had vacuum leaks when subjected to long-pulse duration. The temperature of the cone-type alumina ceramic feedthrough was measured during the ICRF operations. By using gas-cooling techniques, the temperature increase of the ceramic was substantially reduced and saturated within 20 min. Without any gas-cooling techniques, the temperature increased linearly and did not saturate. Therefore, this approach could not be used for steady-state operation. The rf dissipation on the ceramic was calculated using the ANSYS finite element computer code. It was found that damaged feedthroughs had local high heat spots, which could result in vacuum leaks. A 240-mm-diam water-cooled coaxial transmission line was designed and tested for steady-state operation. Specially designed connector components and Teflon insulator disks were tested. During the test operation, the insulation gases of nitrogen, sulfur hexafluoride, and carbon dioxide were used to compare their insulation capabilities for steady state. For the duration of a 10-s pulse, these gases performed well up to 60 kV0p. However, for steady-state operation, carbon dioxide gas could not withstand voltages >40 kV0p. The connector components of the transmission line performed without problems below 50 kV0p and 1 kA0p for 30-min steady-state operation. The performance of the feedthroughs and transmission line exceeded the specifications for steady-state heating in the LHD.
