Thermal design of helium cooled divertor for reliable operation

Lee, Namkyu; Kim, Beom Seok; Kim, Tae‐Hwan; Bae, Ji yeul; Cho, Hyung Hee

doi:10.1016/j.applthermaleng.2016.09.062

Cited by 10 publications

(15 citation statements)

References 46 publications

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“…Tungsten (W) is a typical refractory metal with unique properties, such as high melting point (3410 °C), high density (19.3 g•cm −3 ), high thermal conductivity (173 W•m −1 •K −1 ) and low thermal expansion coefficient (4.5 × 10 -6 •K −1 ) [1]. Due to these combined properties, W has a wide range of applications in rocket engine nozzles, kinetic energy penetrators, cruise balance mass devices and plasma-facing materials (PFMs) for diverters in future fusion reactors [2][3][4][5]. However, W exhibits brittleness at low temperature because of its high ductile-to-brittle transition temperature (DBTT) (> 700 °C), which limits its manufacturing routes.…”

Section: Introductionmentioning

confidence: 99%

Selective laser melting high-performance ZrC-reinforced tungsten composites with tailored microstructure and suppressed cracking susceptibility

et al. 2021

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Selective laser melting (SLM) tungsten (W) constantly suffered from severe cracking phenomenon due to the high melting temperature and low intrinsic ductility of W material. To address this significant issue, active ZrC nanoparticles were introduced into the W matrix to form ZrC/W composites in situ by SLM to enhance the intrinsic toughness of W in this study. It mainly focused on the effect of ZrC nanoparticle on the microstructure and cracking behavior of SLM W. Compared to SLM W, SLM ZrC/W composites showed finer equiaxed grains rather than columnar grains, because the ZrC nanoparticles provided many heterogeneous nucleation sites. Furthermore, ZrC nanoparticles could react with oxygen impurity at the grain boundaries (GBs), and then form stable ZrO 2 and ZrW 2 O 8 to purify and improve the cohesion strength of GBs. The columnar to equiaxed transition (CET) of grains and purified GBs played an important role in inhibiting the formation and propagation of the cracks in SLM W. Therefore, SLM ZrC/W composites exhibited lower crack density and higher mechanical properties compared to SLM W. This study provides a novel approach for suppressing the cracking susceptibility of SLM W.

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Section: Introductionmentioning

confidence: 99%

Selective laser melting high-performance ZrC-reinforced tungsten composites with tailored microstructure and suppressed cracking susceptibility

et al. 2021

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“…Figure 1 shows the MAIJ of the divertor system in nuclear fusion reactors. A divertor unit cell with hexagonal shape consists of a tile, a thimble, and a cartridge [1,42]. The tile is made of tungsten, which has a high melting temperature (3422 • C) and a thermal conductivity of ~100 W/mK over 1000 • C. The width of the top surface was 17.8 mm, and the thickness ranged from 5 to 12 mm; the bottom of the tile had a concave shape.…”

Section: Geometry and Configuration Of Multi-array Impingement Jet Mo...mentioning

confidence: 99%

“…We determined the correlation as a function of the incident heat flux and heat generation by combining mathematical results with those of a simulation, for the comprehensive understanding of heat transfer characteristics. The domain range of heat generation rate and heat flux was 0 to 140 MW/m 3 and 4 to 12 MW/m 2 , respectively, on the basis of past research [1,42]. On the basis of previous work [42], we set the thermal design criteria, which are the maximum temperature of the thimble for relieving the difference of thermal expansion with respect to the tile, as shown in Figure 1, as well as the safety factor, considering thermal stress and yield strength in the divertor module.…”

Section: Introductionmentioning

confidence: 99%

“…The domain range of heat generation rate and heat flux was 0 to 140 MW/m 3 and 4 to 12 MW/m 2 , respectively, on the basis of past research [1,42]. On the basis of previous work [42], we set the thermal design criteria, which are the maximum temperature of the thimble for relieving the difference of thermal expansion with respect to the tile, as shown in Figure 1, as well as the safety factor, considering thermal stress and yield strength in the divertor module. From the results of the simulation, we analyzed the thermophysical behavior of the MAIJ by changing the incident heat flux and heat generation by neutron heating.…”

Section: Introductionmentioning

confidence: 99%

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Heat-Absorbing Capacity of High-Heat-Flux Components in Nuclear Fusion Reactors

Lee

Kim²,

Moon³

et al. 2019

Energies

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Nuclear fusion energy is a solution to the substitution of fossil fuels and the global energy deficit. However, among the several problems encountered for realizing a nuclear fusion reactor, the divertor presents difficulties due to the tremendous heat flux (~10 MW/m2) from high-temperature plasma. Also, neutrons produce additional heat (~17.5 MW/m3) from collisions with the materials’ atoms. This may lead to unexpected effects such as thermal failure. Thus, a comprehensive investigation on the divertor module is needed to determine the heat-absorbing capacity of the divertor module so to maintain the effect of incident heat flux. In this study, using an analytical approach and a simulation, the quantitative effect of heat generation on the thermophysical behavior, such as temperature and thermal stress, was analyzed while maintaining the incident heat flux. Then, a correlated equation was derived from the thermal design criteria, namely, the maximum thimble temperature and the safety factor at the vulnerable point. Finally, on the basis of the thermal design criteria, the heat-absorbing capacity of a nuclear fusion reactor in operating conditions was determined. This study contributes to the understanding of the divertor’s effects in nuclear fusion reactors for high-heat-flux and high-temperature applications.

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“…Tungsten (W), a rare metal with a high melting point of 3420 °C and high hardness, has been widely used in medical and military fields [1]. Besides, W is also a popular material for plasma-facing components and divertor in future nuclear fusion devices [2][3][4][5]. But due to its properties, such as high melting point, brittleness, and high ductile-to-brittle transition temperature, it is difficult to manufacture.…”

Section: Introductionmentioning

confidence: 99%

Selective laser melting of lanthanum oxide-reinforced tungsten composites: microstructure and mechanical properties

Wei

et al. 2021

Tungsten

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In this study, La 2 O 3 nanoparticles were introduced into the tungsten (W) matrix to optimize the microstructure and properties of pure W. The W-La 2 O 3 composites with different mass ratios of La 2 O 3 were manufactured by selective laser melting (SLM). The result showed that the average grain sizes for W-1 wt% La 2 O 3 and W-2 wt% La 2 O 3 were reduced by more than 51.3% compared with that of pure W, and the defects obviously decreased. The microhardness and compressive strength of the SLM W-2 wt% La 2 O 3 sample reached 455 HV and 2194 MPa, respectively. The toughness of the SLM W-2 wt% La 2 O 3 sample also improved significantly. One main reason was that the La 2 O 3 nanoparticles provide many heterogeneous nucleation sites to refine the grains. The other main reason was that La 2 O 3 nanoparticles formed into dislocation loops, which hindered the movement of dislocations and then increased the strength further. This research provided a new method to improve the mechanical properties of SLM W by introducing La 2 O 3 nanoparticles to achieve fine-grains strengthening and Orowan strengthening.

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Thermal design of helium cooled divertor for reliable operation

Cited by 10 publications

References 46 publications

Selective laser melting high-performance ZrC-reinforced tungsten composites with tailored microstructure and suppressed cracking susceptibility

Selective laser melting high-performance ZrC-reinforced tungsten composites with tailored microstructure and suppressed cracking susceptibility

Heat-Absorbing Capacity of High-Heat-Flux Components in Nuclear Fusion Reactors

Selective laser melting of lanthanum oxide-reinforced tungsten composites: microstructure and mechanical properties

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