Examinations for leak tightness of actively cooled components in ITER and fusion devices

Hirai, T.; Barabash, V.; Carrat, R.; Chappuis, P.; Durocher, A.; Escourbiac, F.; Merola, M.; Raffray, R.; Worth, L.; Boscary, J.; Chantant, M.; Chuilon, B.; Guilhem, D.; Hatchressian, Jean-Claude; Hong, Suk–Ho; Kim, K. M.; Masuzaki, S.; Mogaki, K.; Nicolai, D.; Wilson, David J.; Yao, Damao

doi:10.1088/1402-4896/aa8bd4

Cited by 8 publications

(4 citation statements)

References 22 publications

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“…Regarding the integrity of welding, the leak test is vital in the FAT to ensure the critical functionality of the ITER VV. As a non-destructive test, the helium leak test was employed to determine the leak-tightness requirement of the material and surface of the VV [27][28][29]. While helium is applied as a tracer, differentiated pressure conditions are controlled inside and outside of the object to allow helium penetration into any conceivable cracks [29].…”

Section: Helium (Vacuum) Leak Testmentioning

confidence: 99%

Evaluation of the functional acceptability of the ITER vacuum vessel

et al. 2022

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The International Thermonuclear Experimental Reactor (ITER) vacuum vessel (VV) is one of the critical components of the ITER tokamak fusion reactor. The first sector of the ITER VV was delivered to ITER Organization in 2020, and it is ready to assemble into the tokamak system. After manufacturing the ITER VV, an evaluation should ensure that the components are designed and manufactured to meet the functional requirements, such as vacuum leak tightness and structural integrity. The factory acceptance test (FAT) is essential for confirming acceptance in engineering and manufacturing. This paper introduces the engineering process and technical method of the FAT, which is applied explicitly to the first-of-a-kind ITER VV. We establish a visual inspection, pre-pumping assessment, pressure test, helium (vacuum) leak test, and final dimensional inspection for the FAT. The visual inspection revealed no blockages in the cooling channels of the double walls. The pre-pumping assessment conducted to check the vacuum level and residual gas condition, concluded that the inside of the VV was flawless and thus met the leak test requirements of 1 × 10-8 Pa m3/s. We confirmed no leakage or deformation through the pressure test under reduced pressure. The helium leak test demonstrated engineering soundness with leak tightness of 6.08 × 10-9 Pa m3/s, which is more stringent than the allowable limit. Furthermore, three-dimensional metrology was utilized to determine the as-built dimensions of the manufactured sector. Due to unavoidable weld deformation and tight tolerances, the as-built result does not perfectly meet the assigned tolerance level. Nevertheless, it can be considered as advanced information for assembly with in-vessel components and other sectors. Based on the conformance and suitability of the suggested FAT for the first ITER VV sector, we will determine the acceptability of the upcoming VV sectors, which will be manufactured and delivered by Korea shortly.

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Section: Helium (Vacuum) Leak Testmentioning

confidence: 99%

Evaluation of the functional acceptability of the ITER vacuum vessel

et al. 2022

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“…Since the beam collides with the ion dumps, calorimeters, etc., there is a significant rise in temperature, and the temperature has a greater impact on the movement of gas molecules in the vacuum environment. Therefore, the temperature for the inner wall of the neutralizers, the inner wall of the ion dumps, the inner surface of the calorimeters, the inner wall of the bending magnets, and the surface of the gas baffle was set at 600 K. The temperature of the surfaces of the outer walls of the neutralization chamber, ion dumps, calorimeters, and bending magnets is 400 K [10][11][12].…”

Section: Simulation Parameter Settingmentioning

confidence: 99%

Vacuum System Optimization for EAST Neutral Beam Injector

et al. 2021

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The neutral beam injector (NBI) generates a high-energy ion beam and neutralizes it, and then relies on drift transmission to inject the formed neutral beam into the fusion plasma to increase the plasma temperature and drive the plasma current. In order to better cooperate with the Experimental Advanced Superconductive Tokamak (EAST), part of the Chinese major national scientific and technological infrastructure, in carrying out long-pulse high-parameter physics experiments of 400 s and above, this paper considers the optimization of the current design and operation of the NBI beam line with a pulse width of 100 s. Based on an upgraded and optimized NBI vacuum chamber and the structure of the beam-line components, the gas-source characteristics under the layout design of the NBI system are analyzed and an NBI vacuum system that meets relevant needs is designed. Using Molflow software to simulate the transport process of gas molecules in the vacuum chamber, the pressure gradient in the vacuum chamber and the heat-load distribution of the low-temperature condensation surface are obtained. The results show that when the NBI system is dynamically balanced, the pressure of each vacuum chamber section is lower than the set value, thus meeting the performance requirements for the NBI vacuum system and providing a basis for subsequent implementation of the NBI vacuum system upgrade using engineering.

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“…The coolant flow path in the divertor is described in detail in [31]. Water is first fed in parallel to the monoblocks of the OVT from the V-shaped corner formed with the ORP.…”

Section: A Heat Transfer Model For the Iter Plasma Facing Componentsmentioning

confidence: 99%

Effect of strike point displacements on the ITER tungsten divertor heat loads

et al. 2018

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The baseline ITER burning plasma equilibrium is designed to place the divertor strike points deep into the ‘V-shaped’ region formed by the high heat flux handling vertical targets (VT) and the reflector plates (RP). The divertor plasma performance under these conditions has been extensively studied in the past two decades with the SOLPS4.3 plasma boundary code suite. However, during tokamak operation, inaccuracies in the control of the vertical plasma position, or a requirement to avoid damaged monoblocks, could force the strike point position further down the VTs, or even directly on the RPs. In this paper, we present the results from the first SOLPS-ITER modelling in which the consequences of strike point displacements on the divertor plasma behaviour and surface heat loading are assessed. The starting point of the study is a baseline coupled fluid plasma-kinetic neutral solution (without fluid drifts), corresponding to an ITER burning plasma scenario at QDT = 10 with neon seeding for detachment control, PSOL = 100 MW, λq ~ 2 mm and nominal strike point positions. From this baseline condition, the equilibrium is progressively moved downwards in a series of rigid displacements, obtaining new steady-state solutions, up to a maximum displacement of ~8 cm, beyond which the separatrix is too close to the inner dome wing. At this point, the inner strike point is well onto the inner RP while the outer strike point is still on the VT. The different interaction of the recycled neutrals with the SOL plasma when the strike point intersects the inner RP, switching from vertical to horizontal target configuration, enhances the detachment degree at the inboard divertor, mitigating the heat load deposited onto the inner RP. At the outboard divertor the plasma condition is not significantly affected by the downward displacements, nor are the power fluxes to the outer RP. Finally, the heat load profiles computed with SOLPS are used in input for a finite element thermal analysis, considering the full cooling geometry, to assess the response of the VTs and RPs under the conditions exploited in the displaced scenarios. This thermal model, based on a simplified treatment not requiring a full 3D description of the divertor monoblock plasma-facing units, constitutes a new module for the SOLPS-ITER code suite.

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Examinations for leak tightness of actively cooled components in ITER and fusion devices

Cited by 8 publications

References 22 publications

Evaluation of the functional acceptability of the ITER vacuum vessel

Evaluation of the functional acceptability of the ITER vacuum vessel

Vacuum System Optimization for EAST Neutral Beam Injector

Effect of strike point displacements on the ITER tungsten divertor heat loads

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