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Investigation of the effect of thermal cycle on SS/CRZ brazed joint sample
Published in B. Raneesh, Nandakumar Kalarikkal, Jemy James, Anju K. Nair, Plasma and Fusion Science, 2018
K. P. Singh, Alpesh Patel, Kedar Bhope, S. Belsare, Nikunj Patel, Prakash Mokaria, S. S. Khirwadkar
Development of the joining technique for the plasma facing material with structural material is one of challenging area in fusion research [1]. In ITER like tokamak first wall and divertor plasma facing component (PFC) module, SS/CuCrZr (CRZ) joining has the mandatory requirement of good in thermal transfer and sound in structural joints [1].
Fusion
Published in William J. Nuttall, Nuclear Renaissance, 2022
Recognising the possible lost opportunities in having two almost completely separate large-scale fusion research communities on the government payroll, policymakers in the United States have on occasion encouraged a greater level of dialogue between the magnetic and the inertial confinement communities. In 1990, the Fusion Policy Advisory Committee in the United States recommended that inertial and magnetic fusion research for energy production be pursued in parallel, but substantial communication between the two fusion communities did not get underway until 1999. The breakthrough was a 2-week meeting in Snowmass, Colorado, in July 1999 organised by Hermann Gründer and Michael Mauel. Participants were surprised by the level of common concerns encountered and by the extent to which they faced common challenges [62]. For instance, the magnetic confinement community was surprised to hear helpful suggestions from the inertial confinement community concerning the problems of materials stability in plasma-facing components (see Section IV.9.4). The inertial confinement researchers revived the idea that, rather than using solid materials such as graphite, the magnetic confinement community might consider a flowing liquid as the plasma-facing material—liquid lithium was especially recommended. This would cope much better with the bombardment by highly energetic particles, as the movement of the atoms of the liquid would immediately heal structural damage. Furthermore, such a blanket layer would have the benefit of producing tritium for the fusion reaction as a result of nuclear reactions between the fusion neutron flux and the lithium. Small-scale experiments regarding the use of liquid plasma-facing elements in MCF devices have yielded positive results [63]. Despite such past initiatives and experiments, the interactions between defence fusion-related research and MCF research have been consistently weak in both the United States and United Kingdom. Indeed in Europe, the role of Euratom in fusion research has strengthened the requirement that strict separation is maintained. The Brexit process required further consideration of a range of issues and the post-Brexit Nuclear Co-operation Agreement between the United Kingdom and Euratom states [64]: The items subject to this Agreement shall only be used for peaceful purposes and shall not be used for any nuclear weapon or nuclear explosive device, nor for research on or development of any nuclear weapon or other nuclear explosive device or for any military purpose. Article 1
Recent activities in the field of nuclear materials and nuclear fuels
Published in Journal of Nuclear Science and Technology, 2019
Naoyuki Hashimoto, Ken Kurosaki
As a plasma-facing material (PFM) in fusion reactors, W has been proposed due to its outstanding properties. However, the degradation of the material properties such as permeation of hydrogen isotopes through and their trapping in W is one of important issues [1–4]. In order to clarify the key issues, polycrystalline W plate was implanted with 80 keV H2+ ions at room temperature [5]. Isochronal annealing revealed two hydrogen release stages which might be associated with the reported activation energies. In addition, H2 blister formation was observed near the surface of the as-implanted W. The blister distribution remained unchanged after thermal annealing up to 600°C. It would be the critical issue for use of W as PFM. As a blanket materials, the investigation of MX precipitation behavior in the RAFM, F82H [6] revealed that the TaX (X: C and/or N) phase surely varied depending on the chemical composition of alloy and heat treatment; some TaX precipitates were unstable during tempering, MX precipitates were inter-granular, and sub-nano-metric MX were not found in the matrix.
First-Principles Study of Properties and Helium Behavior of Tungsten/Beryllium Interface Structure
Published in Fusion Science and Technology, 2023
Junjie Zhao, Zhaochun Zhang, Haibo Guo, Yang Wang
Tungsten is regarded as the most promising plasma-facing material because of its strong antisputtering ability and no reaction with hydrogen, and the adsorption amount of tritium is only one-tenth of that of graphite in carbon-based materials. In addition, tungsten can still maintain a certain mechanical strength under high-temperature conditions and conduct heat away from the surface.[10–12] However, tungsten will show significant brittleness, helium embitterment, and radiation swelling under low-temperature irradiation conditions.[13,14]
Predicting radiation damage in beryllium
Published in Philosophical Magazine, 2021
Due to its low absorption cross-section and high scattering cross-section, beryllium is used as a neutron reflector and in moderators in the nuclear industry [1,2]. It is also one of the primary choices as the plasma facing material in tokamak fusion reactors such as ITER [3]. In these applications, beryllium is subject to high flux neutron irradiation. This leads to displacement and transmutation of beryllium atoms [4], that is, radiation damage.