Tokamak Energy's ST40 spherical tokamak, operating in a double null diverted configuration, has a design basis of toroidal field Bt = 3 T on-axis (R = 40 cm), and plasma current Ip = 2MA. The procurement and installation of the top and bottom divertors for installation into ST40 was anticipated to be completed on a quick timescale of approximately ten weeks. The difficulties inherent in a tight deadline were exacerbated by the necessary social distancing measures introduced to combat the global crisis of COVID-19. This paper describes the procurement and installation of the divertors, the design is described in the sister paper [1], authored by Daniel Iglesias.

The United Kingdom Atomic Energy Authority is involved in the design and manufacture of the diagnostic windows for ITER. ITER is an international project, with 35 nations collaborating to design, construct, and operate a prototype controlled nuclear fusion reactor in southern France. As well as providing line of sight for diagnostics, the windows also form part of the reactor primary containment boundary and are consequently classified as nuclear Safety Important Class 1 (SIC-1) components. The windows will be the first SIC-1 components in the world which are non-metallic. The current manufacturing process involves diffusion bonding a glass window to an Inconel 625 ferrule via an aluminium interlayer. This report discusses this diffusion bonding process and details the specific challenges related to component qualification for the intended nuclear SIC-1 application.

Most of ITER's diagnostics will be provided with viewing lines (optical, microwave, and spectroscopic) for the monitoring of key characteristics of the plasma or for the achievement of physical measurements inside the vacuum vessel. The nature of the physical signal transmitted through the viewing lines requires the implementation of window assemblies incorporating nonmetallic window. Placed at the vacuum boundary, the window assembly shall also ensure the vacuum integrity required for the plasma. Moreover, the diagnostic window assemblies form part of the ITER primary confinement boundary, and thus, directly related to the nuclear safety. This paper gives an overview of their design and related on-going engineering assessments by analysis or tests in the final design phase.

The effects of radiation damage on materials are strongly dependant on temperature, making it arguably the most significant parameter of concern in nuclear engineering. Owing to the challenges and expense of irradiating and testing materials, material property data is often limited to few irradiation conditions and material variants. A new technique has been developed which enables the investigation of radiation damage of samples subject to a thermal gradient, whereby a wealth of data over a range of irradiation temperatures is produced from a single irradiation experiment. The results produced are practically inaccessible by use of multiple conventional isothermal irradiations. We present a precipitation-hardened copper alloy (CuCrZr) case-study irradiated with a linear temperature gradient between 125 and 440 °C. Subsequent micro-scale post irradiation characterisation (nanoindentation, transmission electron microscopy and atom probe tomography) highlight the capability to observe mechanical and microstructural changes over a wide range of irradiation temperatures. We observed irradiation-softening in CuCrZr that did not occur due to irradiation-enhanced aging of the Cr-precipitates. Excellent reproducibility of the new technique was demonstrated and replicated irradiation-hardening data from several isothermal neutron irradiation studies. Our new technique provides this data at a fraction of the time and cost required by conventional irradiation experiments.

Ceramic components will be used for electrical insulation and optical transparency on the heating and diagnostic systems of fusion reactors. As these form the boundary for the radioactive confinement, a defined procedure is required to demonstrate structural integrity. The established design codes are incompatible with ceramic materials for various reasons, predominantly the brittle nature of ceramics. CCFE and others have started to develop an in-house design code for the use of brittle materials in pressure vessels, this paper discusses the rationale behind the rules. The difficulty of reconciling the statistical nature of failure in ceramics with the deterministic nature in codes is addressed and it is suggested that the only way to achieve this is by a proof testing approach. The inherent weakness of the proof testing methodology, quantifying the strength loss during the qualification test is discussed. Further work is required to determine the validity of the rules experimentally. Crown Copyright (C) 2017 Published by Elsevier B.V. All rights reserved.

Since 2015, within the scope of the Jules Horowitz Reactor (JHR) project a collaborative effort between CCFE in the UK and CEA in France has been undertaken to investigate concepts of test devices for the JHR suitable for the needs of fusion researchers. It is hoped that in having optimized experimental devices designed will facilitate use of the JHR by the fusion community. The project chose to focus on more instrumented test devices as it was felt that post-irradiation examination (PIE) type experiments at conventional temperatures could be undertaken with limited modifications to existing test devices. After internal exploration of the options, three potential test devices were identified; i) testing of ceramic functional materials; ii) testing at cryogenic temperatures; and iii) testing of thermo-mechanical fatigue. Each of these devices has been conceptually designed, demonstrating feasibility. This paper describes each of the conceptual designs at their current level of maturity. Future collaborative work planned between the two parties will aim to develop these devices further.

Embedded RF contacts are integrated within the ITER ICRH launcher to allow assembling, sliding and to lower the thermo-mechanical stress. They have to withstand a peak RF current up to 2.5 kA at 55 MHz in steady-state conditions, in the vacuum environment of the machine. The contacts have to sustain a temperature up to 250 degrees C during several days in baking operations and have to be reliable during the whole life of the launcher without degradation. The RF contacts are critical components for the launcher performance and intensive R&D is therefore required, since no RF contacts have so far been qualified at these specifications. In order to test and validate the anticipated RF contacts in operational conditions, CEA has prepared a test platform consisting of a steady-state vacuum pumped RF resonator. In collaboration with ITER Organization and the CYCLE consortium (CYclotron CLuster for Europe), an R&D program has been conducted to develop RF contacts that meet the ITER ICRH launcher specifications. A design proposed by CYCLE consortium, using brazed lamellas supported by a spring to improve thermal exchange efficiency while guaranteeing high contact force, was tested successfully in the T-resonator up to 1.7 kA during 1200 s, but failed for larger current values due to a degradation of the contacts. Details concerning the manufacturing of the brazed contacts on its titanium holder, the RF tests results performed on the resonator and the non-destructive tests analysis of the contacts are given in this paper. (C) 2015 Elsevier B.V. All rights reserved.