REACTOR TECHNOLOGY | FUSION


Above: ITER achieved a recent milestone lifting the first section of the vacuum chamber into place Photo credit: ITER


V More recently, in July Japan’s Mitsubishi Heavy Industries Ltd (MHI) delivered testing equipment that is to confirm and demonstrate the safety of the Test Blanket Module (TBM) for ITER. The blanket is one of the components that comprises the inner wall of the fusion reactor. It is a critical component that extracts the heat generated by the reactor, as well as providing for the self- sustaining breeding of tritium used as fuel. Designed to prove the feasibility of fusion technology,


construction on ITER first began in 2010 and the initial first plasma was targeted for 2018. ITER is not expected to generate electricity and the unique 35-nation international project was widely expected to hit delays during its development. ITER is nonetheless more than 75% complete and over the last two years components have continued to arrive at the site. Each member has completed first-of-a- kind components that have required engineering innovation in fields as diverse as materials science, electromagnetism, cryogenics and robotics.


Beyond ITER Looking to the next generation of fusion technology, the UK Atomic Energy Authority (UKAEA) has developed a laser-welding robot snake capable of operating inside the pipework of a fusion power plant. The patented DEMO snake will be remotely operated inside the hazardous environments within fusion reactors working in pipes with limited access. The project also required the development of an ultrasonic sensor-system to identify each precise working location as the snake moves through the pipework. The £2.7m (US$2.5m), seven-year project came under


UKAEA’s Remote Applications in Challenging Environments programme (RACE) as part of EUROfusion’s DEMO fusion programme. This is expected to be successor to the ITER project. “In fusion machines, pipework has to be connected and disconnected remotely because of the hazardous environment. Pipework in DEMO is extra challenging


24 | August 2022 | www.neimagazine.com


because of the limited working space,” explained Tristan Tremethick, Lead Mechanical Design Engineer at UKAEA. “Robots are a key part of our mission to deliver low


carbon fusion energy, and we need to become skilled in controlling machines like this one remotely. That’s because they will be used to maintain fusion energy power plants. We won’t be able to send people in, robots will keep them running – it’s the future,” Tremethick added. RACE has also developed a laser cutting tool operating on


the same principles as the welding snake. Elsewhere in the UK, Cerberus Nuclear and Assystem are developing the in-board shield design for the Spherical Tokamak for Energy Production (STEP) reactor, the UKAEA’s prototype fusion plant. The project concerns the extreme environment within


the central column of the STEP fusion reactor where temperatures can range from over 100 million °C in the plasma to below -200°C in the superconducting magnet cryogenic system over the space of just a few metres. Cerberus Nuclear and Assystem are to develop radiation shielding and cooling strategies within the in-board shield section of the central column to protect the sensitive toroidal magnets. Cerberus aims to optimise the shielding in order to maximise the operational life of these components. A concept reactor design is anticipated by 2024 with first


operations expected in the early 2040s. A development site is due to be selected this year from five shortlisted locations across the UK. Systems, engineering and technology consultancy, Frazer-


Nash has undertaken a viability study for the UKAEA into a hydrogen isotopic separation technique, also as part of the STEP programme. The so-called viability and optioneering study will


explore a technique known as a Thermal Cycle Absorption Process (TCAP) for separating and recycling protium, deuterium and tritium.


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