Cerberus, Assystem to design STEP shielding

12 April 2022

Cerberus Nuclear and Assystem have been selected to deliver the Spherical Tokamak for Energy Production (STEP) reactor in-board shield design as part of the STEP Engineering Framework. STEP will be the UK's prototype fusion energy power plant.

A cutaway of the STEP reactor building (Image: UKAEA)

The project concerns the extreme environment within the central column of the STEP fusion reactor, where temperatures can range from over 100 million degrees Celsius within the plasma to less than -200 degrees within just a few metres.

Cerberus Nuclear and Assystem are working closely with the STEP research team at UK Atomic Energy Agency (UKAEA) - which carries out fusion energy research on behalf of the government - to develop radiation shielding and cooling strategies within the in-board shield section of the central column.

The overall aim is to protect the sensitive toroidal magnets within the central column that work to contain the high-temperature plasma. Cerberus' role involves optimisation of the shielding to maximise the operational lifetime of these crucial reactor components. Using its knowledge and expertise in neutronics transport, as well as interaction cross sections, the Warrington-based company will be simulating a wide variety of arrangements to support continued development.

"We are pleased to be working alongside Cerberus Nuclear on this key aspect of STEP. Collectively we will pool the engineering and design expertise, and specialist knowledge needed to ensure success in this project," said Assystem Transitional Energy Business Manager Gary Reed. "Assystem is a well-established fusion engineering company working on multiple international projects, and we are invested in the UK's ambition to accelerate progress in the development of this game-changing technology."

"Cerberus is very proud to be contributing to such a noteworthy project with worldwide importance," added Cerberus Nuclear Director Daniel Cork. "The skills and experience we have in-house regarding radiation shielding is uniquely suited to support the project. Working closely with our colleagues at Assystem we look forward to the challenge of what will be a highly significant and exciting project."

The aim for the first phase of work on STEP is to produce a concept design by 2024. The next phase will include detailed engineering design, while all relevant permissions and consents to build the prototype are sought. The final phase is construction, with operations targeted to begin around 2040. The aim is to have a fully evolved design and approval to build by 2032, enabling construction to begin.

In December 2020, the UK government called on local communities across the country to put forward proposals to host STEP. Communities had until the end of March 2021 to submit their nominations and were required to demonstrate that their local area has the right mix of social, commercial and technical conditions to host the new plant - such as adequate land conditions, grid connection and water supply.

In October last year, UKAEA announced that five sites - one in Scotland and four in England - have been shortlisted to host STEP. These are: Ardeer in North Ayrshire; Goole in East Riding of Yorkshire; Moorside in Cumbria; Ratcliffe-on-Soar in Nottinghamshire; and the so-called 'Severn Edge' bid from South Gloucestershire and Gloucestershire.

On conclusion of its assessment, UKAEA will make a recommendation to the Secretary of State for Business, Energy and Industrial Strategy with the successful site announced around the end of 2022.

Researched and written by World Nuclear News