Above: The main shield plug removed and replaced with a pre-cast concrete temporary shield plug in the 2010s


and constrained inside the reactor itself. Little if any consideration was given by the original reactor designers of the 1950s and 1960s as to how it would eventually be decommissioned.


The engineering design team had to solve the


intricate complexity of safely removing over 300 tonnes of radioactive material piece by piece to remotely decommission the reactor, manage the nuclear waste and progressing one of the UK’s oldest nuclear sites towards site restoration.


Pioneering innovation Safe, responsible and cost-effective disassembly of the Dragon reactor is a necessity if we are to prove the sustainability of nuclear fission as a power source of the future. Given the practicalities of both the accessibility and ambient radiation within the reactor itself, a first of a kind integrated, robotic solution was developed. The first problem to solve was how to physically get close enough to all of the reactor components to segment and remove them. The solution was a remotely-positionable, telescopic mast with a six degree of freedom robotic arm. The arm is capable of handling the weight of a small motorcycle whilst still having impressive dexterity and flexibility to enable manoeuvre within the tight confines of the core. The second part of the problem was how to practically


cut out and remove components made of various metals and of different geometries ranging in thickness from 2mm to 75mm. This is where the work at Dragon has been breaking new ground. Laser cutting is a well-established technology in the


manufacturing industry, but its application in nuclear decommissioning is relatively uncharted. However, when used remotely for reactor dismantling, it offers several


compelling advantages over traditional methods: ● Lower secondary waste compared to other hot cutting techniques


● Fast cutting speed ● Negligible recoil forces ● Very tolerant of stand-off distance from the workpiece ● Can cut through multiple material layers across air gaps


To harness these advantages, a laser cutting system was integrated with the primary core segmentation robot through a collaboration between NRS, Walischmiller GmbH, and TWI Ltd. This integration required extensive


Performing keyhole surgery The feasibility of using laser technology to cut the reactor core’s varying material types and thicknesses was initially tested on mock-up components at the Welding Institute, Cambridge. Further testing followed with a full-scale mock- up at the Winfrith site. Technical data and learning from these trials were then applied to perform keyhole surgery using a snake robot (Lasersnake) to remotely cut a three-tonne heat exchanger vessel known as the Purge Gas Pre-cooler (PGPC) from Dragon’s highly radioactive reactor core in 2018. This was a first for the UK nuclear industry and its success proved laser cutting as the principal technique for reactor core dismantling over the use of alternative hot cutting techniques. Phoebe Lynch, NRS strategic innovation programme


manager, said: “Driving innovation into our mission is our greatest opportunity at NRS. All the learning from the initial operational phase of using laser cutting for the Dragon reactor core provided valuable insights into the feasibility, reliability and safety of this technique. These have been applied to refine the process to deliver this new phase of reactor core dismantling efficiently and pave the way for its broader adoption within the industry.”


The reactor dismantling sequence The project has been divided into 11 distinct campaigns which individually deal with a different set of reactor components: cutting into the upper shield structures to reveal the core, removal of ‘lift out’ items, removal of graphite upper and lower reflectors, removal of steelwork structures, removal of the reactor pressure vessel and thermal shields. Each campaign has a plan covering the:


● Cutting and handling of each component and structure, including a detailed sequence of cuts to be made


● Handling arrangements ● Use of bespoke waste baskets to aid in waste transfer from and/or handling in the core


● Use of waste storage furniture to facilitate packing of waste into HHISO containers or 6m3


packing plans for each package being produced. www.neimagazine.com | October 2025 | 19 box, and detailed


expertise in both robotics and laser technology to be drawn in from the supply chain to ensure seamless operation in the challenging environment of the Dragon reactor.


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