South Korea's KNR Systems Completes Development of Robotic System for PHWR Decommissioning

KNR Systems announced on August 31 that it has completed the development of a platform system for remote cutting and dismantling of radioactive structures in Pressurized Heavy Water Reactors (PHWR), with final delivery scheduled to commence in September this year.

The system originates from a government-commissioned PHWR decommissioning demonstration project. The project, valued at approximately 2.8 billion KRW, was awarded in January last year, with a development period of about seven months. Upon delivery, the equipment will be installed at the Heavy Water Reactor Decommissioning Technology Center of the Korea Research Institute of Decommissioning (KRID) in Gyeongju, for use in PHWR decommissioning demonstrations.

Compared with light water reactors, PHWRs have more complex internal structures and typically higher levels of radioactive contamination, making dismantling operations more difficult. Currently, there are still few demonstration cases of robotic systems for remote cutting and dismantling of commercial PHWR reactor core structures. The platform developed by KNR Systems is primarily intended for dismantling operations in reactor internal areas where personnel cannot easily access directly.

The complete system consists of four components: a horizontal dismantling system for precision cutting and extraction of reactor internal structures, a vertical dismantling system for dismantling large structures and transferring radioactive waste, a heavy lifting system for transporting dismantled materials, and a calandria structure dismantling system for removing structures surrounding the calandria vessel.

Among these, the core equipment is a heavy-duty dual-arm robot. Each robotic arm features a 7-degree-of-freedom design, with the equipment standing approximately 2.4 meters tall, a working radius of approximately 2.5 meters, and a maximum payload of 400 kg per arm. The company stated that the robot adopts a "superhumanoid" design philosophy, enabling fine movements similar to manual operations when handling large structural components.

The system's drive solution utilizes hydraulic precision control technology accumulated by KNR Systems over the past 25 years. The company noted that compared with electric motor drives, hydraulic drives can deliver higher power output per unit volume while reducing reliance on electronic components, making them better suited for nuclear facility decommissioning operations in extreme environments involving radiation, high temperatures, and dust.

The system also integrates intelligent hydraulic control and digital twin simulation technologies, featuring dustproof, waterproof, heat-resistant, seismic-resistant, and radiation-resistant capabilities, enabling precise remote control in underwater environments. KNR Systems plans to leverage this demonstration as a foundation to participate in domestic nuclear power plant decommissioning projects and further expand into overseas markets.

South Korea is advancing or studying controlled-area decommissioning of light water reactors and heavy water reactors, involving projects such as Kori Unit 1 and Wolsong Unit 1. In the long term, countries with PHWR operating experience, including Canada, Argentina, Romania, China, and India, are also regarded as potential markets for related decommissioning technologies.

Nuclear power plant decommissioning typically includes permanent shutdown, decommissioning plan approval, spent fuel removal, dismantlement of radioactive systems and structures, and site restoration. The robotic system developed this time is primarily used in the radioactive structure dismantlement phase, which is one of the technically challenging stages of the decommissioning process.

KNR Systems CEO Kim Myung-han stated that completing the development of nuclear power plant decommissioning robots within seven months using domestic technology demonstrates that the relevant robot design and control technologies can be applied to highly demanding working environments. The company is also developing other robots for extreme environments, including superhumanoid robots for heavy-duty operations and a 1-ton-class quadruped robot.