MYRRHA

MYRRHA. The Multipurpose Hybrid Research Reactor for High-tech Applications (MYRRHA) is a pioneering nuclear reactor and particle accelerator project under development at the SCK CEN nuclear research center in Mol, Belgium. It is designed as a world-first, large-scale accelerator-driven system (ADS), integrating a high-power linear accelerator with a lead-bismuth eutectic cooled subcritical reactor. This innovative configuration aims to demonstrate the feasibility of transmutation of long-lived radioactive waste, significantly advancing nuclear technology and materials research.

Overview

The MYRRHA project represents a major international endeavor in advanced nuclear energy research, spearheaded by the Belgian Nuclear Research Centre (SCK CEN). Its primary mission is to address one of the key challenges of the nuclear fuel cycle: the management of high-level nuclear waste, particularly minor actinides like americium and curium. By operating as a subcritical system driven by an external particle accelerator, MYRRHA offers enhanced safety features compared to conventional critical reactors. The facility is also conceived as a multipurpose research reactor, intended to produce radioisotopes for nuclear medicine, such as those used in cancer therapy, and to serve as a unique neutron source for fundamental research in fields like condensed matter physics.

Design and Technical Specifications

The core technological innovation of MYRRHA is its coupling of a high-power proton linear accelerator (linac) to a fast neutron spectrum reactor. The linac is designed to accelerate a proton beam to an energy of 600 million electronvolts (MeV) with a maximum current of 4 milliamperes (mA). This proton beam will be directed onto a spallation target made of liquid lead-bismuth eutectic (LBE), generating intense neutrons through spallation reactions. These neutrons will then sustain fission in the surrounding subcritical core, which is also cooled by circulating LBE. The reactor design incorporates advanced safety systems and is intended to demonstrate the viability of Generation IV reactor concepts, specifically the Lead-cooled fast reactor (LFR). Key components under development include the high-reliability superconducting radio-frequency cavities for the accelerator and corrosion-resistant materials for handling the LBE coolant.

Research and Development

The development of MYRRHA has involved extensive national and international collaboration, including partnerships with the European Organization for Nuclear Research (CERN), the European Commission through various Framework Programmes for Research and Technological Development, and numerous institutions within the European Union. Critical research and development phases have included the construction and operation of the GUINEVERE experiment, a zero-power ADS proof-of-concept at SCK CEN. Significant engineering challenges have been addressed through projects like the MAX laboratory, focusing on the accelerator front-end, and materials testing in facilities such as the BR2 reactor. The project has also spurred advancements in computational physics models for simulating neutronics and thermal-hydraulics in complex ADS configurations.

Applications and Scientific Goals

The primary application of MYRRHA is the demonstration of partitioning and transmutation (P&T) as a strategy for reducing the radiotoxicity and volume of long-lived high-level waste from conventional nuclear power plants. By transmuting minor actinides into shorter-lived fission products, the technology could reduce the required isolation time for waste in a geological repository from hundreds of thousands of years to a few centuries. Beyond waste management, MYRRHA will function as a versatile irradiation facility for testing advanced nuclear fuel and structural materials for next-generation reactors, including those for space propulsion. Its neutron beams will enable cutting-edge research in nuclear physics, radiobiology, and the study of condensed matter under extreme conditions, supporting a broad scientific community.

Project Status and Timeline

As of the early 2020s, the MYRRHA project is in an advanced design and preparatory construction phase. Following a positive decision by the Belgian federal government in 2018, the project entered the front-end engineering design stage. The construction of the first phase, which includes the full-power linear accelerator and a target station for radioisotope production, is planned to begin in the mid-2020s. The objective is to achieve first proton beam on target by approximately 2036, with the full ADS facility becoming operational in the late 2030s. The project's execution is managed through the MYRRHA vzw consortium, and it is considered a key pillar of the European Sustainable Nuclear Energy Technology Platform (SNETP) and its strategic research agenda.