MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) the world’s first large scale Accelerator Driven System (ADS) that consists of a subcritical nuclear reactor driven by a high power linear accelerator, is a project built by SCK CEN (Belgium nuclear research center) in Belgium. This nuclear complex is scheduled to be commissioned in 2036 at Mol (Belgium).​​
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The phase 1 of this project, entitled MINERVA, consists in design and construct of the first 100 meters accelerator (Linac) section accelerating protons to an energy of 100 MeV. This Linac accelerator requires cryogenic cooling for the radio-frequency superconducting cavities. ​​
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The IRIG team ​was involved by SCK CEN first to design the cryogenic architecturere and then to carry out preliminary cryogenic studies and to define the requirements to design the 2 Kelvin cooling system for the MINERVA Linac superconducting accelerator cavities. The Linac will be composed of 30 cryomodules, including each 2 superconducting cavities made of bulk niobium and cooled by a saturated superfluid helium bath at 2 Kelvin. ​​
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The cryogenic system is a key component of the project. It includes the cryogenic plant, the cryogenic distribution and lines, and the valve boxes connected to the cryomodules containing the cavities. ​​
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​​Following preliminary and conceptual studies initiated in 2021, the IRIG team ​has written the specifications including more than 500 technical requirements for MINERVA cryogenic plant procurement. The cryogenic plant allows to provide superfluid helium at 2 K for cryomodules cooling, helium flow between 40 K and 60 K for the thermal shields and supercritical helium at 5 K for the cooling of the radio-frequency power couplers. ​​
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The power of this cryogenic plant for MINERVA will be around 3500 W equivalent at 4.5 K, consisting of 900 W at 2 K to cool the cavities, and 8600 W to maintain the thermal shields around 50 K. The flow rate of the helium compressors of the cryogenic system is estimated around 320 g/s, requiring about 1.2 MW of electrical power. A heat recovery system will equip the compressor cooling circuit of the MINERVA cryogenic plant (recovering over 90% of the electrical energy injected) and the recover heat will be used for the MINERVA buildings.
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Based on the IRIG technical specifications, the tendering phase for the procurement of this cryogenic plant, managed and financed by SCK CEN, is now open. ​IRIG, acting as expert and technical advisor, will be closely involved in all phases of the cryogenic plant's industrial construction: detailed design, manufacturing, installation and commissioning at the SCK CEN site at Mol, scheduled for 2028. A dedicated new 4-year contract has just been launched in April 2024, following the kick off meeting held on MYRRHA site. ​​
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​Other contracts for supporting MINERVA cryogenic system are under discussion with SCK CEN. In particular for the development and the implementation of a digital twin of the entire cryogenic system (including cryogenic distribution and cryomodules) in order to prepare commissioning and to optimize the cryogenic operation of the MINERVA accelerator, and training operators too.

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