Joint preparatory review for Thorizon One reactor

The Dutch Authority for Nuclear Safety and Radiation Protection (ANVS) and the French nuclear regulator Autorité de Sûreté Nucléaire (ASN) - together with the Institute for Radiological Protection and Nuclear Safety (IRSN), ASN's technical support organisation - have agreed to collaborate on a preparatory review of the Thorizon One. The review aims to understand the reactor's design and safety features, facilitating future licensing in both countries.

The review, Thorizon said, will take place through a series of joint technical meetings starting in the coming months to present the Thorizon One reactor simultaneously to both authorities ahead of pre-license applications expected at the same time in both countries in 2025.

This common preparatory review will aim at both understanding the specific design of this reactor, its safety approach and associated research and development programme, as well as defining the scope of the pre-license applications to ensure the assessment resources are focused on the most significant safety challenges of the Thorizon One reactor project. This is expected to increase the efficiency of the future pre-licensing applications in both countries.

"Thorizon is pleased to advance its molten salt reactor design," said Thorizon CEO Kiki Lauwers. "The early feedback from both nuclear regulators is invaluable for demonstrating the safety of the Thorizon One reactor. This multi-country cooperation will facilitate deploying the reactor in multiple countries in the future."

The company noted this project falls under the memorandum of understanding signed by ASN and ANVS in September last year aimed at collaborating on regulatory initiatives, including the licensing of nuclear installations such as small modular reactors (SMRs), and sharing experiences on new and innovative technologies.

Thorizon - a spin-off from NRG, which operates the High Flux Reactor in Petten - is developing a 250 MWt/100 MWe molten salt reactor (MSR), targeted at large industrial customers and utilities. Thorizon envisions the first MSR in Europe to be operational by 2032.

"Licensing is a critical path in this timeline, making early dialogues with regulators essential," Thorizon said. "To streamline the licensing process, Thorizon One plans to comply with existing safety regulations, use licensed materials and components, and work with experienced companies with prior nuclear licences."

MSRs use molten fluoride salts as primary coolant, at low pressure. They may operate with epithermal or fast neutron spectrums, and with a variety of fuels. Much of the interest today in reviving the MSR concept relates to using thorium (to breed fissile uranium-233), where an initial source of fissile material such as plutonium-239 needs to be provided.