Nuclear safety regulators in Canada and the US have completed their first collaborative project on licensing of SMRs. The Canadian Nuclear Safety Commission (CNSC) and the US Nuclear Regulatory Commission (NRC) have issued a joint report to provide feedback to X-energy on the manufacturing codes it proposes to use in both countries for the reactor pressure vessel of its Xe-100 design.

The report, which was issued yesterday, marks the first tangible result of a programme of cooperation the CNSC and NRC entered into on 15 August 2019, which supplemented an ongoing arrangement of more routine cooperation.

At the time, CNSC president Rumina Velshi said: "Globally, interest and advances in small modular and advanced reactors are growing rapidly. The CNSC and the US NRC are working together as regulatory leaders to ensure the development and deployment of these innovative technologies are done safely and efficiently."

In general, the cooperation agreement has allowed the CNSC and the NRC to take into account the results and insights produced by each others' technical reviews of reactor designs, without prejudicing any decisions they might make as independent licensing authorities in their respective countries.

In this first project, the regulators worked together to assess a white paper submitted to them by X-energy in July 2020. It concerned the construction codes the company would like to use for the reactor pressure vessel of its Xe-100 high temperature reactor design. X-energy proposed to design and analyse the reactor vessel to the requirements of a certain code issued by the American Society of Mechanical Engineers (ASME), but to fabricate it to the quality assurance and requirements of a different ASME code and stamp it as such. The full technical details are available in the joint report.

The CNSC and NRC jointly concluded this approach is "viable" provided X-energy includes certain "additional technical justification" as requested in the report and "addresses both regulators' observations" in the document. "The proposed approach could be used to establish criteria for the Xe-100 design and fabrication of the reactor pressure vessel," the regulators concluded. The CNSC emphasised that this is "informal" feedback which "does not result in any regulatory decision making."

The Xe-100 is an 80 MWe high temperature gas-cooled reactor to be built in packs of up to four. It is undergoing vendor design review with the CNSC, and is participating in the US Department of Energy's Advanced Reactor Demonstration Program. Xe-100 is proposed for construction at both Energy Northwest's Columbia power plant in Washington state and at Ontario Power Generation's Darlington power plant.