Phase 2 Pre-licensing vendor design review: ARC Clean Technology Canada

Executive summary

Background

ARC Clean Technology Canada (ARC) is designing the ARC-100, a 286-MWth (100-MWe) sodium-cooled reactor. On March 9, 2022, the Canadian Nuclear Safety Commission (CNSC), as Canada’s nuclear regulator under the authority of the Nuclear Safety and Control Act, entered into an agreement with ARC to conduct a Phase 2 pre-licensing vendor design review (VDR) of the ARC-100 reactor.

A VDR is an optional service that the CNSC can provide at the request of a vendor. It is a high-level review of the proposed reactor design and takes place during the design process while the design is still evolving. The VDR is intended to provide timely feedback to the vendor on matters related to CNSC regulatory requirements and expectations. This can allow for early identification and resolution of potential regulatory or technical issues in the design and the design process, particularly those that could result in significant changes to the design.

This service does not certify a reactor design, nor does it involve the issuance of a licence under the Nuclear Safety and Control Act. It is not required as part of the licensing process for a new nuclear reactor facility. The conclusions of a VDR do not bind or otherwise influence decisions made by the Commission, with whom the authority resides to issue licences for nuclear reactor facilities. The CNSC’s licensing processes will require a more detailed review of the design and safety case for a specific licence application at a specific site.

A Phase 2 VDR determines if the vendor’s reactor design and design processes meet CNSC regulatory requirements as the design is further developed and refined. This phase focuses on identifying if any potential fundamental barriers to licensing exist or are emerging. The VDR process is described in more detail in REGDOC-3.5.4, Pre-Licensing Review of a Vendor’s Reactor Design.

Phase 2 vendor design review results

The Phase 2 VDR was carried out at ARC’s request for the ARC-100 design. The design is currently in preliminary engineering phases, and certain details have yet to be finalized and confirmed to be ready for implementation. As a result, many of CNSC staff’s findings and technical clarification requests documented in this report relate to work that would need to be completed in order to confirm the implementation of certain aspects of the design or analysis.

This report outlines the CNSC staff review process, the assessment findings, and the conclusions of the review. Based on the documentation submitted, CNSC staff concluded the following:

• Overall, ARC understands and has correctly interpreted the high-level intent of the CNSC’s regulatory requirements for the design of reactor facilities in Canada.
• No fundamental barriers to licensing were identified at this time. The ARC-100 design requires further advancement in some areas for CNSC staff to confirm that it meets all the Canadian regulatory expectations within the scope of a Phase 2 VDR.
• ARC will be required to perform additional work to address the technical clarifications and findings raised in this review, should it or another proponent pursue future VDR work or licence application reviews.

The following is a summary of technical clarifications and findings that will require additional follow-up in any future review:

1. There is a need for extensive details on how human factors are being considered in the design, as the documentation submitted provides very little information in this regard.
2. Validation and verification of the software tools being used to assess the design must be demonstrated.
3. Analyses demonstrating the design’s robustness against malevolent acts must be performed.
4. Security features need to be designed and analyzed so that their effectiveness against threats can be determined.
5. There needs to be further demonstration of capability and effectiveness of the proposed means of reactor control and shutdown, and particularly, the reliance on inherent characteristics (overall negative reactivity coefficient). The negative coefficient will need to be verified for all conditions and circumstances to help support the proposed design for reactor shutdown.
6. The application of the single failure criterion for all safety analyses needs to be demonstrated.
7. The design of the direct reactor auxiliary cooling system (DRACS) and the reactor vessel auxiliary cooling system (RVACS) needs to be finalized, and the design requirements for those systems need to be identified.
8. A quality-assured fuel design system needs to be developed and demonstrated.

If this design is the subject of future VDR work or licence application reviews, the CNSC will follow up on the above-mentioned issues.