Phase 1 Pre-Licensing Vendor Design Review Executive Summary: SMR, LLC.

Executive Summary

Background

SMR LLC is designing a 160 MW(e) (525 MW(th)) light-water reactor, the SMR-160. 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 SMR LLC to conduct a Phase 1 pre-licensing vendor design review (VDR) of the SMR-160 light-water reactor design. The VDR process is described in regulatory document REGDOC-3.5.4, Pre-Licensing Review of a Vendor’s Reactor Design.

The VDR review is an optional service the CNSC provides at the request of a vendor. It is a high-level review of the proposed reactor technology’s conceptual design information against Canadian regulatory requirements and guidance. The service does not involve the issuance of a licence under the Nuclear Safety and Control Act and is not part of the licensing process. The conclusions of such a review do not bind or otherwise influence decisions made by the Commission. 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 1 VDR determines whether, at a general level, the vendor’s reactor design and design processes are demonstrating implementation of CNSC regulatory requirements. It is intended to provide early feedback to the vendor on matter relating to CNSC regulatory requirements and other expectations in the design. It can allow for early identification and resolution of potential regulatory or technical issues in the design process, particularly those that could result in significant changes to the design.

This Phase 1 report outlines the review process followed, the assessment findings and the conclusions of that review.

Application of REGDOC-2.5.2

Regulatory document REGDOC-2.5.2, Design of Reactor Facilities: Nuclear Power Plants, was written to be technology-neutral to the extent practicable. However, the document contains requirements and guidance that incorporate extensive operating experience from the use of water-cooled reactors. It is recognized that vendors of specific technologies may present alternative technological approaches and methodologies; however, alternative approaches remain subject to the same safety objectives, high-level safety concepts and safety management principles articulated in CNSC design and safety analysis documents such as REGDOC-2.5.2 and supporting documentation. Technical expertise, professional judgment and adequately documented processes can also be used to ensure that the application of, or departure from, regulatory requirements is objective and consistent so that the required level of safety is achieved.

Phase 1 vendor design review results

The SMR LLC Phase 1 VDR was carried out at the request of the vendor, over a 24-month period. SMR LLC submitted 130 documents and drawings broken up in five work packages to cover the 19 technical review focus areas, in addition to providing familiarization sessions, responses to requests for additional information, and technical clarifications through letters, emails, meetings, and teleconferences. Based on the documentation submitted, CNSC staff concluded the following:

• Overall, SMR LLC mostly understands and has correctly interpreted the high-level intent of the CNSC’s regulatory requirements for the design of nuclear power plants in Canada pertaining to the scope of the Phase 1 VDR.
• In some cases, owing to the unique characteristics of the design, SMR LLC is proposing alternative approaches and methodologies to address the underlying intent of CNSC regulatory requirements, in accordance with section 11 of REGDOC-2.5.2. SMR LLC has indicated that it intends to adequately justify the use of these alternative approaches, and understands that they will be expected to result in an equivalent or superior level of safety.
• Additional work is required by SMR LLC to address the findings raised as part of this review.

The following points are a summary of clarifications or findings that will require additional follow-up in a future review:

• A theme throughout the Phase 1 assessment was the selection of U.S. standards without a detailed comparison demonstrating that those selected standards will meet Canadian requirements during the design process. CNSC staff expect an explanation as to how design codes and standards are selected and how they either comply with or meet the intent of Canadian requirements.
• In accordance with the philosophy of early implementation of fire protection considerations, as described in CSA N293, CNSC staff expect to see a plan that describes how fire protection assessments are being incorporated into the design as it develops.
• While SMR LLC acknowledged a need to develop a probabilistic safety analysis (PSA), it indicated that several PSA and hazard assessment methodologies would not be prepared until a later date. These methodologies (such as those used to assess external events, combinations of events, internal fires, and floods) are needed both to evaluate the vendor’s understanding of CNSC requirements and to explain how the PSA results will be developed. These results are necessary to demonstrate that the design meets the established safety goals.
• Given the novelty of some of the SMR-160 design and safety features, additional information will be required to confirm:
• adequacy of the R&D activities to substantiate the fuel qualification program, including the role of a first-of-a-kind reactor
• application of the single-failure criterion to the control systems under all operating conditions
• adequacy of the shutdown means under all conditions, including scenarios where the main control room is lost
• applicability of selected design standards for containment structures
• application of research results in the development of the reactor design
• completeness of the R&D program to inform long-term reactor operation, including aging and maintenance of structures, systems and components.

Notwithstanding the above, these issues are foreseen to be resolvable and will be followed up on in future phases of the VDR.