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Executive summary: Preliminary Regulatory Design Assessment – Fuel Design and Qualification of Clean Core Thorium Energy’s ANEEL Fuel Design

The Canadian Nuclear Safety Commission (CNSC) has completed a preliminary regulatory design assessment of Clean Core Thorium Energy LLC’s novel thoria-urania fuel pellet design – also called Advanced Nuclear Energy for Enriched Life (ANEEL) – for intended use in CANDU nuclear reactors.

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Clean Core Thorium Energy LLC (CCTE) is a U.S.-based company that is developing a novel thoria-urania fuel pellet design, which they have named ANEEL (Advanced Nuclear Energy for Enriched Life), for use in CANDU nuclear reactors. The proposed intent of the new fuel design is to create an inherently safer and more efficient fuel pellet/bundle that produces a smaller waste footprint and provides enhanced fuel burn-up while maintaining current geometries and operating characteristics for ease of retrofit.

The Canadian Nuclear Safety Commission (CNSC), as Canada’s nuclear regulator, under the authority of the Nuclear Safety and Control Act, entered into a service agreement with CCTE in March 2023 to conduct a preliminary regulatory design assessment of the CCTE fuel design. CNSC staff performed this assessment by modifying the documented approach for a vendor design review, which is described in REGDOC-3.5.4, Pre-Licensing Review of a Vendor’s Reactor Design, and selecting an applicable subset of focus areas for the assessment. REGDOC-2.5.2, Design of Reactor Facilities, served as the review criteria and is discussed further below.

A preliminary regulatory design assessment is an optional service that the CNSC provides at the request of a vendor. It is a high-level review of the vendor’s proposed technology and corporate structure against Canadian regulatory requirements and guidance. The intention is to provide early feedback to the vendor on matters relating to CNSC regulatory requirements and expectations, which can allow for early identification and resolution of potential regulatory or technical issues in the design and design process, particularly those that could result in significant changes to the design.

The assessment 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 the assessment do not bind or otherwise influence decisions made by the Commission. The CNSC’s licensing process for a proposed project would require a more detailed review of the design and safety case for a specific licence application at a specific site.

As stated in the service agreement, under the scope of this preliminary regulatory design assessment, CNSC staff were to provide:

  1. a general assessment of the proposed fuel design and qualification program to confirm that CCTE would be capable of demonstrating that its programs pertaining to nuclear fuel design and qualification could meet CNSC expectations, applicable regulatory documents, and applicable Canadian codes and standards
  2. regulatory information to CCTE relating to the regulatory process or the requirements associated with the licensing of novel fuel for use in a nuclear power plant facilityThis report outlines CNSC staff’s assessment process and their findings and conclusions.

This report outlines CNSC staff’s assessment process and their findings and conclusions.

Application of REGDOC-2.5.2

REGDOC-2.5.2, Design of Reactor Facilities, was written to be technology‑neutral, to the extent practicable, and applicable to a fulsome nuclear power plant design. It is recognized that vendors of specific technologies may present alternative technological approaches and methodologies. Those novel 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 other 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.

Preliminary regulatory design assessment results

The preliminary regulatory design assessment was carried out at the request of CCTE and was conducted over an approximately 6-month period. CCTE submitted documents relating to 9 applicable focus areas. CCTE also organized familiarization sessions, responded to requests for additional information, and provided technical clarifications through letters, emails and meetings.

Based on the documentation submitted, CNSC staff have concluded the following:

  • Overall, CCTE generally understands and has correctly interpreted the high-level intent of the CNSC’s regulatory requirements as applicable to fuel design and qualification.
  • Additional work will be required to address the technical clarifications and findings raised within this assessment should the use of this fuel design be pursued in a reactor in Canada.
  • The issues documented within this report are foreseen to be resolvable and will need to be followed up on in any future licensee application or review.
  • Any changes to the design would be expected to be documented and described in detail for any prospective future review and/or licensee application for use of the fuel design.

The following points are a summary of the findings and technical clarifications that will require additional follow-up in any future review.


  • The management system is not yet well documented to meet the regulatory requirements, with specific emphasis on the establishment of vendor management. There does not appear to be a system established to ensure that the “smart buyer” model is effective in its documented oversight of current work performed by contractors/partners.

Technical clarifications

  • Given the novelty of some of the design and safety features, in future assessments or licensee applications, information will be required to confirm:
    • the adequacy of the research and development activities to substantiate the fuel qualification program
    • the validation and verification of the capability of the software tools to model the reactor and to analyze the reactor behaviour under all operating modes
  • In several instances, owing to the unique fuel design characteristics of the ANEEL fuel, CCTE 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. CCTE has indicated that it intends to adequately justify the use of these alternative approaches, and it is expected that it will provide evidence that these alternative approaches will result in an equivalent or superior level of safety in future submissions.

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