Oklo made history with the development of the first advanced fission combined license application to the U.S. Nuclear Regulatory Commission (NRC).

Oklo has the longest continuous formal regulatory engagement of any advanced reactor (non-light-water reactor) company and is on track to bring its first plant online before the end of the decade.

U.S. Nuclear Regulatory Commission Licensing Pathways

Background

The NRC offers various licensing pathways for advanced fission facilities. While there are several options available, two pathways have been predominantly used in the past. These pathways are known as the "Part 50" and the "Part 52."

Overall of the U.S. licensing process

Table 1‑1: Summary of reactor licenses, permits, and certificates

NRC license, permit, or certification

CFR Part

Year of initialization

Date of last issuance

Construction permit

10 CFR Part 50

1956

1/27/1978

Operating license

10 CFR Part 50

1956

10/22/2015

Combined operating license

10 CFR Part 52

1989

4/12/2018

Design certification

10 CFR Part 52

1989

10/15/2014

Early site permit

10 CFR Part 52

1989

12/19/2020

10 CFR Part 50

The Part 50 approach, described in Title 10 to the Code of Federal Regulations (10 CFR) Part 50, is a two-step licensing process. It requires the issuance of a construction permit followed by an operating license.

Construction permit

The first step involves filing and obtaining a construction permit, which grants permission for the construction of a nuclear power plant. The application for a construction permit includes a safety analysis report, design information, criteria, comprehensive site data, and assessments of environmental impact and antitrust considerations.

Operating license

After the construction permit is obtained, the next step is to file for an operating license. This license allows the operation of the nuclear power plant. The application for an operating license includes operational and emergency procedures, as well as a Final Safety Analysis Report (FSAR) describing the facility's final design.

10 CFR Part 52

The Part 52 approach, introduced by the NRC in 1989, is outlined in 10 CFR Part 52 and offers more flexibility in licensing options.

Combined license

Under the Part 52 approach, the main type of license is the combined license. This license combines the design information included in a Part 50 construction permit with the operating information typically included in a Part 50 operating license. The combined license application includes a Safety Analysis Report, operational and emergency plans, and specifies inspections, tests, analyses, and acceptance criteria that must be met before the plant begins operation.

Optional incorporation of design certification

Design certifications are optional and describe reactor designs without specifying a particular site. They are typically sought by reactor designers who do not intend to operate the nuclear power plant. A combined license can reference an NRC-approved design certification, streamlining the regulatory review of the site, as design-related issues are resolved beforehand.

Optional incorporation of early site permit

Early site permits are also optional and focus on the characterization of a site without specifying a particular reactor design. The permit is initially valid for a minimum of 10 years and a maximum of 20 years, with the possibility of renewal. The early site permit allows the utility that will own and operate the nuclear power plant to perform environmental and site characterization analyses separately from determining the reactor design.

Steps in the licensing approaches

10 CFR Part 50 licensing approach

Construction permit application: The following outlines the high-level steps for submittal, review, and approval of a construction permit application.

  1. Applicant submission: The applicant submits a safety analysis report, design information, comprehensive site data, and environmental impact assessments.
  2. Acceptance for technical review and docketing: The NRC determines whether the application contains sufficient information for a detailed review and dockets the application information in the agency's document database.
  3. Technical review: The NRC staff reviews the application to ensure compliance with regulations and prepares a Safety Evaluation Report.
  4. Review by the Advisory Committee on Reactor Safeguards (ACRS): The ACRS, an independent group, evaluates the application and presents its advice to the Commission.
  5. Environmental review: The NRC conducts an environmental review and issues a Draft Environmental Impact Statement for public comment, followed by a Final Environmental Impact Statement.
  6. Public hearing: A public hearing is held before a construction permit is issued.

Operating license application: The same steps are then required to be repeated for submittal, review, and approval of an operating license application.

10 CFR Part 52 licensing approach

Combined license application: The combined license application is submitted to include all aspects for review and approval to support construction and operation, including a Safety Analysis Report, operational and emergency plans, and specified inspections, tests, analyses, and acceptance criteria.

  1. Review and approval: The NRC reviews the combined license application, ensuring compliance with regulatory requirements. Once approved, the NRC grants the combined license.
  2. Authorization for operation: After verifying that all required inspections, tests, analyses, and acceptance criteria are met, the NRC authorizes the operation of the facility.

The high level steps for submittal, review, and approval are similar to that of a Part 50 license application, but need only be completed once for a combined license application, since it includes information for the construction and operation.

Business model for Part 52

The Part 52 pathway allows for a streamlined process when a company is designing, constructing, and operating a facility. It facilitates greater speed and repeatability by licensing nuclear power plants of the same design using the R-COLA/S-COLA approach. The reference combined operating license (COLA) serves as a basis for subsequent COLAs, reducing the review focus to changes from the reference application. COLAs require a final safety analysis report and an environmental report.

By following the appropriate NRC licensing pathway, advanced fission facilities can navigate the regulatory process efficiently and ensure compliance with safety and environmental regulations.

Regulatory FAQs

To construct and operate a commercial reactor in the U.S., the NRC must license the facility. The NRC issues many licenses, including standard design certifications, early site permits, limited work authorizations, construction permits, operating licenses, and combined licenses. All license application processes follow the same general review steps: they are submitted by an NRC applicant, the NRC determines if they are acceptable for review (i.e., the acceptance review process), license applications are reviewed by the NRC, and, if the review is successful, they are approved, and the license is issued.

The acceptance review is mandated by the NRC’s regulations, and, the direct interpretation of the regulatory importance of acceptance is to identify that the application is complete. Once the application has been accepted for docketing, the NRC performs a technical review until they have reasonable assurance that they have met their mission and have completed all the steps in the review process, dependent on the license application type.

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Although there are many NRC licensing pathways for an advanced fission facility, only two are generally considered because they have been historically used. The first is the “Part 50 approach,” which is how today’s reactors are licensed and is described in Title 10 to the Code of Federal Regulations (10 CFR) Part 50. The Part 50 licensing approach is two steps and requires both a construction permit and an operating license. In 1989, the NRC introduced the “Part 52 approach,” which refers to 10 CFR Part 52 and includes numerous combinations of licensing approaches. Specifically of relevance to Oklo is the combined license approach, and Oklo has already used it for the Aurora at the Idaho National Laboratory (Aurora-INL). The Part 50 and 52 approaches are summarized in Table 1‑1; note that these are only a selected subset of Part 52 approaches.

Table 1‑1: Summary of reactor licenses, permits, and certificates

NRC license, permit, or certification

CFR Part

Year of initialization

Date of last issuance

Construction permit

10 CFR Part 50

1956

1/27/1978

Operating license

10 CFR Part 50

1956

10/22/2015

Combined operating license

10 CFR Part 52

1989

4/12/2018

Design certification

10 CFR Part 52

1989

10/15/2014

Early site permit

10 CFR Part 52

1989

12/19/2020

10 CFR Part 50 licensing approach

A Part 50 approach requires first the filing and approval of a construction permit, then the filing and approval of an operating license to operate a nuclear power plant. A construction permit allows the construction of the nuclear power plant, and an operating license allows the operation of the plant.

10 CFR Part 52 licensing approach

A Part 52 approach requires the issuance of a combined license, which combines the design information typically included in a Part 50 construction permit and the operating information typically included in a Part 50 operating license.

Although the Part 52 approach allows different pathways to licensing a plant, all pathways require a combined license application submission. The optionality in Part 52 is nuanced in the components of the combined license application.

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When a company submits an application, a design for your technology is submitted, showing how it behaves and how it is safe by analyzing it against a number of challenging but nonetheless plausible scenarios. You’re trying to show that you’ve engineered the system so thoroughly that it doesn’t pose any undue risk even in extraordinary circumstances. The way regulators look at that is largely procedural and they’ve mostly looked at these proposals in the context of light water reactors. The problem is that the process doesn’t extend well to next generation systems where you have high degrees of inherent passive safety. The system is basically “physics safe.”  If something destroys the cooling procedures during operation, the system will heat up and thermally expand, but that expansion actually shuts the reactor down by causing more neutrons to leak out of the reactor than are staying in it. So there’s this natural feedback that cause you to shut down that is based on physics. You’re always able to stay cool by the natural circulation of the coolants. These are all well-known and understood in operational contexts. That presents an opportunity to look at these things fundamentally differently from a regulatory process perspective. 

At Oklo, we are at the tip of the spear on this. There is a lot of newness here. So right now, there are a lot of opportunities for the NRC staff and agencies to look at these things more organically and enabling this type of review. Empowering staff to do that would be worth a lot. But because it’s a lot easier for them to do things as they’ve done them before, it adds a lot of inefficiency given the inherent differences between legacy and advanced nuclear technologies. So it’s much harder for them to stick their neck out and do something more efficient and modern that’s appropriate for the technology. If you actually align those things, that’s going to help a lot because you’re going to enable smart, technical, capable people in the agency to do their job.


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Design certifications, an optional part of a Part 52 licensing approach, describe the reactor design without providing information on a specific site. Generally, a reactor designer that does not intend to own and operate the nuclear power plant applies for a design certification. As part of performing the safety analyses required in a design certification application, the reactor designer assumes bounding site characteristics (e.g., a bounding flood event) to evaluate external hazard challenges to the safety of the reactor design. If an applicant chooses, a combined license can reference an NRC-approved design certification that stipulates the safety case for the reactor. The benefit of incorporating a design certification is to streamline the regulatory review of the site since regulatory issues surrounding the design review should have been resolved before filing a combined license application.

Historically, nuclear power plants have been designed by reactor design companies, such as Westinghouse, then constructed, owned, and operated by a utility. The reactor design company applies for the design certification, and the utility applies for a combined license application based on the design certification. Design certifications provide a regulatory pathway for reactor design developers that are not the owner operators to have a design certified by the NRC. After issuance by the NRC, the design certification is valid for 15 years and becomes part of the regulations contained in 10 CFR. A design certification application must contain the standard design's proposed inspections, tests, analyses, and acceptance criteria. These proposed inspections, tests, analysis, and acceptance criteria provide the basis from which the NRC authorizes a nuclear power plant to begin operations after a combined license application is approved.

Additionally, early site permits are the complement of a design certification and are an optional part of a Part 52 licensing approach. An early site permit describes the site of the reactor without providing information on a specific reactor design. As part of performing the safety analyses required in an early site permit application, the early site permit applicant assumes bounding reactor design characteristics (e.g., amount of water required). The utility that owns and operates the nuclear power plant applies for an early site permit to perform the environmental and site characterization analyses separately from determining the reactor design to be built at the site. The early site permit is initially valid for no less than 10 and no more than 20 years and can be renewed for 10 to 20 years.

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Historically, projects have been designed by one company, constructed by another, and finally operated by a separate company. The use of Part 50 licensing pathways has been informed by this approach, allowing for the construction of a designed facility to ultimately be turned over to an operating utility. For a company that is both designing, constructing, and operating a facility, the Part 52 pathway Oklo is pursuing allows for greater speed and repeatability by licensing nuclear power plants of the same design utilizing the R-COLA/S-COLA approach. Specifically, the first COLA serves as the “reference” COLA, which can then be incorporated in “subsequent” COLA’s, where future reviews are focused only on the content that changes from the reference application.  COLAs must include both a final safety analysis report and an environmental report.

Oklo submitted and remains the only advanced reactor company to have submitted an application for both construction and operation of its design and have it accepted for review.  As owner and operator, Oklo is not only designing but constructing and operating a facility. The Part 52 pathway Oklo is pursing allows for greater speed and repeatability by licensing nuclear power plants of the same design utilizing the COLA approach.

In other words, Oklo will gain staff approval of its design for both its first deployment and subsequent deployments through its combined license application review, while also receiving approval to construct and operate, pending completion of key inspection and testing.  Specifically, the first COLA serves as the “reference” COLA, which can then be incorporated in subsequent COLAs, where future reviews are focused only on the content that changes from the reference application. COLAs must include both a final safety analysis report and an environmental report. Ultimately, any entity seeking to operate an advanced reactor will need to submit for an operating license with the NRC.

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In 2020, Oklo submitted the first ever advanced fission license application to build and operate its first plant. In 2022, the U.S. Nuclear Regulatory Commission requested additional information to resume the application. Oklo has since added additional staff with decades of NRC experience. Oklo has been able to reach resolution of the items identified in the denial and is now preparing for an application readiness review.

Oklo's regulatory interactions are captured on the NRC website here.

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Oklo has a site use permit at INL, and fuel from INL and DOE. At present, Oklo is actively engaged with the NRC as it prepares to submit an application within 12 months. Oklo has begun preliminary long-lead procurement activities.

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