Spent fuel storage and transportation comprises one of three sub-arenas that the staff of the U.S. Nuclear Regulatory Commission (NRC) identified in considering which areas of the waste management arena to target for greater use of risk information. This page summarizes the following aspects of this sub-arena:
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Objective
Utilize risk information on a case-by-case basis to prioritize and address regulatory initiatives in spent fuel storage and radioactive materials transportation.
Basis
SECY-99-100 and SECY-04-0182, as well as the related staff requirements memorandum (SRM), provide the conceptual framework for risk-informing the NRC's waste activities. Guidance on how to apply this framework is provided in "Risk-Informed Decision-Making for Material and Waste Applications". In particular, individual risk-informed applications must meet the established screening criteria.
In this subarena, the NRC staff is limited in its ability to risk-inform the agency's regulatory activities because it is not cost-beneficial to perform risk-assessment of each of the numerous storage or transport designs. As a result, the agency has conducted (or sponsored) risk assessments for a few selected designs. In addition, the staff may apply risk assessments to specific activities on a case-by-case basis, provided that the screening criteria are met. For example, the staff has completed and documented a pilot study PRA of a dry cask storage facility, and determined that the risk from that facility was negligibly small.
The goal described below meets the screening criterion for cost/benefit by assessing risk impacts by judgment.
Goals
The staff has established the following goal for risk-informed and performance-based activities in this subarena:
- Produce updated versions of NUREG-1536, "Standard Review Plan for Dry Cask Storage Systems," and NUREG-1567, "Standard Review Plan for Spent Fuel Dry Storage Facilities."
List of Risk-Informed and Performance-Based Activities
This list shows the ongoing licensing initiatives, projects, and activities that the staff of the U.S. Nuclear Regulatory Commission (NRC) has targeted for greater use of risk information in the Spent Fuel Storage and Transportation Sub-Arena within the Waste Management Arena:
Regulatory Framework for Spent Fuel Storage and Transportation
Summary Description
As shown in existing probabilistic risk assessment studies, the risk associated with dry cask storage is very low. The goal of this effort was to develop a framework for spent fuel storage to enable the staff to perform a more risk-informed regulatory review, improve guidance, streamline casework activities, help assess 10 CFR 72.48 changes, and evaluate requests for exemptions to the regulation while maintaining appropriate margins of safety and security. NMSS/DSFM developed a scoping and implementation plan for risk-informing storage regulatory activities.
The NRC's graded approach to improve the dry cask storage regulatory process takes into consideration quantitative and qualitative risk insights, as well as, qualitative evaluations that rely on safety functions, defense-in-depth, and engineering judgement, while also maintaining safety and security and ensuring that the associated regulatory requirements are met.
Previous Fiscal Years
FY 2015
After meetings with internal and external stakeholders and consideration of the relatively low risk of dry cask storage based on previously conducted industry and NRC probabilistic risk assessments, the NRC decided to develop a graded approach primarily based on safety functions and defense-in-depth considerations.
FY 2016
The staff continued to work with internal and external stakeholders on developing a graded approach.
FY 2017
As a continuation of the efforts to improve efficiency, the staff and industry developed a set of graded-approach criteria to evaluate licensing requirements in the technical specifications and Certificate of Compliance to determine what information can be relocated to the final safety analysis report (FSAR) or removed. Licensing information appropriate for the FSAR can be evaluated for change by the more efficient 10 CFR 72.48 change process. TN Americas, LLC, submitted a pilot amendment application to test this improvement process.
FY 2018
Several tasks in this plan have been completed. These include identifying applicable risk information and defining the application of defense-in-depth for dry cask storage. Staff continued to review the TN Americas, LLC (now Orano TN) pilot amendment application. Orano TN and the staff held public meetings to resolve questions and achieved progress toward completing the pilot application review.
FY 2019
To evaluate the graded approach concept, staff chose to conduct a pilot project on an evaluation of an amendment to a Certificate of Compliance submitted by Orano TN. The review of the graded approach pilot amendment from Orano TN is complete and the amendment to the Certificate of Compliance is currently in the rulemaking process and scheduled for issuance in the first quarter of FY 2020. The approach used to evaluate this pilot amendment is paving the way for developing guidance that would streamline the format and content requirements for the Certificate of Compliance and Technical Specification. A public meeting with NEI and stakeholders will be held for discussing the lessons learned from this pilot application. Staff will continue to collaborate with industry and stakeholders to revise guidance to improve the efficiency of spent fuel storage regulatory activities. Additionally, an addendum to draft/proposed IMC 2690 has been developed that provides risk-informed guidance to the selection of inspection samples in the 10 CFR 72.48 inspection process. This addendum is based on a graded-approach rating of components important to safety and provide guidance for screening licensee's 72.48 biennial summaries.
The NRC completed an assessment of the current ISFSI inspection program in September 2019. The staff is in the process of evaluating the recommendations to determine which will make a more effective ISFSI inspection program that is focused on the most risk significant activities.
The NRC is also participating in an industry effort by Electric Power Research Institute (EPRI) to quantify the safety margins in NRC's criteria for spent fuel peak cladding temperature and the bias and uncertainties associated with the thermal computer codes and the associated input parameters.
FY 2020
FY 2020
In FY 2020, the staff has been exploring a method of evaluation (MOE) approach for spent fuel dry storage system shielding design certification applications under 10 CFR Part 72. This approach is a new concept in FY 2020 to enhance risk-informed review approaches using an MOE. During FY 2020, the staff conducted public meetings with NEI where this new approach was discussed. The MOE approach seeks meeting the shielding performance goals as specified in 10 CFR 72.236(d) using an approved methodology rather than explicit a definition of the contents of the model.
In FY 2020, the staff continued work on the graded approach for spent fuel certificates of compliance. The goal of this approach is to streamline the process for review and certification of spent fuel dry storage designs following the principles of risk-informed regulations. The graded approach provides the framework for reducing the level of detail in and establishing an appropriate level of information in technical specifications (TS) and the safety analysis reports for cask shielding design by focusing on the information necessary to ensure safety in accordance with the regulations. In a January 8, 2020, letter to the Nuclear Energy Institute, the NRC endorsed the use of the graded approach program (ADAMS Accession No. ML19353D373). In FY 2021, the staff plans to explore additional activities that will incentivize the use of the graded approach.
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Thermal Evaluation Model Topical Report
Summary Description
Capitalizing on the Division of Fuel Management's efforts to enhance the spent fuel storage licensing process over the last several years, on November 8, 2019, NEI submitted a white paper containing sixteen recommendations to explore further enhancements related to dry storage performance safety margin. The goal of the white paper is to leverage industry experience with loading and maintenance of dry cask spent nuclear fuel storage systems to identify improvements to the regulatory framework for licensing these systems. The staff has held eight workshops during this fiscal year to align on the recommendations, develop implementations plans, and status implementation efforts. In general, the white paper, and more importantly, the staff's leadership on this initiative align well with the agency's direction to become a modern risk-informed regulator, especially as the staff develops plans to further risk-inform its approach to spent fuel storage licensing. The staff has made great progress in implementing changes that address several of the of the sixteen recommendations in the white paper.
In addition to the method of evaluation (MOE) topical report, other initiatives related to the overall effort identified in this website include: Regulatory Framework for Spent Fuel Storage and Transportation and the Risk Tool for Spent Fuel Dry Cask Storage.
FY 2020
FY 2020
In FY 2020, the staff has been reviewing the Holtec Thermal Evaluation Topical Report (TR). This review implements an approach that reduces numerous reviews of analysis calculations by the staff during licensing actions and, instead includes a generic approval (topical report, Quality Model) for the bulk of the steps required to complete numerical modeling calculations. The process of implementing the TR in our reviews will incorporate all regulatory tools at our disposal and will achieve efficiencies in licensing reviews that have incorporated risk insights.
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Risk Tool for Spent Fuel Dry Cask Storage
Summary Description
The NRC staff is developing a guidance document to include risk information in the review of dry cask license applications and license amendments. The tool is based on risk studies, past safety evaluation reports, and staff expert knowledge. This dry cask Risk Tool would be used to rate specific licensing actions in four different color coordinated results which correspond to high (red), medium (yellow), or low (green) risk, and outside the scope of the tool (blue). This preliminary risk rating can then be used alongside other information and staff experience to determine the level of review required for a specific requested licensing action.
FY 2020
FY 2020
The development of the dry cask Risk Tool began in September 2019. Major activities have included the construction of the draft tool by Idaho National Laboratory followed by review and contributions from a working group of senior NRC technical reviewers. Work on this project is now transitioning from development of the Risk Tool to creating a guidance document for implementation and developing training materials for educating staff in its application. A public meeting to communicate the tool to industry stakeholders took place on September 9th (ADAMS Accession No. ML20248H381).
The level of effort required for evaluating a requested licensing action will also depend on the quality of the application, uniqueness of the design, and the methodology used for demonstrating compliance. The inclusion of the dry cask Risk Tool in the planning of reviews will support allocating more time to difficult/high risk items to further ensure adequate safety, while making lower risk reviews more efficient.
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Page Last Reviewed/Updated Monday, January 04, 2021