ML23061A144

Pre-Application Engagement on Material Qualification Issues for Advanced Reactor Licensing

ML23061A144
Person / Time
Issue date:	03/02/2023
From:	Office of Nuclear Reactor Regulation
To:
References
Download: ML23061A144 (2)

Text

Pre-Application Engagement on Material Qualification Issues for Advanced Reactor Licensing Summary:

The NRC staff is summarizing key issues in the area of materials qualification that prospective applicants should consider addressing during pre-application activities. The NRC staff encourages prospective applicants for advanced reactor designs to consider these issues as part of future pre-application activities.

Pre-application engagement and development of materials qualification plans, when appropriate, are encouraged for all materials used in safety-related or risk-significant applications. Robust material qualification plans generally have the following attributes:

1) The plan demonstrates how data is collected in accordance with the ASME BPV Code (the Code),

including any endorsement conditions;

2) The plan addresses how appropriate environmental testing (e.g.., coolant, environment, irradiation) was performed;

3) Data supports operating and accident conditions; and

4) Data is provided to support the use of non-Code qualified materials.

Pre-application engagement in this area is encouraged because of the significant lead time for materials testing. Pre-application engagement provides opportunities for the NRC staff and prospective applicants to discuss the following topics prior to submittal of an application to allow for an efficient review in these areas. The methods of engagement, level of detail, maturity of testing programs, and, if needed, approval of qualification plans (e.g., material qualification topical reports), will vary depending on several factors, including the proposed application type (e.g., construction permit).

ASME Code-Required Testing (with Conditions)

• NRC staff anticipates that most applicants will need to qualify materials and designs to the rules in Section III, Division 5, of the Code (Division 5) because many of the proposed designs operate at temperatures and/or in environments where codes and standards endorsed or incorporated by reference for light water reactors do not apply. The NRC has developed Regulatory Guide 1.87, revision 2, Acceptability of ASME Code Section III, Division 5, High Temperature Reactors, which endorses the use of the 2017 edition of Division 5, with conditions.

• If a prospective applicant plans to use the edition of Division 5, as endorsed in RG 1.87, with conditions, NRC staff encourages it to discuss its plan for meeting the Code requirements with the staff.

• If a prospective applicant plans to use a different edition of the Code, or a different code or standard (e.g., ASME BPV Code Section VIII), it would be beneficial if it described the differences in the Code or standard it seeks to use and Division 5, and justified the acceptability of those differences.

Performance of Environmental Testing

• Division 5 states that the rules do not cover deterioration that may occur in service as a result of radiation effects, corrosion, erosion, thermal embrittlement, or instability of the material; however, it states that these effects shall be taken into account for design or service life of SSCs.

• Given the significance of these degradation modes to reactor design and operation, the NRC encourages prospective applicants to consider pre-application engagement discussions on addressing these potential degradation modes.

• The staff considers this area valuable for pre-application engagement for a number of reasons, including the fact that data on degradation modes may be time consuming to gather and the results of environmental testing could impact design, or component lifetime. For example, such data is important for developing corrosion or degradation rates for the specific reactor environment and understanding the impacts on mechanical and thermal properties. This data is needed to determine if the design is adequate and to set appropriate limits on coolant purity.

Data Supports Reactor Design and Operating Envelopes

• A prospective applicant that seeks to use historic or current data (e.g., being obtained at an external research facility, such as a national laboratory) might wish to engage with the staff on how the data applies to its plant and supports reactor design and operating envelopes, including operating temperatures, fluences and other required environmental conditions such as coolant impurity levels. In addition, a discussion on how the applicant plans to use the data to bound potential accident scenarios is encouraged.

• A prospective applicant may wish to engage with the staff regarding data acquisition. If the prospective applicant does not plan to follow the standards specified in Division 5, it would be beneficial if the prospective applicant described the standards that will be applied, for example, the Quality Assurance Program. It would help familiarize the staff with these standards if the prospective applicant identified the differences between the standards the prospective applicant intends to follow and those in Division 5 and described its approach for demonstrating that the proposed standards are adequate.

Use of non-Code Qualified Materials

• If proposed materials are not Code-qualified, the NRC staff encourages a prospective applicant to discuss plans for developing a material qualification plan to ensure data will be obtained to support the necessary material/mechanical properties to ensure components comprised of the materials can perform their intended functions.

• If a prospective applicant plans to deviate from the Code or use materials that are not Code-qualified, it may wish to engage with the staff as part of any pre-application activities.