scope:

This standard

(1) provides design criteria for liquid-fuel MSRs that match the safety intent of the Code of Federal Regulations (CFR) Title 10, Part 50, Appendix A [3], general design criteria (GDCs) following an equivalent process to that performed by NRC Regulatory Guide (RG) 1.232 [4] for modular high-temperature gas-cooled reactors (MHTGRs) and sodium-cooled fast reactors (SFRs);

(2) provides definitions of MSR terminology important for safety evaluation;

(3) describes distinctive safety considerations for MSRs; and

(4) provides an MSR-focused description of a risk-informed design process following the methodology described in NEI 18-04 [5] and ANSI/ANS-53.1-2011 (R2021) [6].

This standard also provides guidance related to MSR NPP characteristics that will impact the risk-informed selection of licensing-basis events. This standard does not address fissile material separations, plant security, or safeguards issues. Criteria for adequately executing construction and for safely operating and maintaining the nuclear plant are addressed only to the extent that they affect design provisions.

This standard applies to all liquid-fuel MSR NPPs, independent of level of power production and energy end use. It also applies to plant configurations that include more than one reactor unit (modules) on a site. This standard is intended to apply to all liquid salt MSR fuel compositions. The heat transport system is not restricted to a particular configuration, and thus, this standard applies to loop, pool, hybrid, or other arrangements. This standard also pertains to on-site storage of used fuel prior to its removal for recycling or long-term storage. While this standard is not intended to apply to nonpower MSR designs, the content of this standard could assist the design, development, and licensing of research reactors using MSR technology.