Document: NRC Regulatory Guide
Document ID: da269da5-7390-4252-b08f-bdb7aeb8beaf
Document Type: regulatory_guide
Title: Developing Principal Design Criteria for Non-Light Water Reactors + HISTORY - HISTORY 02/2017 – DG-1330 , Proposed Revision 0
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1630/ML16301A307.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.232
CFR Part: 
CFR Title: 

Content:
tainties in determining (1) material properties, (2) the effects of irradiation and coolant chemistry on material properties, (3) residual, steady-state, and transient stresses, and (4) size of flaws. “Reactor coolant pressure boundary” has been relabeled as “reactor helium pressure boundary” to conform to standard terms used for mHTGRs. Specific examples are added to the mHTGR-DC to account for the high design and operating temperatures and unique potential coolants. APPENDIX C. MODULAR HIGH-TEMPERATURE GAS-COOLED REACTOR DESIGN CRITERIA Appendix C to DG-1330, Page C-16 IV. Fluid Systems Criterion mHTGR-DC Title and Content NRC Rationale for Adaptions to GDC 32 Inspection of reactor helium pressure boundary. Components that are part of the reactor helium pressure boundary shall be designed to permit (1) periodic inspection and functional testing of important areas and features to assess their structural and leaktight integrity, and (2) an appropriate material surveillance program for the reactor vessel. “Reactor coolant pressure boundary” has been relabeled as “reactor helium pressure boundary” to conform to standard terms used for mHTGRs. The staff modified the LWR GDC by replacing the term “reactor pressure vessel” with “reactor vessel,” which the staff believes is a more generically applicable term. A non-leaktight system may be acceptable for some designs provided that (1) the system leakage does not impact safety functions under all conditions, and (2) leakage is consistent with SARRDL. 33 Reactor coolant makeup. Not applicable to mHTGR. The mHTGR does not require reactor coolant inventory maintenance for small leaks to meet the SARRDLs, which replaces the concept of the specified acceptable fuel design limits, as discussed in GDC 10. Therefore, ARDC 33 is not applicable to the mHTGR design. 34 Passive residual heat removal. A passive system to remove residual heat shall be provided. For normal operations and anticipated operational