Document: NRC Regulatory Guide
Document ID: 9c99a4b7-8619-41f0-b716-262bfdb03941
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:
herefore, 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 occurrences, the system safety function shall be to transfer fission product decay heat and other residual heat from the reactor core to an ultimate heat sink at a rate such that specified acceptable system radionuclide release design limits and the design conditions of the reactor helium pressure boundary are not exceeded. During postulated accidents, the system safety function shall provide effective core cooling. Suitable redundancy in components and features and suitable interconnections, leak detection, and isolation capabilities shall The word “passive” was added, based on the definition of a mHTGR. In definitions Section 3.1 of the DOE report titled “Guidance for Developing Principal Design Criteria for Advanced (Non-Light-Water) Reactors” (Ref. 17), the mHTGR design has a low power density and hence residual heat is removed by a passive system. “Ultimate heat sink” has been added to explain that, if mHTGR-DC 44 is deemed not applicable to the design, the residual heat removal system is then required to provide the heat removal path to the ultimate heat sink. APPENDIX C. MODULAR HIGH-TEMPERATURE GAS-COOLED REACTOR DESIGN CRITERIA Appendix C to DG-1330, Page C-17 IV. Fluid Systems Criterion mHTGR-DC Title and Content NRC Rationale for Adaptions to GDC be provided to ensure the system safety function can be accomplished, assuming a single failure. “Reactor coolant pressure boundary” has been relabeled as “reactor helium pressure boundary” to conform to standard terms used for mHTGRs. The SARRDL replaces the ARDC specified acceptable fuel design limits as described in the rationale to mHTGR-DC 10. The mHTGR-DC 34 incorporates the postulated accident residual heat removal requirements contained in GDC 35. Effective core cooling under postulated