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:
s is the key to meeting dose limits, as a different approach to defense in depth is employed in an mHTGR. The SARRDL concept allows for some small increase in circulating radionuclide inventory during an AOO. To ensure the SARRDL is not violated during an AOO, a normal operation radionuclide inventory limit must also be established (i.e., appropriate margin). The radionuclide activity circulating within the helium coolant boundary is continuously monitored such that the normal operation limits and SARRDLs are not exceeded. The SARRDLs will be established so that the most limiting license-basis event does not exceed the siting regulatory dose limits criteria at the exclusion area boundary (EAB) and low-population zone (LPZ), and also so that the 10 CFR 20.1301 annualized dose limits to the public are not exceeded at the EAB for normal operation and AOOs. The NRC has not approved the concept of replacing specified acceptable fuel design limits with SARRDLs. The concept of the TRISO fuel being the primary fission product barrier is intertwined with the concept of a functional containment for mHTGR technologies. See the rationale for mHTGR-DC 16 for further information on the Commission’s current position. APPENDIX C. MODULAR HIGH-TEMPERATURE GAS-COOLED REACTOR DESIGN CRITERIA Appendix C to DG-1330, Page C-5 II. Multiple Barriers Criterion mHTGR-DC Title and Content NRC Rationale for Adaptions to GDC The word “coolant” has been replaced with “heat removal,” as helium coolant inventory control for normal operation and AOOs is not necessary to meet the SARRDLs, due to the reactor system design. 11 Reactor inherent protection. Same as ARDC The reactor core and associated systems that contribute to reactivity feedback shall be designed so that, in the power operating range, the net effect of the prompt inherent nuclear feedback characteristics tends to compensate for a rapid increase in reactivity. The wording has been changed to broaden the applicability from