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:
ing 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 “coolant systems” to additional factors (including structures or other fluids) that may contribute to reactivity feedback. These systems are to be designed to compensate for rapid reactivity increase. 12 Suppression of reactor power oscillations. The reactor core and associated control and protection systems shall be designed to ensure that power oscillations that can result in conditions exceeding specified acceptable system radionuclide release design limits are not possible or can be reliably and readily detected and suppressed. Helium in the mHTGR does not affect reactor core susceptibility to coolant-induced power oscillations; therefore, a separate mHTGR- specific DC is appropriate. The word “coolant” was deleted and the specified acceptable fuel design limits were replaced by SARRDLs. The discussion on the SARRDL is given in mHTGR-DC 10. 13 Instrumentation and control. Instrumentation shall be provided to monitor variables and systems over their anticipated ranges for normal operation, for anticipated operational occurrences, and for accident conditions, as appropriate, to ensure adequate safety, including those variables and systems that can affect the fission process and the integrity of the reactor core, reactor helium pressure boundary, and functional containment. Appropriate controls shall be provided to maintain these variables and systems within prescribed operating ranges. “Reactor coolant pressure boundary” has been relabeled as “reactor helium pressure boundary” to conform to standard terms used for mHTGRs. The criterion has been modified to reflect the use of the mHTGR functional containment. See the mHTGR-DC 16 rationale. 14 Reactor helium pressure boundary. The reactor helium pressure boundary shall be designed, fabricated, erected,