Document: NRC Regulatory Guide
Document ID: 2559e7e3-22aa-4dda-8fee-ac029c2a69e4
Document Type: regulatory_guide
Title: Guidance for Residual Heat Removal
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0407/ML040750334.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.139
CFR Part: 
CFR Title: 

Content:
ting to the US. Nucleer Regulatory Commisson. Washington, D.C. 20555. Attention: Drectvor Divison of Document Control. A. INTRODUCTION General Design Criterion (GDC) 19, "Control Room," of Appendix A, "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50, "Licensing of Production and Utilization Facilities," requires that it be possible to take actions from the control room to maintain the power plant in a safe condition during normal operation or in the case of an accident. GDC 34, "Residual Heat Removal," requires that a system to remove residual heat be provided. GDC 34 defines the system's safety function as the transfer of fission product decay heat and other residual heat from the reactor core after the reactor is shut down so that acceptable design limits of the fuel and the reactor coolant pressure boundary are not exceeded. Furthermore, GOC 34 requires that the system safety function can be accomplished assuming the availability of only onsite or offsite power, coincident with a single failure. This guide describes a method acceptable to the NRC staff for complying with the Commission's regulations with regard to the removal of decay heat and sensible heat after a reactor shutdown. B. DISCUSSION The safe shutdown of a nuclear power plant following an accident not related to a loss-of- coolant accident CLOCA) has been typically interpreted as a hot standby. Consequently, considerable emphasis has been placed on the hot-standby condition of a power plant in case of an accident or abnormal occurrence. A similar degree of emphasis has been placed on long- term cooling, which is typically achieved by the residual heat removal (RHR) system. The RHR system starts to operate when the reactor coolant pressure and temperature are sub- stantially lower than their hot-standby condition values. It is the intent of this guide to place the same degree of emphasis on the entire range of reactor coolant temperatures and pressures, including the range between