Document: NUREG-0800
Document ID: 757f66f9-1dd5-4125-9970-089087134ad9
Document Type: srp
Title: FIRE PROTECTION PROGRAM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0905/ML090510170.pdf
Revision Date: 2023-06
Chapter: 9
Section ID: 9.5.1.1
CFR Part: 
CFR Title: 

Content:
eas to the extent that they could adversely affect safe-shutdown capabilities, including operator actions. 2. Passive Plant Safe-Shutdown Condition As discussed in SECY-94-084, the definitions of safe shutdown as contained in the Commission=s regulations and guidelines do not address the inherent limitations of passive residual heat removal (RHR) systems. In GDC 34 of Appendix A to 10 CFR Part 50, the NRC regulations require that the design include a RHR system to remove residual heat from the reactor core so that specified acceptable fuel design limits are not exceeded. GDC 34 further requires suitable redundancy of the components and features of the RHR system to ensure that the system safety functions can be accomplished, assuming a loss of offsite power or onsite power, coincident with a single failure. The NRC promulgated these requirements to ensure that the RHR system is available for long-term cooling to ensure a safe-shutdown state. Post-fire safe shutdown for currently operating LWRs is defined in RG 1.189 as those conditions specified in the Technical Specifications. RG 1.139 specifies Cold Shutdown as 93.3 EC (200 EF) for pressurized-water reactor and 100 EC (212 EF) for boiling-water reactors (BWRs). Passive reactor designs are limited by the inherent ability of the passive heat removal processes and cannot reduce the temperature of the reactor coolant system below the boiling point of water for heat transfer to occur between the reactor coolant and the heat sink. The plant designs include cooling systems to bring the reactor to cold shutdown or refueling condition; however, these systems are not safety grade. These non-safety-grade systems (i.e., makeup water to the heat sink and cool-down capability) are necessary to maintain long-term cooling (i.e., beyond 72 hours) and should be capable of accomplishing their respective functions without damage to the fuel as demonstrated by design and analysis. Based on the discussion and recommendations of