Document: NUREG-0800
Document ID: 16922d4c-3f36-4add-8a31-0ec35a44f030
Document Type: srp
Title: REACTOR COOLANT SYSTEM HIGH POINT VENTS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0707/ML070770005.pdf
Revision Date: 2023-06
Chapter: 5
Section ID: 5.4.12
CFR Part: 
CFR Title: 

Content:
REVIEW RESPONSIBILITIES Primary - Organization responsible for review of reactor thermal-hydraulic systems in Pressurized Water Reactors (PWRs) and Boiling Water Reactors (BWRs) Secondary - None I. AREAS OF REVIEW All light-water nuclear power reactors are required to contain reactor coolant system (RCS) high-point vents in accordance with 10 CFR 50.46a. With the exception of high points in steam generator tubes, RCS high-point vents must be provided at all RCS locations where accumulation of noncondensible gases could inhibit natural circulation core cooling. The following criteria also apply: 1. The high-point vents must be remotely operated from the control room. 2. Design of the vents and associated controls, instruments, and power sources must conform to Appendices A and B to 10 CFR Part 50 (see SRP Chapter 17 for review guidance). 3. The design must ensure that the vents will perform their safety function. 4. The design must ensure that an inadvertent or irreversible actuation of a vent will not occur. The specific areas of review are as follows: 1. The location, size, discharge capacity, functions, and discharge area(s) of the vent system. 5.4.12-2 Revision 1 - March 2007 2. Supporting loss-of-coolant accident (LOCA) analyses for breaks in the vent line to demonstrate compliance with 10 CFR 50.46 unless vent line flow area is restricted to prevent the flow from exceeding the charging capability in the event of a vent line break. 3. For standard design certifications (DCs) and combined licenses (COLs), compliance with the 10 CFR 50.34(f) and 10 CFR 52.79(b) requirement to demonstrate that high- point vents should not lead to an unacceptable increase in the probability of LOCA accidents. 4. Redundancy and failure modes of the valve train. 5. Procedures for using the vent system and the bases for these procedures. 6. Information available to the operator for initiating and terminating vent system operation. 7. System environmental qualification to demonstrate