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:
gory B valves. 11. The reactor coolant vent system (i.e., vent valves, block valves, position indication devices, cable terminations, and piping) should be seismically and environmentally qualified in accordance with IEEE 344, as supplemented by Regulatory Guide 1.100 and Regulatory Guide 1.92. Environmental qualifications must be in accordance with 10 CFR 50.49. 12. The reactor coolant vent system should be designed to withstand the dynamic loads that will be encountered during operation from high RCS pressure to the approximate atmospheric pressure at the vent system exhaust. 13. Procedures to effectively operate the vent system must consider when venting is needed and when it is not needed. A variety of initial conditions for which venting may be required should be considered. Operator actions and the necessary instrumentation should be identified. 5.4.12-6 Revision 1 - March 2007 14. The reactor coolant vent system should meet the quality assurance acceptance criteria provided in SRP Chapter 17. Technical Rationale The technical rationale for application of these acceptance criteria to the areas of review addressed by this SRP section is discussed in the following paragraphs: 1. 10 CFR 50.46a requires that light-water nuclear power reactors be designed with RCS high-point vents to maintain adequate core cooling if the accumulation of noncondensible gases would cause the loss of function of the core cooling systems. During the Three Mile Island Unit 2 accident, a substantial volume of hydrogen was generated in the primary system. To resolve concerns that such a gas volume could interfere with postaccident natural circulation or pump operation, the foregoing regulation was promulgated. This rule establishes specific design requirements that all license applicants must meet. Compliance with 10 CFR 50.46a assures that there is a means to exhaust gases from the RCS that might otherwise inhibit long-term cooling following an accident, thereby ensuring the