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:
wer supply, or control system should not prevent isolation of the vent path. On boiling water reactors, block valves are not required in lines with safety valves used for venting. 4. The design should incorporate sufficient redundancy to minimize the probability of inadvertent actuation. Other methods to reduce the chances of inadvertent actuation, such as removing power or administrative controls, may be considered. 5. Since the RCS vent will be part of the RCPB, all requirements for the RCPB must be met. 6. The size of the vent should be smaller than the size corresponding to the definition of a LOCA (Appendix A to 10 CFR Part 50, 10 CFR 52.47(a)(1)(ii), and 10 CFR 52.79(b)) to avoid unnecessary challenges to the ECCS, unless the applicant provides justification for a larger size. 7. Vent paths to the containment should discharge into areas that provide good mixing with containment air and are able to withstand steam, water, noncondensibles, and mixtures of the above. 8. The vent system should be operable from the control room and provide positive valve position indication. Power should be supplied from emergency buses. 9. It is important that the control room displays and controls for the RCS vents do not increase the potential for operator error. A human-factor analysis should be performed that considers the following: A. The use of this information by an operator during both normal and abnormal plant conditions B. Integration into emergency procedures C. Integration into operator training D. Other alarms during an emergency and need for prioritization of alarms 10. The design should have provisions for testing the operability of the reactor coolant vent system. Testing should be performed in accordance with Subsection IWV of Section XI of the ASME Code for Category 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