Document: NRC Regulatory Guide
Document ID: 5810150e-ee20-4cd1-b72f-6e918a603f73
Document Type: regulatory_guide
Title: Applications for Nuclear Power Plants (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1523/ML15233A056.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.206
CFR Part: 
CFR Title: 

Content:
valuation) whose failure would cause a reactor scram or the actuation of a safety-related system A review of the licensee event reports for currently operating reactors did not identify occurrences of piping failures in the CWS up to the turbine building that resulted in plant scrams or safety system actuations. The turbine building demarcation may be important, since the piping within the building could, depending on plant design, cause internal plant flooding or safety system actuations, or prevent other SSCs from fulfilling their safety-related functions. Applicants need to perform design-specific reviews to ensure that piping failures in the CWS up to the turbine building are not identified in other analyses (e.g., FSAR, probabilistic risk assessment) as being a plausible initiating event for a reactor scram or safety system actuation. Therefore, CWS piping could be considered preconstruction in certain circumstances. DG-1325, Page-117 Circulating Water Intake Structure Depending on the plant design, it is possible for an applicant to demonstrate, similar to CWS piping up to the turbine building, that the plant intake structure does not have a safety function (e.g., some plant intakes only provide makeup to the CWS). This conclusion would not apply to related SSCs, such as pumps, travelling screens, or other active components associated with the CWS, because there are many examples of plant transients and safety system actuations that have loss of circulating water flow as an initiating event. To expand the preconstruction activities beyond the intake structure, applicants need to perform design-specific reviews to ensure that a loss of CWS flow caused by pump failures or screen blockage is not a plausible initiating event for a reactor scram or safety system actuation. Therefore, the facility design will determine whether intake structures and related components are within the scope of construction. Cooling Towers Depending on the plant design, it is possible