Document: NRC Regulatory Guide
Document ID: 6f0a99f2-d25a-44e3-b7f2-3286449a9752
Document Type: regulatory_guide
Title: Water Sources for Long-Term Recirculation Cooling Following a Loss-of-Coolant Accident (Rev. 5)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2126/ML21266A185.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.82
CFR Part: 
CFR Title: 

Content:
h the strainer. Testing and extrapolation to the plant scale should also consider sacrificial strainer area, the number of strainers in service, and the flow through each strainer. In general, testing demonstrates that increasing strainer area and approach velocity increases penetration. Observations have also shown that penetration decreases significantly with fiber load on the strainer. Penetration testing should account for all fiber that was added to the test. In tests observed by the NRC staff, fiber penetration amounts were measured by careful drying and weighing of the filters used to collect the fiber, with filters dried and weighed both before and after use to ensure consistent results. The drying and weighing process can significantly affect results and constitutes a critical step in testing. Any fiber that did not reach the strainer should be accounted for and evaluated in the test report. Licensees may use test results that were not performed for their specific strainer design if they can justify that the results are prototypical or conservative with respect to their plant. Penetration testing and evaluation should consider strainer hole size, strainer geometry, flow profile across the strainer, flow conditions, fiber type, water chemistry, licensee actions that may change flow rates, and sacrificial strainer area. DG-1385, Page 33 1.3.12.8 The analyses and testing should consider worst-case single failures. For example, licensees with plant designs that include low-pressure safety injection (LPSI) pumps that shut down during the switchover from the refueling water storage tank to the sump should consider one LPSI train failure to stop. This assumption leads to a conservatively calculated maximum flow rate to and through the screen. Alternatively, licensees may demonstrate that the pump can be secured by operator action before significant effects on debris transport and strainer performance occur. 1.3.12.9 The time dependence of debris arrival at the