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:
ws downstream of the test strainer to determine the amount of debris passing through the strainer. The sampling should be performed with a frequency that ensures adequate characterization of the total bypass content. This debris could damage or clog components, such as pumps, throttle valves, or components within the reactor core. Licensees may use the downstream debris characteristics to determine the likelihood that DG-1385, Page 32 downstream blockage or wear and abrasion could threaten long-term core cooling or affect heat transfer of the fuel cladding. The conditions for the limiting downstream sampling tests will typically differ from the conditions for the limiting debris bed head loss tests because a filtering debris bed will reduce the quantity of debris that passes through the strainer. A larger strainer surface area, higher flow rates, a low rate of introduction of debris into the water, or thinner debris beds can result in greater debris penetration. Licensees may need to conduct separate strainer penetration tests for fibrous and particulate debris, to avoid crediting filtration caused by one debris type that might affect the other debris type. Another method that has been successfully used to characterize the bypass content is to collect bypass debris in a filter with very small pore size, downstream of the strainer. The NRC staff has not accepted sampling of downstream fluid samples for quantification of penetrated debris. However, sampling results may help determine debris characteristics and trends in the amount of penetration over time. The NRC has not issued guidance on performing strainer penetration testing. However, the NRC has observed penetration testing conducted by some vendors and has concluded that the test results are conservative with respect to penetration that could occur in the plant. Penetration testing is conducted only for fibrous debris. In general, head loss testing guidance applies to penetration testing. Penetration testing