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:
nce conditions. Licensees should conduct a proper analytical evaluation of the similarity of the test tank and the actual plant conditions. The NRC staff considers CFD codes to be useful tools in such evaluations. Surrogate debris materials used in head loss testing should be either the actual plant materials or suitable substitutions. Licensees should justify substitutions by comparing the important characteristics of the plant debris sources and the surrogate, to verify that the debris preparation creates prototypical or conservative debris characteristics. NEI has developed a fibrous debris preparation procedure that has been used in strainer head loss and penetration testing. This procedure is described in “ZOI Fibrous Debris Preparation: Processing, Storage and Handling,” Revision 1, issued January 2012 (Ref. 49). In a letter dated April 26, 2012 (Ref. 50), the NRC recognized that the NEI protocol could produce the intended surrogate debris for testing, but that the results depended on human actions not fully controlled by the procedure. The NRC staff has observed debris produced using the NEI procedure and has found it acceptable for use in head loss and penetration testing. However, because of the human factors involved, the NRC expects licensees to verify that the surrogate materials have the desired characteristics. 2. Regulatory Positions Specific to Pressurized-Water Reactors Evaluations of the susceptibility of a PWR to debris blockage should address the considerations and events shown in Figure 3. 2.1 Emergency Core Cooling System Sumps, Strainers, and Debris Interceptors DG-1385, Page 34 Distribution of water sources and containment spray between the sumps should be considered in the calculation of boron concentration in the sumps for evaluating post-LOCA subcriticality and shutdown margins. Typically, these calculations are performed assuming minimum boron concentration and maximum dilution sources. Similar considerations should also be included