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:
greed that no further action was required. This was documented in the NRC letter entitled “Closure of Potential Issues Related to Emergency Core Cooling Systems Strainer Performance at Boiling Water Reactors,” dated June 29, 2018 (Ref. 23). The BWROG analysis included an evaluation of the potential for in-vessel effects. The NRC staff reviewed the BWROG work and determined that it had reached acceptable conclusions. The NRC documented its findings in a staff technical evaluation issued May 2018 (Ref. 24). Safety analyses, including analyses of debris transport in and to the suppression pool, should include the effects of the LOCA progression, because LOCAs of different sizes will affect the duration of LOCA-related hydrodynamic phenomena (e.g., condensation oscillation, chugging, and blowdown). These phenomena and long-term recirculation hydrodynamic conditions will affect the transport of debris in the suppression pool. Debris that is transported to the suppression pool during a LOCA or that is present in the suppression pool before a LOCA could block or damage the suction strainers; head loss effects should therefore be evaluated through prototypical strainer testing. (See Information Notice (IN) 94-57, “Debris in Containment and the Residual Heat Removal System,” dated August 12, 1994 (Ref. 25); IN 95-06, “Potential Blockage of Safety-Related Strainers by Material Brought inside Containment,” dated January 25, 1995 (Ref. 26); and IN 95-47, “Unexpected Opening of a Safety/Relief Valve and Complications Involving Suppression Pool Cooling Strainer Blockage,” dated October 4, 1995 (Ref. 27).) The strainer testing methodology should be similar to that used for the resolution of GSI-191 and GL 2004-02, as discussed in Section C.1.3 of this guide. The head loss evaluation should consider the filtration of particulate, fibrous, chemical, and coating debris by the accumulated debris bed. The head loss characteristics of a debris bed depend on the types and