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:
A • chemical reaction products generated within the containment or the reactor vessel Licensees1 should evaluate debris generation, debris transport, upstream and downstream effects, and blockage of ECCS strainers to ensure that they do not jeopardize the ability of the ECCS to provide long-term post-LOCA core cooling. Licensees should evaluate all potential debris sources, including, but not limited to, insulation materials (e.g., fibrous, particulate, and metallic), fire barrier materials, filters and other fiber-bearing materials, latent debris, shielding blankets, corrosion products, chemically reactive materials and their reaction products, and paints or coatings. Section C and Appendix A to this guide provide relevant information for such evaluations. Further information appears in NUREG/CR-6808, “Knowledge Base for the Effect of Debris on Pressurized Water Reactor Emergency Core Cooling Sump Performance,” issued February 2003 (Ref. 6), which summarizes research conducted before 2003 on BWR and PWR ECCS suction strainers. The NRC issued an updated report, NUREG/CR-7172, “Knowledge Base Report on Emergency Core Cooling Sump Performance in Operating Light Water Reactors,” in January 2014 (Ref. 7). More recent technical guidance appears in an NRC letter to the Nuclear Energy Institute (NEI), entitled “Revised Guidance for Review of Final Licensee Responses to Generic Letter 2004-02, ‘Potential Impact of Debris Blockage on Emergency Recirculation during Design Basis Accidents at Pressurized-Water Reactors,’” dated March 28, 2008 (Ref. 8), and in the memorandum “U.S. Nuclear Regulatory Commission Staff Review Guidance for In-Vessel Downstream Effects Supporting Review of Generic Letter 2004-02 Responses,” dated September 4, 2019 (Ref. 9). It is desirable to use ECCS suction strainers to protect the pump inlets from debris that may block restrictions in the systems served by the ECCS pumps or damage components. Suction strainers are passive