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:
ed acceptable conclusions. The NRC documented its findings in a staff technical evaluation issued in May 2018 (Ref. 24). DG-1385, Page 38 Figure 4 Debris blockage considerations for BWR LOCA sequences (see NUREG/CR-6224, Figure 1-1) LOCA Debris Generation Potential Pipe Break Locations Drywell Debris Transport Wetwell Debris Transport Suction Strainer Blockage Drywell Type (MK I, II, III) Wetwell Type (MK I, II, III) Debris Materials Transported to Strainer Drywell Break Location Debris Pressure Drop (Insulation Dependent) Volume of Insulation Debris Introduced Transient Buildup of Debris on Strainer LOCA Blowdown Transport LOCA-Induced Hydrodynamic Conditions (Chugging and Blowdown) Head Loss Incurred across Debris Bed Break Jet Blast Debris Transport Other Particulates or Material Present Size Distribution of Debris Generated Insulation Types, Locations, Amounts Break Jet Destruction Model Targeted and Destroyed Insulation Type and Volume of Debris Generated Intervening Structures Debris Transport vs. Settling (Turbulence and Intake Effects) NPSH Available versus NPSH Required Latent Debris and Miscellaneous Debris Particulate Transport and Infiltration Debris Transported to Wetwell DG-1385, Page 39 Time > LOCA (Seconds) LOCA Event Progression Debris Generation Drywell Transport Suppression Pool Phenomena Suppression Pool Transport ECCS Response 0 Figure 5 Events that may affect debris blockage for BWR LOCA sequences (see NUREG/CR-6224, Figure B-1) • End of blowdown • ECCS injection commences • Flooded reactor core • Design flow from break • Reactor pressure vessel blowdown • Choked flow and quasi-stead y jet expanding into drywell • High-energy phase • Chugging, condensation oscillation • High-intensity turbulence • Addition of drywell debris • Continued resuspension • Fully mixed conditions • Debris break-up • Pressure equalization • Transport by break flow • Formation of water pool on drywell floor. • Pressure wave • Dynamic