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:
bulent pool dynamics, gradually decreasing turbulent intensity • Increasing height • Depressurization and cooldown of cont. • Vapor flow velocity btwn compartments minimal • Sprays form a thin liquid film on struct. • Generation by erosion/corrosion • Paint chips and delaminating • Pool starts forming • Thin sheets of fast moving water • LPSI inject • Ramps to design flow • Design flow out of the break • Borated water (2,000 ppm) • Cont. sprays terminated in large dry (at 2 hours) • Fan coolers operate • Switchover to sump (t < 1800 s) • Cooldown of cont. • Licensing issues • Several pool turnovers • Low turbulence • Hot-leg injection End Injection 100 1,000 10,000 • Transport to sump strainer • Accumulation • Suction from sump • RHR heat exchanger (H-X) • Flow through sump • Recirculation flow patterns • Steady pool height 0 DG-1385, Page 37 3. Regulatory Positions Specific to Boiling-Water Reactors Evaluations of the susceptibility of a BWR to debris blockage should address the considerations and events shown in Figures 4 and 5. These figures are from NUREG/CR-6224, which gives more detail on the information in the figures. The URG and the associated NRC staff SE (Ref. 19) contain additional guidance. 3.1 Suppression Pools and Debris Interceptors 3.1.1 For the purposes of evaluating strainer performance, licensees should assume that the level of water in the suppression pool or wetwell is the minimum value given in the technical specifications, reduced by the drawdown caused by suppression pool water in the drywell and the sprays. 3.1.2 Debris interceptors in the drywell in the vicinity of the downcomers or vents may reduce debris transport to the suppression pool. Debris interceptors between the drywell and wetwell should not reduce the suppression capability of the containment. 3.2 Debris Sources, Generation, and Transport 3.2.1 Licensees should assume the amount of particulates in the suppression pool before