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:
t, spray transport, washdown transport, and transport within the containment pool. Consideration of containment pool debris transport should address (1) debris transport during the pool fill phase, as applicable, and during the recirculation phase, (2) the velocity and turbulence in the sump, suppression pool, or storage tank (i.e., turbulence caused by the flow of water to the ECCS strainers, water splashing down from the break, containment spray drainage, and the discharge of pressure-relief flowpaths such as from downcomers, vents, and safety/relief valve spargers), and (3) the density, characteristic size, and other properties of the debris. Section 3.2.3 of the SE for NEDO-32686-A (the URG) and Section 3.6 of the SE for NEI 04-07 discuss staff-accepted methods to evaluate debris transport. NUREG/CR-6369, “Drywell Debris Transport Study,” issued September 1999 (Ref. 43), is also a useful reference for debris transport evaluations. Section 3.6.4 of NEI 04-07 contains a sample calculation for debris transport that the staff finds acceptable. 1.3.4.2 Transport analyses within the containment pool should include debris that may be transported through the following modes: (1) floating along a water surface, including debris that may DG-1385, Page 25 float temporarily because of air entrapment, (2) traveling with the containment flow (i.e., debris suspended within the flow) because of neutral buoyancy or turbulence (e.g., individual fibers and fine particulates), and (3) settling to the floor and tumbling along the floor to reach the strainer. 1.3.4.3 The debris transport analyses should consider each type of insulation (e.g., fibrous, calcium silicate, and reflective metallic), as well as other debris such as chemical precipitates, coatings, and latent debris. The debris size (e.g., fine, readily suspendable, small, large, or intact) should also be considered. The analyses should also consider the potential for further decomposition of the debris as it is