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:
-16 CAP head available hatm Time from LOCA ht hvp hmin hatm CAP head available Time from LOCA ht hvp hmin Figure B-8 Illustration of “hatm” and “CAP head available” for Tpmax > Tsat Figure B-9 Illustration of “hatm” and “CAP head available” for Tpmax < Tsat DG-1385, Appendix B, Page B-17 Table B-1 Comparison of Symbols and Definitions in NEDC-33347P-A/NEDO-33347-A, Revision 2, and Figure B-7 Variable NEDC-33347P-A/NEDO-33347-A, Revision 2, Symbol or Definition Symbol or Definition from Figure B-7 NPSH versus time NPSH as a function of time (Note 1) Transient NPSH Wetwell (for BWRs) and sump pool (for PWRs) airspace pressure (psia) Pww is called “available wetwell pressure” in Appendices A and B, in psig. ht (Note 2) Saturation vapor pressure at pool temperature (psia) Pv hvp (Note 2) Density of pool water (lbm/ft3) ρw Not defined; assumed to be included in the pressure head values. Absolute pressure head available above pool surface for NPSH analysis to determine CAP Included in Pww term; called “available WW pressure” in Appendices A and B, in psig hatm (Note 2) Assumed minimum absolute pressure head above pool surface during normal operation The containment (drywell/wetwell) initial pressure is at its minimum value (NEDC-33347P-A/ NEDO-33347-A, Revision 2, Section 3.1). hmin (Note 2) Transient pool temperature during accident Suppression pool temperature; included in the Pv and ρw terms (Note 3) Tp Saturation temperature at hmin Not used Tsat Peak pool temperature during accident Maximum suppression pool temperature, included in the Pv and ρw terms (Note 3) Tpmax Elevation of pool surface above the pump suction (ft) Hpool Included in the NPSHa term Elevation of pump suction (ft) Hpump Included in the NPSHa term Suction strainer and suction line losses from pool to pump (ft) Hloss Included in the NPSHa term CAP available in NPSH analysis Available wetwell pressure (assumed absolute initial wetwell pressure above pool surface) (hatm −