Auxiliary Feedwater (AFW) System

The AFW is used in all pressurized water reactor designs. The main purpose of the AFW system is to provide feedwater to the steam generators to maintain a heat sink in the event of (1) a loss of main feedwater, (2) a reactor trip and loss of offsite power, and (3) a small break loss of coolant accident. The system, at some plants, can also provide a source of feedwater to the steam generators during plant startup and shutdown. However, the system cannot supply sufficient feedwater flow during power operation. At most plants, the system can only supply adequate feedwater to the steam generators with steam loads less than 5% of rated flow.

The initial system study is documented in "Auxiliary/Feedwater System Reliability, 1987-1995" (NUREG/CR-5500, Volume 1 ). The links below provide the current information for the study and latest results.

Current Results (SPAR-based):

• AFW 2022 Summary Update

Historical Results (SPAR-based):

• AFW 2020 Summary Update
• AFW 2018 Summary Update
• AFW 2016 Summary Update
• AFW 2014 Summary Update
• AFW 2013 Summary Update
• AFW 2012 Summary Update
• AFW 2011 Summary Update
• AFW 2010 Summary Update
• AFW 2009 Summary Update
• AFW 2008 Summary Update
• AFW 2007 Summary Update
• AFW 2006 Summary Update

Historical Results (LER based):

• AFW 2005 Summary Update
• AFW 2004 Summary Update
• AFW 2003 Summary Update
• AFW 2002 Summary Update
• AFW 1995 Executive Summary  (from original NUREG)
• "Auxiliary/Feedwater System Reliability, 1987-1995" (NUREG/CR-5500, Volume 1 )

Supporting Information:

• AFW System Description
• AFW System Fault Tree