Transient & Accident Safety Analysis


Each time, a change is made to a nuclear power plant, the licensee must evaluate whether an unreviewed safety question exists. The law that governs this is referred to as 10 CFR 50.59. If an unreviewed safety question exists, the licensee must obtain NRC permission to perform the change. This law also applies to certain tests.

Every year the licensee also must submit to the NRC an update of all facility changes performed within the year for which NRC approval was not needed.

Each cycle, the licensee must re-analyze the impact of various types of transients and accidents. The reason these studies are done each cycle is that the fuel characteristics may change; thus the different types of accidents and transients could affect the fuel differently. Some of the typical transients and accidents analyzed are reported in Section 14 of the Nuclear Power Plants' Final and Updated Safety Analysis Reports. Examples include:

  • Loss of Feedwater
  • Anticipated Transients without Scram
  • Bypass of the feedwater heaters
  • Small Break Loss of Coolant Accident (SB-LOCA)
  • Large Break Loss of Coolant Accident (LB-LOCA)
  • Rod Ejection Accident
  • Fuel Handling Accident (Spent Fuel Area)
  • Fuel Handling Accident (Containment)
  • Rupture of Steam Pipe (Large/Small)
  • Environmental Consequences of LOCA
  • Long Term Cooling following LOCA
  • Dilution events
  • Subcriticality Events
  • Steam Generator Tube Rupture (PWR only)
  • Uncontrolled rod withdrawal (subcritical/at power)
  • Loss of Reactor Coolant Flow
  • Loss of all AC Power
  • Control rod misalignment
  • Chemical and Volume Control System Malfunction
  • Startup of an Inactive Reactor Coolant Loop
  • Loss of External Electrical Load
  • Accidental Release of Radioactive Liquids
  • Accidental Release of Waste Gas

Copyright 1996-2006. The Virtual Nuclear Tourist. All rights reserved. Revised: December 21, 2005.