PSY/CS330 Human Factors
04/30/2001
Day 1-4
Detailed Description of Three-Mile Island
u4:00 am, March 28, 1979
uMain feedwater pump stops due to a polisher blocking coolant flow
ldue to resin build up.
lResulting Hardware Effects and Actions:
uElectrical generators and turbines shut down.
uTemperature of water in the reactor rises.
uPressure in reactor water builds and escapes from relief valve.
ucontrol rods automatically drop stopping the nuclear reactions.
uemergency feedwater pump starts
lThis should have been a mild failure - unworthy of news attention.
The hardware effects and actions were expected and normal.  All started out according to plan expected by the engineers- it was humans who stepped in and messed up the system.  But why they stepped in is understandable as will be seen below.