Accidents Characterization Study Guide
Three Mile Incident
oWhat Happened?
The Three Mile Island nuclear plant had two pressurized light-water
reactors. On March 28, 1979, a cooling malfunction caused part of the
core to melt in Reactor 2. Some radioactive gas was released
oWhere it Happened?
This happened on Three Mile Island in Harrisburg, Pennsylvania
oWhy it Happened?
It happened because of a malfunction and operator error that resulted in
inadequate cooling water circulation to the reactor core causing it to
overheat and suffer a partial meltdown
oHealth Effects
Some health effects included psychological stress, radiation exposure
Chernobyl Accident
oWhat Happened?
On April 26, 1986, the Number Four RBMK reactor at the nuclear power
plant at Chernobyl, Ukraine, went out of control during a test at low-
power, leading to an explosion and fire that demolished the reactor
building and released large amounts of radiation into the atmosphere.
oWhere it Happened?
It happened in Chernobyl, Ukraine
oWhy it Happened?
The Chernobyl disaster occurred when technicians at nuclear reactor Unit
4 attempted a poorly designed experiment. They shut down the reactor's
power-regulating system and its emergency safety systems, and they
removed control rods from its core while allowing the reactor to run at 7
percent power.
