Where the nuclear fuel rods are housed.
On November 29, 1955, the reactor at EBR-I suffered a partial meltdown during a coolant flow test.
The flow test was trying to determine the cause of unexpected reactor responses to changes in
coolant flow. It was subsequently repaired for further experiments, which determined that thermal
expansion of the fuel rods and the thick plates supporting the fuel rods was the cause of the
unexpected reactor response.