Melting of the fuel
The dangerous condition that can occur in a nuclear reactor and due to overheating is a nuclear meltdown.
Meltdown
The dangerous condition we know as a meltdown is one wherein the reactor core becomes too hot and fuel rods or plates melt.
Overheating of the reactor fuel rods could damage the zircaloy sheaths and enable gaseous fission products to enter the reactor coolant stream. This alone would not be dangerous, but if a loss of coolant had caused the overheating then this could release activity into the secondary containment. What would follow from this depends on the individual design of the plant.
This sounds like a nuclear core meltdown, reactor meltdown, or just a meltdown.
meltdowngeneration of hydrogen gas when water contacts overheated zirconium alloy on fuel pellets, possible hydrogen explosion (chemical not nuclear)warping of fuel rodswarping of control rods making it impossible to move them to regulate the reactorstructural failuresetc.
Yes, that could be dangerous, especially if combined with or caused by a loss of coolant You are probably looking for either "nuclear meltdown" or "China Syndrome."
In dealing with a nuclear reactor SCRAM stands for Safety Control Rod Activator Mechanism. Nuclear reactors can be quite dangerous.
A nuclear meltdown is an informal term for a severe nuclear reactor accident that results in core damage from overheating. A meltdown occurs when the heat generated by a nuclear reactor exceeds the heat removed by the cooling systems to the point which at least one nuclear fuel plate exceeds its melting point.
A safe reactor don't emit a significant or dangerous quantity of any radiation. But in the core of the reactor all the types of nuclear radiations are emitted.
the level of overheating required for a "melt down" of the nuclear reactor once in operation there.
A Nuclear Reactor.