The damage could have been repaired with a large investment but on May 17, 1979, the government, dissatisfied with high costs, low performance and accidents, decided to decommission the plant.
Seventy metal uranium wires, each clad in a compound of magnesium and beryllium, are bundled together to form a fuel rod.
On February 22, 1977, during a fuel change, a combination of human mistakes and design problems caused the worst nuclear accident in Czechoslovak history.
In this instance however humidity absorbers covering the rods were not removed, causing local overheating of the fuel (since transmission of heat to the coolant gas was reduced).
The active zone was damaged, heavy water came into contact with the coolant and both primary and secondary circuits were contaminated.
25% of the fuel elements in a heavy water moderated carbon dioxide cooled 100 MW(e) power reactor were damaged due to operator error.
The silica gel pellets blocked the flow of the coolant resulting in overheating of the fuel and the pressure channel holding it.
Through leaks in the steam boilers (similar basic design to a MAGNOX or AGR plant) some parts of the secondary circuit became contaminated.