 INES 0 |
Core instability occurred during maintenance performed in the switchyard |
During maintenance, performed in the switchyard, a false signal showing "generator disconnected" was transmitted to the power control system. As the signal aspect was considered unclear, partial scram (one group of control rods inserted) was manually started. However, depending on faulty reheater control, the feed water temperature dropped, leading to increasing reactor power.
As a result of decreasing recirculation flow and decreasing feed water temperature the power level became oscillating. About 18 seconds after start of the oscillations the reactor was tripped automaticlly depending on high neutron power. All safety systems functioned as expected.
Justification of Rating: None
Event date: Thu, 25-02-1999
