energy
Gösgen nuclear plant back online after automatic shutdown
Gösgen nuclear power station in Solothurn was reconnected to the grid after an automatic reactor shutdown during a functional test. The plant operator says safety systems responded as intended and that no additional radioactivity was released; output is being gradually restored.
Gösgen was back on the Swiss grid by Tuesday evening, hours after an automatic shutdown halted its reactor during a functional test. The plant in the canton of Solothurn was resynchronised at 5.50pm, operator Kernkraftwerk Gösgen-Däniken AG announced. Output is now being increased gradually towards full capacity.
The shutdown happened at 6.40am on Tuesday, October 20, when an undervoltage on the control busbars triggered an automatic reactor scram. The operator said the plant’s safety-related systems responded as intended and that the event caused no additional release of radioactivity.
The restart followed authorisation from the Swiss Federal Nuclear Safety Inspectorate, known as Ensi. That approval cleared the way for the plant to reconnect to the grid. Gösgen’s return marks the shift from an automatic shutdown to a controlled restoration of output, with the operator increasing production step by step.
Trace the shutdown to the test
An undervoltage on the control busbars triggered the shutdown during a functional test on Tuesday morning. The plant operator said the resulting automatic reactor scram took place at 6.40am. A reactor scram is the rapid shutdown of a reactor, initiated automatically in this case after the electrical condition was detected.
The operator said all safety-related systems responded as intended. It also reported that the shutdown caused no additional release of radioactivity. Those statements describe the plant’s response to the event and its reported radiological outcome.
The functional test was under way when the undervoltage occurred. Gösgen remained disconnected from the grid until Tuesday evening, when the plant was resynchronised at 5.50pm. The event therefore took the station from a morning shutdown to a same-day return to the grid, followed by a gradual increase in output. The operator’s account identifies the control busbar voltage as the cause of the automatic shutdown.
Secure regulatory clearance
Ensi authorised Gösgen’s restart before the plant was reconnected to the grid on Tuesday evening. The Swiss Federal Nuclear Safety Inspectorate’s approval came after the automatic shutdown, allowing the operator to bring the station back online.
The plant’s reconnection at 5.50pm was followed by a gradual increase in output. Kernkraftwerk Gösgen-Däniken AG said production is being raised towards 100%, rather than restored all at once. The sequence places the regulator’s authorisation before the return to grid operation and the ongoing ramp-up.
For Solothurn, the development means the Gösgen station has resumed supplying electricity after the interruption caused by the morning’s functional test. The operator’s report says safety-related systems worked as intended during the shutdown and confirms no additional radioactivity was released. The station’s output will continue to rise as the operator carries out its stated gradual restoration.