The Unit 2 reactor at the Byron nuclear power plant in Illinois has been shut down since January 31, following a loss of offsite power incident. On Monday of this week, repairs had been completed, and operators were attempting to power up the reactor.
During startup, there was a problem with steam turbine pressure, which resulted in a turbine trip. Since the reactor was at less than 30 per cent power, no automatic reactor trip occurred. Because of the pressure increase, the Byron control room staff entered emergency procedures and scrammed the reactor.
Byron did not tell the NRC how long they thought the unit would be out of service.