A couple of Event Reports on the NRC website today have a common thread: Reactors that were shut down earlier in the week failed to work properly when operators attempted to restart them:
1. As I told you yesterday, Unit 3 at the Browns Ferry nuclear power plant in Alabama experienced an automatic reactor trip Tuesday after losing a 500 KV power source. Yesterday morning, operators were attempting to restart the aging GE Mark I reactor when they received indications that a number of control rod assemblies were inserting themselves into the reactor. Technicians scrammed the reactor manually at that time.
2. Monday afternoon, there was a reactor trip in Unit 1 at the River Bend nuclear power plant in Louisiana, followed by a small fire in a manhole containing cables for the reactor. Yesterday evening, operators were attempting to restart the unit when they noticed an electrical transient in the Control Room when they attempted to start one of the Reactor Feed Pumps. The operators manually scrammed the reactor from 33 per cent power. Following the scram, a report from the Turbine Building indicated smoke in the Reactor Feed Pump ‘B’ cabinet. The plant Fire Brigade responded, but did not find a fire. Subsequent investigation found damage to cabling and circuit boards in the Turbine Room. The plant’s Technical Support Center and Operations Support Center lost power during the event. One switchgear remains out of service as of today’s report.