Now that Limerick nuclear plant Unit 2 is back up and running after two unplanned shutdowns in less that 36 hours, it seems it is Unit 1’s turn to shut down unexpectedly.
Unit 1 shut down unexpectedly at about 10:15am Friday. The cause is under investigation. Unit 2 shut down due to a faulty turbine valve earlier in the week.
Unit 1 experienced an automatic scram at 10:15am, said Neil Sheehan, a spokesperson for the Nuclear Regulatory Commission (NRC).
“There were no complications during the shutdown, safety systems responded as expected, and the cool down of the reactor is proceeding safely,” Sheehan said.
“Workers were performing testing on plant instrumentation when the Unit 1 turbine tripped offline, automatically shutting down the reactor,” said April Schilpp, senior manager of communications with Exelon Nuclear.
Schilpp and Sheehan said the precise cause of the shutdown was still under investigation.
“Our Senior Resident Inspector went to the plant’s control room immediately after the scram and is independently verifying whether plant operators are following the appropriate steps and procedures. He will continue to gather information on what occurred and the company’s response to it,” Sheehan said.
Unit 2, which returned to service Thursday, was operating at 93 percent power on Friday, the company said.
The company said that there is no risk to the public and that there were no injuries associated with the shutdown.
The two shutdowns this week come at a sensitive time for Exelon Nuclear, which this month is applying to the NRC for an extension of the operating licenses on Unit 1 and Unit 2. If they gain the extensions, the plant will can continue to operate into the 2040s.
Sheehan said Friday’s scram, like the previous incident earlier in the week, will count as a “hit” on one of the agency’s performance indicators for the plant.
“A plant has to have more than three unplanned scrams during that 7,000-hour period to receive increased NRC oversight,” Sheehan said.
The Limerick site’s “unplanned scrams” indicator stood at 0.8 as of the end of the first quarter of 2011.