Duke Energy Progress shut down the Shearon Harris nuclear plant in Wake County on Wednesday after the company discovered that the reactor vessel – which holds the plant’s nuclear fuel and contains the nuclear reaction – showed early indications of corrosion and cracking.
The Nuclear Regulatory Commission reported Thursday morning that plant officials made the discovery earlier this week during a review of ultrasonic data that had been recorded in spring 2012.
The year-old data showed a one-quarter-inch flaw in the reactor vessel head, the term for the lid that is bolted on top of the vessel to maintain superheated water under high pressure.
It’s not clear why it took Progress a year to discover the corrosion, a question the NRC will attempt to answer in its review of the incident. General concerns about vessel head corrosion increased in the wake of the discovery in 2002 of a grapefruit-size cavity in the reactor vessel of the Davis-Besse Nuclear Power Station in Ohio, which is owned by FirstEnergy Corp. Continue reading