Regulators to look at Oconee Nuclear Station weld crack

Greenville NewsJuly 18, 2014 

The three containment units at Oconee Nuclear Station house the nuclear reactors and steam generators.

TIM DOMINICK — tdominick@thestate.com Buy Photo

The Nuclear Regulatory Commission staff has scheduled a regulatory conference with officials of Duke Energy for July 31 to discuss an apparent violation of NRC requirements.

The apparent violation involved a crack in a weld on the Unit 1 high pressure injection system at the Oconee Nuclear Station near Seneca about 30 miles west of Greenville, according to the NRC.

GreenvilleOnline.com first reported in November the shutdown of Unit 1 after a leak was discovered in what Duke Energy described as the reactor's containment building.

“On Nov. 11, 2013, the licensee (Duke Energy) determined that a leak in the 1B2 high pressure injection line was pressure boundary leakage. Unit 1 was subsequently shutdown as required ... ,” according to an NRC document.

“Your measures failed to identify and correct a significant condition adverse to quality involving a crack in a weld located in the Unit 1 High Pressure Injection (HPI) system,” according to the document addressed to Duke Energy.

NRC and Duke Energy officials will discuss the safety significance of the apparent violation related to an undetected crack in a weld that led to reactor coolant system pressure boundary leakage and a forced shutdown of Unit 1, NRC officials said.

The weld was located in the high pressure injection system that would provide water to help cool the reactor core during an accident if pressure in the system remained high, according to the NRC.

There was no immediate safety concern because the crack was repaired, but the NRC determined that the method used by the plant to check for cracks didn’t provide acceptable coverage as required and did not identify the crack before it began leaking.

The regulatory conference is scheduled for 9 a.m. in the NRC’s Region II office at 245 Peachtree Center Ave., NE, Suite 800, Atlanta. The meeting is open to the public, and NRC officials will be available to answer questions after the meeting.

The apparent violation has preliminarily been classified as “greater than green.” The NRC evaluates regulatory performance at commercial nuclear power plants with a color-coded system which classifies findings as green, white, yellow or red, in increasing order of safety significance.

No decisions on the final safety significance or any additional NRC actions will be made at the regulatory conference, NRC officials said.

Those decisions will be made by NRC officials later.

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