Nuclear Reactors 25 - Cracks at Shearon
The operators of the Shearon Harris nuclear plant near New Hills, North Carolina have announced that a quarter inch crack was found in a reactor sensor. The operators said that there was no evidence that any radioactive materials had leaked and they shut the plant down to be on the safe side. They did not know how long it would take to repair the crack but insisted that they had plenty of electrical capacity in the area and it would not be necessary to purchase external power. Not operating the reactor could cost Duke Energy up to one million dollars a day.
So far, this sound fine. A problem was found and is being dealt with before it poses a public risk. Unfortunately , when you drill a little deeper, the situation becomes more complex. When Duke took the reactor offline for refueling a year ago, ultrasonic scans were made of the system. Now they report that “secondary review” of the ultrasonic scans just revealed “primary water stress corrosion cracking on a temperature sensor near where cooling rods attach to the reactor head.” So here is a question. Did they know about what the scans revealed a year ago? If they did, why did they wait to take action? If they didn’t, why did they wait for a year to check ultrasonic scans of critical components in the reactor? They did say that there were inspections of the top of the reactor during the refueling that did not reveal any leakage. If they were inspecting, why would they not look at the ultrasonic scans taken at the same time?
Any crack in the reactor shell could eventually widen into a leak. A leak at the location of the identified crack could have allowed coolant to escape from the system. If sufficient coolant leaked out, the reactor could have been at risk for a meltdown. In such a case, release of radiation would be very probable. Either Duke did not report a potential problem or they were not diligent enough when they were refueling the system.
The Nuclear Regulatory Commission is sending someone to the power plant to question the operators. There will be a public Question and Answer session. Apparently this particular problem with cracks in sensors is not new. It has been known to be a possibility for over ten years. The U.S. nuclear fleet is aging and it is important that a close watch be kept for appearance of common problems. At the very least, Duke procedures for inspecting reactors need to be reviewed and improved.
Duke Energy acquired the Crystal River nuclear plant in Florida recently. The reactors at the plant were shut down in 2009 because serious cracks were discovered and have not been restarted. Duke has announced that it may shut Crystal River permanently. How many more reactors can Duke afford to shut down before It loses enough money to drop its involvement in the nuclear industry? And what will happen to those reactors that have to be decommissioned and the existing waste that must be disposed of if Duke does leave the business and cannot find buyers for the reactors? Will the taxpayers be left with a bill in the billions of dollars?
