Five cracks found in a reactor head at the only currently operating nuclear plant at V.C. Summer in Jenkinsville are under repair, but S.C. Electric & Gas officials said Monday the company plans to replace the aging vessel head in 2017.
The five cracks, uncovered in inspections last week during a routine plant shutdown, did not penetrate the wall of the reactor head, the utility said, and posed no danger to workers at the site or the public.
Located about 25 miles north of Columbia, V.C. Summer in Fairfield County has been in shutdown – a regularly scheduled outage for maintenance and refueling – since April 4.
The plant undergoes such an outage, which lasts an average of 46 days, every 18 months.
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The five areas SCE&G identified for repair were small and virtually undetectable by normal eyesight, officials with the chief subsidiary of Cayce-based energy giant SCANA Corp. said. They were verified by robotic inspection and ultrasound testing.
“These pre-emptive inspections and repairs are designed to detect and correct even the slightest imperfections to prevent an actual problem,” said James Patrick Flynn, an SCE&G spokesman, in response to questions about the discovery of new cracks. “It is not unusual to detect additional small indications (cracks) after 18 months of operation. The detection technology allows us to catch these tiny indications early before they become problems.”
The discovery and repair of the new cracks are not expected to significantly impact the duration of the maintenance outage, Flynn said.
During an outage at the Summer plant, SCE&G, one of the largest utilities in the state, depends on its other generating facilities to produce electricity for its 678,000 electrical customers.
V.C. Summer’s 966-megawatt reactor has been generating electricity since January 1984. In that time, the SCANA-owned subsidiary said the plant has undergone 21 routine maintenance and refueling outages and would undergo two additional outage shutdowns under the 2017 replacement time frame.
“It’s good to hear they’re going to replace it,” said Tom Clements, an anti-nuclear activist based in Columbia. “And I think that’s an admission that they expect the vessel head to continue to degrade, potentially causing a safety problem.”
Clements, Savannah River Site Watch director, had been critical of the Nuclear Regulatory Commission and SCE&G for not assigning a life expectancy to the time frame the Summer nuclear reactor could be safely repaired once an initial crack is detected.
Clements said the cracks found in the current outage inspection had been anticipated by SCE&G and were a sure sign of aging and damage due to aging that could only be expected to increase with time in the 30-year-old reactor.
SCE&G is building two new reactors at the V.C. Summer plant in a nearly $10 billion project. They are among only a handful of new reactors permitted in recent years. The new reactors will use a different design and are being built in conjunction with Santee Cooper, the state-owned utility. Those reactors are set to go online in late 2017 and 2018, respectively.
“Cracking in the reactor vessel definitely poses a safety risk,” Clements said. “The cracks just discovered do not appear to be all the way through the reactor wall but if not properly repaired could possibly develop into very serious through-wall cracks.”
The ongoing outage inspections are critical, Clements said, because a through-wall leak could portend the uncontrolled release of radioactive water.
“Anyway, I welcome the news that they have finally set a date for when they’re going to replace the vessel head and I hope there’s no through-wall cracking before that time.”
In the fall of 2012, the Summer plant’s previous outage, inspections turned up flaws in four welded holes in the reactor vessel head and those problems were repaired, the company said.
Even before the current inspections, SCE&G said its long-range plans were to replace the reactor vessel head.
“We ordered a new reactor vessel head before the start of our current outage,” Flynn said. “Because of the highly specialized production process, reactor vessel heads take years to be produced.”