Editorial

Tighten up

A maintenance lapse at a Progress Energy nuclear plant demands a serious response.

February 4, 2012 

Raleigh-based Progress Energy generates about a quarter of its electricity from four nuclear power plants in three states. Although the utility's Shearon Harris plant in southwestern Wake County appears to be well-run, the same can't be said of other Progress Energy nuclear facilities.

In a particular fix is its Crystal River plant in Florida's Citrus County, out of action for over two years following a botched steam generator replacement project. According to The Tampa Bay Times, "The result was three cracks in the reactor's concrete containment building, which has kept the plant offline since fall 2009." Repairs and other work may take until 2014.

An N&O news story last year said Progress' H.B. Robinson plant near Hartsville, S.C., "ranks among the three worst-performing nuclear plants in the nation" due to shutdowns caused by small fires and malfunctions.

The fourth facility, the two-unit Brunswick Nuclear Plant near Southport, in mid-November experienced an "unusual event" - the lowest of the Nuclear Regulatory Commission's four levels of emergency classifications - that the NRC traces to seriously mishandled maintenance.

No one's health or safety was endangered, but the incident, detailed below, was troubling. Clearly, Progress Energy - or Duke Energy, when it completes its in-the-works merger with Progress - needs to ramp up training and do more to safeguard maintenance operations against error.

The Nov. 16 shutdown at Brunswick's Unit 2 was caused by a coolant leak from a pressurized vessel that produces steam. Mildly radioactive water flowed out of the chamber rather than boiling inside. At one point, according to an N&O account, "the water was flowing out at a rate of over 10 gallons a minute, about 100 times more volume than would flow out under normal circumstances."

Why? Because, an NRC team found, maintenance personnel failed to properly tighten certain head studs, bolt-like devices. Lack of training caused the crew to assume, incorrectly, that instrumentation linked to a stud tensioning machine was displaying a factor of 10 times the actual pressure, said a report in the Wilmington Star-News.

As a result, according to the NRC, "instead of pressurizing the tensioning device to 13,000 psi, the team actually pressurized the device to 1,300 psi." Later, Progress Energy personnel were "able to rotate 8 nuts by hand, 10 nuts by wrench with no agitation, 31 nuts by wrench and agitation, and 15 nuts by wrench with additional agitation," the NRC said.

Got that? Those investigating the leak were able to turn some of the nuts on a reactor pressure vessel by hand. That's not tight enough for a tire change.

The NRC said nine of the 12 workers on the reassembly job were not qualified for the task. Agreed, nuclear power plant operation and maintenance is highly technical. No one involved meant to cause harm. And nuclear power is a relatively clean source of "baseload" electricity. But just as surely, incidents and accidents at nuclear plants can have huge consequences. At a minimum, training deficiencies are staring Progress Energy officials in the face.

The Nov. 16 incident is said to be the only one of its type yet recorded in the United States. Make sure it stays that way.

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