How safe is the Catawba nuclear plant?

Three Mile Island, 1979. Chernobyl, 1986. Fukushima Dai-ichi, 2011.

These nuclear disasters in Pennsylvania, Ukraine, and Japan come up often in conversations about the nuclear industry's growing pains.

That's because each disaster was followed by more research, more standards, and more regulation, according to York County emergency management officials and officials at Duke Energy's Catawba Nuclear Station.

After Japan's current crisis, "the book will be rewritten" again, said Cotton Howell, director of York County's emergency management office, as he thumbs through binder after binder filled with what he calls "living" - or ever changing - emergency planning information.

Inside the binders lie the details of how York County officials would respond to an emergency at the Catawba power plant, located between S.C. 274 and the Catawba River, within miles of most York County residents.

The plan includes how to inform and evacuate residents, plus get school children and even pets into their guardians' care, Howell said.

The federal government requires nuclear plants to notify local officials within 15 minutes of any nuclear emergencies. The emergencies can range in severity, with the least hazardous events including severe weather, earthquakes, and unexpected events such as fires, power loss, or spilt diesel fuel.

The plant is built to withstand these hazards, said Tom Arlow, emergency planning manager at the power plant, which is co-owned by Duke and several municipal power organizations in the Carolinas.

The remaining emergency classifications involve events within the plant that range in severity of threat to the public.

Only once has the plant issue an "alert" - the second lowest of four threat levels. A loose valve in the coolant system came open as the plant heated up and caused a leak of about 10 gallons of water a minute, said Jim Morris, site vice president for the Catawba Nuclear Station.

The event took 13 minutes to resolve, Howell recalled, and there was some question as to whether it warranted an "alert."

The greatest potential threats come from damage to the multiple barriers designed to protect the public from radioactive material.

Efforts to prevent disasters include redundant safety features, on-site inspectors, highly trained staff and security personnel. But despite the plant's track record of no radioactive releases, emergency officials are prepared to deal with worst-case scenarios, Howell and Morris said.

Howell criticized a California nuclear plant official who said on television that a disaster like Japan's could never happen at his nuclear power plant.

"If you'd talked to Tokyo Power a week before March 11, they'd have said the same thing."

Emergency planning

Throughout the year, plant and county staff run emergency drills for different scenarios, Arlow said.

Every other year, a team of more than 40 federal inspectors evaluate local and state agencies and plant personnel on their ability to handle a nuclear disaster, Howell said. Hospitals are periodically evaluated on how they can handle contaminated patients.

A system of 88 sirens in York, Gaston, and Mecklenburg counties are the first alert for residents. In the event of a real emergency, the siren will repeat several times. Residents should turn to local media for further instructions, which may include seeking shelter or evacuating.

Outside of quarterly tests, the system has been used only five times in the last 30 years for tornado warnings, Howell said. The next test is scheduled for April 13 at 11:50 a.m.

The county also has an evacuation plan, which includes procedures for schools. Local media would help communicate safety routes and shelters.

Emergency workers would help direct traffic toward shelters and scan those arriving for contamination.

Potassium iodide helps prevent the thyroid gland from absorbing radioactive iodine. Tablets are available through county health departments at no cost to residents living within 10 miles of a nuclear plant.

During an emergency, the county will also provide transportation and other services for residents with special needs.

The Catawba plant

The Catawba Nuclear Station, which came online in 1985, provides more than 2,000 megawatts of electricity to residents.

A maze of steel-reinforced concrete, the plant was designed to withstand tornados, floods, and earthquakes that register more than 7.3 on the Richter scale. That was the size of Charleston's 1886 earthquake.

But Howell said a lot of the standards used to design nuclear plants to withstand earthquakes are based on theory. The Japanese earthquake will provide more data to evaluate those standards.

In addition to numerous automatic emergency shut-down features, the plant has diesel generators that can pump water from the Catawba to cool reactors in the event of a loss of power.

Among the nation's 104 plants, Catawba ranks 22nd in risk of damage from an earthquake, with a 1 in 27,027 chance each year, according to a report by MSNBC.

Nuclear reactions in the reactor core heat water to about 600 degrees Fahrenheit. That water generates steam that powers giant turbines to create electricity.

The Catawba plant has two pressurized water reactors as opposed to boiling water reactors - the other popular type of reactor.

A boiling system circulates water from the reactor, where it's heated and becomes radioactive, to a steam generator located outside of the reactor containment area.

A pressurized system keeps the radioactive water circulating inside the building that houses the reactor, providing more layers of protection between radioactive material and the public, Howell said.

Radioactive fuel assemblies are used three times for 18-month periods each before being retired. Fuel assemblies stacked 13 feet high are stored in a 40-foot pool until cool enough for dry-cask storage, where they'll stay indefinitely under close monitoring.

If the plant lost its ability to cool the pool, the water would be boiling within 12 hours, said Steve Putnam, safety assurance manager for the Catawba Nuclear Station.

Nuclear reporting

As part of a highly regulated industry, all nuclear power plants must share "reportable events" with the U.S. Nuclear Regulatory Commission. Most events are routine, according to the NRC website.

The Catawba station reported several events in the 1980s, when the plant was beginning operation, Howell said.

Over the years, the number of reported events have dropped dramatically. The plant reported fewer than 20 in the last five years.

The plant has been cited only three times by the commission.

NRC documents show that in 1998, operators did not take appropriate steps to address a low-flow problem with an air system. In 1999, two breakers were left off after maintenance, rendering a back-up shut-off system inoperable for about two weeks. In 2005, the plant provided inaccurate reporting in connection with the testing of mixed oxide fuel, which contain weapons grade plutonium.

In all three incidents, the commission found that the violations weren't intentional and that officials took appropriate actions to correct the issues.

Jamie Self 803-329-4062

This story was originally published March 27, 2011 at 12:00 AM with the headline "How safe is the Catawba nuclear plant?."