10/12/02

In a potentially serious new development, inspectors have found rust stains where they had not found them before - on the bottom of the Davis-Besse nuclear reactor.

For the last seven months, officials at Davis-Besse and the Nuclear Regulatory Commission have been focused on rust on the reactor's lid - where leaking nozzles that passed through the lid ate a dangerous, footprint-sized hole.

Rust at the opposite end of the reactor could mean that nozzles there may also have been leaking and causing corrosion in recent years.

If laboratory tests now under way show the nozzles are cracked and that reactor coolant has been seeping out, repairs could pose another major obstacle to restarting the facility, which has been shut down since February.

FirstEnergy Corp., owner of the damaged power plant near Toledo, said yesterday a contractor inspecting the bottom of the reactor discovered what appeared to be boric acid deposits and rust stains on the reactor's side and near some of the 52 nozzles, or tubes, that carry instrument wiring through the base of the vessel.

The instruments monitor the nuclear reaction in the reactor's core.

The light residues, called "trailings," may have formed when workers spray-washed the reactor's lid during refueling shutdowns in the 1990s, said company spokesman Todd Schneider.

Or they might be tell-tale evidence of cracks in the instrument nozzles, which are made of the same nickel alloy as those in the lid.

"We don't believe there is any leaking from those nozzles," said Schneider.

Federal regulators, who learned of the situation this week, are taking a wait-and-see approach.

"There is no evidence at this point to show that they have leakage," said Jan Strasma, spokesman for the Nuclear Regulatory Commission.

"I would not say the situation is serious at this point," he said. "It's too soon to know." The agency has asked FirstEnergy to submit a written report early next week, Strasma said.

Boric acid, normally in the reactor's coolant to help enable nuclear fission, leaked through cracks in the reactor's lid nozzles over several years and ate a large rust hole through the 6½-inch steel lid - leaving only a thin stainless steel liner to contain the reactor's radioactive coolant.

An inspector scraped samples of the residue from 12 of the bottom nozzles in an attempt to determine whether the corrosion ran down from the lid or leaked from a bottom nozzle. Some of the test results were inconclusive, and further analysis has been ordered.

The inconsistent lab results do "not necessarily show a leak," Schneider said. "It could be just the way the concentration of boric acid built up, or the way the reactor head was cleaned at one time.

"I wouldn't call it rust. It's more like staining, like washing a black car with well water."

Though the bottom nozzles are made of the same material as those that cracked in the lid, the lower nozzles are not subjected to temperatures as high as 600 degrees, Schneider said.

"The temperature is much cooler, making these nozzles less susceptible to cracking," he said.

However, neither the industry nor the NRC fully understands how the stress cracks form. Research is ongoing.

FirstEnergy's contractor wrote a brief account of the initial inspection of the reactor bottom after the stains were found on June 30. A second summary was written on Sept. 30.

While available to the agency, these so-called condition reports are not formally submitted to the NRC, Strasma said. More than 7,000 such reports have been compiled by workers and inspectors this year.

The NRC has created a special committee to determine whether FirstEnergy's repairs to the reactor and reforms of its management are sufficient to allow the plant to restart.

The company has pushed back its deadline to have the plant ready for restarting until "early next year." But the NRC has final authority.

To reach these Plain Dealer reporters:

jfunk@plaind.com, 216-999-4138

jmangels@plaind.com, 216-999-4842