It is still to be determined whether FirstEnergy Nuclear Operating Co. will repair or replace the damaged nuclear reactor head at its Davis-Besse nuclear plant in Ohio, and the Nuclear Regulatory Commission (NRC) has established a special oversight panel to monitor corrective actions and evaluate the readiness of the plant to return to service.

While FirstEnergy has presented a plan to the NRC for a major repair to the plant (see NGI, April 29 ), the decision as to whether repair or replacement will be required has not been made, according to NRC spokesman Jan Strasma. FirstEnergy is still exploring the possibility of getting a replacement reactor head from a mothballed plant or from one which has not gone into service. The company has ordered a new reactor head, but that would not be ready for two years, Strasma told NGI last week. Questioned as to the seriousness of the problem and the corrective action, the NRC spokesman said, “There is definitely a safety concern. This is a big deal. It is very significant.”

There is no danger while the plant is down and the reactor head is off. The problem, if there is one, would come when it restarts, Strasma explained. The special oversight panel composed of management personnel and staff of the NRC will “coordinate the agency’s activities in assessing the performance problems associated with the corrosion damage to the reactor vessel head at the Davis-Besse Nuclear Power Plant, monitoring corrective actions, and evaluating the readiness of the plant to resume operations,” according to the NRC’s announcement Tuesday.

The Davis-Besse plant, located near Oak Harbor, OH, has been shut down since mid-February for refueling and maintenance. While repairing cracks in control rod tubes that penetrate the reactor vessel head, plant personnel discovered corrosion had eaten a cavity through six inches of carbon steel on the top of the reactor pressure vessel, the apparent result of corrosive coolant leakage from the reactor core. Less than half an inch of the reactor vessel’s stainless steel liner remained in the bottom of the cavity. The Nuclear Information and Resource Service, a nuclear watchdog group, said the thin layer of stainless steel was all that was separating the reactor’s highly radioactive and pressurized internal environment (2500 psi) from blasting into the reactor containment building, damaging safety equipment and possibly setting into motion a core melt accident.

The oversight panel will include NRC management personnel and staff from the Region III office in Lisle, IL, the NRC headquarters office in Rockville, MD, and the NRC resident inspector office at the Davis-Besse site. John Grobe, director of the Region III Division of reactor safety, will chair the panel. “The plant will not restart until the NRC is satisfied that all current safety concerns have been resolved… The oversight activities will be conducted under the agency’s Inspection Manual Chapter 0350, which establishes the procedures to be followed for the oversight of utility performance for plants that are shut down as a result of significant performance problems or events,” the NRC said.

The panel will hold public meetings periodically with FirstEnergy representatives in the vicinity of the Davis-Besse plant to review the status of activities associated with the corrosion damage.

In a letter to investors following the NRC’s announcement of the oversight panel, FirstEnergy said delays in its timetable for returning to service in the third quarter could result. The company has secured on-peak energy to replace generation from Davis-Besse through the end of August. Net replacement power costs are expected to be between $10-15 million per month through June, and between $20-25 million per month for July and August.

NRC’s documents on the Davis-Besse inspection are posted on the NRC’s web site at: https://www.nrc.gov/reactors/operating/ops-experience/vessel-head-degradation.html

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