The NRC’s confirmatory action letter is designed to address issues that contributed to the March 12 discovery of cracks and leakage in multiple Control Rod Drive Mechanism (CRDM) nozzles. The CRDM nozzles guide the control rods into the reactor core to shut down the reactor.
- Source NRC -
The Nuclear Regulatory Commission today sent a Confirmatory Action Letter to FirstEnergy Nuclear Operating Co. (FENOC) committing the company to actions needed to assure the NRC that FENOC can safely restart the Davis-Besse Nuclear Power Station. The plant is located in Oak Harbor, Ohio about 40 miles southeast of Toledo.
The NRC’s confirmatory action letter is designed to address issues that contributed to the March 12 discovery of cracks and leakage in multiple Control Rod Drive Mechanism (CRDM) nozzles. The CRDM nozzles guide the control rods into the reactor core to shut down the reactor. The letter details and confirms FENOC’s agreement to take certain actions in response to the identified cracks. Issues associated with the cracks are being reviewed by the NRC and the agency’s special inspection team.
The Davis-Besse commitments include:
• Shutting the plant down no later than October 1, 2011 and replacing the reactor head with a newly manufactured reactor head before returning to operation
• Providing technical information regarding the time at which the next inspection of the existing reactor head would be required, based on reactor head temperatures, regardless of the 2011 planned shut down
• Providing a sample of the CRDM nozzles to the NRC for independent crack analysis
• Strengthening its leakage monitoring procedures
“The Confirmatory Action Letter will allow the agency to have a clear set of commitments and expectations and ensures the utility understands the NRC must have confidence for them to continue to safely operate the plant,” said NRC Region III Regional Administrator Mark Satorius. “Replacing the reactor head is a substantial action which will provide increased assurances that the people and the environment remain safe. However, we will not hesitate to shut down or place additional restrictions on the plant if necessary.” The NRC also determined that, based upon a review of the information to date, the current reactor head is suitable for operation at least through October 1, 2011. Specifically, the special inspection team determined the nozzle examinations conducted by the utility were comprehensive and satisfactorily identified which nozzles needed to be fixed and that the subsequent repairs met the strict regulatory requirements for placing the head back into service. The NRC’s independent evaluation of the crack growth rate also provided assurance of a low probability of leakage through the shut down date. The commitment to replace the reactor head in 2011 also addresses NRC concerns regarding the uncertainties for new cracks and the rate at which new cracks could grow. Additionally, the NRC has reasonable assurance that, while highly unlikely, if cracks were to develop, the structural integrity of the reactor head would be maintained at least until the 2011 shut down.
Although there is some additional analysis and information required from the utility, the NRC has been provided with reasonable assurances that there will be no undue risk to the health and safety of the public prior to the replacement of the reactor head. Therefore, the NRC’s focus will continue to remain on the corrective actions, root cause of the problems and continued safe operation of the plant.
The March 12 discovery occurred while plant workers were conducting an NRC required inspection of the reactor head and found early indications of cracks in the CRDM nozzles. There was no danger to the public from these cracks. The plant was shut down in a refueling outage when the problem was identified. In total, the utility repaired 24 CRDM nozzles. The NRC is providing oversight on the issue and is independently assessing the utility’s actions.
Though a date has not yet been set, the NRC will schedule a public meeting near the plant to present the results of the agency’s special inspection.
Issuance of a confirmatory action letter does not preclude the NRC from taking other additional actions for any violations of NRC requirements that may be identified.
A copy of the confirmatory action letter is available on the NRC Web site at www.nrc.gov/reading-rm/adams/web-based.html using the number ML101740519 or from the Region III Office of Public Affairs.
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