The Nuclear Regulatory Commission will increase its level of oversight at the Ginna nuclear power plant following the finalization of a “white” (low to moderate safety significance) inspection finding for the facility.

The finding, which involves a violation of NRC requirements, is based on a failure to properly implement flooding protection measures at the plant, located in Ontario, N.Y., and operated by Exelon Generation Co. LLC.

Specifically, NRC inspectors determined that electrical cable penetrations that could allow for the flow of water from a manhole into battery rooms were not properly sealed for many years. The batteries are part of the plant’s credited emergency back-up power capabilities for events during which off-site power — the plant’s normal source of electricity — is lost. The flooding could have disabled not only the batteries but also other emergency back-up sources of power for the plant.

While the company made modifications to fix the problem late last year, the NRC is taking enforcement action because of the length of time the vulnerability existed.

"Work to ensure nuclear power plants are protected to the greatest extent possible from flooding hazards has taken on even greater importance following the events in Fukushima, Japan, in March 2011," NRC Region I Administrator Bill Dean said. "While the vulnerability at the Ginna nuclear power plant has now been addressed, this violation calls attention to the fact that this issue did not receive the kind of attention it required for far too long."

Under the NRC’s Reactor Oversight Process, inspection findings are classified by color based on their safety significance. The colors range from "green," for a very low safety issue, to "white," "yellow" or "red," which connotes high safety significance. Because this finding has been finalized as "white," the plant will move from the Licensee Response Column of the NRC’s Action Matrix to the Regulatory Response Column and be subject to additional inspections by the agency.

An NRC inspection report issued in February notes that Constellation – the owner of record for the plant until recently — failed to identify the need to correct two non-hydrostatically sealed cable penetrations between a manhole located on site property and a battery room after the flood height the plant must be able to withstand was changed in 1983. In addition, the company neither promptly corrected the problem in May 2013 when the condition was identified nor took timely action in early September 2013 when it was presented with evidence by NRC inspectors challenging its May 2013 evaluation that the penetrations did not represent a potential vulnerability.

The NRC’s determined that various extreme, low likelihood Deer Creek flooding scenarios could lead to water flowing into the manhole in question and then into both of the plant’s battery rooms through the inadequate penetration seals.

Prior to making a final enforcement decision, the NRC offered the company the opportunity to take part in a Regulatory Conference to provide additional information regarding the apparent violation, to submit a written response or to accept the finding without any formal response. The company submitted a written response dated March 14 in which it stated that, among other things, it had initiated a root cause analysis to better understand why the issue was not identified earlier through the plant’s problem identification and resolution program.