O-Rings At Indian Point Still Leaking: NRC

CORTLANDT, NY — The Nuclear Regulatory Commission's most recent inspection of Indian Point Units 2 and 3 focused once again on the leaking water seals that sit between the lid of the reactors and the reactor vessels. There is a history of o-ring leakage at Indian Point 2 and 3 dating back to the 1990s.

Entergy, which owns the soon-to-be-shut-down nuclear reactors, even had an unscheduled shutdown in June, to work on the problem in Unit 3.

According to the NRC, o-rings are flexible gaskets that create a leak-proof sealed connection. They are usually made of flexible synthetic materials because of their elasticity and durability, but some are comprised of metal. In order to perform their function, they are compressed between parts to form a seal.

But, as the NRC third-quarter inspection pointed out, "Corrective actions to address the various causal factors over the years have not been completely effective at preventing recurrence of the issue."

In the case of nuclear power reactors, o-rings are used to help seal the flange connection where multi-ton reactor vessel heads are attached to the vessel. They must be designed to withstand severe conditions, such as temperature and pressure fluctuations and radiation impacts.

In the inspection, which was completed Sept. 30, the NRC documented the finding as of "very low safety significance."

"The bottom line for us (in terms of potential enforcement) is that the leakage has not exceeded the plant’s technical specifications, even though both units are operating on their outer o-rings," spokesman Neil Sheehan said in an email to Patch.

Still, NRC inspectors said "Entergy should further evaluate the categorization of the RPV (reactor pressure vessel) head installation procedure to ensure it meets requirements and expectations and ensures that previous corrective actions continue to be implemented as intended.”

Indian Point spokesman Jerry Nappi said Entergy has an approach.

"Engineers previously identified steps that we believe will lessen the chance for future leakage past this seal," he told Patch. "It’s important to note that any water that did leak past these seals is entirely contained within the reactor building and does not reach the environment."

SEE: Indian Point Replacing O-Rings in Unit 3