CORTLANDT, N.Y. -- As work continues to replace 227 degraded baffle-former bolts in Unit 2 at Indian Point, the Nuclear Regulatory Commission said that similar problems had been found in the bolts dating back as far as the late 1980s.
According to Neil Sheehan, public affairs ffficer with the NRC, cracking was identified in baffle-former bolts – the bolts securing the baffle plates to the baffle-former plates — in pressurized-water reactors (PWRs) in France. (Both Indian Point Units 2 and 3 are PWRs.) The degradation is caused by what is known as irradiation-assisted stress corrosion cracking.
In 2009, the Electric Power Research Institute developed a standard industry program for evaluating the aging reactors. The safety-check program was adopted by the NRC in 2012. Under this new standard, U.S. PWRs were to conduct an initial ultrasonic examination of all of their baffle-former bolts when the plant had between 25 and 35 years of service.
Sheehan said this is exactly what was being done at Indian Point Unit 2 during the current outage. It was adhering to the standards of the 2012 update. In the course of this review, it was determined that 227 of 832 baffle-former bolts at the plant were degraded, which means any indication of cracking. What’s more, two bolt heads were missing.
The number of degraded baffle-former bolts was the largest seen to date at a U.S. reactor.
Entergy, Indian Point’s owner, is in the process of analyzing the condition and replacing the degraded bolts. It will also assess any implications for Indian Point Unit 3, Sheehan said.
Once complete, the NRC will review the company’s analysis and bolt-replacement to ensure safety. In addition, an NRC metallurgical specialist is on-site reviewing the company’s evaluations of the bolts.
Sheehan said it's important for residents to understand that NRC staff will ensure the condition is fully understood and addressed prior to the plant returning to service.
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