On March 13, 2017, Indian Point Unit 3 entered its scheduled refueling and maintenance outage, which included a specialized examination of bolts on the baffle structure, which surrounds the nuclear fuel inside the reactor. Entergy committed to conducting these bolt inspections at Unit 3 two years ahead of schedule (from 2019 to 2017) after engineers identified and replaced similar bolts on the baffle structure inside Unit 2’s reactor last year.
Entergy previously took comprehensive actions to inspect and address the baffle bolt issue at Indian Point Unit 2 in 2016, including replacement of all bolts that exhibited indications during Ultrasonic Testing, as well as some additional bolts without indications to help prevent similar failures.
Previous independent engineering analysis demonstrated the ability for Unit 2 to operate safely prior to the identification of degraded bolts. The analysis also determined that Unit 3 was safe to operate until the current refueling outage.
Ultrasonic Testing (UT) at Unit 3 identified:
The total number of bolts that will be replaced is 270. The number of bolts to be replaced at Unit 3 this year is consistent with the number of bolts that were replaced at Unit 2 last year – 278.
A bolt with an indication identified through UT analysis does not necessarily mean the bolt is failing to perform its intended function (i.e. carry load). For example, a certain percentage of bolts classified as “failed” at Unit 2 last year still carried the required amount of load when subsequently sent to a lab for testing and analysis.
The results of the baffle bolt inspections at Unit 3 are bounded by the analysis we completed last year. In other words, that analysis concluded, based on assumptions consistent with this year’s actual test results for Unit 3, that the plates held in place by the baffle bolts would perform their function, which is to direct cooling water through the fuel assemblies and allow control rods to be inserted into the reactor in order to safely shut down the plant.
Inspections confirmed that the plates secured by these bolts were not damaged, and remained structurally sound and capable of performing their safety function while Unit 3 was in operation. The U.S. Nuclear Regulatory Commission (NRC) monitors our performance in this and other areas to ensure the plant is safe now and on an ongoing basis.
The bolt issues will be corrected prior to returning Indian Point Unit 3 to operation.
Entergy will perform another inspection of the baffle bolts during Unit 2’s next refueling outage in early 2018 and during Unit 3’s final refueling outage in early 2019.