ML17171A187

NRC Staff Presentation - Baffle-Former Bolt Inspections at Indian Point

ML17171A187
Person / Time
Site:	Indian Point
Issue date:	06/14/2017
From:	David Rudland Office of Nuclear Reactor Regulation
To:
Setzer T
References
Download: ML17171A187 (5)

Text

BaffleFormer Bolt Inspections at Indian Point Remarks by David L. Rudland Chief, Vessel and Internals Integrity Branch Office of Nuclear Reactor Regulations U.S. Nuclear Regulatory Commission June 14, 2017 ML17171A187

Baffleformer Assembly Direct coolant flow through the core and provides lateral support to the core during a seismic event or loss-of-coolant accident (LOCA).

Stainless steel bolts are 5/8 dia. x ~2 long 2

Baffle Bolt Inspection

• MRP227A covers inspection of reactor internals

- MRP Letter 2017011 dictated interim guidance

• Ultrasonic inspection technique

- One probe per bolt, several sensors and channels of data

- Qualified for detection only - go/no go

• Technique appears conservative

- >50% of bolts removed retained some load carrying capacity 3

Indian Point, Unit 2 Indian Plant Point, Unit 3 EFPY@ Date of UT Exam Total number of baffle-former 28.6 31.1 Mar Mar 2017 2016 Date of UT Exam 0 No. of visually failed 31 bolts at IP2/3 is 832/unit bolts No. of bolts with UT 256 182 4 indications 3 No. of bolts that could 14 not be UT examined Total No. of Potentially 259 227 Degraded Bolts Recent Inspections at Indian Point 270 278 No. of Bolts Replaced No. Bolts with UT 35 103 indications that failed upon removal

Conclusion

• Structural integrity of baffleformer assembly is maintained at Indian Point due to

- Replacement of all bolts with UT indications

- Replacement of additional nondegraded bolts for margin and

- Subsequent bolt inspections at every refueling outage

• NRC will continue to inspect bolt examination results through the baseline inspection program at Indian Point

• More broadly, the NRC staff will continue to closely monitor the baffleformer bolt operating experience and updated inspection guidance to ensure structural integrity 5