ML13226A179

Email T. Nazario to R. Haag, Subj: Mockup for RPV Stud Hole Sleeving

ML13226A179
Person / Time
Site:	Mcguire, Watts Bar, Cook, Comanche Peak, McGuire
Issue date:	01/26/2012
From:	Nazario T NRC/RGN-II/DCP/CPB3
To:	Haag R NRC/RGN-II/DCP/CPB3
References
FOIA/PA-2013-0139
Download: ML13226A179 (2)

Text

Nazarlo, Tomy From: Nazario. Tomy Sent: Thursday, January 26, 2012 12:34 PM To: Haag, Robert

Subject:

M.gwkup for RI-.Stud Hole Sleeving Attachments: ocurment.pdf Bob, The NRC has been notified that PCI/WEC will be performing a mock-up of the reactor pressure vessel (RPV) stud hole sleeving machining equipment and machining sequencing at their Lake Bluff, IL facility on March 16, 2012. The residents and the Regional Mechanical/Materials Branch have been closely following this activity to ensure that we fully understand not only the technical and engineering aspects of this remedlation effort, but also observe the work as it is performed In the field.

Historically only three plants that we know of have sleeved RPV stud holes and those Include Comanche Peak, DC Cook, and McGuire. Watts Bar Unit 2 has one stud hole that was sleeved during the manufacturing of the RPV flange and three additional holes that are scheduled to be sleeved in April. Therefore, this will be the only plant in the US that we are aware of to have a total of 4 sleeved RPV stud holes.

An NRC observation of this mock-up will be beneficial for the following reasons;

" This remediation effort is not routinely performed In the nuclear industry and this type of machining has not been performed since the 1990s.

• This would allow an NRC inspector(s) to become familiarwith the machining equipment and the critical steps of the machining process. This machining equipment Is custom made. No one in CCI or NRR currently has knowledge on this sleeving process.

" Once the PCI/WEC machinists are on-site, they get their work done efficiently and expediently, as observed with the machining of the stud hole threads. Therefore, during an NRC Inspection, we may slow them down to gain knowledge of the process.

" The PCI/WEC machinists have time/schedule restraints and the NRC does not want to be the reason for delays.

" Observation of this mock-up would be considered part of the inspection preparation and planning

" It will allow the NRC to better determine what inspection specialization/assistance we may need before the work takes place.

I would recommend that the Regional Mechanical/Materials Branch (Scott Freeman's group) attend the mockup. Dave Failla has been very involved with reviewing the initial engineering evaluation and inspecting the machining of the RPV stud holes. We have also Informed NRR of TVA's plans to sleeve the RPV stud holes last December. My only other recommendation would be that we ensure that the same individual that observes the mockup be the one to also be onsite when the sleeving takes place.

Please let me know if you have any questions.

Tomy Tomy A. Nazarlo Senior Resident Inspector U.S. Nuclear Regulatory Commission Watts Bar Nuclear Plant 1260 Nuclear Plant Rd.

Spring City, TN 37031

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