On February 17, 2010, Duke Energy (Duke) completed a reportability determination which concluded that a defect associated with Nelson Stud attachment to embed plates is reportable under Part 21. The embed plates with Nelson studs were procured safety-related from DuBose National Energy Services, Inc. (DuBose) on December 18, 2008. Receipt of the material began as early as August 1, 2009. When delivered to the on-site storage location, it was identified that a Nelson Stud was missing from one of the plates. Follow-up investigation and evaluation identified that automatically timed stud welding procedures/process control weaknesses in the areas of cleanliness and operator/equipment performance have resulted in cold weld joints and weld failures. Duke will provide follow up written notification within 30 days pursuant to Part 21.21(d)(3)(ii).
Initial Safety Significance: None. The potentially defective embedded plates installed in the Protected Service Water (PSW) Building prior to this discovery have not been placed into service. These plates will be removed, abandoned, or re-engineered prior to placing the system in service. However, the embed plates described were to be used for a variety of QA Condition 1 functions, including reaction points for PSW Building structural steel framing and support/restraint of PSW electrical equipment. Depending upon the installation location of these embedded plates and the number and location of ineffectively attached Nelson studs, this deviation could have created a substantial safety hazard were it to remain uncorrected.
Corrective Action(s):
1. Notified vendor (DuBose).
2. Re-work all embeds by installing a fillet weld on each stud.
3. Determine whether the installed embeds will be removed, abandoned, re-engineered.
The licensee notified the NRC Resident Inspector.