ENS 46375

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v t e ENS Event
16:40 Oct 28, 2010
Title	Defect Discovered in Tube Steel That Could Be Used in Various Safety Related Structual Applications
Event Description	On October 28, 2010, Duke Energy completed a reportability determination which concluded that a defect associated with four inch by four inch tube steel with one-half inch wall thickness is reportable under Part 21. The tube steel was procured safety-related from Mackson, Inc. on May 26, 2010. Receipt of the material occurred on June 14, 2010. During construction of the Protected Service Water (PSW) ductbank elevated cable raceway, Craft reported a longitudinal crack in the tube steel, approximately four feet in length, adjacent to a raceway fabrication weld. The crack was located in the manufacturer's longitudinal seam weld in the tube steel. Follow-up investigation and laboratory evaluation revealed that the structural steel tubing in question contains surface breaking flaws located along the centerline of the seam weld which are attributable to lack of fusion that occurred during tubing manufacture. Additional testing of samples from the same heat of material indicated that the seam weld flaw depth varied with some localized areas reaching depths of at least 40 percent through the wall thickness prior to raceway fabrication welding. According to documents received from the supplier, during dedication, the supplier performed chemical, physical and 100 percent visual exam in accordance with their accepted dedication procedures for ASTM A500 for Grade B material. However, the supplied product did not conform to the requirements of ASTM A500 in that the longitudinal butt joint was not welded across its thickness (Reference ASTM A500, Section 6.2). Duke Energy will provide follow-up written notification within 30 days pursuant to Part 21.21(d)(3)(ii). Initial Safety Significance: None. The defective tube steel utilized in the PSW structure was not placed into service. Tube steel sections of the same heat of material not used in pre-fabrication efforts were scrapped. Those installed were cut out or evaluated for acceptability by Engineering. The failure of this weld significantly impairs the structural properties of the hollow structural section. The generic implications associated with the potential to use these structural members in various nuclear safety-related applications at this site and at other stations results in a substantial safety hazard were it to remain uncorrected. Corrective Action(s): 1. Notified supplier, Mackson, Inc. 2. Re-worked all uses of the defective structural tube steel. 3. Developed additional, required testing for safety -related tube steel. The supplier (Mackson, Inc) indicated to Oconee that no other nuclear power plants have received this type of tube steel from Mackson. Oconee also has concluded that the condition is confined to only one heat of the tubing used onsite. All the tube steel of this heat has been either disposed of, removed, or verified acceptable. The licensee has notified the NRC Resident Inspector.

ENS 46375 +/-
Where
Oconee South Carolina (NRC Region 2)
Reporting

10 CFR 21.21
Time - Person (Reporting Time:+16.98 h0.708 days <br />0.101 weeks <br />0.0233 months <br />)
Opened:	Sandra Severance 09:39 Oct 29, 2010
NRC Officer:	Bill Huffman
Last Updated:	Oct 29, 2010
46375 - NRC Website
v • d • e

v t e Emergency Notification System
Oconee with 10 CFR 21.21, Notification of failure to comply or existence of a defect and its evaluation
WEEKMONTHYEAR2011-06-07T15:52:00 [Table view]
[ENS list for Oconee]

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