United States Nuclear Regulatory Commission - Protecting People and the Environment

Morning Report for February 28, 2006

Headquarters Daily Report

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REGION II

CRACKING INDICATIONS IN CORE SHROUD TIE RODS

Licensee/Facility:

SOUTHERN NUCLEAR OPERATING CO., INC.
Hatch 1, Hatch 2
BAXLEY, Georgia
Dockets: 05000321, 05000366
[1] GE-4, [2] GE-4
License No:
Notification:

MR Number: 2-2006-0001
Date: 02/28/2006

Call from Licensee

Discussion:

This report supplements Event Number 42372, dated February 23, 2006, regarding crack-like indications reported on the Upper Support Horizontal Support Surfaces for two core shroud tie rods located at 135 degrees and 225 degrees. Unit 1 is currently shutdown for a scheduled refueling outage and the indications were identified during the In-Vessel Visual Inspection (IVVI) of the tie rods. Four tie rods, located 90 degrees apart, were installed in 1994 and last inspected during the 1997 Unit 1 Refueling Outage. The licensee has determined that indications on the tie rods at 135 and 225 degrees did not exist at that time. IVVI also identified a loose bolt where the tie rod located at 315 degrees azimuth connects to the upper stabilizer assembly.

Unit 1 upper stabilizer assemblies are fabricated from an Inconel alloy. Based on available information, we believe this is the first identified case in US commercial reactors of core shroud tie rod horizontal support cracking. The licensee is currently working on operability and extent of condition determinations and repair/disposition of these indications.

Regional Action: The resident inspectors are monitoring the licensee's investigation of these indications and coordinating actions with NRR.

Accession Numbers:

Accession No Accession Date
ML060590290 02/28/2006

Contacts:

Name Office Abbrev Phone No E-Mail
FULLER, JUSTIN D R2 (404) 562-4655 JDF@nrc.gov
Page Last Reviewed/Updated Thursday, March 29, 2012