ML040790025
| ML040790025 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 03/18/2004 |
| From: | Marschall C NRC/RGN-IV/DRS/EMB |
| To: | Blevins M TXU Energy |
| References | |
| EA-04-009 IR-04-006 | |
| Download: ML040790025 (10) | |
See also: IR 05000445/2004006
Text
March 18, 2004
M. R. Blevins, Senior Vice President
and Principal Nuclear Officer
TXU Energy
ATTN: Regulatory Affairs
Comanche Peak Steam Electric Station
P.O. Box 1002
Glen Rose, TX 76043
SUBJECT: COMANCHE PEAK STEAM ELECTRIC STATION, UNIT 1 - NRC
SUPPLEMENTAL INSPECTION REPORT 05000445/2004-006
Dear Mr. Blevins:
On March 4, 2004, the US Nuclear Regulatory Commission (NRC) completed an inspection at
your Comanche Peak Steam Electric Station, Unit 1. The enclosed report documents the
inspection findings, which were discussed on March 4, with Steve Ellis, Systems Engineering
Manager, and other members of your staff.
As required by the NRC Reactor Oversight Process Action Matrix, this supplemental inspection
was performed in accordance with Inspection Procedure 95001. The purpose of the inspection
was to examine the causes for and actions taken related to the White finding associated with
the failure to identify and correct an indicated flaw in a steam generator tube during Refueling
Outage 1RF08. This supplemental inspection was conducted to provide assurance that the
root causes and contributing causes of the events resulting in the White finding are understood,
to independently assess the extent of condition, and to provide assurance that the corrective
actions for risk significant performance issues are sufficient to address the root causes and
contributing causes and to prevent recurrence. The inspection consisted of selected
examination of representative records and interviews with personnel.
The NRC concluded that your staff performed a thorough evaluation of the failure to identify
and correct the steam generator tube flaw in Refueling Outage 1RF08. We also determined
that your corrective actions fully addressed the root and contributing causes for the missed
flaw, and that you have implemented appropriate actions to prevent recurrence.
TXU Energy -2-
In accordance with 10 CFR 2.390 of the NRCs "Rules of Practice," a copy of this letter
and its enclosure will be available electronically for public inspection in the NRC Public
Document Room or from the Publicly Available Records (PARS) component of NRCs
document system (ADAMS). ADAMS is accessible from the NRC Web site at
http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).
Sincerely,
/RA/
Charles S. Marschall, Chief
Engineering Branch
Division of Reactor Safety
Docket: 50-445
License: NPF-87
Enclosure:
Inspection Report 05000445/2004-006
cc w/enclosure:
Roger D. Walker
Regulatory Affairs Manager
TXU Generation Company LP
P.O. Box 1002
Glen Rose, TX 76043
George L. Edgar, Esq.
Morgan Lewis
1111 Pennsylvania Avenue, NW
Washington, DC 20004
Terry Parks, Chief Inspector
Texas Department of Licensing
and Regulation
Boiler Program
P.O. Box 12157
Austin, TX 78711
The Honorable Walter Maynard
Somervell County Judge
P.O. Box 851
Glen Rose, TX 76043
TXU Energy -3-
Richard A. Ratliff, Chief
Bureau of Radiation Control
Texas Department of Health
1100 West 49th Street
Austin, TX 78756-3189
Environmental and Natural
Resources Policy Director
Office of the Governor
P.O. Box 12428
Austin, TX 78711-3189
Brian Almon
Public Utility Commission
William B. Travis Building
P.O. Box 13326
1701 North Congress Avenue
Austin, TX 78711-3326
Susan M. Jablonski
Office of Permitting, Remediation and Registration
Texas Commission on Environmental Quality
MC-122
P.O. Box 13087
Austin, TX 78711-3087
TXU Energy -4-
Electronic distribution by RIV:
Regional Administrator (BSM1)
DRP Director (ATH)
DRS Director (DDC)
Senior Resident Inspector (DBA)
Branch Chief, DRP/A (WDJ)
Senior Project Engineer, DRP/A (TRF)
Staff Chief, DRP/TSS (PHH)
RITS Coordinator (KEG)
Rebecca Tadessee, OEDO RIV Coordinator (RXT)
ADAMS: Yes * No Initials: nlh
Publicly Available * Non-Publicly Available * Sensitive Non-Sensitive
RI:EB C:EB C:PBA C:EB
WCSifre/lmb CSMarschall WDJohnson CSMarschall
/RA/ /RA/ /RA/ /RA/
03/11/04 03/11/04 03/17/04 03/12/04
OFFICIAL RECORD COPY T=Telephone E=E-mail F=Fax
ENCLOSURE
U.S. NUCLEAR REGULATORY COMMISSION
REGION IV
Docket: 50-445
License: NPF-87
Report No.: 05000445/2004-006
Licensee: TXU Electric
Facility: Comanche Peak Steam Electric Station, Unit 1
Location: FM-56
Glen Rose, Texas
Dates: March 4, 2004
Inspector: W. Sifre, Reactor Inspector
Approved By: Charles S. Marschall, Chief
Engineering Branch
Division of Reactor Safety
-2-
SUMMARY OF FINDINGS
IR 05000445/2004-006; March 4, 2004; Comanche Peak Steam Electric Station, Unit 1: 95001,
Supplemental Inspection for a White Finding.
The report covered a two-day period of inspection by a regional reactor inspector. The NRCs
program for overseeing the safe operation of commercial nuclear power reactors is described in
NUREG-1649, "Reactor Oversight Process," Revision 3, dated July 2000.
NRC-Identified and Self Revealing Findings
Cornerstone: Barrier Integrity
The U.S. Nuclear Regulatory Commission (NRC) performed this supplemental inspection to
assess the licensees evaluations associated with the failure to identify and correct an indicated
flaw in a steam generator tube during Refueling Outage 1RF08. The failure to remove the tube
from service resulted in a primary coolant leak that caused operators to shut the plant down.
The NRC concluded, based on the condition of the tube (as determined by in-situ testing) that
the failure to identify the flaw and remove the tube from service was a performance deficiency
with risk significance characterized as White (low to moderate risk significance). During this
supplemental inspection, performed in accordance with Inspection Procedure 95001, the
inspectors determined that the licensee performed a comprehensive evaluation of the causes
and extent of the performance deficiency that resulted in failure to identify the flaw. The
licensee's evaluation resulted in changes in processes and practices for eddy current analysis,
improved peer review, and more supervisory oversight. The root-cause evaluation also resulted
in additional reviews of the eddy current data obtained in Refueling Outage 1RF09, insuring that
analysts identified similar defects. In addition, the licensee applied the lessons learned during
the subsequent refueling outage for Unit 2.
Report Details
1 INTRODUCTION
The U.S. Nuclear Regulatory Commission (NRC) performed this supplemental inspection to
assess the licensees evaluation associated with the failure to identify a steam generator tube
flaw that resulted in a leak. This performance issue was previously characterized as "white" in
NRC Inspection Report 50-445/02-09 and is related to the barrier integrity cornerstone in the
reactor safety strategic performance area.
4OA2 Problem Identification and Resolution
a. Problem Identification
On September 26, 2002, Comanche Peak Steam Electric Station, Unit 1, developed a
steam generator tube leak that resulted in a unit shutdown on September 28. The NRC
conducted a special inspection to evaluate the effectiveness of the examination
methods used to examine the degraded tube during the previous outage, and determine
whether licensee evaluators missed an opportunity to identify the degraded tube. The
team determined that the licensee failed to identify and correct a degraded steam
generator tube during Refueling Outage 1RF08 and this failure directly resulted in a
steam generator tube leak. The team determined that this failure was a violation of
10 CFR Part 50, Appendix B, Criterion XVI. The NRC performed a Phase 3 analysis of
this condition and determined that the change in large early release frequency ( LERF)
was 5.5x10-7/year. This frequency determination corresponded with a "white" finding in
the significance determination process.
b. Root Cause and Extent of Condition Evaluation
The inspection team identified that the licensees Refueling Outage 1RF08 eddy current
analysis guidelines were written to analyze freespan indications either without the
presence of a ding or to a smaller threshold in the presence of a ding. The indication
that resulted in the leak did not meet the guideline reporting criteria because the ding
was masked by the probe wobble signal. This condition resulted in both the primary and
secondary analysts applying the non-conservative criteria for non-ding locations. This
resulted in the flaw not being identified and the tube remained in service until it leaked.
The inspectors reviewed the licensees root-cause analysis and found that the licensee
had identified that the computerized primary analysis process was rule-based and would
not have identified the indication. The licensee further found that the work process for
eddy current analysis was less than adequate in that it relied on a single individual to
perform a detailed task with no peer, independent, nor supervisory review.
Based on this review, the inspectors concluded that the licensee clearly understood the
root causes and contributing causes for the failure to identify the flawed tube prior to the
developed leak. The inspectors further concluded, based on the licensee actions
described in NRC Inspection Report 50-445/02-09, that the licensee fully addressed the
extent of condition and extent of cause for the missed flaw.
-2-
c. Corrective Actions
The inspectors reviewed the licensees initial corrective actions that included revision of
the eddy current process and plugging of the failed tube. This review is described in
detail in NRC Inspection Report 50-445/02-09. The inspector found that the licensee
has initiated following long-term corrective actions:
- Licensee and vendor lead analysts are assigned to review the performance of
primary and secondary analysts daily by comparing their calls to those of the
resolution analysts.
- Additional controls have been incorporated into the automated data screening
software to ensure correct sorts are used.
- The resolution analysts are separated into two teams and resolution of data is
performed independently with the most conservative call taking precedence.
- Lead analysts have been assigned on each shift to provide increased oversight
and guidance.
- History look up requirements have been changed to require review back to the
first inservice inspection as opposed to only the last inservice inspection.
- Additional training and testing has been added on data look ups for changes in
signal.
The inspectors concluded that the corrective actions described in NRC Inspection
Report 50-445/02-09 fully addressed the root causes and contributing causes for the
missed flaw and that those actions combined with the actions stated above will prevent
recurrence. Additional detail of the special inspection team's evaluation of the causes
and corrective actions can be found in NRC Inspection Report 50-445/02-09.
4OA5 Other Activities
1. (Closed) AV 05000458/2002007-01 Failure to identify and correct an indicated flaw in a
steam generator tube during Refueling Outage 1RF08.
As documented in NRC Special Inspection Report 05000445/2002-09, the inspectors
identified a violation of 10 CFR Part 50, Appendix B, Criterion XVI for failure to promptly
identify a flaw in Comanche Peak, Unit 1, Steam Generator No. 2 Tube R41C71 and
correct it by removing it from service. As a result, in September 2002, the flaw
developed into a leak that caused operators to shut the plant down. The tube
subsequently failed in situ testing.
The final significance determination was completed and documented in Final
Significance Determination for a White Finding and Notice of Violation, (EA-04-009)
dated February 13, 2004. The finding was determined to be of low to moderate safety
significance (White) because the tube failed in-situ testing. This failure indicated a
-3-
higher probability of inservice failure for the tube during postulated initiating events and
core damage sequences. (VIO 05000445/2004006-01)
2. (Closed) VIO 05000445/2004006-01 Failure to identify and correct an indicated flaw in a
steam generator tube during Refueling Outage 1RF08.
As documented in section 4OA2, above, the inspectors determined that the licensee
performed a comprehensive evaluation of the causes and extent of the performance
deficiency that resulted in failure to identify the flaw. The licensees evaluation resulted
in changes in processes and practices for eddy current analysis, improved peer review,
and more supervisory oversight. The root-cause evaluation also resulted in additional
reviews of the eddy current data obtained in Refueling Outage 1RF09, insuring that
analysts identified similar defects. In addition, the licensee applied the lessons learned
during the subsequent refueling outage for Unit 2.
4OA6 MANAGEMENT MEETINGS
Exit Meeting Summary
On March 4, 2004, the inspectors presented the inspection results to Mr. S. Ellis and
other members of his staff who acknowledged the findings. The inspectors asked the
licensee whether any materials examined during the inspection should be considered
proprietary. Several documents were identified as proprietary information by the
licensee. The inspectors ensured that the proprietary documents were returned to
licensee.
Regulatory Performance Discussion
On March 18, 2004, Charles Marschall, Chief, Engineering Branch, Division of Reactor
Safety, NRC Region IV, conducted a Regulatory Performance meeting by telephone
conference with the following Comanche Peak managers and staff:
Name Title
Steve Ellis Systems Engineering Manager
Fred Madden Regulatory Affairs Manager
Tim Hope Regulatory Performance Manager
Bob Kidwell Licensing Engineer
The participants discussed the performance deficiencies associated with the failure to
identify and correct the steam generator tube flaw. The discussion also addressed the
corrective action taken by the licensee, and the results achieved.
ATTACHMENT
SUPPLEMENTAL INFORMATION
KEY POINTS OF CONTACT
Licensee personnel
G. Dyes, Nuclear Overview Auditor
S. Ellis, Manager, Systems Engineering
T. Hope, Manager, Regulatory Performance
B. Kidwell, Licensing Engineer
F. Madden, Manager, Regulatory Affairs
B. Mays, Manager, Steam Generator Replacement Project
V. Polizzi, Manager, Site Engineering, Westinghouse
K. Studer, Manager, System Engineering Smart Team
M. Sunseri, Manager, Nuclear Overview
T. Weyandt, Steam Generator Coordinator
NRC personnel
D. Allen, Senior Resident Inspector
V. Klein, Intern
LIST OF ITEMS OPENED, CLOSED, AND DISCUSSED
Opened and Closed
05000458/2004006-01 VIO Failure to identify and correct an indicated flaw in a steam
generator tube during Refueling Outage 1RF08
(Section 4OA5)
Closed
50-445/0202-01 LER Steam Generators Meeting C-3 Category
50-445/02-09-01 APV Failure to Identify and Correct a Degraded Steam
Generator Tube during Refueling Outage 1RF08
LIST OF DOCUMENTS REVIEWED
TXU Unit 1 Steam Generator Eddy Current Analysis Guidelines - 1RF09, Revision 5
TXU Unit 1 Steam Generator Eddy Current Analysis Guidelines - 1RF10, Revision C
Westinghouse Report WPT-16430, "TXU Generation LP Comanche Peak Steam Electric
Station Unit 1 1RF09 Steam Generator Pulled Tube Report"