ML072540537
| ML072540537 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 09/10/2007 |
| From: | Casto C Division Reactor Projects II |
| To: | Gordon Peterson Duke Energy Carolinas, Duke Power Co |
| References | |
| EA-07-219 IR-07-008 | |
| Download: ML072540537 (15) | |
See also: IR 05000369/2007008
Text
OFFICIAL USE ONLY - PROPRIETARY INFORMATION
DOCUMENT TRANSMITTED HEREWITH CONTAINS OFFICIAL USE ONLY - PROPRIETARY
INFORMATION. WHEN SEPARATED FROM ENCLOSURE 2, THIS DOCUMENT IS
DECONTROLLED.
September 10, 2007
Duke Power Company LLC
d/b/a Duke Energy Carolinas, LLC
ATTN:
Mr. G. R. Peterson
Vice President
McGuire Nuclear Station
12700 Hagers Ferry Road
Huntersville, NC 28078-8985
SUBJECT:
MCGUIRE NUCLEAR STATION - NRC INSPECTION REPORT
05000369/2007008 AND 05000370/2007008; PRELIMINARY GREATER THAN
GREEN FINDING
Dear Mr. Peterson:
On September 4, 2007, the U.S. Nuclear Regulatory Commission (NRC) completed an
inspection at your McGuire Nuclear Station. The inspection was related to your September
2006 discovery of duct tape in the Unit 2 emergency core cooling system (ECCS) sump. This
issue had been previously documented in Section 1R20 of NRC Inspection Report 05000369/2006005 and 05000370/2006005, issued on January 30, 2007, and identified as
unresolved item (URI)05000370/2006005-02. The unresolved item was also addressed in
NRC Inspection Report 05000369/2007002 and 05000370/2007002. The enclosed report
documents the inspection results for that issue, which were discussed on September 4, 2007,
with you and members of your staff.
The performance deficiency involves a failure to take adequate corrective actions for an
identified nonconforming condition. This nonconforming condition involves the 1996 discovery
that the ECCS cold leg injection throttle valves had the potential for clogging during high
pressure recirculation because the narrow plug to seat clearances were smaller than the ECCS
sump screen openings. Specifically, McGuire Nuclear Stations resolution to this
nonconformance was to credit periodic inspections of the ECCS sump to ensure each Units
ECCS sump remained free of foreign material that could clog the respective ECCS cold leg
injection throttle valves. The credited periodic ECCS sump inspections were subsequently
revealed to be ineffective, by the unrelated September 2006 discovery of a significant amount
of aged yellow duct tape inside the Unit 2 ECCS sump around the suction and guard pipe of
both ECCS trains.
OFFICIAL USE ONLY - PROPRIETARY INFORMATION
2
DOCUMENT TRANSMITTED HEREWITH CONTAINS OFFICIAL USE ONLY - PROPRIETARY
INFORMATION. WHEN SEPARATED FROM ENCLOSURE 2, THIS DOCUMENT IS
DECONTROLLED.
PIP M-96-0530, written to document the nonconforming condition discovered in 1996, was
found to be an accept-as-is design change. This design change was not processed in
accordance with the McGuire design control program that implements 10 CFR 50, Appendix B,
Criterion III, Design Control; the resolution did not include an evaluation of this change under 10 CFR 50.59; and the resolution did not include a change to the licensing basis as required by 10 CFR 50.71(e) to update the Updated Final Safety Analysis Report (UFSAR).
This finding was assessed based on the best available information, including influential
assumptions, using the applicable Significance Determination Process (SDP) and was
preliminarily determined to be a Greater Than Green Finding. Enclosed is a summary of the
SDP Phase 3 analysis. It reflects a finding of greater than very low safety significance
because, in the event of being in the high pressure ECCS recirculation phase for small break
and medium break loss of coolant accidents (LOCAs), there was a lack of reasonable
assurance that the Unit 2 ECCS cold leg high and intermediate head injection throttle valves
would remain unclogged such that their associated systems would be capable of performing
their safety-related function. More specifically, as the yellow duct tape found in Unit 2 was not
environmentally qualified for expected sump LOCA conditions, the logical conclusion is that it
can be expected to come loose from the guard pipes. In absence of test data or analysis to the
contrary, a significant portion of this tape would then be expected to transport from the sump,
through both trains of intermediate and high head safety injection pumps, and clog the four
intermediate and four high head cold leg injection throttle valves due to their small openings.
The finding does not represent a current safety concern because the tape has since been
removed and the original nonconforming condition has been corrected with a plant modification.
The finding is also identified as an apparent violation (AV) of 10 CFR 50, Appendix B, Criteria
XVI, Corrective Action, for failure to take adequate corrective actions for an identified
nonconformance involving the discovery that the ECCS cold leg injection throttle valves have
the potential for clogging during high pressure recirculation because the narrow plug to seat
clearances were smaller than the ECCS sump screen openings. The details of this AV are
discussed in the enclosed inspection report. This apparent violation is being considered for
escalated enforcement action in accordance with the NRC Enforcement Policy. The current
Enforcement Policy is included on the NRCs website at http://www.nrc.gov/reading-
rm/adams.html.
In accordance with Inspection Manual Chapter (IMC) 0609, we intend to complete our
evaluation using the best available information and issue our final determination of safety
significance within 90 days of this letter. The significance determination process encourages
an open dialogue between the staff and the licensee; however, the dialogue should not impact
the timeliness of the staffs final determination. Before we make a final decision on this matter,
we are providing you an opportunity to: (1) present to the NRC your perspectives on the facts
and assumptions used by the NRC to arrive at the finding and its significance at a Regulatory
Conference or (2) submit your position on the finding to the NRC in writing. If you request a
Regulatory Conference, it should be held within approximately 30 days of the receipt of this
letter and we encourage you to submit supporting documentation at least 1 week prior to the
OFFICIAL USE ONLY - PROPRIETARY INFORMATION
3
DOCUMENT TRANSMITTED HEREWITH CONTAINS OFFICIAL USE ONLY - PROPRIETARY
INFORMATION. WHEN SEPARATED FROM ENCLOSURE 2, THIS DOCUMENT IS
DECONTROLLED.
conference in an effort to make the conference more efficient and effective. If a Regulatory
Conference is held, it will be open for public observation. The NRC will also issue a press
release to announce the conference. If you decide to submit only a written response, such a
submittal should be sent to the NRC within 30 days of the receipt of this letter.
Please contact Mr. Jim Moorman at (404) 562-4647 within 10 business days of the date of your
receipt of this letter to notify the NRC of your intentions. If we have not heard from you within
10 days, we will continue with our significance determination and enforcement decisions and
you will be advised by separate correspondence of the results of our deliberations on this
matter.
Since the NRC has not made a final determination in this matter, a Notice of Violation is not
being issued at this time. In addition, please be advised that the number and characterization
of the apparent violations may change as a result of further NRC review.
In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter and
your response (if any) 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 A. Casto, Director
Division of Reactor Projects
Docket Nos.: 50-369, 50-370
Enclosures:
1. NRC Inspection Report 05000369,370/2007008 w/attachment: Supplemental Information
2. SDP Phase 3 Summary (OFFICIAL USE ONLY - PROPRIETARY INFORMATION)
cc w/encl: (See page 4)
_
OFFICE
RII:DRP
RII:DRS
EICS
RII:DRP
RII:dRP
SIGNATURE
JHM /RA/
RHB /RA/
SES /RA for/
JHM /RA for/
JHM /RA for/
NAME
JMoorman
RBernhard
CEvans
JBrady
REul
DATE
09/07/2007
09/06/2007
09/07/2007
09/07/2007
09/07/2007
E-MAIL COPY?
YES
NO YES
NO YES
NO YES
NO YES
NO YES
NO YES
NO
OFFICIAL USE ONLY - PROPRIETARY INFORMATION
4
DOCUMENT TRANSMITTED HEREWITH CONTAINS OFFICIAL USE ONLY - PROPRIETARY
INFORMATION. WHEN SEPARATED FROM ENCLOSURE 2, THIS DOCUMENT IS
DECONTROLLED.
cc w/encl:
C. J. Thomas
Compliance Manager (MNS)
Duke Power Company LLC
d/b/a Duke Energy Carolinas, LLC
Electronic Mail Distribution
cc w/o encl:
R. L. Gill, Jr., Manager
Nuclear Regulatory Issues
and Industry Affairs
Duke Power Company LLC
d/b/a Duke Energy Carolinas, LLC
526 S. Church Street
Charlotte, NC 28201-0006
Lisa F. Vaughn
Associate General Counsel
and Managing Attorney
Duke Energy Corporation
526 South Church Street-EC07H
Charlotte, NC 28202
Kathyrn B. Nolan
Senior Counsel
Duke Energy Corporation
526 South Church Street-EC 07H
Charlotte, NC 28202
David A. Repka
Winston & Strawn LLP
Electronic Mail Distribution
Beverly Hall, Chief, Radiation
Proctection Section
N. C. Department of Environmental
Health & Natural Resources
Electronic Mail Distribution
County Manager of Mecklenburg County
720 East Fourth Street
Charlotte, NC 28202
OFFICIAL USE ONLY - PROPRIETARY INFORMATION
5
DOCUMENT TRANSMITTED HEREWITH CONTAINS OFFICIAL USE ONLY - PROPRIETARY
INFORMATION. WHEN SEPARATED FROM THE ENCLOSURE 2, THIS DOCUMENT IS
DECONTROLLED.
Letter to G. R. Peterson from Charles A. Casto dated September 10, 2007
SUBJECT:
MCGUIRE NUCLEAR STATION - NRC INSPECTION REPORT
05000369/2007008 AND 05000370/2007008; PRELIMINARY GREATER THAN
GREEN FINDING
Distribution w/o encl:
J. Stang, NRR
C. Evans, RII
L. Slack, RII
OE Mail
RIDSNRRDIRS
PUBLIC
Enclosure 1
U.S. NUCLEAR REGULATORY COMMISSION
REGION II
Docket Nos:
50-369, 50-370
License Nos:
Report Nos:
05000369/2007008, 05000370/2007008
Licensee:
Duke Energy Corporation
Facility:
McGuire Nuclear Station, Units 1 and 2
Location:
12700 Hagers Ferry Road
Huntersville, NC 28078
Dates:
April 30, 2007 through September 4, 2007
Inspectors:
J. Brady, Senior Resident Inspector
R. Eul, Resident Inspector
Approved by:
James H. Moorman,III, Chief
Reactor Projects Branch 1
Division of Reactor Projects
Enclosure 1
SUMMARY OF FINDINGS
IR05000369/2007008 and 05000370/2007008; 04/30/2007 - 09/04/2007; McGuire
Nuclear Station; Other Activities.
The report covered the review and closure of an Unresolved Item for Unit 2. One
apparent violation (AV) (potentially greater than Green) was identified. The significance
of most findings is indicated by their color (Green, White, Yellow, Red) using IMC 0609,
Significance Determination Process (SDP). Findings for which the SDP does not apply
may be Green or be assigned a severity level after NRC management review. The
NRC's program for overseeing the safe operation of commercial nuclear power reactors
is described in NUREG-1649, Reactor Oversight Process, Revision 4, dated
December 2006.
A.
NRC-Identified and Self-Revealing Findings
Cornerstone: Mitigating Systems
TBD. The inspectors identified an apparent violation of 10 CFR 50, Appendix B,
Criterion XVI, Corrective Action, for the failure to take adequate corrective action
for a nonconformance, identified in Problem Investigation Process (PIP) M-96-
0530, associated with potential clogging of the Emergency Core Cooling System
(ECCS) cold leg injection throttle valves during high pressure recirculation.
Specifically, the licensee failed to adequately implement PIP credited inspections
of the inside of the ECCS sump, as evidenced by the 2006 discovery of a
significant amount of aged yellow duct tape inside the Unit 2 ECCS sump around
the suction and guard pipe of both ECCS trains. In addition, the licensee failed
to identify and take actions to process a design change per their design control
program for the resolution discussed in PIP M-96-0530, to evaluate the
resolution/change under 10 CFR 50.59, and to process a licensing basis change
under 10 CFR 50.71(e) to revise the UFSAR.
This finding is greater than minor because, if left uncorrected, the tape could
have a detrimental affect on the availability and reliability of both trains of high
and intermediate head ECCS pump when called upon during an accident. In
particular, the tape had the potential to have detrimental effects on the high
pressure recirculation function due to potential clogging of the ECCS throttle
valves, which have openings as small as 0.1 inches wide in the radial dimension.
The issue was evaluated under IMC 0609, Significance Determination Process,
Phase II, and was determined to be a greater than green finding. A Phase III
risk assessment was performed by a Region II Senior Reactor Analyst who also
found the issue to be potentially greater than green. This finding is being
considered for escalated enforcement action in accordance with the NRC
Enforcement Policy. This finding has a cross-cutting aspect of appropriate
correct actions in the area of problem identification and resolution (P.1.d).
(Section 4OA5)
Enclosure 1
Report Details
4.
OTHER ACTIVITIES
4OA5 Other Activities
(Closed) URI 05000370/2006005-02, Duct tape in Unit 2 Emergency Core Cooling
a.
Inspection Scope
This issue was unresolved pending NRC review of the documents 1 thru 7, listed in the
attachment. The inspectors reviewed the documents to determine whether past
evaluations, analysis, and corrective actions for potential clogging concerns associated
with the ECCS cold leg injection throttle valves were adequate. The inspectors also
reviewed these documents to determine how the duct tape around the unit 2 ECCS
suction pipe could have gone undiscovered until September 2006.
b.
Findings
Introduction: The inspectors identified an apparent violation (AV) for a failure to take
adequate corrective action for a nonconformance associated with potential clogging of
the ECCS cold leg injection throttle valves during high pressure recirculation.
Description: While reviewing PIP M-06-4324, the inspectors determined that on
September 28, 2006, the licensee found 12 square feet of yellow duct tape wrapped
around the ECCS suction and guard pipe in both trains of the emergency core cooling
system (ECCS) sump (5 square feet in Train A, 7 square feet in Train B). There
appeared to have been more tape installed at one time, however, boric acid in the sump
had dissolved what could have been up to 6 additional square feet (2.5' in Train A, 3.5'
in Train B) of duct tape. The licensee documented this discovery in PIP M-06-4324 and
initiated a significant event investigation team (SEIT). During the investigation the
licensee discovered that in the September 2002, Unit 1 outage, a licensee manager had
found and removed three or four pieces of duct tape, six to eight inches in length, from a
similar location in the Unit 1 ECCS sump. No corrective action document (PIP) was
initiated and no extent of condition review performed for Unit 2 at that time.
The inspectors reviewed PIP M-96-0530, which was initiated to conduct an operating
experience review of NRC Information Notice 96-27, Potential Clogging of High
Pressure Safety Injection Throttle Valves During Recirculation. The PIP problem
description identified that during the recirculation phase of a postulated LOCA, the
ECCS throttle valves may have the potential to collect debris and clog, resulting in
partial or complete loss of core cooling flow. The PIP identified a nonconformance, in
that the ECCS cold leg injection throttle valve plug to seat clearances were smaller than
the ECCS sump screen openings. This nonconformance was contrary to the design
and licensing basis for both units in that the ECCS sump screen should have had the
smallest size opening in the system so that anything passing through the screen would
not clog the ECCS system (UFSAR Section 6.5). The PIP resolution provided an
4
Enclosure 1
accept-as-is disposition for this nonconforming design. This accept-as-is disposition
credited a combination of design, system configuration, motive force, and administrative
controls for assurance that the ECCS throttle valves would not become clogged. With
the above combination of PIP corrective actions, the licensee considered this issue
resolved. One of the administrative controls credited was a periodic inspection of the
sump area inside the sump screen to ensure that the Emergency Sump remained free
of debris. This inspection was performed during each refueling outage. Any debris
found inside the sump was to be evaluated and removed. In addition, other credited
administrative controls included inspections of the reactor building prior to unit startup to
remove debris that could impede ECCS return flow and establishment of a foreign
material control process for online reactor building entries. No additional corrective
action was considered necessary in response to this nonconformance.
The inspectors found that the resolution was inadequate to correct the identified
nonconformance for the following reasons:
1.
The performance of the inspections inside the sump were inadequate in that they
did not find the significant amounts of duct tape on the Unit 2 ECCS sump guard
pipe that had the potential to clog the ECCS throttle valves.
2.
The resolution was an accept-as-is design change which was not processed in
accordance with the licensees design control program that implements
10 CFR 50, Appendix B, Criterion III.
3.
The resolution did not include an evaluation of this change under 10 CFR 50.59.
4.
The resolution did not include a change to the licensing basis as required by
10 CFR 50.71(e) to update the UFSAR.
Analysis: The performance deficiency involves a failure to take adequate corrective
actions for an identified nonconformance. Specifically, the licensee chose to credit
periodic inspections of the ECCS sump to ensure each Units ECCS sump remained
free of foreign material that could clog the respective ECCS cold leg injection throttle
valves. The credited periodic ECCS sump inspections were, however, subsequently
revealed to be ineffective, by the unrelated September 2006 discovery of a significant
amount of aged yellow duct tape inside the Unit 2 ECCS sump around the suction and
guard pipe of both ECCS trains. As this tape was not environmentally qualified for
expected sump loss of coolant accident (LOCA) conditions, there was a lack of
reasonable assurance that the Unit 2 ECCS cold leg high and intermediate head
injection throttle valves would remain unclogged during the high pressure recirculation
phase of ECCS safety injection for small break and medium break LOCAs.
This issue is greater than minor because, if left uncorrected, the tape could have a
detrimental affect on the availability and reliability of both trains of ECCS when called
upon during an accident. In particular, the tape had the potential to have detrimental
effects on the high pressure recirculation function due to potential clogging of the ECCS
throttle valves which have plug to seat openings as small as 0.1 inches wide in the radial
5
Enclosure 1
dimension. The issue was evaluated under IMC 0609, Significance Determination
Process and was determined to be a potentially greater than green finding by Phase II
analysis. A Phase III risk assessment was performed by a Region II Senior Reactor
Analyst which also found the issue to be potentially greater than green. This finding has
a cross-cutting aspect of appropriate correct actions in the area of problem identification
and resolution (P.1.d).
Enforcement: 10 CFR 50 Appendix B Criterion XVI, Corrective Action, states that
measures shall be established to assure that conditions adverse to quality, such as
deficiencies, deviations, and nonconformances are promptly identified and corrected. In
the case of significant conditions adverse to quality, the measures shall assure that the
cause of the condition is determined and corrective action taken to preclude repetition.
The identification of the condition, cause of the condition, and the corrective action
taken shall be documented and reported to appropriate levels of management. This
requirement is implemented through the Duke Quality Assurance Program Topical
Report and procedure NSD 208, Problem Identification Process. Contrary to the above,
from approximately June 3,1996 until September 28, 2006, the licensee failed to
adequately correct a significant condition adverse to quality related to the
nonconformance identified in PIP M-96-0530 for ECCS injection throttle valve plug to
seat clearances being smaller than ECCS sump screen openings. Specifically, the
licensees corrective action failed to adequately implement credited inspections of the
inside of the ECCS sump as evidenced by the 2006 discovery of a significant amount of
aged yellow duct tape inside the Unit 2 ECCS sump around the suction and guard pipe
of both ECCS trains, failed to process the resolution discussed in PIP M-96-0530 as a
design change per their design control program, failed to evaluate the resolution/change
under 10 CFR 50.59, and failed to process a licensing basis change under
10 CFR 50.71(e) to revise the UFSAR. This finding is identified as an apparent
violation, AV 05000370/2007008-01: Failure to Take Adequate Corrective Action For A
Nonconformance Associated With ECCS Throttle Valves. It is being considered for
escalated enforcement action in accordance with the NRC Enforcement Policy.
Accordingly, for administrative purposes, URI 05000370/2006005-02 is considered
closed.
4OA6 Meetings, Including Exit
On September 4, 2007, the resident inspectors presented the inspection results to Mr.
G. Peterson and other members of his staff. The inspectors confirmed that proprietary
information was not provided or examined during the inspection.
Attachment
SUPPLEMENTAL INFORMATION
KEY POINTS OF CONTACT
Licensee
Ashe, K., Manager, Regulatory Compliance
Brown, S., Manager, Engineering
Crane, K., Regulatory Compliance
Evans, K., Superintendent, Maintenance
Kammer, J., Manager, Safety Assurance
Mooneyhan, S., Radiation Protection Manager
Nolin, J., Manager, Mechanical and Civil Engineering (MCE)
Parker, R., Superintendent, Work Control
Peterson, G., Site Vice President, McGuire Nuclear Station
Repko, R., Station Manager, McGuire Nuclear Station
NRC personnel
J. Moorman, Chief, Reactor Projects Branch 1
J. Stang, Project Manager, NRR
LIST OF ITEMS OPENED, CLOSED, AND DISCUSSED
Opened
Failure to Take Adequate Corrective Action For A
Nonconformance Associated With ECCS Throttle
Valves. (Section 4OA5)
Closed
Duct Tape In Unit 2 ECCS Sump (Section 4OA5)
LIST OF DOCUMENTS REVIEWED
Section 4OA5: Other Activities
1.
SEIT report, which was documented in PIP M-06-4364.
2.
Westinghouse report dated December 20, 2006, titled McGuire Operability
Determination for Duct Tape in Containment Sump.
3.
Duke Materials Engineering and Lab Services Report dated October 18, 2006, Titled
Characterization of Degraded Duct Tape from MNS ECCS System.
4.
Duke Materials Engineering and Lab Services Report dated February 15, 2007, titled
Evaluation of New Duct Tape.
2
Attachment
5.
NRC Information Notice (IN) 96-27 titled Potential Clogging of High Pressure Safety
Injection Throttle Valves During Recirculation.
6.
PIP M-96-00530, issued to document the licensees review and evaluation of IN 96-27
7.
Licensee document dated 2/21/07 titled, McGuire ECCS Throttle Valve Duct Tape Flow
Testing
8.
UFSAR Section 6.3 and 6.5