05000414/LER-2004-001, Re Reactor Coolant System Pressure Boundary Leakage Due to Small Cracks Found in Steam Generator Channel Head Bowl Drain Line on 2C & 2D Steam Generators
| ML043280501 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 11/09/2004 |
| From: | Jamil D Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 04-001-00 | |
| Download: ML043280501 (12) | |
| Event date: | |
|---|---|
| Report date: | |
| 4142004001R00 - NRC Website | |
text
_ Duke OrPowere A Duke Energy Company D.M. JAMIL Vice President Duke Power Catawba Nuclear Station 4800 Concord Rd. / CN01 VP York, SC 29745-9635 803 831 4251 803 831 3221 fax November 9, 2004 U. S. Nuclear Regulatory Commission ATTENTION:
Document Control Desk Washington, DC 20555-0001
SUBJECT:
Duke Energy Corporation Catawba Nuclear Station Unit 2 Docket No. 50-414 Licensee Event Report 414/04-001 Revision 0 Reactor Coolant System Pressure Boundary Leakage Due to Small Cracks Found in Steam Generator Channel Head Bowl Drain Line on 2C & 2D Steam Generators Attached please find Licensee Event Report 414/04-001 Revision 0, entitled "Reactor Coolant System Pressure Boundary Leakage Due to Small Cracks Found in Steam Generator Channel Head Bowl Drain Line on 2C & 2D Steam Generators."
This Licensee Event Report does not contain any regulatory
commitments
Questions regarding this Licensee Event Report should be directed to R. D. Hart at (803) 831-3622.
Sincerely, Dhiaa Jamil Attachment www. dukepower. corn
U.S. Nuclear Regulatory Commission November 9, 2004 Page 2 xc:
W.D. Travers U.S. Nuclear Regulatory Commission Regional Administrator, Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, GA 30303 E.F. Guthrie Senior Resident Inspector (CNS)
U.S. Nuclear Regulatory Commission Catawba Nuclear Station S.E. Peters (addressee only)
NRC Project Manager (CNS)
U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 10-B3 11555 Rockville Pike Rockville, MD 20852-2738
Abstract
On September 16, 2004, with Catawba Unit 2 in MODE 6 entering a refueling outage, a visual examination was performed on the steam generator (SG) 2A, 2C &
2D lower head bowl drains.
Reactor Coolant System (RCS) pressure boundary leakage was identified on the 2C and 2D SG bowl drains.
The 2A SG lower head bowl drain did not have any pressure boundary leakage.
The pressure boundary leakage path was suspected to be the nozzle coupling to vessel weld.
This event was reported to the NRCOC at 1131 on September 17, 2004 pursuant to 10 CFR 50.72 (b)(ii)(A). The most probable cause of the SG Bowl Drain leak is primary water stress corrosion cracking (PWSCC).
The 2C & 2D SG bowl drain leaks were subsequently repaired, examined and tested.
The 2A SG bowl drain was also repaired similar to the 2C & 2D SG bowl drains as a preventive measure.
The 2B SG bowl drain had been repaired in 2001 due to a similar leak (LER 414/01-002).
A corrective action from the previous LER was the development of a program to address Alloy 600 issues which included the inspections that discovered the events in this LER.
This issue is not applicable to Unit 1 because the SGs are a different design that does not have a similar drain line. The overall safety significance of this event was determined to be minimal and there was no actual impact on the health and safety of the public.
NRC FORM 366 (6-2004)
(If more space Is required, use additional copies of (If more space Is required, use additional copies of (If more space Is required, use additional copies of (If more space Is required, use additional copies of (If more space Is required, use additional copies of NRC Form 366A) (17) sounded, and the small amounts of boric acid crystal deposits that were observed had caused no observable corrosion to the SG vessel.
From a nuclear safety perspective, it has been concluded that any leakage due to typical PWSCC is not a challenge to nuclear safety.
Reasons in support of this conclusion are:
- Leak rates from these cracks were very low
- Cracks were axial in orientation thus minimizing any potential for a catastrophic failure of a nozzle.
For the previous LER, a calculation was performed to determine the probable consequences on the RCS if the cracks on the bowl drain lines would not have been detected.
The conclusion reached was that due to the cracks being in the radial/axial orientations, there would have been no catastrophic failure of the bowl drain connection.
Engineering has evaluated the failures identified in this LER and no observations or other issues related to these failures has been identified or discovered that would lead to a different conclusion from that reached in previous LER.
Therefore, the overall safety significance of this event was determined to be minimal and there was no actual impact on the health and safety of the public.
ADDITIONAL INFORMATION
The 2B SG bowl drain experienced a similar leak in the fall of 2001 and was reported to the NRC as LER 414/01-002 on November 12, 2001.
The event reported in this LER has the same root cause.
Therefore, this event was determined to be recurring in nature.
However, this event only affected the SG bowl drains for Unit 2 and those SG bowl drains have been repaired to preclude recurrence.
The Unit 1 SGs are of a different design and are not susceptible to this event.
Catawba has implemented an Alloy 600 inspection program to monitor other areas that have Alloy 600.
Therefore, no further corrective actions are necessary.
Energy Industry Identification System (EIIS) codes are identified in the text as [EIIS: XX].
This event is considered reportable to the Equipment Performance and Information Exchange (EPIX) program.
This event did not include a Safety System Functional Failure nor involve a personnel error.
There were no releases of radioactive materials, radiation exposures or personnel injuries associated with this event.
VERIFY HARD COPY AGAINST WEB SITE IMMEDIATELY PRIOR TO EACH USE Nuclear Policy Manual - Volume 2 NSD 227 NRC CORRESPONDENCEREVIEW ANDCONCURRENCE FORM Applicable Site(s) ONS E0 MNS El CNS
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Submittal Title/Subject:
LER 414-04-001, Reactor Coolant System Pressure Boundary Leakage Due to Small Cracks Found In Steam Generator Channel Head Bowl Drain Line on 2C & 2D Steam Generators
Background Information
Scheduled Submittal Date:
11/09104 Mandatory Submittal Date? (YIN)
N PORC Approval Date Submittal Lead Name 11/04/04 NSRB Approval Date NA Commitment Revle&_L Randall D. Hart Phone 831-3622 Content Development (Attach additional Information as needed)
Contributor Name/Site Scope/extent of Contribution or Portion Contributed Randall D. Hart Originator W. 0. Callaway Engineering review Individual Review (Attach additional Information as needed)
Reviewer Name/Site Signature Portions or Subjects Reviewed and Nature of Review a lc-60150 umje genera/lofnL
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Name l_Signature l
Nature of Review Submittal Lead Dg, O___
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SA Manager (Optional)
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Name Signature Nature of Review AIA-This completed form must be presented with the original submittal for signature. The form may be filled In with reference to e-mailed Information In place of actual signatures and required Information so long as the e-mailed Information Is maintained with the copy of this form that Is sent to Master file.
12 REVISION 1 VERIFY HARD COPY AGAINST WEB SITE IMMEDIATELY PRIOR TO EACH USE
Catawba Nuclear Station LER 414/04-001-00 PIP C-04-04663 ENCLOSURE 1 Signature Sheet Rb QL%
Prepared By:
Reviewed By:
Approved By:
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ENCLOSURES:
- 1. Safety Review Signature Sheet
- 2. References
- 3. Corrective Action Schedule
- 4. Cause Code Summary
- 5. Personnel Contacted
Catawba Nuclear Station LER 414/04-001-00 PIP C-04-04663 ENCLOSURE 2 REFERENCES 1.
2.
3.
4.
5.
6.
LER 414/04-001-00 PIP C-04-04663 Catawba TS 3.4.13 and Bases LER 414-01-002 UFSAR Section 5.4.2 DBD CNS-1553.NC-00-0001, Rev. 14, Reactor Coolant System (NC).
ENCLOSURE 3 CORRECTIVE ACTION SCHEDULE Corrective Action Person(s)
Contacted Person(s)
Assigned Due Date See PIP C-04-04663
Catawba Nuclear Station LER 414/04-001-00 PIP C-04-04663 ENCLOSURE 4 CAUSE CODE ASSIGNMENT SHEET CAUSE CODE:
See PIP C-04-04663 ENCLOSURE 5 PERSONNEL CONTACTED Personnel Contacted:
- 1. Dave Ward
- 2. W. 0. Callaway