05000315/LER-2013-001, Regarding Unit 1 Reactor Coolant System Weld Defect and Pressure Boundary Leakage
| ML13151A021 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 05/28/2013 |
| From: | Gebbie J Indiana Michigan Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| AEP-NRC-2013-46 LER 13-001-00 | |
| Download: ML13151A021 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3152013001R00 - NRC Website | |
text
z INDIANA MICHIGAN POWER5 A unit of American Electric Power Indiana Michigan Power Cook Nuclear Plant One Cook Place Bridgman, MI 49106 Indiana Michigan Power.com AEP-NRC-2013-46 10 CFR 50.73 May 28, 2013 Docket No. 50-315 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Donald C. Cook Nuclear Plant Unit 1 LICENSEE EVENT REPORT 315/2013-001-00 UNIT 1 REACTOR COOLANT SYSTEM WELD DEFECT AND PRESSURE BOUNDARY LEAKAGE In accordance with the criteria established by 10 CFR 50.73, Licensee Event Report System, the following report is being submitted:
LER 315/2013-001-00: "Unit I Reactor Coolant System Weld Defect and Pressure Boundary Leakage" There are no commitments contained in this submittal.
Should you have any questions, please contact Mr. Michael K. Scarpello, Regulatory Affairs Manager, at (269) 466-2649.
Sincerely, kJIUA&-
Joel P. Gebbie Site Vice President SJM/dmb Enclosure c:
C. A. Casto, NRC Region III J. T. King, MPSC S. M. Krawec, AEP Ft. Wayne, w/o enclosures MDEQ - RMD/RPS NRC Resident Inspector T. J. Wengert, NRC Washington, DC V-A
NRC Form 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES 10/31/2013 (10-2010)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Donald C. Cook Nuclear Plant Unit 1 05000-315 1 of 3
- 4. TITLE Unit 1 Reactor Coolant System Weld Defect and Pressure Boundary Leakage
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH YEAR FACILITY NAME DOCKET NUMBER NUMBER NO.
05000 FACILITY NAME DOCKET NUMBER 03 31 2013 2013 001 00 05 28 2013 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
El 20.2201(b)
El 20.2203(a)(3)(i) 0l 50.73(a)(2)(i)(C)
[I 50.73(a)(2)(vii) 5 E
20.2201(d)
El 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(A)
[] 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
[I 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
[I 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A)
El 50.73(a)(2)(iv)(A)
[I 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4) 0 %
El 20.2203(a)(2)(iv) 11 50.46(a)(3)(ii)
[E 50.73(a)(2)(v)(B)
H 73.71(a)(5)
El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)S OTHER Specify in Abstract below 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D) or in cycle, and that this leak was not in a location to impact the function of any equipment necessary to mitigate RCS leaks, this condition did not represent any significant risk to the unit and did not pose a risk to the health and safety of the public.
Corrective Actions
Completed Corrective Actions ASME Section XI Repair and Replacement activities have been completed that include the modification of the piping to shift the natural frequency, revised.fillet welds, and replacement of the elbow.
Vibration analysis was completed on the cantilever piping where the defect was identified and other similar components on the RCS to address the extent of condition. All readings were found acceptable without the need for additional analysis.
Planned Corrective Actions
Material failure analysis of the socket weld and associated piping is pending at the time of this report and a full causal evaluation will follow.
A revision to this LER will be provided if the material failure analysis or causal evaluation results in substantial changes in the cause or planned corrective actions.
Previous Similar Events
LERs for CNP Unit 1 and Unit 2 for the past five years were reviewed for similar events. The following was identified:
05000315-2008-004-00, Non-Isolable Reactor Coolant System Pressure Boundary Leak On April 25, 2008, personnel at CNP Unit 1 identified a non-isolable RCS pressure boundary leak on a 3/4-inch instrument line connected to the RCS. Technical Specification LCO 3.4.13 limits the RCS to no pressure boundary leakage and is applicable in Modes 1, 2, 3, and 4.
The apparent cause was determined to be vibratory fatigue based on the piping configuration making it susceptible to high cycle fatigue, with the source of energy being the Reactor Coolant Pump. High cycle fatigue caused flaw propagation and the subsequent leak.
The apparent cause documented in the LER in 2008 is apparently the same as the current weld failure in this LER, as described as cyclic fatigue. The weld repairs and corrective actions are different for each event. The repair in 2008 was completed using a seal weld and weld overlay under the requirements of Code Case N-666. The current event repair included removing the elbow, modifying the piping, and use of a different fillet weld profile. It is noted that the 2008 and current events involve the same elbow component with the defects located at opposite socket welds.
Corrective actions taken in the 2008 event would not have prevented the current reportable event, based on the different location of the previous weld defect and the nature of the repairs completed.