05000315/LER-2011-001, For Donald C. Cook, Unit 1, Regarding Reactor Trip Due to Main Turbine Trip
| ML11320A110 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 11/07/2011 |
| From: | Gebbie J Indiana Michigan Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| AEP-NRC-2011-65 LER 11-001-00 | |
| Download: ML11320A110 (3) | |
| 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 |
| 3152011001R00 - NRC Website | |
text
INDIANA MICHIGAN POWER A unit of American Electric Power November 7, 2011 Indiana Michigan Power Cook Nuclear Plant One Cook Place Bridgman, MI 49106 AEPcom AEP-NRC-2011-65 10 CFR 50.73 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 315/2011-001-00 REACTOR TRIP DUE TO MAIN TURBINE TRIP In accordance with the criteria established by 10 CFR 50.73, Licensee Event Report System, the following report is being submitted:
LER 315/2011-001-00: "Reactor Trip Due to Main Turbine Trip."
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, Joel P. Gebbie Site Vice President JEN/jen Enclosure c:
J. T. King - MPSC, w/o enclosure S. M. Krawec - AEP Ft. Wayne, w/o enclosure MDEQ - WHMD/RPS, w/o enclosure NRC Resident Inspector M. A. Satorius - NRC Region III P. S. Tam - NRC Washington DC fJ(2 1&
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 2
- 4. TITLE Unit 1 Reactor Trip Due To Main Turbine Trip
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 09 07 2011 2011 001 00 11 07 2011 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)
F1 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii)
El 20.2201(d)
El 20.2203(a)(3)(ii)
El 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)
E]
50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL [I
20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A) 0 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
C]
20.2203(a)(2)(iii)
[]
50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4) 100 El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B) 73.71 (a)(5)
El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
U OTHER Specify in Abstract below I El 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D) or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (Include Area Code)
Michael K. Scarpello, Regulatory Affairs Manager (269) 466-2649MANU-REPORTABLE MANU-REPORTABLE TO
CAUSE
SYSTEM COMPONENT FACTURER TO EPIX
CAUSE
SYSTEM COMPONENT FACTURER EPIX
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION El YES (If Yes, complete 15. EXPECTED SUBMISSION DATE).
0 NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On September 07, 2011, at 0854 hours0.00988 days <br />0.237 hours <br />0.00141 weeks <br />3.24947e-4 months <br />, Donald C. Cook Nuclear Plant (CNP) Unit 1 Reactor tripped automatically due to a trip of the main turbine. All control rods fully inserted and the auxiliary feedwater system (AFW) started and performed as designed.
The reactor trip was uncomplicated and all major plant components functioned as designed; as such, there were no safety system functional failures. The reactor trip was reported in accordance with 10 CFR 50.72(b)(2)(iv)(B) and the AFW actuation was reported in accordance with 10 CFR 50.72(b)(3)(iv)(A). The reactor trip and AFW actuation are reportable as a Licensee Event Report (LER) in accordance with 10 CFR 50.73(a)(2)(iv)(A).
The main turbine tripped due to an automatic turbine trip signal generated by the main turbine thrust bearing wear detection system. The initial investigation has concluded that there was no actual thrust bearing wear condition. The cause of the inadvertent trip signal has been determined to be a result of inadequate installation of sensing equipment. This inadequate installation resulted in a spurious trip signal common to both channels.
Corrective actions have been taken to correct the installation.
NRC FORM 366 (10-2010)
Conditions Prior to Event
100 percent reactor power.
Description of Event
On September 07, 2011, at 0854 hours0.00988 days <br />0.237 hours <br />0.00141 weeks <br />3.24947e-4 months <br />, Donald C. Cook Nuclear Plant (CNP) Unit 1 Reactor [AC] tripped automatically due to a trip of the main turbine [TRB]. All control rods [AA] fully inserted and the auxiliary feedwater system (AFW) [BA] started and performed as designed.
The reactor trip was uncomplicated and all major plant components functioned as designed; as such, there were no safety system functional failures. The reactor trip was reported in accordance with 10 CFR 50.72(b)(2)(iv)(B) and the AFW actuation was reported in accordance with 10 CFR 50.72(b)(3)(iv)(A). The reactor trip and AFW actuation pre reportable as a Licensee Event Report (LER) in accordance with 10 CFR 50.73(a)(2)(iv)(A).
Cause of Event
The main turbine tripped due to an automatic turbine trip signal generated by the main turbine thrust bearing wear detection system [JJ]. The initial investigation has concluded that there was no actual thrust bearing wear condition. The cause of the inadvertent trip signal has been determined to be a result of inadequate installation of sensing equipment. This inadequate installation resulted in a spurious trip signal common to both channels. Corrective actions have been taken to correct the installation. A Root Cause Evaluation (RCE) is in progress, and a supplement to this LER will be submitted following the evaluation if results are substantially different than what is being reported here.
Analysis of Event
The event is not considered to be risk significant as there were no risk significant equipment failures to pose elevated risk. It is recognized that there was an actuation of a main turbine protective circuit; subsequently, all systems responded as designed.
Based on review of the control room log and Plant Process Computer [CPU] information, along with the post-trip review from which the information above was obtained, all plant systems performed as designed to shut down the unit and remove decay heat. No risk-significant equipment functions were affected or failed and no significant operator actions outside those required for normal trips were required.
Corrective Actions
Completed Corrective Actions The following corrective actions were taken to correct the installation inadequacy:
The thrust probes have been routed through separate conduits to provide circuit separation.
The thrust probe connectors have been sealed to keep lubricating oil out.
The thrust probe cabling in the junction boxes has been wrapped with an EMI (Electro Magnetic Interference) mesh tape to protect circuits from cross-communication interference.
Planned Corrective Actions
None.
Previous Similar Events
LERs for CNP Unit 1 and Unit 2 for the past three years were reviewed for similar events. While there have been manual reactor trips, there have been no automatic reactor trips due to actuation of main turbine trip circuitry.