05000461/LER-2009-005, Regarding Manual Scram on High Water Level Due to Reactor Recirculation Pump Trip
| ML093510017 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 12/08/2009 |
| From: | Kearney F Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SRRS 5A.108, U-603932 LER 09-005-00 | |
| Download: ML093510017 (5) | |
| 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 |
| 4612009005R00 - NRC Website | |
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Nuclear Clinton Power Station 8401 Power Road Clinton, IL 61727-9351 10 CFR 50.73 SRRS 5A.108 U-603932 December 8, 2009 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461
Subject:
Licensee Event Report 2009-005-00 Enclosed is Licensee Event Report (LER) No. 2009-005-00: Manual Scram on High Water Level Due to Reactor Recirc Pump Trip. This report is being submitted in accordance with the requirements of 10 CFR 50.73.
There are no regulatory commitments contained in this letter.
Should you have any questions concerning this report, please contact D. L. McMillan, at (217)-937-3920.
Respectfully, FeA eaarn/yý Site Vice President Clinton Power Station RSF/blf
Enclosures:
Licensee Event Report 2009-005-00 cc:
Regional Administrator - NRC Region III NRC Senior Resident Inspector - Clinton Power Station Office of Nuclear Facility Safety - IEMA Division of Nuclear Safety
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2010 (9-2007)
, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Clinton Power Station, Unit 1 05000461 1 OF 4
- 4. TITLE Manual Scram on High Water Level Due to Reactor Recirc Pump Trip
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEAUMENTIA R
FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR IENUENT NLREV MONTH DAY YEAR None 05000 NUMBER NO.MNT DA YER FACILITY NAME DOCKET NUMBER 10 15 09 2009 005 -
00 12 08 09 None 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
[l 20.2201(b)
El 20.2203(a)(3)(i) 0l 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii)
[1 20.2201(d) 0l 20.2203(a)(3)(ii)
[I 50.73(a)(2)(ii)(A)
[3 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
[I 20.2203(a)(4) 11 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
[] 20.2203(a)(2)(i)
El 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)
El 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
[I 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
[1 73.71(a)(4) 96.6 El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71 (a)(5)
[I 20.2203(a)(2)(v)
Z 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
[E OTHER El 20.2203(a)(2)(vi)
[E 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below or in Initial investigation at the 3B and 4B feed breakers [BKR] for the 'B'.RR pump motor [MO] revealed that the ground relays [64] had actuated on both breakers. Further troubleshooting and megger testing of the motor determined the cause of 'B' Reactor Recirculation pump trip was a phase to ground fault inside the pump motor. The motor has been sent to a vendor for failure analysis.
Upon trip of the 'B' AR pump, an immediate operator action is to shut the AR pump discharge valve for the idle reactor recirculation pump to prevent reverse rotation of the pump. During this event, operators attempted to close the 'B' RR pump discharge valve, 1 B33F067B, but it would not fully close. Issue Report 979732 was initiated to investigate and correct the failure of valve 1 B33F067B to fully close.
No other inoperable equipment or components directly affected this event.
Issue Report 979700 was initiated to investigate this event and initiate corrective actions.
The NRC Operations Center was notified at 0806 hours0.00933 days <br />0.224 hours <br />0.00133 weeks <br />3.06683e-4 months <br /> about this reactor scram via Event Notification 45433.
CAUSE OF EVENT
The cause of this event is attributed to the failure of the 'B' AR pump motor. The pump motor was shipped to a vendor for failure analysis. The vendor concluded that the failure in the AR pump motor was a B-Phase turn-to-turn fault located at a connection end coil knuckle. The failure was limited to a single coil end turn knuckle of the winding and was located in a position that is not susceptible to air flow or foreign material. The affected area was cut out and the remaining windings passed all electrical testing. The apparent cause of the failure was a random insulation breakdown of the original winding that resulted in a turn-to-turn failure.
Clinton Power Station is designed to stay on line with a single recirculation pump trip. A review of the response of the Feedwater Level Control System (FWLCS) [JB] to the 'B' AR Pump trip on 10/15/09 identified that it was very similar to that of a previous event on 2/10/08 when the 'B' AR Pump tripped to off and an unexpected reactor scram occurred on high RPV water Level 8.
The cause of the 2/10/08 Reactor Scram identified that FWLCS tuning was inadequate to ensure that Reactor water level does not approach the Level 8 Scram setpoint when a single AR pump trips off. Specifically, the FWLCS turbine driven reactor feed pump flow control cards are not tuned to provide adequate response.
Consequently, the feedwater demand signal did not decrease fast enough to reduce feedwater pump flow after the RR pump trip. In response to the cause an action plan was developed to correct the plant response to a single AR pump trip including dynamic tuning of the FWLCS. At the time of this 10/15/09 event, all of the actions were not completed from the 2/10/08 event and are not expected to be completed until startup from refueling outage C1R12. C1R12 is scheduled to begin in January 2010.
SAFETY ANALYSIS
This event is reportable under the provisions of 10 CFR 50.73 (a) (2) (iv) (A) as an event that resulted in a manual reactor scram while the reactor was critical. No significant safety consequences resulted from this event because required safety systems were available and functioned as designed within safety limits. The reactor was shut down safely and maintained in a safe shut down condition.
This reactor scram event was compared to similar previous events and the plant response and behavior was almost identical to the previous events. The reactor scram was compared to Updated Safety Analysis Report (USAR) Section 15.3, Decrease in Reactor Coolant System Flow Rate. The fission product barriers (fuel clad, reactor, pressure boundary, containment) were not challenged during this event. No Safety Relief Valves lifted during this event and pressure control maintained by Main Steam Line Drains and the RCIC system. The Motor Driven Reactor Feed Pump was used to maintain RPV water level.
This event report does not identify any safety system functional failures.
CORRECTIVE ACTION
A spare RR pump motor was installed in place of the 'B' RR pump motor that failed. The 'B' RR pump motor that failed will be repaired and placed in stores.
PREVIOUS OCCURRENCES
LER 2008-001 was a previous similar event. A reactor scram event occurred on 2/10/08 as a result of an unexpected trip of the 'B' RR pump. This event is discussed further in the CAUSE OF EVENT section of this report.
COMPONENT FAILURE DATA
The Reactor Recirculation Pump B motor was manufactured by General Electric, and is 6300 horsepower, 6600 volts, 484 amps, 3-phase, non-safety, Critical Class 1, continuous run motor, model 264X805.PRINTED ON RECYCLED PAPERPRINTED ON RECYCLED PAPER