| U.S. Nuclear Regulatory Commission
Operations Center Event Reports For
11/29/2011 - 11/30/2011 ** EVENT NUMBERS ** |
 | Power Reactor | Event Number: 47485 | Facility: SOUTH TEXAS
Region: 4 State: TX
Unit: [ ] [2] [ ]
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: ROBERT BRINKLEY
HQ OPS Officer: HOWIE CROUCH | Notification Date: 11/29/2011
Notification Time: 06:55 [ET]
Event Date: 11/29/2011
Event Time: 03:29 [CST]
Last Update Date: 11/29/2011 | Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
| Person (Organization):
THOMAS FARNHOLTZ (R4DO)
|
| Unit | SCRAM Code | RX CRIT | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode | | 2 | A/R | Y | 100 | Power Operation | 0 | Hot Standby | Event Text AUTOMATIC REACTOR TRIP DUE TO TURBINE TRIP ON GENERATOR LOCKOUT
"At 0329 CST on 11/29/2011, Unit 2 experienced an automatic Reactor Trip while the plant was stable at 100% power in Mode 1. All systems actuated as designed. The reactor trip was caused by Generator Lockout.
"All ESF systems actuated as designed. The following systems actuated: Auxiliary Feedwater [AFW] and Feedwater Isolation.
"All control rods fully inserted. Steam Dump system valve FV 7485 failed open and was manually isolated. This caused a letdown isolation that was restored. No primary/secondary relief valves lifted. There were no electrical bus transfer problems. Normal operating temperature and pressure [of] 567 degrees F and 2235 psig [is being maintained]. There were no significant TS LCOs entered."
The electrical grid is stable and is supplying power to the plant via a normal shutdown electrical line-up. Decay heat is being removed via steam dumps to the condenser with AFW supplying the steam generators. There was no effect on Unit 1.
The licensee has notified the NRC Resident Inspector.
* * * UPDATE ON 11/29/11 AT 1312 EST FROM BRINKLY TO HUFFMAN * * *
The licensee has issued a press release concerning this event. The NRC Resident Inspector will be notified. R4DO (Farnholtz) informed. |
| Part 21 | Event Number: 47488 | Rep Org: FLOWSERVE
Licensee: FLOWSERVE
Region: 1
City: LYNCHBURG State: VA
County:
License #:
Agreement: Y
Docket:
NRC Notified By: JEFF McCONKEY
HQ OPS Officer: BILL HUFFMAN | Notification Date: 11/29/2011
Notification Time: 17:25 [ET]
Event Date: 08/02/2011
Event Time: [EST]
Last Update Date: 11/29/2011 | Emergency Class: NON EMERGENCY
10 CFR Section:
21.21 - UNSPECIFIED PARAGRAPH
| Person (Organization):
WAYNE SCHMIDT (R1DO)
BINOY DESAI (R2DO)
KENNETH RIEMER (R3DO)
THOMAS FARNHOLTZ (R4DO)
PT 21 GRP (E-MAIL) ()
| Event Text PART 21 NOTIFICATION ON LIMITORQUE SMB-5T ACTUATOR CLUTCH LUG FAILURE
The following is a summary of information was received from Limitorque via facsimile:
"On August 2, 2011, Flowserve-Limitorque was notified by Browns Ferry Nuclear (BFN) Generating Station that a Limitorque SMB-5T valve actuator (1-MVOP-074-052) had failed to run open automatically during the performance of a stroke test. Electrical maintenance personnel working at the valve reported an abnormal mechanical noise. Upon disassembly, it was found that the driving lugs on both the sliding clutch gear and the flexible clutch were seriously worn with a significant amount of deformation. Further investigation by BFN showed that the declutch mechanism would not allow full engagement of the drive lugs on the sliding clutch and flexible clutch. These lugs must be engaged for motor operation to take place. The declutch mechanism required adjustment to allow full drive lug engagement.
"Following reassembly of the SMB-5T on 1-MVOP-074-052, an inspection was performed of the SMB-5T on valve 1-MVOP-074-066 which was manufactured and supplied to TVA at the same time. This actuator was functioning normally at the time of the inspection. Disassembly of the clutch compartment revealed evidence of deformation of the clutch drive lugs. To better evaluate the operation of the clutch components, the grease was cleaned out of the compartment and a boroscope used so that the action of the clutch could be seen. Boroscope examination of several declutching and re-clutching tests showed that the clutch lugs would not engage fully. The major contributing factor in this issue was found to be the external declutch lever stop screw adjustment. Adjustment of the lever stop screw significantly improved the lug engagement. Subsequently, BFN personnel inspected four additional SMB-5T actuators. The declutch components were found to be adjusted correctly and no indications of abnormal clutch lug wear were found.
"The potential for this issue is limited to SMB-5 and SMB-5T actuators only. Other sizes of SMB/SB/SBD actuators are not affected. This issue, when it occurs can affect the safety related function of the actuator by preventing proper motorized operation. Indications of the issue can include failure to complete valve stroke, failure to remain in motorized operation, intermittent motorized operation resulting in longer than expected stroke time, and/or abnormal noise in the clutch compartment.
"Limitorque performed an investigation per the guidelines of 10 CFR Part 21. The failure of 1-MVOP-074-052 to operate was due to damage to the drive lug interface between the sliding clutch and the flexible clutch which resulted in the actuator disengaging from electric motor operation in mid-stroke of the valve. This lug damage occurred over time during normal operation of the actuator and is directly attributable to an assembly set-up error resulting in partial lug engagement. The actuators which were investigated at BFN Unit 1 were of relatively recent manufacture, having been shipped from the Limitorque factory in 2004. Limitorque's review of existing SMB-5/5T assembly procedures followed by interviews with assembly personnel led to the conclusion that the root cause of this event was that the Limitorque factory assembly procedure documents for the SMB-5/5T lack adequate detail to ensure reliable long term functionality of the clutching mechanism.
"Limitorque's review of previous industry operating experience did not show any history of problems related to drive lug engagement and/or declutch components in SMB-5/5T actuators. However to address the potential issue of insufficient drive lug engagement, Limitorque will issue a Maintenance Update to the MOV Users Group for distribution to the utilities (on or before January 15, 2012) containing recommendations for site inspection of the SMB-5/5T clutch mechanism as well as detailed instructions for set-up, adjustment and verification of proper clutch operation. As part of our internal corrective action, Limitorque will develop enhanced assembly and service procedures for the SMB-5/5T to include sufficient detail to ensure the proper set-up and function of the clutching mechanism. Limitorque assembly, field service, and QC personnel will be trained in the enhanced procedures."
Technical contacts:
John Thilking 434-522-9862
Jeff McConkey 434-845-9738 |
| Power Reactor | Event Number: 47489 | Facility: CLINTON
Region: 3 State: IL
Unit: [1] [ ] [ ]
RX Type: [1] GE-6
NRC Notified By: KEN LEFFEL
HQ OPS Officer: STEVE SANDIN | Notification Date: 11/29/2011
Notification Time: 21:47 [ET]
Event Date: 11/29/2011
Event Time: 17:28 [CST]
Last Update Date: 11/29/2011 | Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
| Person (Organization):
KENNETH RIEMER (R3DO)
|
| Unit | SCRAM Code | RX CRIT | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode | | 1 | A/R | Y | 16 | Power Operation | 0 | Hot Shutdown | Event Text UNIT EXPERIENCED AN AUTOMATIC REACTOR SCRAM DURING A PLANNED SHUTDOWN
"During a planned shutdown in preparation for refueling outage C1R13, shortly after tripping the main turbine, an automatic reactor scram occurred due to high reactor steam dome pressure. Preliminarily, per the plant process computer, the reactor pressure was observed to reach approximately 1074 psig approximately 26 seconds after main steam bypass valves unexpectedly closed. An investigation will be conducted to determine the cause of the bypass valve closure and reactor scram. No safety relief valves lifted as a result of the pressure increase.
"This event is being reported under 10 CFR 50.72(b)(2)(iv)(B) as an event or condition that results in actuation of the reactor protection system when the reactor was critical."
The licensee is manually controlling the steam bypass valves to remove decay heat via the main condenser. All control rods fully inserted. The Unit is in a normal shutdown electrical lineup.
The licensee informed the NRC Resident Inspector. |
| Power Reactor | Event Number: 47490 | Facility: DUANE ARNOLD
Region: 3 State: IA
Unit: [1] [ ] [ ]
RX Type: [1] GE-4
NRC Notified By: MARK GILBERT
HQ OPS Officer: HOWIE CROUCH | Notification Date: 11/30/2011
Notification Time: 11:39 [ET]
Event Date: 11/30/2011
Event Time: 09:35 [CST]
Last Update Date: 11/30/2011 | Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(xiii) - LOSS COMM/ASMT/RESPONSE
| Person (Organization):
KENNETH RIEMER (R3DO)
|
| Unit | SCRAM Code | RX CRIT | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode | | 1 | N | Y | 100 | Power Operation | 100 | Power Operation | Event Text PLANT PROCESS COMPUTER OUT OF SERVICE DUE TO PLANNED MAINTENANCE
"A planned maintenance evolution at the Duane Arnold Energy Center (DAEC) to replace power supplies in the plant process computer will result in a loss of some Safety Parameter Display System (SPDS) indications for a duration of less than 5 hours. No other indicators or annunciators will be unavailable during this maintenance to affect the plant's ability to assess or monitor an accident or transient in progress.
"This notification is being made pursuant to 10 CFR 50.72(b)(3)(xiii)."
The NRC Resident Inspector has been notified.
* * * UPDATE ON 11/30/11 AT 1442 EST FROM GILBERT TO HUFFMAN * * *
The licensee reports that the plant process computer work has been completed and SPDS has been functionally tested and returned to an operable status.
The licensee will notify the NRC Resident Inspector. R3DO (Riemer) notified. |
| Power Reactor | Event Number: 47491 | Facility: SOUTH TEXAS
Region: 4 State: TX
Unit: [ ] [2] [ ]
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: ROBERT BRINKLEY
HQ OPS Officer: BILL HUFFMAN | Notification Date: 11/30/2011
Notification Time: 16:13 [ET]
Event Date: 11/20/2011
Event Time: 05:46 [CST]
Last Update Date: 11/30/2011 | Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(v)(C) - POT UNCNTRL RAD REL
50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
| Person (Organization):
THOMAS FARNHOLTZ (R4DO)
|
| Unit | SCRAM Code | RX CRIT | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode | | 2 | N | N | 0 | Hot Shutdown | 0 | Hot Standby | Event Text TURBINE TRIP PROTECTION DISABLED WHILE IN MODE 3
"On November 20, 2011 at 0546 hours [CST], STP Unit 2 transitioned modes from Mode 4 to Mode 3. Prior to the mode change, all Solid State Protection System (SSPS) generated turbine trip signals were defeated by a maintenance work activity that installed a jumper in both channels (Train R and S) of non-class relays to the turbine trip circuit. The SSPS signals to the non-class relays that were defeated by the jumpers included the turbine trip from reactor trip breakers open (P4), turbine trip from a reactor trip signal (P-16), and the turbine trip from Steam Generator HI- HI (P-14). T.S. 3.3.2 Items 5a (P4) and 5b (P-14) are required in Modes 1, 2, and 3. The jumpers were removed around 0930 on November 20, 2011 with U2 still in Mode 3.
"Both the UFSAR and TS bases identify that the turbine trip mitigates the consequences of an accident. The TS bases states that an ESFAS initiated turbine trip mitigates the consequences of a steam line break or loss of coolant accident. The accident analysis for SGTR also assumes a turbine trip on a reactor trip to isolate the steam path.
"Although Unit 2 was in Mode 3, with the reactor trip breakers open, and turbine throttle valves closed while the jumpers were installed, this condition is conservatively considered to be a safety system functional failure. If not corrected, this condition could have prevented the fulfillment of the accident mitigating and control of the release of radiation safety functions. A review of the performance of this activity in previous outages was conducted. It was identified that during 2RE14 in April of 2010, a work package for this activity was not closed until after Mode 3. The 60 day LER will address if the jumpers were installed in Mode 3 in April, 2010.
"This was determined to be reportable within 8 hours as required by 10 CFR 50.72(b)(3)(v) parts (C) and (D)."
The licensee did not determine the reportability of this event until 1415 CST on 11/30/11. The licensee has notified the NRC Resident Inspector. |
| Power Reactor | Event Number: 47492 | Facility: PILGRIM
Region: 1 State: MA
Unit: [1] [ ] [ ]
RX Type: [1] GE-3
NRC Notified By: KEN GRACIA
HQ OPS Officer: BILL HUFFMAN | Notification Date: 11/30/2011
Notification Time: 22:09 [ET]
Event Date: 11/30/2011
Event Time: 17:47 [EST]
Last Update Date: 11/30/2011 | Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
| Person (Organization):
WAYNE SCHMIDT (R1DO)
|
| Unit | SCRAM Code | RX CRIT | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode | | 1 | N | Y | 100 | Power Operation | 100 | Power Operation | Event Text HIGH PRESSURE COOLANT INJECTION DECLARED INOPERABLE
"On November 30, 2011, at 1747 hours [EST], with the reactor at 100% core thermal power and steady state conditions, Pilgrim Nuclear Power Station (PNPS) declared the High Pressure Coolant Injection (HPCI) system inoperable due to the HPCI turbine control valve (HPCI-24) failing to go open during planned post-maintenance testing. The HPCI-24 is a hydraulically operated control valve and its normal position is closed. The HPCI-24 valve has a safety function to open on a demand signal during certain event mitigation scenarios requiring the HPCI system operation.
"Based on the turbine control valve failing to open during post-maintenance testing and a subsequent check out run per PNPS Procedure 8.5.4.1, the HPCI system was declared inoperable at 1747 hours and the appropriate LCO was entered. An investigation of the event is underway and continuing.
"This event had no impact on the health and/or safety of the public.
"The NRC Resident Inspector bas been notified.
"This is an 8-hour notification made in accordance with 50.72(b)(3)(v)(D)." | |