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Event Notification Report for September 21, 2001

                    U.S. Nuclear Regulatory Commission
                              Operations Center

                              Event Reports For
                           09/20/2001 - 09/21/2001

                              ** EVENT NUMBERS **

38263  38300  

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|Power Reactor                                    |Event Number:   38263       |
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| FACILITY: WATTS BAR                REGION:  2  |NOTIFICATION DATE: 09/04/2001|
|    UNIT:  [1] [] []                 STATE:  TN |NOTIFICATION TIME: 16:54[EDT]|
|   RXTYPE: [1] W-4-LP,[2] W-4-LP                |EVENT DATE:        09/04/2001|
+------------------------------------------------+EVENT TIME:        13:04[EDT]|
| NRC NOTIFIED BY:  RODEN                        |LAST UPDATE DATE:  09/20/2001|
|  HQ OPS OFFICER:  CHAUNCEY GOULD               +-----------------------------+
+------------------------------------------------+PERSON          ORGANIZATION |
|EMERGENCY CLASS:          NON EMERGENCY         |JOHN MONNINGER       R2      |
|10 CFR SECTION:                                 |                             |
|ARPS 50.72(b)(2)(iv)(B)  RPS ACTUATION - CRITICA|                             |
|AESF 50.72(b)(3)(iv)(A)  VALID SPECIF SYS ACTUAT|                             |
|                                                |                             |
|                                                |                             |
+-----+----------+-------+--------+-----------------+--------+-----------------+
|UNIT |SCRAM CODE|RX CRIT|INIT PWR|   INIT RX MODE  |CURR PWR|  CURR RX MODE   |
+-----+----------+-------+--------+-----------------+--------+-----------------+
|1     M/R        Y       100      Power Operation  |0        Hot Standby      |
|                                                   |                          |
|                                                   |                          |
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                                   EVENT TEXT                                   
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| REACTOR MANUALLY TRIPPED FROM 100% POWER DUE TO STEAM GENERATOR LEVEL        |
| APPROACHING THE LO-LO LEVEL SETPOINT                                         |
|                                                                              |
| While operating at 100% power, the Watts Bar Unit 1 reactor was manually     |
| tripped at approximately 1304 EDT on September 4, 2001 due to steam          |
| generator (SG) level approaching the Lo-Lo level setpoint.  Just prior to    |
| the manual trip of the reactor, an abnormal voltage alarm was received on    |
| 125V Vital Battery Board 1-1.  The immediate cause of the trip is considered |
| to be the loss of the 1-1 Vital AC Inverter which caused a feedwater         |
| regulating valve to close.   Subsequently, the maintenance power supply was  |
| used to restore power to the 1-1 vital AC bus.                               |
|                                                                              |
| All control rods inserted properly in response to the reactor trip.  The     |
| Auxiliary Feedwater (AFW) System actuated as expected.  However, subsequent  |
| to the initial actuation signal, additional operator action was required     |
| to[manually] start 1B motor driven pump.   After the 1B pump was             |
| successfully started, the motor driven AFW pump 1A was secured based on      |
| instrument indications available to the operating staff.   After power was   |
| restored to the vital AC bus, the 1A pump was subsequently started and       |
| performed properly.   Inspections are currently underway to determine the    |
| exact cause of the loss of the 1-1 Vital Inverter and basis for the 1B pump  |
| failing to [auto] start.                                                     |
|                                                                              |
| No ECCS injection occurred, but the steam generator atmospheric relief       |
| valves lifted and fully reseated.                                            |
|                                                                              |
| The manual actuation of the Reactor Protection System (RPS) is being         |
| reported as a four hour report under 10 CFR 50.72 (b)(2)(iv).  The actuation |
| of the Auxiliary Feedwater System (an engineered safety feature) is being    |
| reported as an eight hour report under 10 CFR 50.72 (b)(3)(iv).              |
|                                                                              |
| The plant is stable in mode 3.                                               |
|                                                                              |
| The NRC Resident Inspector was notified.                                     |
|                                                                              |
| * * * UPDATE 1244EDT ON 9/20/01 FROM CHARLES TOUCHSTONE TO S. SANDIN * * *   |
|                                                                              |
| The following information was received as an update:                         |
|                                                                              |
| "This report supplements the report made by TVA at approximately 1654 on     |
| September 4, 2001 - NRC Event Report 38263.                                  |
|                                                                              |
| "Description of Event:                                                       |
|                                                                              |
| "While operating at 100% power, the Watts Bar Unit 1 reactor was manually    |
| tripped at approximately 1305 EDT on September 4, 2001, due to the level of  |
| Steam Generator (SG) Number 1 approaching the low-low level setpoint. The    |
| immediate cause of the trip is considered to be the loss of the 1-I Vital AC |
| Inverter which caused the Number 1 SG feedwater regulating valve to close.   |
| Subsequently, the maintenance power supply was used to restore power to the  |
| 1-I Vital AC board.                                                          |
|                                                                              |
| "10 CFR 50.72 Notification:                                                  |
|                                                                              |
| "Initial notification to NRC of the reactor trip was made by WBN Operations  |
| at 1654 EDT The manual actuation of the Reactor Protection System (RPS) was  |
| reported as a four hour report under 10 CFR 50.72 (b)(2)(iv). The actuation  |
| of the Auxiliary Feedwater System (an engineered safety feature) was         |
| reported as an eight hour report under 10 CFR 50.72 (b)(3)(iv). This report  |
| supplements the initial report and is being reported under the same          |
| criteria.                                                                    |
|                                                                              |
| "Cause of the Event:                                                         |
|                                                                              |
| "The root cause of the reactor trip was the failure of the sensing/current   |
| limiting card installed in vital battery charger 6-S or its associated edge  |
| connector. The failure of the component resulted in the DC output of the     |
| charger rising to 209V. The high DC output voltage resulted in a high input  |
| to inverters 1-I and 2-I. Inverter 1-I input and output fuses were blown,    |
| while inverter 2-I continued without failure. This occurred because inverter |
| 1-I is equipped with parallel 5 and 15 KVA constant voltage transformers     |
| (CVTs), which are more sensitive to high input voltage than the type used in |
| inverter 2-1 which utilizes a single 20 KVA CVT. The inverters are rated for |
| a maximum input of 140 volts.                                                |
|                                                                              |
| "Equipment Response:                                                         |
|                                                                              |
| "All control rods inserted properly in response to the reactor trip. For     |
| WBN, the AFW system consist of a turbine driven AFW (TDAFW) pump and two     |
| trains (Train A and Train B) of motor driven AFW (MDAFW) pumps. The design   |
| calls for the MDAFW arid TDAFW pumps to start due to the loss of both Main   |
| Feedwater (MFW) pumps or an AMSAC actuation, In addition, the MDAFW pumps    |
| will actuate on low-low S/G level in any S/G and the TDAFW pump will actuate |
| on low-low level in any two S/Gs. For this event, actuation of the TDAFW     |
| pump resulted from the required logic being met for SGs Number 1 and 4.      |
| Based on data obtained subsequent to the reactor trip, an auto start for the |
| TDAFW train was initiated immediately after S/G low-low level setpoints were |
| met.                                                                         |
|                                                                              |
| "Subsequent to the initial AFW actuation signal, additional operator action  |
| was required to start the 1A-A and 1B-B motor driven pumps. For the Train A  |
| MDAFW, the pump did not receive an auto start signal due to the loss of      |
| Vital Board 1-I. This resulted from the power for the signal generating      |
| circuit being lost with the Vital Board. The evaluation performed to         |
| establish the cause for the Train B MDAFW not starting found that the        |
| breaker for the pump did not close as a result of the automatic signal       |
| initiated by the low SG level. The breaker was subsequently tested and       |
| performed as designed and therefore, no conclusive cause was found for the   |
| breaker not closing. However, it was established that the most likely cause  |
| of the problem was dirty relay contacts on the 1X and 30RX relays."          |
|                                                                              |
| The licensee informed the NRC resident inspector.  Notified R2DO(Sparks).    |
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|General Information or Other                     |Event Number:   38300       |
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| REP ORG:  CALIFORNIA RADIATION CONTROL PRGM    |NOTIFICATION DATE: 09/20/2001|
|LICENSEE:  STEVEN RAAS AND ASSOCIATES, INC.     |NOTIFICATION TIME: 15:15[EDT]|
|    CITY:  WATSONVILLE              REGION:  4  |EVENT DATE:        09/19/2001|
|  COUNTY:                            STATE:  CA |EVENT TIME:        16:30[PDT]|
|LICENSE#:  5214                  AGREEMENT:  Y  |LAST UPDATE DATE:  09/20/2001|
|  DOCKET:                                       |+----------------------------+
|                                                |PERSON          ORGANIZATION |
|                                                |JOHN PELLET          R4      |
|                                                |SUSAN FRANT          NMSS    |
+------------------------------------------------+                             |
| NRC NOTIFIED BY:  ROBERT GREGER                |                             |
|  HQ OPS OFFICER:  STEVE SANDIN                 |                             |
+------------------------------------------------+                             |
|EMERGENCY CLASS:          NON EMERGENCY         |                             |
|10 CFR SECTION:                                 |                             |
|NAGR                     AGREEMENT STATE        |                             |
|                                                |                             |
|                                                |                             |
|                                                |                             |
|                                                |                             |
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                                   EVENT TEXT                                   
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| AGREEMENT STATE REPORT INVOLVING A DAMAGED TROXLER GAUGE                     |
|                                                                              |
| "A Troxler model 3401B moisture density gauge (serial #016692) was run over  |
| by earth moving/compacting equipment while the gauge was in use (i.e., the   |
| source rod was extended). The source rod was bent such that the source could |
| not be retracted into the shielded position. The unshielded source contained |
| nominally 10 mCi of Cs-137. The source rod was cut by the fire department    |
| with the source in a lead 'pig' provided by the UC Santa Cruz health physics |
| program. The source and the gauge housing will be sent to Troxler for        |
| repairs."                                                                    |
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