Event Notification Report for October 20, 1999
U.S. Nuclear Regulatory Commission Operations Center Event Reports For 10/19/1999 - 10/20/1999 ** EVENT NUMBERS ** 35790 36309 36310 36311 36312 +------------------------------------------------------------------------------+ |Fuel Cycle Facility |Event Number: 35790 | +------------------------------------------------------------------------------+ +------------------------------------------------------------------------------+ | FACILITY: PADUCAH GASEOUS DIFFUSION PLANT |NOTIFICATION DATE: 06/03/1999| | RXTYPE: URANIUM ENRICHMENT FACILITY |NOTIFICATION TIME: 14:44[EDT]| | COMMENTS: 2 DEMOCRACY CENTER |EVENT DATE: 06/02/1999| | 6903 ROCKLEDGE DRIVE |EVENT TIME: 16:30[CDT]| | BETHESDA, MD 20817 (301)564-3200 |LAST UPDATE DATE: 10/19/1999| | CITY: PADUCAH REGION: 3 +-----------------------------+ | COUNTY: McCRACKEN STATE: KY |PERSON ORGANIZATION | |LICENSE#: GDP-1 AGREEMENT: Y |DAVID HILLS R3 | | DOCKET: 0707001 |DON COOL NMSS | +------------------------------------------------+ | | NRC NOTIFIED BY: THOMAS WHITE | | | HQ OPS OFFICER: FANGIE JONES | | +------------------------------------------------+ | |EMERGENCY CLASS: N/A | | |10 CFR SECTION: | | |OCBA 76.120(c)(2)(i) ACCID MT EQUIP FAILS | | | | | | | | | | | | | | +------------------------------------------------------------------------------+ EVENT TEXT +------------------------------------------------------------------------------+ | THREE SPRINKLER SYSTEMS DECLARED INOPERABLE DUE TO CORRODED HEADS (24-hour | | report) | | | | The following text is a portion of a facsimile received from Paducah: | | | | "On 06/02/99 at 1630 CDT, the Plant Shift Superintendent (PSS) was notified | | that numerous sprinkler heads were corroded, affecting 16 sprinkler systems | | in C-337 and one system in C-333, such that the ability of the sprinklers to | | flow sufficient water was called into question. Subsequently, these | | sprinkler systems were declared inoperable, and TSR-required actions | | establishing roving fire patrols were initiated. This deficiency was | | detected during scheduled system inspections conducted by Fire Protection | | personnel. Currently, functionality of the sprinkler heads has not been | | fully evaluated by Fire Protection personnel, and the remaining cascade | | buildings are currently being inspected, and if necessary, this report will | | be updated to identify any additional areas. | | | | "It has been determined that this event is reportable under | | 10CFR76.120(c)(2) as an event in which equipment is disabled or fails to | | function as designed." | | | | The NRC resident inspector has been notified of this event. | | | | | | * * * UPDATE AT 1022 EDT ON 06/04/99 FROM CAGE TO TROCINE * * * | | | | "Two sprinkler heads on system D-1 in C-337 and two sprinkler heads on | | system 27 in C-335 were identified to also be corroded. These were | | identified to the PSS on 06/03/99 at 1600 CDT and 1601 CDT, respectively, | | and determined to require an update to this report by the PSS. | | | | "It has been determined that this event is reportable under | | 10CFR76.120(c)(2) as an event in which equipment is disabled or fails to | | function as designed." | | | | Paducah personnel notified the NRC resident inspector of this update. The | | NRC operations officer notified the R3DO (Hills) and NMSS EO (Combs). | | | | * * * UPDATE AT 2152 EDT ON 06/17/99 FROM WALKER TO POERTNER * * * | | | | "Three sprinkler heads on system C-15 and five sprinkler heads on system B-8 | | in C-333 were identified to also be corroded. The PSS was notified of this | | condition at 1300 CDT on 06/17/99 and determined that an update to this | | report was required." | | | | "It has been determined that this event is reportable under | | 10CFR76.120(c)(2) as an event in which equipment is disabled or fails to | | function as designed." | | | | Paducah personnel notified the NRC resident inspector of this update. The | | NRC operations officer notified the R3DO (Madera). | | | | * * * UPDATE 1440 EDT 6/18/1999 FROM UNDERWOOD TAKEN BY STRANSKY * * * | | | | "Two sprinkler heads on system C-15 and one sprinkler head on system B-8 in | | C-333 were identified to have corrosion. The PSS was notified of this | | condition at 1350 CDT on 06/18/99. The area of the fire patrol for system | | C-15 was expanded to include the two heads identified as corroded. The one | | head on system B-8 was in the area already being patrolled. The PSS | | determined that an update to this report was required." | | | | The NRC resident inspector has been informed of this update. Notified R3DO | | (Madera). | | | | * * * UPDATE 1315 EDT 6/25/1999 FROM WALKER TAKEN BY STRANSKY * * * | | | | "Two sprinkler heads on system D-8 and three sprinkler heads on system D-7 | | in C-337 were identified to have corrosion. The PSS was notified of the | | condition on system D-8 at 0125 CDT on 06/25/99 and at 1019 CDT on 06/25/99 | | for system D-7. Both systems were immediately declared inoperable and LCO | | fire patrol actions were implemented. It was determined that an update to | | this report was required." | | | | The NRC resident inspector has been informed of this update. Notified R3DO | | (Jordan). | | | | * * * UPDATE 2119 EDT 7/30/1999 FROM CAGE TAKEN BY STRANSKY * * * | | | | "Five sprinkler heads and one sprinkler piping tee on C-337 system D-7 were | | identified to have corrosion. The PSS was notified of these corroded system | | parts and declared the system inoperable at 0931 CDT on 07/30/99. LCO | | required fire patrols of the affected area were initiated. The PSS | | determined that an update to this event report was required." | | | | The NRC resident inspector has been informed of this update. Notified R3DO | | (Wright). | | | | * * * UPDATE 1655 EDT 7/31/1999 FROM WHITE TAKEN BY STRANSKY * * * | | | | "Two sprinkler heads on C-337 System D-1 were identified to have corrosion. | | The PSS was notified of these corroded system parts and declared the system | | inoperable at 1155 CDT on 7/31/99. LCO required fire patrols of the | | affected area were initiated. The PSS determined that an update to this | | report was required." | | | | The NRC resident inspector has been informed of this update. Notified R3DO | | (Wright). | | | | * * * UPDATE 1546 EDT 8/10/1999 FROM WHITE TAKEN BY STRANSKY * * * | | | | "Two sprinkler heads on C-337 system C-15 were identified to have corrosion. | | The PSS was notified of these corroded system parts and declared the system | | inoperable at 1130 CDT on 8/10/99. LCO required fire patrols of the | | affected area were initiated. The PSS determined that an update to this | | report was required." | | | | The NRC resident inspector has been informed of this update. Notified R3DO | | (Burgess). | | | | * * * UPDATE AT 1154 EDT 8/22/99 FROM WALKER TO POERTNER * * * | | | | Four adjacent sprinkler heads on C-333 System B-1 were identified to have | | corrosion. The PSS was notified of the corroded system parts and declared | | the system inoperable at 0918 CDT on 8/22/99. LCO required fire patrols | | were initiated. The PSS determined that an update to this report was | | required. | | | | It has been determined that this event is reportable under 10CFR76.120(c)(2) | | as an event in which equipment is disabled or fails to function as | | designed. | | | | The NRC resident inspector will be notified. | | | | The NRC operations officer notified the R3DO (Clayton). | | | | * * * UPDATE 2015 EDT ON 8/28/99 FROM W.F. GAGE TO S. SANDIN * * * | | | | The following information was provided as an update to this report: | | | | "Two adjacent sprinkler heads on C-337 System D-11 were identified to have | | corrosion. The PSS was notified of these corroded system parts and declared | | the system inoperable at 1420 [CDT] on 8/28/99. LCO required fire patrols | | of the affected area were initiated. The PSS determined that an update to | | this report was required." | | | | Paducah personnel informed the NRC resident inspector. The NRC operations | | officer notified the R3DO (Leach) and NMSS EO (Piccone). | | | | * * * UPDATE 2037 EDT ON 8/29/99 FROM KEVIN BEASLEY TO S. SANDIN * * * | | | | The following information was provided as an update to this report: | | | | "Two adjacent sprinkler heads on C-337 System D-15 were identified to have | | corrosion and the PSS declared the system inoperable at 0925 [CDT] on | | 8/29/99. Also two adjacent heads on C-337 System D-10 were identified to | | have corrosion and the PSS declared the system inoperable at 1450. LCO | | required fire patrols for both of the affected areas were initiated in the | | time frame required by TSR. The PSS determined that an update to this | | report was required." | | | | Paducah personnel informed the NRC resident inspector. The NRC operations | | officer notified the R3DO (Leach) and NMSS EO (Piccone). | | | | * * * UPDATE AT 0930 EDT ON 9/1/99 BY ERIC WALKER TO FANGIE JONES * * * | | | | Add two adjacent sprinkler heads on C-337 D-14. Paducah personnel informed | | the NRC Resident Inspector. The NRC operations officer notified the R3DO | | (David Hills) and NMSS (Robert Pierson). | | | | * * * UPDATE AT 1133 EDT ON 9/8/99 BY TOM WHITE TO FANGIE JONES * * * | | | | Add two adjacent sprinkler heads on C-331 System 26, system declared | | inoperable at 2155 CDT on 9/7/99. An LCO required fire patrol for the | | affected area was initiated in the time frame required by the TSR. Paducah | | personnel informed the NRC Resident Inspector. The NRC operations officer | | notified the R3DO (Monte Phillips) and NMSS (Josie Piccone). | | | | * * * UPDATE AT 0948 ON 9/30/99 BY ERIC WALKER TO DOUG WEAVER * * * | | | | Add two adjacent sprinkler heads on C-333 System B-15 were identified to | | have corrosion and the PSS declared the system inoperable at 0815 on | | 9/30/99. An LCO required fire patrol for the affected area was initiated in | | the time frame required by the TSR. The PSS determined that an update to | | this report was required. | | Paducah personnel informed the NRC resident inspector. The NRC operations | | officer notified the R3DO (Vegel) and NMSS (Cool). | | | | | | *** UPDATE ON 10/13/99 @ 1600 BY WALKER TO GOULD *** | | | | Two adjacent sprinkler heads on C-333 System A-11 were Identified to have | | corrosion and the PSS declared the system inoperable at 1307 on 10-13-99. An | | LCO required fire patrol for the affected area was initiated in the time | | frame required by the TSR, The PSS determined that an update to this report | | was required. Paducah personnel informed the NRC resident inspector. The | | NRC operations officer notified the R3DO (Madera) and NMSS (Moore). | | | | * * * UPDATE 1520 10/19/1999 FROM UNDERWOOD TAKEN BY STRANSKY * * * | | | | Six sprinkler heads on C-337 System D-16 were identified to have corrosion | | and the PSS declared the system inoperable at 1052 CDT on 10/19/99. An LCO | | required fire patrol for the affected area was initiated in the time frame | | required by the TSR. The PSS determined that an update to this report was | | required. The NRC resident inspector has been informed of this update. | | Notified R3DO (Jorgensen). | | | | * * * UPDATE 2140 10/19/1999 FROM WALKER TAKEN BY STRANSKY * * * | | | | Seven sprinkler heads on C-337 System A-7 were identified to have corrosion, | | and another four had been painted over. In addition, three adjacent | | sprinkler heads pm C-337 System A-8 were identified to have corrosion. The | | PSS declared the systems inoperable at 1900 CDT on 10/19/99. LCO required | | fire patrols for the affected areas were initiated in the time frame | | required by the TSR. The PSS determined that an update to this report was | | required. The NRC resident inspector has been informed of this update. | | Notified R3DO (Wright). | +------------------------------------------------------------------------------+ +------------------------------------------------------------------------------+ |Power Reactor |Event Number: 36309 | +------------------------------------------------------------------------------+ +------------------------------------------------------------------------------+ | FACILITY: PALO VERDE REGION: 4 |NOTIFICATION DATE: 10/19/1999| | UNIT: [1] [] [] STATE: AZ |NOTIFICATION TIME: 07:36[EDT]| | RXTYPE: [1] CE,[2] CE,[3] CE |EVENT DATE: 10/19/1999| +------------------------------------------------+EVENT TIME: 00:49[MST]| | NRC NOTIFIED BY: DAN MARKS |LAST UPDATE DATE: 10/19/1999| | HQ OPS OFFICER: LEIGH TROCINE +-----------------------------+ +------------------------------------------------+PERSON ORGANIZATION | |EMERGENCY CLASS: N/A |LINDA SMITH R4 | |10 CFR SECTION: | | |AESF 50.72(b)(2)(ii) ESF ACTUATION | | | | | | | | | | | +-----+----------+-------+--------+-----------------+--------+-----------------+ |UNIT |SCRAM CODE|RX CRIT|INIT PWR| INIT RX MODE |CURR PWR| CURR RX MODE | +-----+----------+-------+--------+-----------------+--------+-----------------+ |1 N N 0 Refueling |0 Refueling | | | | | | | +------------------------------------------------------------------------------+ EVENT TEXT +------------------------------------------------------------------------------+ | UNEXPECTED EMERGENCY DIESEL GENERATOR START | | | | The following text is a portion of a facsimile received from the licensee: | | | | "The following event description is based on information currently | | available. If through subsequent reviews of this event, additional | | information is identified that is pertinent to this event or alters the | | information being provided at this time, a follow-up notification will be | | made via the ENS or under the reporting requirements of 10CFR50.73." | | | | "On October 19, 1999, at approximately 0049 MST, Palo Verde Unit 1 | | experienced an unexpected start of the Train A Emergency Diesel Generator. | | In addition, many Train-A components actuated to the post Safety Injection | | Actuation (SIAS) condition. No safety injection pumps or valves actuated, | | and no injection into the reactor coolant system occurred. Train A Leg 2-4 | | (half leg) annunciation alarms were received and immediately cleared for | | SIAS, Containment Isolation Actuation Signal (CIAS), Main Steam Isolation | | Signal (MSIS), Containment Spray Actuation Signal (CSAS), Auxiliary | | Feedwater Actuation Signal (AFAS-1 and AFAS-2), and Recirculation Actuation | | Signal (RAS). The Train A Emergency Diesel Generator received a start | | signal, started from a standby condition, and ran unloaded until it was shut | | down. Based on initial investigation, a Plant Protection System (PPS) power | | supply anomaly is suspected to be the cause of this condition. The unit is | | stable with all fuel removed from the reactor vessel to the spent fuel pool | | during a scheduled refueling outage (U1R8)." | | | | "Palo Verde personnel are investigating the PPS power supplies and power | | sources to the power supplies. There was no valid actuation signal. The | | event did not result in any challenges to the fission product barrier or | | result in any releases of radioactive materials. There were no adverse | | safety consequences or implications as a result of this event. The event | | did not adversely affect the safe operation of the plant or health and | | safety of the public." | | | | The licensee stated that all systems functioned as required in response to | | this event; however, the root cause of the event is under investigation. | | There were no maintenance activities involving the power supplies ongoing at | | the time of the event. Spent fuel pool cooling was not affected by this | | transient. | | | | The licensee notified the NRC resident inspector. | +------------------------------------------------------------------------------+ +------------------------------------------------------------------------------+ |Fuel Cycle Facility |Event Number: 36310 | +------------------------------------------------------------------------------+ +------------------------------------------------------------------------------+ | FACILITY: GE NUCLEAR ENERGY |NOTIFICATION DATE: 10/19/1999| | RXTYPE: URANIUM FUEL FABRICATION |NOTIFICATION TIME: 10:16[EDT]| | COMMENTS: LEU CONVERSION (UF6 TO UO2) |EVENT DATE: 10/18/1999| | LEU FABRICATION |EVENT TIME: 15:15[EDT]| | LWR COMMERICAL FUEL |LAST UPDATE DATE: 10/19/1999| | CITY: WILMINGTON REGION: 2 +-----------------------------+ | COUNTY: NEW HANOVER STATE: NC |PERSON ORGANIZATION | |LICENSE#: SNM-1097 AGREEMENT: Y |CAUDLE JULIAN R2 | | DOCKET: 07001113 |BRIAN SMITH NMSS | +------------------------------------------------+ | | NRC NOTIFIED BY: LON PAULSON | | | HQ OPS OFFICER: LEIGH TROCINE | | +------------------------------------------------+ | |EMERGENCY CLASS: N/A | | |10 CFR SECTION: | | |NBNL RESPONSE-BULLETIN | | | | | | | | | | | | | | +------------------------------------------------------------------------------+ EVENT TEXT +------------------------------------------------------------------------------+ | NRC BULLETIN 91-01 RESPONSE - CRITICALITY CONTROL (24-HOUR NOTIFICATION) | | | | The following text is a portion of a facsimile received from the licensee: | | | | "EVENT DESCRIPTION: At approximately 1515 on October 18, 1999, during | | packaging of materials in drums for burial, administrative controls | | associated with drum loading were violated. The quantity of uranium | | involved was 2,083.3 grams U at 3.6% enrichment. This amount of uranium is | | under the safe batch value of 27,411 grams U at 3.6% enrichment. Therefore, | | no unsafe condition existed." | | | | "Controls were reestablished within 4 hours by direct removal of the | | material inadvertently added to the drum during preparation for shipment. | | This event is reported pursuant to NRC Bulletin 91-01 (within 24 hours) due | | to the failure to comply with procedural controls. Associated operations | | have been shutdown pending investigation and implementation of corrective | | actions." | | | | "SAFETY SIGNIFICANCE OF EVENTS: Low safety significance - [The] actual | | uranium content in [the] drum [was] determined to be 2,083.3 grams U (3.6% | | enrichment)[, which is] below the safe batch mass limit of 27,411 grams U | | (3.6% enrichment)." | | | | "POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW | | CRITICALITY COULD OCCUR): Multiple failure modes [are] required before a | | criticality accident could occur." | | | | "CONTROLLED PARAMETER(S) (MASS, MODERATION. GEOMETRY, CONCENTRATION, ETC.): | | Mass [and] mass/concentration. [Mass was not controlled.]" | | | | "ESTIMATED AMOUNT, ENRICHMENT, [AND] FORM OF LICENSED MATERIAL (INCLUDE | | PROCESS UNIT AND % WORST BASE CRITICAL MASS): Composite sample analysis | | showed 75 [grams of] U235 at 3.60% enrichment (2,083.3 grams U). [The] safe | | batch value is 986.8 [grams of] U235 at 3.6% (27,411 grams U) where [the] | | safe batch is defined to be 45% of the minimum critical mass." | | | | "NUCLEAR CRITICALITY SAFETY CONTROL OR CONTROL SYSTEM(S) AND DESCRIPTION OF | | THE FAILURES OR DEFICIENCIES: Administrative controls on queuing materials | | and loading the drum were violated." | | | | "CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: | | (1) Drum preparation operation was shutdown, (2) [Nuclear safety Engineering | | (NSE)] [has] oversight of content removal from drum #1 to empty drum #2 [as | | well as] re-sampling of both drums[, and] (3) Investigation and | | implementation of corrective actions [is] pending." | | | | The licensee plans to notify the NRC Region 2 Office (David Ayres), North | | Carolina Emergency Management (Mel Fry), and New Hanover County Emergency | | Management (Dan Summers). (Call the NRC operations officer for a site | | contact telephone number.) | +------------------------------------------------------------------------------+ +------------------------------------------------------------------------------+ |Power Reactor |Event Number: 36311 | +------------------------------------------------------------------------------+ +------------------------------------------------------------------------------+ | FACILITY: CATAWBA REGION: 2 |NOTIFICATION DATE: 10/19/1999| | UNIT: [1] [2] [] STATE: SC |NOTIFICATION TIME: 13:06[EDT]| | RXTYPE: [1] W-4-LP,[2] W-4-LP |EVENT DATE: 10/19/1999| +------------------------------------------------+EVENT TIME: 11:00[EDT]| | NRC NOTIFIED BY: MARCUS ABERNATHY |LAST UPDATE DATE: 10/19/1999| | HQ OPS OFFICER: BOB STRANSKY +-----------------------------+ +------------------------------------------------+PERSON ORGANIZATION | |EMERGENCY CLASS: N/A |KERRY LANDIS R2 | |10 CFR SECTION: | | |NLTR LICENSEE 24 HR REPORT | | | | | | | | | | | +-----+----------+-------+--------+-----------------+--------+-----------------+ |UNIT |SCRAM CODE|RX CRIT|INIT PWR| INIT RX MODE |CURR PWR| CURR RX MODE | +-----+----------+-------+--------+-----------------+--------+-----------------+ |1 N Y 100 Power Operation |100 Power Operation | |2 N Y 100 Power Operation |100 Power Operation | | | | +------------------------------------------------------------------------------+ EVENT TEXT +------------------------------------------------------------------------------+ | DESIGN ISSUE REGARDING BULK HYDROGEN SUPPLY PIPING IN VICINITY OF RWST | | | | "A licensee audit of the design, operation, and maintenance of the site bulk | | hydrogen systems identified an apparent deviation from the approved Fire | | Protection Program. It was observed that a section of hydrogen supply piping | | located in a safety-related area appeared not to meet the requirements in | | section C.5.d.5 of Branch Technical Position (BTP) CMEB 9.5-1 (SRP). BTP | | CMEB 9.5-1, section C.5.d.5 requires that 'hydrogen lines in safety related | | areas should be either designed to seismic Class I requirements, or sleeved | | such that the water (i.e. guard) pipe is directly vented to the outside, or | | equipped with an excess flow valve so that in case of a line break, the | | hydrogen concentration in the affected areas will not exceed 2%.' An | | immediate evaluation determined that this is an old design issue and it does | | not present a current operability issue. In the Catawba SSER No. 2, the | | staff indicated that the bulk hydrogen system at Catawba was designed in | | accordance with the requirements of BTP CMEB 9.5-1. Other hydrogen lines | | that are located in safety related areas are either seismically designed or | | supplied with an excess flow check valve. The piping in question travels | | from the hydrogen bulk storage house, is buried in the yard, enters the | | Refueling Water Storage Tank (RWST) trench, and proceeds into the auxiliary | | building. It appears that the failure to seismically design the hydrogen | | piping located in the RWST trench was an oversight. Engineering is | | evaluating appropriate long-term corrective actions. | | | | "The licensee's staff has completed an evaluation and determined that this | | situation constitutes a deviation from the approved Fire Protection Program | | as described in the Facility Operating License (FOL) condition 2.C.(8) | | | | "Catawba FOL NPF-35 (Unit 1) and NPP-52 (Unit 2) require a 24-hour | | notification to the NRC for deviations from the approved Fire Protection | | Program. The above deviation is being reported under that license condition | | criterion. A follow-up report describing the cause of the deviation and | | corrective actions will be submitted to the NRC within 30 days." | | | | The licensee has notified the resident NRC inspector of this issue. | +------------------------------------------------------------------------------+ +------------------------------------------------------------------------------+ |Power Reactor |Event Number: 36312 | +------------------------------------------------------------------------------+ +------------------------------------------------------------------------------+ | FACILITY: DRESDEN REGION: 3 |NOTIFICATION DATE: 10/19/1999| | UNIT: [] [2] [] STATE: IL |NOTIFICATION TIME: 19:21[EDT]| | RXTYPE: [1] GE-1,[2] GE-3,[3] GE-3 |EVENT DATE: 10/19/1999| +------------------------------------------------+EVENT TIME: 17:31[CDT]| | NRC NOTIFIED BY: GLEN MORROW |LAST UPDATE DATE: 10/19/1999| | HQ OPS OFFICER: BOB STRANSKY +-----------------------------+ +------------------------------------------------+PERSON ORGANIZATION | |EMERGENCY CLASS: N/A |GEOFFREY WRIGHT R3 | |10 CFR SECTION: | | |ACCS 50.72(b)(1)(iv) ECCS INJECTION | | |AESF 50.72(b)(2)(ii) ESF ACTUATION | | | | | | | | +-----+----------+-------+--------+-----------------+--------+-----------------+ |UNIT |SCRAM CODE|RX CRIT|INIT PWR| INIT RX MODE |CURR PWR| CURR RX MODE | +-----+----------+-------+--------+-----------------+--------+-----------------+ | | | |2 N N 0 Refueling |0 Refueling | | | | +------------------------------------------------------------------------------+ EVENT TEXT +------------------------------------------------------------------------------+ | MANUAL ECCS INJECTION INTO REACTOR VESSEL | | | | The licensee manually initiated the "2B" core spray subsystem to restore | | reactor vessel water level after observing a decrease in reactor vessel | | water level. At the time of the event, the reactor vessel was flooded up | | above the main steam lines. The licensee had removed the "B" main steam line | | plug in order to perform some refueling outage activities when the level | | decrease was observed. Level decreased approximately six inches before | | recovering. | | | | Reactor vessel water level was restored to normal and the "B" main steam | | line plug was reinstalled. Upon investigation, the licensee discovered that | | the "2E" electromatic relief valve (ERV) was open, creating a flow path from | | the main steam line to the suppression pool. The ERV was closed by the | | licensee. The licensee is currently investigating the cause of the ERV | | opening. | | | | The NRC resident inspector has been informed of this event by the licensee. | +------------------------------------------------------------------------------+
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