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The query [[Category:ENS Notification]] [[Site::Duane Arnold]] [[Scram::+]] was answered by the SMWSQLStore3 in 0.3072 seconds.


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 Entered dateSiteRegionScramReactor typeEvent description
ENS 5401220 April 2019 09:54:00Duane ArnoldNRC Region 3Manual ScramAt 0507 (CDT on April 20, 2019), the DAEC (Duane Arnold Energy Center) experienced a trip of both reactor feed pumps. Operators inserted a manual scram. All control rods inserted, as required. As a result of the feed pump trips and scram, HPCI and RCIC automatically injected. Also, containment isolations occurred, as expected for this event. All systems responded as designed. Operators are currently taking the unit to cold shutdown conditions. Vessel level is being controlled by RCIC with Condensate System available. Pressure is being controlled using Main Steam Line drains and the Main Condenser is available. Normal electrical lineup remains. The cause of the reactor feed pumps tripping is believed to be an instrument air leak to flow control valves, causing loss of suction to both feed pumps. The licensee notified the NRC Resident Inspector.
ENS 5367619 October 2018 21:44:00Duane ArnoldNRC Region 3Automatic ScramAt 1725 CDT, a Feedwater Regulating valve failed closed, resulting in a reactor level transient, which initiated a reactor trip, Primary Containment Isolation System signals to valves in Groups 2, 3, and 4 and initiation of High Pressure Coolant Injection and Reactor Core Isolation Cooling. All control rods inserted and level has been restored to normal. The cause of the feedwater valve failure is under investigation. All other systems responded as expected. This report is being made under 10 CFR 50.72 (b)(2)(iv)(B), (b)(3)(iv)(A) and (b)(2)(iv)(A). The Senior Resident Inspector has been informed. Decay heat is being removed via the main condenser and reactor vessel water level is being maintained by the condensate and feedwater systems.
ENS 4714311 August 2011 15:29:00Duane ArnoldNRC Region 3Manual ScramGE-4At 1138 CDT, while in the process of shutting down as required by Technical Specifications (Reference EN# 47142), with the reactor at approximately 15 percent power, a manual scram was inserted in order to complete the TS Required Action of being in Mode 3 within 12 hours. Upon inserting the manual scram, reactor water level dropped below 170 inches resulting in Primary Containment Isolation System (PCIS) Groups 2, 3 and 4 being received. This reactor water level response is considered normal following a reactor scram from power due to void collapse in the reactor vessel. Reactor water level is currently being controlled in the normal band. All PCIS group isolations went to completion and were subsequently reset. The PCIS isolations all functioned properly. This event is being reported pursuant to 10 CFR 50.72(b)(3)(iv)(A). The NRC Resident Inspector has been notified.
ENS 4587326 April 2010 05:18:00Duane ArnoldNRC Region 3Manual ScramGE-4This report is being made under 50.72(b)(2)(iv)(B) for inserting a manual reactor scram due to rising vibrations on the #6 turbine bearing. A planned reactor shutdown was in progress with reactor power at 13.8% when turbine vibrations approached procedural limits which would require a manual scram of the reactor. The scram was uncomplicated; all control rods fully inserted. The reactor is in Mode 3, Hot Shutdown. Cooldown has been established to the condenser using main steam line drains. The NRC Resident Inspector has been informed.
ENS 454218 October 2009 18:06:00Duane ArnoldNRC Region 3ScramGE-4

This report is being made under CFR 50.72(b)(2(iv)(B) for a automatic reactor scram which is preliminarily believed to have been caused while restoring reactor pressure vessel level/pressure instrumentation to service during performance of surveillance test 3.3.3.2-09 Reactor Water Level and Pressure Instruments Calibration . In addition, this report is being made under CRF 50.72(b)(3)(iv)(A) due to PCIS (Primary Containment Isolation System) Groups 2, 3 and 4 being received when reactor water level dropped below 170 due to the expected level shrink immediately following a reactor scram. All isolations went to completion. Reactor water level was recovered to normal vessel level as expected under post scram conditions. The following Technical Specification LCOs (Limiting Conditions of Operation) were in affect at the time of the reactor scram: TS 3.7.5, Required Action A.1, 30 day completion time for 'B' Control Building Chiller;

TS 3.7.2, Required Action A.1, 7 day completion time for 'B' River Water Supply loop;
TS 3.3.3.1, Function 6, Required Action A.1, 30 day completion time for position indication of MO-1949B, 'B' Residual Heat Removal Heat Exchanger Vent;
TS 3.7.1, Required Action A.1, 30 day completion time for 1P22D, 'D' Residual Heat Removal Service Water Pump.

All rods fully inserted during the scram. The plant is in a normal shutdown electrical lineup with offsite sources powering the safety busses. No safety or relief valves lifted during the transient. Decay heat is being removed via the steam bypass (valves to the) condenser. The licensee notified the NRC Resident Inspector.

ENS 449653 April 2009 03:27:00Duane ArnoldNRC Region 3Manual ScramGE-4This report is being made under (10 CFR) 50.72(b)(2)(iv)(B) for inserting a manual reactor scram due to indicated reactor water level of 205 inches and rising. The exact cause of the reactor water level increase is not known at this time. However, STP (Surveillance Test Procedure) 3.3.3.2-09, 'Reactor Water Level and Pressure Instruments Calibration' was in progress at the time and is likely the cause of the level transient. In addition, this report is being made under (10 CFR) 50.72(b)(3)(iv)(A) due to PCIS (Primary Containment Isolation System) groups 2, 3 and 4 being received when reactor water level dropped below 170 inches following the reactor scram. All isolations went to completion. This level response is considered normal following a reactor scram from power and reactor water level is currently being controlled in the normal band. All PCIS group isolations were reset. All rods fully inserted during the scram. The plant is in a normal shutdown electrical lineup with offsite sources powering the safety busses. No safety or relief valves lifted during the transient. Decay heat is being removed via the steam bypass to condenser valves. The licensee has notified the NRC Resident Inspector.
ENS 448211 February 2009 21:28:00Duane ArnoldNRC Region 3Manual ScramGE-4(The licensee manually inserted a reactor scram) due to imminent loss of heat sink (condenser). Circulating water to the condenser suffered an unisolable break resulting in loss of suction source to pumps with cavitation. (The) plant was stabilized per emergency operating procedures. Containment isolations signals operated per design with Groups 2, 3, and 4 received. Plant response (was) complicated with (an) unexpected loss of one 161 KV bus in the switchyard. This was caused by a breaker failure lockout of the bus caused by signal from the output breaker. This output breaker did open. Cause of the breaker failure being investigated. (The) power loss (of the 161 KV bus) had minor plant effect. One power supply to essential service offsite transformer 1X3 (was) lost due to the bus lockout. (The) transformer and offsite circuit remained available. (The) plant did sustain a temporary loss of spent fuel pool cooling system. Cooling has been restored with no level or temperature complications. Essential power (remained) available with both onsite SBDG's (Standby Diesel Generators) and offsite circuits (current source). All ECCS available. All safety related equipment operat(ed) as designed, except Reactor Core Isolation Cooling (RCIC) turbine which had difficulty in automatic control. Manual control (of RCIC) was effective. This is not unexpected during the conditions it was operating (low flow). The licensee was shutting down to enter a refueling outage as the time of the event. Circulating water to one cooling tower had been isolated when a riser on the second cooling tower ruptured and resulted in loss of supply to the circwater pumps. All systems functioned as required except for the lockout of the 161KV bus and RCIC automatic control. Rods fully inserted. The plant is in a normal electrical configuration except for the loss of the 161 KV bus which does not supply any safety related busses. No safety relief valves lifted during the transient. Cooling is currently via HPCI and RCIC to the torus with torus cooling via essential service water. The plant is currently stable at 600 psi and being cooled-down to cold shutdown. The NRC Resident Inspector has been notified.
ENS 432712 April 2007 12:48:00Duane ArnoldNRC Region 3Manual ScramGE-4

This report is being made under 50.72(b)(2)(iv)(B) for inserting a manual scram due to lowering reactor pressure vessel level. The lowering level resulted from a loss of non-essential 4160 VAC bus 1A2 and subsequent loss of 'B' Reactor Feed Pump. In addition this report is being made under 50.72(b)(3)(iv)(A), 'Any event or condition that results in valid actuation of any systems listed in paragraph (b)(3)(iv)(B) of this section due to PCIS groups 2, 3, and 4 being received when reactor water level dropped below 170". All isolations went to completion. The reactor water level drop is normal following a scram from full power due to void collapse in the reactor vessel. After the initial scram, vessel level rose to 211" causing the 'A' Reactor Feed Pump to trip. Before a Reactor Feed Pump could be restarted and adequate feed flow established, another scram signal and isolation occurred when vessel level dropped below 170". Control rods were already fully inserted and isolation valves in the isolated condition when this occurred. Reactor water level was restored to normal and the PCIS group isolations were reset. The current plan is to remain in Hot Standby (Mode 3) and determine the cause of the loss of 1A2 non-essential 4160 VAC bus. The licensee informed the NRC Resident Inspector.

  • * * UPDATE PROVIDED BY MIKE DAVIS TO JEFF ROTTON AT 1621 EDT ON 04/02/07 * * *

This update is being added to clarify that the second scram on 170 " vessel level described in the original report also constituted a 50.72 (b)(3)(iv)(A) reportable event. The licensee notified the NRC Resident Inspector. Notified R3DO (Kozak)

ENS 4324718 March 2007 22:07:00Duane ArnoldNRC Region 3Manual ScramGE-4This report Is being made under 50.72(b)(2)(iv)(B) for inserting a manual reactor scram due to high levels of reactor coolant chlorides, sulfates, and conductivity. These elevated chemistry parameters may be due to a possible resin intrusion following the placement of a Condensate Demineralizer in service. In addition, this report is being made under 50.72(b)(3)(iv)(A), 'Any event or condition that results in valid actuation of any systems listed in paragraph (b)(3)(iv)(B) of this section' due to PCIS groups 2, 3, and 4 being received when reactor water level dropped below 170 inches. All isolations went to completion. The reactor water level drop is normal following a scram from 28% power due to void collapse in the reactor vessel. Reactor water level was restored to normal and the PCIS group isolations were reset. The current plan is to cooldown the plant and enter Mode 4. The scram was characterized as uncomplicated. All rods fully inserted. No safety relief valves lifted. Reactor water low level was approximately 165 inches and was restored with normal reactor feedwater. Decay heat is currently being removed via steam line drains. There were no electrical alignment or grid issues as a result of the transient. No significant Technical Specification LCOs were in effect at the time of the scram. The licensee notified the NRC Resident Inspector.
ENS 429666 November 2006 04:57:00Duane ArnoldNRC Region 3Automatic ScramGE-4On 6 November 2006 at 0110 an automatic reactor scram was received. This report is being made under 10 CFR 50.72 (b)(2)(iv)(B), 'any event or condition that results in actuation of the reactor protection system (RPS) when the reactor is critical.' The plant also received Group 2, 3 and 4 isolations from the low level signal as reactor water dropped due to the reactor scram. The isolations are being reported under 10 CFR 50.72 (b)(3)(iv)(A), 'any event or condition that results actuation of any of the systems listed in paragraph (b)(3)(iv)(B) of this section.' The scram is believed to be the result of a turbine trip but is currently being investigated further. Main Turbine surveillance testing was in progress at the time but it is not known if the testing caused the turbine trip and subsequent Reactor Scram. Reactor pressure is currently being controlled by the turbine bypass valves and steamline drains. No actuations of Safety Relief Valves were required or occurred. Both Reactor Recirculation pumps tripped as part of RPT. The 'B' Recirc pump has been restarted. Reactor level dropped following the scram resulting in the isolations but was recovered and is currently being maintained by the normal feedwater systems. All isolations went to completion and have been reset at this time. The plant electrical buses transferred without incident and are currently in a normal shutdown alignment. The current plan is to remain in Mode 3 while investigations determine the cause of the turbine trip and reactor scram. All control rods fully inserted on the trip. Currently the plant is using offsite power but diesel generators are available. The licensee notified the NRC Resident Inspector.
ENS 4035325 November 2003 17:43:00Duane ArnoldNRC Region 3Manual ScramGE-4Unit was in process of returning to operation following repair of condenser expansion joint. During power ascension, a manual reactor scram was inserted due to degrading condenser vacuum. During the reactor water level transient after the scram, reactor water level dropped below 170 inches and caused the isolation of PCIS groups 2, 3, and 4. All isolations went to completion. This reactor water level drop is normal following a scram from 20% power due to void collapse in the reactor vessel. Reactor water level was restored to normal using the feedwater system and the PCIS group isolations are being reset. Current plan is to remain in Mode 3 during condenser vacuum troubleshooting and repair. All rods were fully inserted during the scram, no SRVs lifted, and the electric distribution system is in a normal lineup for plant condition. The MSIVs are open with decay heat being removed to the main condenser using the bypass valves. No additional specified system actuations occurred. Licensee notified the NRC Resident Inspector.
ENS 403017 November 2003 04:15:00Duane ArnoldNRC Region 3Manual ScramGE-4Inserted a Manual Reactor Scram due to high reactor coolant conductivity. Source of high reactor coolant conductivity is not certain at this time. In addition, this report is being made under 50.72(b)(3)(iv)(A), 'Any event or condition that results in valid actuation of any systems listed in paragraph (b)(3)(iv)(B) of this section' due to PCIS groups 2, 3, and 4 being received when reactor water level dropped below 170". All isolations went to completion. The reactor water level drop is normal following a scram from 45% power due to void collapse in the reactor vessel. Reactor water level was restored to normal and the PCIS group isolations were reset. The current plan is to cool down the plant and enter Mode 4, plant cool down is being achieved using the RCIC system until the source of the conductivity transient is identified and isolated. The licensee indicated shortly prior to the scram a coolant chemistry transient was in progress. The limit for reactor coolant conductivity is 5 micro mhos per centimeter and the highest conductivity reading reached was 8 micro mhos per centimeter. The licensee speculates the most likely source of the high conductivity is related to an off service condensate demineralizer. There were no automatic ECCS initiations. No SRVs lifted. All control rods properly inserted. The licensee notified the NRC Resident Inspector.