|ML19105B171||Salem||31 May 2019||Issuance of Amendment Nos. 329 and 310 Revise Reactor Trip System and Engineered Safety Feature Actuation System Instrumentation, Main Steam Isolation Valves, and Add New TS|
|ENS 54095||Atc Nuclear||29 May 2019 04:00:00||En Revision Imported Date 6/10/2019|
EN Revision Text: PART 21 NOTIFICATION - INTROL POSITIONERS POTENTIAL LATENT DEFECT The following is an excerpt of the Part 21 information received via email: Introl Positioners used by stations in G32 Terry Turbine control applicators have the potential to contain a latent defect. The defect is the result of internal corrosion which has been identified in Tl Operational Amplifiers Part No.TL084CN on the SL3EX Controller Boards of the turbine throttle valve positioner. It is believed the likely cause is associated with the ingress of solder flux into the IC Chip package on the controller board due to delamination caused by the soldering process during fabrication. The corrosion over time can result in intermittent open circuiting and high resistance in the aluminum metallization. Chlorine ionic contamination can also result in high leakage currents within the component circuitry. Failures may be manifested by a reduced valve position signal disproportional to the expected demand condition, no actuation signal (i.e. throttle valve remaining full open), or other anomalous unexpected behavior. There are three TL084CN chips on each SL3EX Controller Board within the positioner assembly. There have been two documented failures to date occurring in 2015 and 2019 in installed systems. Date determination was made: May 29, 2019 Affected sites: Farley, SONGS, Cooper, Almaraz Trillo Nuclear Power Plant (Spain), Clinton, Harris, Wolf Creek, Point Beach, Hatch, Watts Bar, Sequoyah. Stations are advised to work directly with Curtiss-Wright SAS via the technical contacts below. Randy F. Iantorno Project Manager, T: 585.596.3831, M: 585.596.9248, email email@example.com or Justin Pierce 585.596.3866.
The following is a synopsis of information received via E-mail: Shearon Harris Nuclear Plant experienced an overspeed trip of the Turbine Driven Auxiliary Feedwater Pump (TDAFW) on January 18, 2019 during routine system testing. Upon receipt of the initial start signal, the valve remained in the fully open position causing the TDAFW to trip on overspeed. Investigation into the overspeed trip revealed the positioner was not controlling the actuator properly in response to the governor command signal. This situation and subsequent troubleshooting led to replacement with the site spare positioner. Once installed, the system responded as expected and the suspect positioner was sent to Curtiss-Wright SAS (CW SAS) for evaluation. In a joint effort between CW SAS and Paragon Energy Solutions (PES), the positioner was tested and evaluated to determine the cause of the failure. Corrective action which has been, is being, or will be taken: - The three TI chips on the affected board have been successfully replaced at PES. The repaired positioner will be configured and returned to Shearon Harris. - The evaluation of suspect chips has been limited to those removed from the failed positioner, along with some supplied to PES by CW SAS. Work is ongoing in this area. - A complete list of potentially affected installations is listed in the PES Part 21 Report dated May 31, 2019. - Although this defect has the potential of preventing the Electronic Governor Speed Control System (EGSCS) from performing its intended safety function, it does not prevent the Terry Steam Turbine from operating. If the EGSCS fails, the turbine can be operated manually using the Trip and Throttle Valve (TTV) to control speed by regulating steam flow to the turbine. - Steps are being taken to develop a plan to replace chips on affected positioner boards. This is still in the preliminary stages and specific recommendations will follow. Notified R1DO (Carfang), R2DO (Rose), R3DO (Kozak), R4DO (Kellar), Part 21 Reactors E-mail group, and Part 21 Materials E-mail group.
|ML19085A525||Palo Verde||29 May 2019||Issuance of Amendments Nos. 209, 209, and 209 - Regarding Adoption of Risk Informed Completion Times in Technical Specifications (CAC Nos. MF6576, MF6577, and MF6578; EPID L-2015-LLA-0001)|
|ENS 54087||Wolf Creek||24 May 2019 18:10:00||Loss of Offsite Power Due to Fire on Startup Transformer||At 1310 CDT on 5/24/2019, Wolf Creek experienced a loss of offsite power to the safety-related NB02 bus, due to an external fire on a bushing on the startup transformer. The NB02 bus was reenergized when the 'B' Emergency Diesel Generator started and the output breaker automatically closed. The shutdown sequencer automatically started equipment as expected. Due to the undervoltage condition on the NB02 bus, an AFAS-T (Auxiliary Feedwater Actuation Signal) signal was generated which started the turbine driven auxiliary feedwater pump. Turbine load was reduced to maintain reactor power less than 100% in response to the start of turbine driven and 'B' motor driven auxiliary feedwater pumps. The fire was extinguished using a fire extinguisher at 1320 CDT. The unit is stable at 97% power. The NB02 bus remains on the 'B' Emergency Diesel Generator (EDG). The other EDG is operable in standby. The NRC Resident Inspector was notified.|
|ENS 54077||Watts Bar||22 May 2019 06:33:00||Manual Reactor Trip Due to Failure of Main Feedwater Regulating Valve||On May 22, 2019, at 0233 EDT, Watts Bar Nuclear Plant (WBN) Unit 2 reactor was manually tripped due to a failure of the #2 Main Feedwater Regulating Valve during power ascension following a refueling outage. Concurrent with the reactor trip, the Auxiliary Feedwater system actuated as designed. All Control and Shutdown rods fully inserted. All safety systems responded as designed. The unit is currently stable in Mode 3, with decay heat removal via Auxiliary Feedwater and Steam Dumps. Unit 2 is in a normal shutdown electrical alignment. This reactor trip and system actuation is being reported under 10 CFR 50.72(b)(3)(iv)(A) and 10 CFR 50.72(b)(2)(iv)(B). There was no impact to WBN Unit 1. The NRC Senior Resident has been notified."|
|ML18347B330||Watts Bar||22 May 2019||Issuance of Amendment Regarding Revision to Watts Bar Unit 2 Technical Specification 4.2.1 Fuel Assemblies, and Watts Bar Units 1 and 2 Technical Specifications Related to Fuel Storage|
|ENS 54072||Turkey Point||18 May 2019 15:08:00||Manual Reactor Trip Due Grid Disturbance||This is a non-emergency notification to the NRC Operations Center in accordance with 10 CFR 50.72(b)(2)(iv)(B) for a valid actuation of the Reactor Protection System (RPS) (four hour notification) and 10 CFR 50.72(b)(3)(iv)(A) for a valid Engineered Safeguards (ESF) actuation (eight hour notification) due to Auxiliary Feedwater (AFW) initiation. Unit 3 manual reactor trip following grid disturbance. Following the grid disturbance, a manual reactor trip was initiated due to lowering steam generator water levels. All control rods fully inserted. AFW started as expected. All other systems responded as expected. Current reactor temperature is 547 degrees F. Current reactor pressure is 2235 psig. Decay heat is being removed through the Atmospheric Steam Dumps (no known primary to secondary Reactor Coolant System leakage exists). The unit is in a normal post-trip electrical lineup. There was no affect on Unit 4. The cause of the grid disturbance is under investigation. The licensee notified the NRC Resident Inspector.|
|ENS 54069||Callaway||17 May 2019 04:03:00||En Revision Imported Date 6/6/2019|
EN Revision Text: REACTOR TRIP DUE TO SOURCE RANGE HI FLUX SIGNAL This is an 8-hour, non-emergency notification for a valid reactor trip signal with the reactor not critical, and a valid auxiliary feedwater system actuation in accordance with 10 CFR 50.72(b)(3)(iv)(A) - Valid System Actuation.
At 2303 (CDT) on May 16, 2019, the plant was administratively in mode 2 due to withdrawing control rods for startup following refuel. The reactor had not been declared critical. The P-6 permissive at 10E-10 Amps was met for one of two Intermediate Range detectors allowing for block of the Source Range high flux trip (1E5CPS). Prior to performing the block, the Source Range high flux trip setpoint was exceeded and a reactor trip received. All systems responded as expected. A feedwater isolation signal was received due to the reactor trip with feedwater temperature less than 564 degrees Fahrenheit. Auxiliary feedwater was started to maintain steam generator levels. The plant is being maintained stable in mode 3 with no complications. The NRC Resident Inspector was present during the startup and was notified of the reactor trip.
A correction is being made for the sixth sentence in the second paragraph above, which states, 'A Feedwater Isolation signal was received due to the reactor trip with feedwater temperature less than 564 degrees Fahrenheit.' Within this sentence, 'feedwater temperature' is to be replaced with 'reactor coolant system temperature.' The licensee has notified the NRC Senior Resident Inspector.
|ENS 54064||Comanche Peak||15 May 2019 02:51:00||Voltage Transient Due to Loss of Offsite Switchyard||At 2151 CDT, on 14 May 2019, Comanche Peak Nuclear Power Plant (CPNPP) experienced a voltage transient within the onsite 138kV switchyard due to the loss of one of the offsite switchyards supplying power to the CPNPP 138kV switchyard. The reduction in safeguards bus voltage due to the transient caused the Unit 2 safeguard busses to load shed and perform a slow transfer to power supplied from 345kV transformer XST2A. Unit 2 was subjected to actuation of both blackout sequencers causing an automatic start of both motor driven Auxiliary Feedwater (AFW) pumps as well as the turbine-driven AFW pump. No emergency diesel generators started by design. All AFW pumps have been returned to standby status. All other safety systems functioned as designed. Unit 1 is currently defueled, and was unaffected by this event. The licensee has notified the NRC resident inspector."|
|IR 05000336/2019001||Millstone||14 May 2019||Integrated Inspection Report 05000336/2019001 and 05000423/2019001|