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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 56993 | 23 December 2023 06:00:00 | 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | Part 21 - MINI-GEN Signal Generator Defect | The following is a summary of the information provided by Fairbanks Morse Engine via email: Arkansas Nuclear One (ANO) Unit 2 had a failure of a mini-gen signal generator on the opposed piston emergency diesel generator. Bench testing after removal from the engine showed an erratic signal, and this was confirmed by Fairbanks Morse. Fairbanks Morse destructive analysis revealed wear of the dynamic surface on the stator bushing inside diameter. The cause of the worn stator bushing is most likely due to inadequate lubrication on the dynamic surfaces, outside diameter of the shaft and inside diameter of the stator bushing. Possible causes of inadequate lubrication could be failure to apply enough lubrication to the dynamic surfaces during the manufacturing process or deterioration/evaporation over time. Fairbanks Morse has implemented corrective actions to address this issue, and they are estimated to be completed by May 23, 2024. Affected plants with potentially defected parts: Arkansas Nuclear One, Edwin I. Hatch Nuclear Plant, Joseph M. Farley Nuclear Generating Station, Limerick Generating Station, and Prairie Island Nuclear Generating Plant. Point of Contact: Martin Kurr Quality Assurance Manager Fairbanks Morse 608-364-8247 Martin.Kurr@fmdefense.com Fairbanks Morse Notification Report Number: 23-02 | Emergency Diesel Generator | |
| ENS 56992 | 22 December 2023 06:00:00 | 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | Part 21 - Air Start Valve (Bent Bottom Stem) | The following is a summary of the information provided by Fairbanks Morse Engine via email: Prairie Island Nuclear Generating Plant (PINGP) was conducting a planned replacement of emergency diesel generator air start solenoid valves when it discovered that the bottom stem appeared to be bent and observed air leakage. PINGP returned five valves to Fairbanks Morse, and they returned them to the manufacturer, ASCO. ASCO reassembled one valve and confirmed there was air leakage through the valve. The leakage path was from the air supply port to the exhaust port when the valve was in the de-energized normally open state. ASCO functionally tested the remaining four valves and found a second valve that also leaked. ASCO and Fairbanks Morse have implemented corrective actions to address this issue. Fairbanks Morse will notify PINGP and Limerick Generating Station. Affected plants with potentially defected parts: Prairie Island Nuclear Generating Plant and Limerick Generating Station. Point of Contact: Martin Kurr Quality Assurance Manager Fairbanks Morse 608-364-8247 Martin.Kurr@fmdefense.com Fairbanks Morse Notification Report Number: 23-01 | Emergency Diesel Generator | |
| ENS 56200 | 27 October 2022 05:00:00 | 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | Part 21 Report - Fairbanks Morse Engine Emerency Diesel Generator Electronic Speed Control Module | The following information was provided by Fairbanks Morse (FM) via email: Facilities affected: FM Sales Order Item Affected Facility Serial Number 40135890 12996949 Farley 22436624 40132483 12996949 Limerick 22444358 40130845 12996949 Limerick 22444359 40130158 12996949 Hope Creek 22277182 Basic component which fails to comply or contains a defect: Emergency Diesel Generator Electronic Speed Control Module, Woodward 2301A Nature of defect: In some 2301A controls, 1 nF capacitors may have been loaded in place of 150 pF capacitors. This could affect circuitry controlling the units' crystal, speed signal and reset dynamics, and power supply operation. Safety hazard which could be created by such defect: This issue can prevent affected 2301A controls from starting up or may lead to unscheduled shutdown of affected controls. It can also prevent the prime mover from obtaining a stable speed response, causing it to hunt or overspeed. In some cases, the RESET potentiometer may run out of range to adjust the unit for stable operation or desired prime mover speed response, resulting in prime mover performance outside of specification limits. Fairbanks Morse Engine will notify affected licensees no later than 3 Nov 2022, and repair returned affected units. Additional corrective actions will be documented in the Fairbanks Morse corrective system under PD-1102. Any installed affected Speed Control should be removed from service as soon as practical and returned to Fairbanks Morse for repair. If affected controller is installed and licensee experiences unstable speed response, the electronic speed control should be turned off and the emergency diesel generator should be allowed to operate using the mechanical governor system. POC: Martin Kurr, Quality Assurance Manager (608) 364-8247 | Emergency Diesel Generator |