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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 55827 | 7 February 2022 04:00:00 | 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | Part 21 - CURTISS-WRIGHT Actuator Brake Wiring Deficency Report | The following information was provided by Curtiss-Wright Nuclear Division via fax: The Tennessee Valley Authority (TVA) Browns Ferry Plant notified us (QualTech NP, Curtiss-Wright Nuclear Division) of two separate RCS/Dresser actuator failures which we had provided as safety related components. According to TVA, the first failure occurred on February 7, 2022, after being installed for approximately 167 days. The 2nd failure occurred on February 9, 2022, and was in service for approximately 24 hours when it failed. According to TVA in both cases the actuator's brake assembly wire harness shorted out to the frame, causing the on-board fuse to blow, disabling the actuator. The electrical short was caused by the wire harness laying against a sharp edge of the metal frame, which over time led to fraying of the wire insulation and subsequent bare wire to frame contact. Both units were returned to QualTech NP for evaluation and our findings confirmed TVA's assessment. The root cause of the issue is friction between the wires and the sharp metallic edge that over time cut through the insulation via vibration, which in turn shorted the power leads to the frame. This shorting effect was due to poor positioning and restraint of the wire harness/bundle by the manufacturer during assembly. It is not considered a design flaw, but a workmanship issue caused by the factory assembler. The corrective action taken with the two units was to install new brake assemblies and reposition the wire harness to prevent contact with the sharp edge. In addition, wire ties were added to restrain the wire's movement and keep it away from the sharp edge. As a follow up action, the associated dedication plan will be revised to inspect for this workmanship issue and correct as needed. Additional details are provided in the failure evaluation. QualTech NP has only sold this part to TVA (Browns Ferry) and could not find any additional failures of this type reported by the industry. Identification of the customer's orders and hardware involved are provided in the evaluation. Please phone (513) 528-7900 if you should have any questions. | ||
| ENS 49199 | 17 July 2013 15:30:00 | 10 CFR 30.50(b)(2) | Moisture Gauge Shutter Stuck in Open Position | TVA's Paradise Fossil Plant uses a coal scan moisture monitor with a sealed source containing 3 millicuries of Cesium-137. The gauge is used to monitor the moisture in the coal being transferred on a common feed line to three units at Paradise Fossil Plant. On July 17, 2013 at 1030 CDT, the shutter on the moisture gauge was determined not to be operable. The shutter failed in the open position. The shutter failure discovery was made during the six month shutter test. The issue is being entered into the corrective action program. No personnel radiation exposure was received. The source is not shuttered, but the gauge is in the operating position and is in a safe condition. A twenty-four hour notification is required per 10 CFR 30.50(b)(2) due to failure of the moisture monitor shutter to close. NRC Region II Duty Officer and NRC Region I Duty Officer will be notified. Gauge model TBM-201. Licensee stated that there is no danger of personnel exposure. | ||
| ENS 47046 | 12 July 2011 18:30:00 | 10 CFR 30.50(b)(2) | Moisture Density Gauge Shutter Stuck in the Closed Position | Tennessee Valley Authority Paradise Fossil Plant uses an Ohmart Model SR1-A density gauge with a sealed source containing up to 1,562 milliCuries of Cesium 137. The gauge is used to monitor the density of the limestone slurry at the Unit 2 scrubber. On July 12, 2011 at 1330 (CDT) the shutter on the density gauge was determined to be not operable. It was determined that the shutter failed in the closed position when the operator received a slurry density high alarm. The shutter failure is in the closed and safe position. The gauge has been entered into the corrective action program and will be repaired by the manufacturer at a later time. There were no personnel exposures, no damages to other equipment, and no additional compensatory actions necessary since the shutter is failed closed/safe position. The licensee notified the R2DO (Freeman). | ||
| ENS 46008 | 14 June 2010 15:18:00 | 10 CFR 26.719, FFD Reporting requirements | Non-Licensed Supervisor Fitness for Duty | A non-licensed employee supervisor had a confirmed positive for alcohol during a follow-up fitness-for-duty test. The employee's access to TVA nuclear plants has been terminated. Contact the Headquarters Operations Officer for additional details. |