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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 57245 | 23 July 2024 18:00:00 | 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | Part 21 - HPCI Rupture Disc Not within Technical Requirements | The following information was provided by the licensee via phone and email: Tennessee Valley Authority (TVA) completed an engineering evaluation for a Fike Metal Products 16-inch rupture disc, part number 16-CPV-C, which had failed in March 2024 during an event previously reported to the NRC as Event Notification 57036 and Licensee Event Report 260/2024-002-00. The evaluation determined that the failure of the rupture disc constituted a failure to comply by a basic component which resulted in a substantial safety hazard. The rupture disc was procured as a non-safety related item from Fike Corporation and commercially dedicated by Paragon Energy Solutions. The disc was supplied to TVA in a satisfactory condition meeting all acceptance criteria. During a routine flowrate surveillance test, the high-pressure coolant injection (HPCI) inner rupture disc developed a hole which caused the Unit 2 HPCI turbine to trip. This resulted in (Browns Ferry Unit 2) entering Technical Specification (TS) Limiting Condition for Operation (LCO) 3.5.1 Condition `C', which is a 14-day shutdown LCO. Per HPCI system design criteria, turbine casing protection disc rupture pressure shall be at 175 psig plus 1 or minus 10 psig and the rupture discs shall be sized for a flow capacity of 600,000 pounds per hour at 200 psig, minimum. The failed HPCI inner rupture disc did not experience pressures above 45 psig since being installed; therefore, the HPCI turbine inner rupture disc did not meet its technical requirements. On July 23, 2024, the Browns Ferry Nuclear Plant Site Vice President was notified of the requirement to report this event under 10 CFR 21.21. This is a non-emergency notification required by 10 CFR 21.21(d)(3)(i). A written notification in accordance with 10 CFR 21.21(d)(3)(ii) will be provided within 30 days. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: Both Fike Corporation and Paragon Energy Solutions have been informed of the HPCI inner rupture disc not meeting technical requirements. Known potentially affected plants include Browns Ferry Units 1, 2, and 3.
The following information was provided by the licensee via phone and email: The purpose of this notification is to retract a previous event notification, EN 57245, reported on 7/25/24. Continued evaluation has concluded that the failure of the disc was not the result of a failure to comply by a basic component, therefore, the NRC non-emergency 10 CFR 21.21 (d) report was not required and the NRC EN 57245 can be retracted. The licensee has notified the NRC Resident Inspector. Notified R2DO (Masters) and Part 21/50.55 Reactors group (Email). | ||
| ENS 48650 | 29 December 2012 06:00:00 | 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | Part 21 - Anti-Rotation Pin Failure in 10-Inch Anchor Darling (Flowserve) Double Disc Gate Valve | The following is a summary of the information received from TVA - Browns Ferry via facsimile: On December 29, 2012 it was determined that sufficient data existed to determine a defect existed in a 10-inch Anchor Darling double disc gate valve installed in Browns Ferry Unit 1. In November, 2012 during a scheduled refueling, the High Pressure Coolant Injection valve, 1-FCV-073-0002 failed its local leak rate test with gross leakage identified on the upstream (reactor side) disc. The downstream side of the discs showed acceptable leakage. When maintenance was performed on the valve, the disc retainer bolt was found sheared. Further investigation revealed that the anti-rotation pin had failed. A review of work order history determined that this valve was installed during the Unit 1 recovery in 2007. The cause of the anti-rotation pin failure was determined to be that the stem was not adequately torqued to the upper wedge at the manufacturing plant. This cause was confirmed by internal inspections of the valve that were performed at Browns Ferry. Flowserve Corporation is also conducting an investigation. The licensee identified 15 other applications of this particular 10-inch valve in all three Browns Ferry units. For all those valves except 2-FCV-073-0002, documentation exists demonstrating that the stem to upper wedge was torqued to manufacturer requirements, determined through MOVATS (Motor-Operated Valve Analysis and Test System) testing that the anti-rotation pin is not sheared, or determined through visual inspection that the anti-rotation pin remains intact. 2-FCV-073-0002 is considered to be non-conforming and will be inspected during the next scheduled Unit 2 refueling. The licensee has notified the NRC Resident Inspector of this notification. | High Pressure Coolant Injection |