Semantic search
| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 52947 | 5 September 2017 15:11:00 | 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Primary Containment Declared Inoperable Due to Both Airlock Doors Open Simultaneously | On September 5, 2017 at 1111 EDT, with the reactor at 100 percent core thermal power and steady state conditions, plant personnel identified that both doors of the emergency personnel airlock of the equipment hatch were open simultaneously due to failure of the interlock. Personnel were at both the outside and inside doors, personnel heard air movement through the air lock. Immediate action was taken to close the inner containment personnel airlock door and it was verified closed. Both doors of the emergency personnel airlock of the equipment hatch were open for less than one minute. There was no radioactive release as a result of the event. The cause of the interlock failure is under investigation. This condition requires an 8-hour non-emergency notification in accordance with 10 CFR 50.72(b)(3)(ii)(A), the condition of the nuclear power plant, including its principal safety barriers (primary containment), being seriously degraded. This condition is also reportable under 10 CFR 50.72(b)(3)(v)(C) as an event or condition that could have prevented fulfillment of a safety function needed to control the release of radioactive material. The NRC Resident Inspector has been notified. | Primary containment | |
| ENS 52415 | 7 December 2016 23:00:00 | 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Unisolable Reactor Coolant System Boundary Leakage | While TMI (Three Mile Island) Unit 1 was in a hot shutdown condition, leakage was identified coming from an RCS (reactor coolant system) pressure boundary on a welded connection on the 'A' Reactor Coolant Pump. The leakage is unisolable from the RCS and is less than 0.5 gpm. Planned actions are to cooldown Unit 1 to cold shutdown conditions in order to repair the leakage. The licensee will be notifying the Pennsylvania Emergency Management Agency and has notified the NRC Resident Inspector. | Reactor Coolant System | |
| ENS 49512 | 7 November 2013 11:00:00 | 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Reactor Coolant System Cold Leg Drain Line Ultrasonic Indication | On Thursday, November 7, 2013, while performing planned inspections on a 2 inch reactor coolant system drain line, TMI technicians identified an indication of a flaw on the weld internal diameter of an elbow to pipe weld on the line. This flaw is determined to not meet acceptable criteria and a repair is being developed. This condition is reportable under 10CFR50.72(b)(3)(ii). No actual impact occurred during plant operations. The NRC Senior Resident Inspector has been notified. | Reactor Coolant System | 05000289/LER-2013-001 05000289/LER-2017-002 |
| ENS 40296 | 4 November 2003 19:30:00 | 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Pressurizer Heater Bundle Diaphragm Plate Degraded Condition | On November 4, 2003, during the TMI Unit 1 15th (T1R15) refueling outage, an inspection of the Pressurizer Heater Bundle (PHB) Diaphragm Plate was completed. This Inspection identified a leak path emanating from the lower Pressurizer Heater Bundle. The initial indication of a potential Reactor Coolant System (RCS) leak was boric acid residue located between the PHB Diaphragm Plate and the PHB Cover Plate. Initially the leak was believed to be from a seal weld, which is considered comparable to a gasket leak. Following disassembly of the PHB Cover Plate and performance of NDE, it was determined that the pathway was through the edge of the PHB Diaphragm Plate. This degraded condition of the PHB Diaphragm Plate is indicative of a RCS pressure boundary leak. This notification is being made in accordance with 10 CFR 50.72(b)(3)(ii)(A)." The licensee provided the following pre-refuel outage information: RCS Leak Rate = less than 0.1 gallons per minute Activity = 0.45 microcuries/milliliter TS (Technical Specifications) Limits: No leakage (3.1.6.4) Secondary System Activity = less than 1E-10 microcuries/milliliter The licensee has notified the NRC Resident Inspector. * * * UPDATE ON 11/24/03 AT 0114 EST FROM JOHN SCHORK TO HOWIE CROUCH * * * Subsequent to the initial report made on 11/4/03, the Pressurizer Heater Bundle (PHB) Diaphragm Plate was repaired. On November 23, 2003 during performance of post-maintenance testing inspections with the plant in Hot Shutdown, steam was observed emanating from either the seal weld or the PHB diaphragm plate. This update is being made to EN 40296 because the observed leak is being conservatively classified as a leak from the Primary System Pressure Boundary and is being addressed in a manner consistent with TMI Technical Specifications 3.1.6.4 and 3.1.6.6. An evaluation of the safety implications of the leak has been initiated. A condition report has been generated to capture all of the actions that have been and will be taken in response to the leak. The plant is being taken to cold shutdown in order to perform an inspection and repair of the leak. The plant continues to be subcritical with all control rods fully inserted and the Reactor Coolant System boron concentration is at the refueling boron concentration. The plant continues to remain in the T1R15 refueling outage. The NRC TMI-1 Sr. Resident Inspector has been notified of the leak. No other notifications were made to the State, Local or other governmental agencies. No press release has been issued regarding the event. The cause and corrective action to repair the leak will be addressed in the licensee event report being submitted in response to EN 40296. The location of the leak observed on November 23, 2003 is in the immediate vicinity of the lower Pressurizer Heater Bundle. There has been no determination of the volumetric leak rate. The leak consists (of) steam wisping from the location. The start date of the leak is November 23, 2003 and the leak was initially observed during hot shutdown checks at 1930 hours on November 23, 2003. There has been no radiological release to the environment as a result of this leak. The licensee has notified the NRC Senior Resident Inspector. Notified R1DO (John Rogge) and NRR (William Ruland). | Reactor Coolant System Control Rod | 05000289/LER-2003-003 |