If a criteria is reached according to NUREG-1022 then a Licensee to the NRC must submit a Licensee Event Report to explain what happened.
Reporting Criteria
Writing LERs
Explain exactly what happened during the entire event or condition, including how systems, components, and operating personnel performed. Do not cover specific hardware problems in excessive detail. Describe unique characteristics of a plant as well as other characteristics that influenced the event (favorably or unfavorably).
- Avoid using plant-unique terms and abbreviations, or, as a minimum, clearly define them.
- The audience for LERs is large and does not necessarily know the details of each plant.
- Include the root causes, the plant status before the event, and the sequence of occurrences.
- Describe the event from the perspective of the Operator (i.e., what the operator saw, did, perceived, understood, or misunderstood).
- If several systems actuate during an event, describe all aspects of the complete event, including all actuations sequentially, and those aspects that by themselves would not be reportable.
- For example, if a single component failure (generally not reportable) occurs following a reactor scram (reportable), describe the component failure in the narrative of the LER for the reactor scram.
- It is necessary to discuss the performance and status of equipment.
- Paraphrase pertinent sections of the latest submitted Safety analysis report (SAR) rather than referencing them because not all organizations or individuals have access to SARs.
- Extensive cross-referencing would be time consuming considering the large number of LERs and reviewers that read each LER.
- Ensure that each component's safety-significant effect on the event or condition is clearly and completely described.
- Do not use statements such as "this event is not significant with respect to the health and safety of the public" without explaining the basis for the conclusion.
Specific information that should be included, as appropriate, is described in paragraphs 50.73(b).
Submissions of LERs
Section 50.73(d) of the NUREG-1022 states that submmissions must be done with Form NRC 366 as described by section 50.4. Submissions are to be done within 60 days of the event. If that happens to be a weekend or a holiday then it must be the next working day. If a Licensee knows that a report will be late or needs an additional day or so to complete the report, the situation should be discussed with the appropriate NRC regional office. See Section 2.5 for further discussion of discovery date.
LER Forwarding Letter and Cancellations
The cover letter forwarding an LER to the NRC should be signed by a responsible official. There is no prescribed format for the letter. The date the letter is issued and the report date should be the same. Licensees are encouraged to include the NRC resident inspector and the Institute of Nuclear Power Operations (INPO) in their distribution. Multiple LERs can be forwarded by one forwarding letter. Cancellations of LERs submitted should be made by letter. The letter should state that the LER is being canceled (i.e., formally withdrawn). The bases for the cancellation should be explained so that the staff can understand and review the reasons supporting the determination. The notice of cancellation will be filed and stored with the LER and acknowledgement made in various automated data systems. The LER will be removed from the LER data base.
Voluntary LERs
Indicate information-type LERS (i.e., Voluntary LERs) by checking the "Other" block in Item 11 of the LER form and type "Voluntary Report" in the space immediately below the block. Also give a sequential LER number to the voluntary report as noted in Section 5.2.4(5). Because not all requirements of 50.73(b), "Contents," may pertain to some voluntary reports, licensees should develop the content of such reports to best present the information associated with the situation being reported. See Section 2.7 for additional discussion of Voluntary LERs.
How To Find LERs
See also
LER list
by site
1 year
| | Site | Start date | Reporting criterion | System | Topic |
|---|
| 05000263/LER-2025-003, Condition Prohibited by Technical Specifications for Not Implementing Setpoint Change of Primary Containment Isolation Valve | Monticello | 18 June 2036 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Primary containment | |
| 05000373/LER-2025-001, Automatic Scram on Turbine Control Valves Fast Closure on Generator Lockout | LaSalle | 31 December 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Reactor Protection System
Emergency Core Cooling System
Control Rod | Temporary Modification |
| 05000400/LER-2025-002, Incorrect Current Value Used During Power Range Nuclear Instrument Calibration | Harris | 29 December 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Feedwater | |
| 05000445/LER-2025-002, Pressure Transmitter Inoperable for a Duration Prohibited by TS | Comanche Peak | 29 December 2025 | | Reactor Coolant System | Time of Discovery
Anticipated operational occurrence
Past operability |
| 05000237/LER-2025-002, Valid Reactor Protection System Actuation While Shutdown | Dresden | 26 December 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Reactor Protection System
Control Rod | Scram Discharge Volume |
| 05000334/LER-2025-001, Condition Prohibited by Technical Specifications and Event or Condition That Could Have Prevented Fulfillment of a Safety Function | Beaver Valley | 23 December 2025 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | Unanalyzed Condition
Time of Discovery
Past operability
Large early release frequency
Through-Wall Leak |
| 05000382/LER-2025-004, Station Air Leak in Control Room Envelope Results in a Condition That Could Have Prevented Fulfilment of a Safety Function | Waterford | 23 December 2025 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function | Control Room Envelope | Stress corrosion cracking |
| 05000321/LER-2025-002, Reactor Protection System Instrumentation for Turbine Control Valve Fast Closure Inoperable | Hatch | 19 December 2025 | 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor
10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
10 CFR 50.73(a)(2) | Reactor Protection System
Electrohydraulic Control | Past operability |
| 05000338/LER-2025-002, Automatic Reactor Trip Due to PRNI High Negative Rate | North Anna | 17 December 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Reactor Protection System
Auxiliary Feedwater
Control Rod | Negative Flux Rate Trip |
| 05000482/LER-2025-003, Loss of Voltage on ESF Bus Results in Automatic Actuation of Emergency Diesel Generator | Wolf Creek | 17 December 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Emergency Diesel Generator
Main Transformer | |
| 05000482/LER-2025-002, Loss of Both Trains of Control Room Air Conditioning Causes Condition That Could Have Prevented Fulfillment of a Safety Function | Wolf Creek | 17 December 2025 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function | Control Room Emergency Ventilation | |
| 05000482/LER-2025-001, Improperly Breached Control Building Doors Cause a Condition Prohibited by Technical Specifications | Wolf Creek | 17 December 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | |
| 05000461/LER-2025-003, Scram Turbine Hydraulic Oil Leak | Clinton | 16 December 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Feedwater
Reactor Protection System
Main Condenser
Electro-Hydraulic Control | Safe Shutdown |
| 05000388/LER-2025-001, Event Involving the Trip of the Unit 2 Main Generator and Subsequent Automatic Reactor Scram | Susquehanna | 16 December 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2) | Reactor Protection System
Main Condenser | Arc flash |
| 05000395/LER-2025-004, (Vcsns), Actuation of the Reactor Protection and Emergency Feedwater Systems | Summer | 12 December 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Steam Generator
Feedwater
Emergency Feedwater System | |
| 05000370/LER-2025-002, Reactor Trip, Auxiliary Feedwater Actuation, and Refueling Water Storage Tank Inoperability Due to Relief Valve Leak | Mcguire | 9 December 2025 | | Steam Generator
Reactor Coolant System
Auxiliary Feedwater | Boric Acid
Downpower |
| 05000458/LER-2025-007, Division 1 Balance of Plant Isolation Results in Manual Reactor Trip | River Bend | 8 December 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Feedwater
Service water
Reactor Protection System
Main Turbine | |
| 05000280/LER-2025-002, Fault on Transformer Feeder Cable Caused Automatic Start of Emergency Diesel Generator | Surry | 8 December 2025 | | Emergency Diesel Generator | Reserve Station Service Transformer |
| 05000461/LER-2025-002, Automatic Scram on High Reactor Water Level | Clinton | 5 December 2025 | | Feedwater
Reactor Protection System | Safe Shutdown |
| 05000370/LER-2025-001-01, Condition Prohibited by Technical Specifications Due to Emergency Diesel Ventilation Damper Malfunction | Mcguire | 4 December 2025 | | Auxiliary Feedwater | FLEX
Loss of Offsite Power
Offsite Circuit |
| 05000456/LER-2025-002, Liquid Penetrant Indication in Control Rod Drive Mechanism Nozzle Seal Weld Repair Due to Subsurface Weld Defects Opening from Thermal and Pressure Stresses During Operation | Braidwood | 4 December 2025 | | Control Rod | Liquid penetrant
Pressure Boundary Leakage
Through-Wall Leakage
Seal weld |
| 05000400/LER-2025-001, Fuel Assembly Incorrectly Placed in Spent Fuel Pool B | Harris | 2 December 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | Unanalyzed Condition |
| 05000445/LER-2025-001, (Cpnpp), Manual Reactor Trip from a Loss of Both Main Feedwater Pump Due to a Failure to Reset a Signal Fault | Comanche Peak | 24 November 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Steam Generator
Feedwater
Reactor Protection System
Auxiliary Feedwater | Temporary Modification
Overspeed trip
Overspeed |
| 05000318/LER-2025-002, Condition Prohibited by Technical Specifications Due to Condition 3.7.12.A Required Restoration Time Exceeded | Calvert Cliffs | 21 November 2025 | | Steam Generator
Main Turbine | |
| 05000313/LER-2025-001, Automatic Reactor Trip Due to Fault on the B Main Phase Transformer | Arkansas Nuclear | 20 November 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Steam Generator
Feedwater
Reactor Protection System
Control Rod | Arc flash
Coast down |
| 05000317/LER-2025-001-01, Control Room Loss of Ventilation Due to Smoke Detector Failure Causing Common Supply Damper to Shut | Calvert Cliffs | 19 November 2025 | | HVAC
Control Room Emergency Ventilation
Control Room Envelope | Manual Operator Action |
| 05000446/LER-2025-003, Failure of Turbine Electrohydraulic Control System Results in Manual Trip of Unit 2 and Actuation of the Auxiliary Feedwater System | Comanche Peak | 13 November 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Steam Generator
Auxiliary Feedwater
Main Turbine
Electrohydraulic Control
Main Steam | |
| 05000387/LER-2025-001-01, (SSES) Unit 1, Manual Reactor Scram Following Loss of Cooling to Main Transformer | Susquehanna | 13 November 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Feedwater
High Pressure Coolant Injection
Reactor Protection System
Main Transformer
Main Turbine
Emergency Core Cooling System
Main Steam Line
Safety Relief Valve
Main Condenser
Main Turbine Bypass System | |
| 05000277/LER-2025-003, Invalid Actuation Due to Transformer Trip | Peach Bottom | 13 November 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Service water
Primary Containment Isolation System
Reactor Water Cleanup | Coast down |
| 05000461/LER-2025-001, MSIV B21-F022D Limit Switch Failed Testing | Clinton | 12 November 2025 | | Reactor Protection System
Main Steam Line
Main Steam | Operability Determination |
| 05000366/LER-2025-003, Manual Reactor Scram Due to Trip of Both Reactor Recirculation Pumps | Hatch | 11 November 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Reactor Protection System
Reactor Recirculation Pump | |
| 05000306/LER-2024-002-01, Reactor Trip and auto-start Actuation of Auxiliary Feedwater Due to High Negative Neutron Flux Rate Trip | Prairie Island | 10 November 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Steam Generator
Reactor Protection System
Auxiliary Feedwater
Control Rod
Main Steam | |
| 05000318/LER-2024-001-02, Submittal of Manual Reactor Trip Due to 22 Steam Generator Feed Pump Trip | Calvert Cliffs | 7 November 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Steam Generator
Feedwater
Reactor Protection System
Auxiliary Feedwater
Main Condenser | |
| 05000254/LER-2025-006, High Pressure Coolant Injection Inoperable Due to Turbine Inlet Valve Failure to Open | Quad Cities | 4 November 2025 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function | High Pressure Coolant Injection
Reactor Core Isolation Cooling
Core Spray
Automatic Depressurization System
Low Pressure Coolant Injection | |
| 05000370/LER-2025-001, Condition Prohibited by Technical Specifications Due to Emergency Diesel Ventilation Damper Malfunction | Mcguire | 3 November 2025 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Auxiliary Feedwater | FLEX
Loss of Offsite Power
Offsite Circuit |
| 05000414/LER-2025-004, Through Wall Leak in Letdown Piping | Catawba | 3 November 2025 | 10 CFR 50.73(a)(1), Submit an LER
10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded | Steam Generator
Reactor Coolant System
Feedwater
Emergency Core Cooling System
Main Steam | Boric Acid
Time of Discovery
Pressure Boundary Leakage
Through Wall Leak
Operational leakage |
| 05000387/LER-2025-002, Both Sub-Systems of the Control Room Emergency Outside Air Supply System Impacted by Concurrent, Unrelated Equipment Issues in the Control Structure Heating, Ventilation & Air | Susquehanna | 3 November 2025 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function | HVAC | Control Room Habitability |
| 05000416/LER-2025-005, Loss of Secondary Containment Due to Unsecured Roof Hatch | Grand Gulf | 3 November 2025 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function | Secondary containment | |
| 05000318/LER-2025-001-01, Loss of Site Transformer U-4000-12 | Calvert Cliffs | 30 October 2025 | | Emergency Diesel Generator | |
| 05000315/LER-2025-002, Supplemental Diesel Generators (DG) Unavailable Resulting in Emergency DGs Inoperable Greater than Allowed by TS | Cook | 29 October 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Emergency Diesel Generator | Probabilistic Risk Assessment
Large early release frequency |
| 05000260/LER-2025-003-01, Primary Containment Isolation and Manual Reactor Trip Due to Dual Recirculation Pump Trips | Browns Ferry | 27 October 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Reactor Protection System
Primary Containment Isolation System
Primary containment | |
| 05000282/LER-2025-003, Nuclear Instrumentation Over-Temperature Delta Temperature Function Inoperable Due to Defective Potentiometers | Prairie Island | 23 October 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Reactor Protection System | Past operability |
| 05000237/LER-2024-001-01, Containment Cooling Service Water Valve Failure Resulted in a Condition Prohibited by Technical Specifications and Loss of Safety Function | Dresden | 23 October 2025 | 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat
10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Service water
Low Pressure Coolant Injection | Past operability
Overtravel
Fuel cladding |
| 05000249/LER-2024-002-02, Low Pressure Coolant Injection Pump Suction Relief Valve Inoperable as a Primary Containment Isolation Valve Resulted in a Condition Prohibited by Technical Specifications | Dresden | 23 October 2025 | | Primary containment
Low Pressure Coolant Injection | |
| 05000251/LER-2025-005, A Main Steam Isolation Valve Failed to Fully Close Resulting in Loss of Safety Function | Turkey Point | 22 October 2025 | 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat | Main Steam Isolation Valve | |
| 05000327/LER-2025-001-01, Manual Reactor Trip Due to Reboot of the Distributed Control System and Lowering Steam Generator Levels | Sequoyah | 22 October 2025 | 10 CFR 50.73(b)(3)(iv)(A) | Steam Generator
Reactor Protection System
Auxiliary Feedwater | |
| 05000296/LER-2025-002, Reactor Core Isolation Cooling Inoperable Due to Failed Ramp Generating Signal Converter | Browns Ferry | 20 October 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | High Pressure Coolant Injection
Reactor Core Isolation Cooling | |
| 05000458/LER-2025-002-01, For River Bend Station, Unit 1, Unidentified Drywell Leakage Increase Results in Shutdown | River Bend | 20 October 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded
10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown | Reactor Coolant System
Feedwater
Residual Heat Removal | Unanalyzed Condition
Stress corrosion cracking
Pressure Boundary Leakage
Unidentified leakage |
| 05000458/LER-2025-005, For River Bend Station, Unit 1, Containment Unit Coolers Inoperable Due to Compensatory Measures | River Bend | 20 October 2025 | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Primary containment | Unanalyzed Condition
Loss of Offsite Power
Operability Determination |
| 05000458/LER-2025-006, For River Bend Station, Potential Loss of Safety Function of Control Building Chillers Due to a Valve Mispositioned | River Bend | 20 October 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor
10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat
10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
10 CFR 50.73(a)(2)(i)
10 CFR 50.73(a)(2)(x)
10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded
10 CFR 50.73(a)(2)(iii)
10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown
10 CFR 50.73(a)(2)(ix)(A), Prevented Safety Function in Multiple System
10 CFR 50.73(a)(2)(viii)(A)
10 CFR 50.73(a)(2)(viii)(B) | | Safe Shutdown |