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 |
|---|
| 05000265/LER-2024-002-01, Turbine Trip and Automatic Scram Due to Digital EHC Power Supply Intermittent Failure | Quad Cities | 30 October 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Reactor Protection System
Main Turbine
Control Rod | Safe Shutdown
Feedwater Heater |
| 05000259/LER-2024-003, Valid Specified System Actuation Caused the Automatic Start of Emergency Diesel Generators | Browns Ferry | 29 October 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Reactor Protection System
Emergency Diesel Generator
Primary Containment Isolation System | Safe Shutdown |
| 05000259/LER-2024-001-02, Secondary Containment Isolation Valve Inoperable Due to Mechanical Failure | Browns Ferry | 28 October 2024 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Secondary containment
Standby Gas Treatment System | Safe Shutdown
Time of Discovery
Past operability
Probabilistic Risk Assessment
Temporary Modification |
| 05000186/LER-2024-003, University of Missouri Research Reactor, Specification Deviation from Technical Specification 3.2.g.21 | University of Missouri-Columbia | 25 October 2024 | | Reactor Protection System | |
| 05000400/LER-2024-001-01, Automatic Reactor Trip Due to Main Generator Lock-Out | Harris | 23 October 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Reactor Protection System
Emergency Diesel Generator | |
| 05000282/LER-2024-001-01, Auxiliary Building Special Ventilation System Inoperable During Movement of Irradiated Fuel Assemblies | Prairie Island | 22 October 2024 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | Past operability |
| 05000499/LER-2024-003, Containment Isolation Valve Inoperable Resulting in Condition Prohibited by Technical Specification and Prevention of Fulfillment of Safety Function | South Texas | 22 October 2024 | 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 | | |
| 05000482/LER-2024-001-01, Mode 3 Entry with One Auxiliary Feedwater Pump Train Inoperable Due to Missed Post-Maintenance Testing | Wolf Creek | 22 October 2024 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Steam Generator
Reactor Coolant System
Feedwater
Auxiliary Feedwater | Time of Discovery |
| 05000482/LER-2024-002, Technical Specification Required Shutdown Due to Inoperable Auxiliary Feedwater Discharge Valve | Wolf Creek | 21 October 2024 | 10 CFR 50.73(a)(2)(i)
10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown | Steam Generator
Reactor Coolant System
Feedwater
Service water
Auxiliary Feedwater | Enforcement Discretion
Overspeed trip
Overspeed |
| 05000499/LER-2024-002, Two Control Room Envelope HVAC Trains Inoperable Resulting in a Condition That Could Have Prevented Fulfillment of a Safety Function | South Texas | 17 October 2024 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2) | HVAC
Control Room Envelope | Boric Acid
Large early release frequency |
| 05000327/LER-2024-001, Reactor Trip Due to a Turbine Trip | Sequoyah | 17 October 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(iv), System Actuation | Feedwater
Reactor Protection System
Auxiliary Feedwater | Safe Shutdown |
| 05000395/LER-2024-002, Loss of Control Room Emergency Filtration System | Summer | 15 October 2024 | | Control Room Emergency Filtration System | |
| 05000423/LER-2024-001, Loss of Safety Function and Condition Prohibited by Technical Specifications for Loss of Secondary Containment Boundary | Millstone | 14 October 2024 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Secondary containment
Primary containment
Main Steam | Foreign Material Exclusion
Integrated leak rate test |
| 05000373/LER-2023-001-01, Air Circuit Breaker (Acb) Mechanically Operated Contacts (MOC) Switch Failed to Actuate | LaSalle | 9 October 2024 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | Time of Discovery
Offsite Circuit |
| 05000445/LER-2024-002-01, Condition Prohibited by Technical Specifications Due to Inoperable Remote Shutdown System Functions | Comanche Peak | 3 October 2024 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Emergency Diesel Generator
Remote shutdown
Control Rod | Safe Shutdown
Time of Discovery
Post Accident Monitoring
Past operability
Temporary Modification |
| 05000483/LER-2024-002, Concurrent Inoperability of Control Room Air Conditioning System Train and Opposite Train Emergency Diesel Generator Results in Condition Prohibited by Technical Specifications Limiting | Callaway | 1 October 2024 | | Emergency Diesel Generator | |
| 05000446/LER-2024-001-01, Unit Two, Recurring Reactor Scrams Associated with Main Feedwater System Modifications | Comanche Peak | 30 September 2024 | | Steam Generator
Feedwater
Reactor Protection System
Auxiliary Feedwater
Main Turbine | Overspeed |
| 05000423/LER-2023-006-02, Pressurizer Power Operated Relief Valve Failed to Open During Surveillance Testing Resulting in a Condition Prohibited by Technical Specifications | Millstone | 26 September 2024 | 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
10 CFR 50.73(a)(2)(viii)(A) | Reactor Coolant System
Feedwater
Residual Heat Removal
Emergency Core Cooling System
Decay Heat Removal | Stroke time
Time Critical Operator Action
Measurement Uncertainty Recapture |
| 05000335/LER-2024-001, Unplanned Reactor Scram | Saint Lucie | 25 September 2024 | | Feedwater
Main Steam Isolation Valve
Auxiliary Feedwater | |
| 05000328/LER-2024-001, Reactor Trip Due to an Electrical Trouble Turbine Trip | Sequoyah | 25 September 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(iv), System Actuation | Feedwater
Reactor Protection System
Auxiliary Feedwater | Safe Shutdown |
| 05000338/LER-2024-001-01, Automatic Reactor Trip Due to Prni High Negative Rate | North Anna | 24 September 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Reactor Protection System
Auxiliary Feedwater
Control Rod | Negative Flux Rate Trip |
| 05000461/LER-2023-002-01, Reactor Core Isolation Cooling Inoperable Prior to Mode Change | Clinton | 24 September 2024 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Reactor Core Isolation Cooling
High Pressure Core Spray | |
| 05000498/LER-2024-004, Loss of Offsite Power Resulting in Unit 1 Automatic Reactor Trip and Actuation of Emergency Diesel Generators and Auxiliary Feedwater Pumps | South Texas | 19 September 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(iv)(B)(6)
10 CFR 50.73(a)(2)(iv)(B)(1)
10 CFR 50.73(a)(2)(iv)(B)(8) | Steam Generator
Reactor Coolant System
Reactor Protection System
Emergency Diesel Generator
Auxiliary Feedwater
Main Transformer | Shutdown Margin
Large early release frequency
Offsite Circuit |
| 05000346/LER-2021-001-01, Emergency Diesel Generator Speed Switch Failure Due to Direct Current System Ground | Davis Besse | 19 September 2024 | 10 CFR 50.73(a)(1), Submit an LER
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Emergency Diesel Generator
Auxiliary Feedwater | Time of Discovery
Offsite Circuit |
| 05000282/LER-2024-001, Auxiliary Building Special Ventilation System Inoperable During Movement of Irradiated Fuel Assemblies | Prairie Island | 16 September 2024 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | Past operability |
| 05000318/LER-2024-002, Automatic Reactor Trip Due to Main Turbine Loss of Load | Calvert Cliffs | 16 September 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Reactor Protection System
Main Turbine | |
| 05000387/LER-2024-002, B Diesel Generator Inoperable Due to Failed Excitation System Linear Reactor | Susquehanna | 16 September 2024 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | Mission time
Probabilistic Risk Assessment |
| 05000316/LER-2024-002-01, Manual Reactor Trip Following Rapid Downpower for Steam Leak | Cook | 12 September 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Steam Generator
Reactor Protection System
Auxiliary Feedwater
Main Turbine
Decay Heat Removal
Control Rod | Probabilistic Risk Assessment
Downpower |
| 05000317/LER-2024-003, A Diesel Generator Inoperable Due to Potential Transformer Failure | Calvert Cliffs | 6 September 2024 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
10 CFR 50.73(a)(2)(i) | Emergency Diesel Generator | Operability Determination |
| 05000390/LER-2024-002, Automatic Reactor Trip Due to Main Generator Protection Relay Actuation | Watts Bar | 5 September 2024 | | Feedwater
Reactor Protection System
Auxiliary Feedwater
Main Transformer | Safe Shutdown
Temporary Modification |
| 05000354/LER-2024-001-01, Invalid Primary Containment Integrated Leak Rate As-Found Test (ILRT) Supplement | Hope Creek | 5 September 2024 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded | Primary containment | |
| 05000454/LER-2024-001, Both Trains of Control Room Ventilation Temperature Control System Inoperable | Byron | 5 September 2024 | | Reactor Coolant System | |
| 05000277/LER-2024-003, Automatic Reactor Scram Following Main Turbine Trip Due to Degraded Condenser Vacuum | Peach Bottom | 5 September 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Feedwater
Reactor Protection System
Primary Containment Isolation System
Primary containment
Main Turbine
Reactor Pressure Vessel
Emergency Core Cooling System
Main Condenser | |
| 05200025/LER-2024-002, Manual Reactor Protection System and Automatic Safeguards Actuation Due to an Unexpected Change in Position of a Main Feedwater Pump Minimum Flow Control Valve | Vogtle | 5 September 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Steam Generator
Feedwater
Reactor Protection System
Residual Heat Removal
Emergency Core Cooling System | |
| 05000333/LER-2024-002, Reactor Protection System Electric Power Monitoring System Trip Caused Primary Containment Isolation | FitzPatrick | 4 September 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2) | Reactor Protection System
Primary Containment Isolation System
Primary containment
Reactor Building Ventilation
Reactor Water Cleanup
Standby Gas Treatment System
Main Steam Line | |
| 05000499/LER-2024-001-01, Supplement to Automatic Reactor Trip and Actuation of Two of Three Emergency Diesel Generators | South Texas | 29 August 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(iv)(B)(1)
10 CFR 50.73(a)(2)(iv)(B)(8) | Steam Generator
Reactor Coolant System
Feedwater
Reactor Protection System
Emergency Diesel Generator
Auxiliary Feedwater
Main Transformer
HVAC
Residual Heat Removal
Emergency Core Cooling System
Control Room Envelope
Control Rod
Main Steam
Containment Spray | Shutdown Margin
Mission time |
| 05000263/LER-2024-002, Low Pressure Coolant Injection Inoperable Due to Motor Valve Failure | Monticello | 27 August 2024 | 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 | Core Spray
Residual Heat Removal
Emergency Core Cooling System
Low Pressure Coolant Injection | |
| 05000416/LER-2024-003, Feedwater Inlet Check Valve Incorrectly Determined Operable | Grand Gulf | 26 August 2024 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Feedwater
Primary containment
Control Rod | Past operability |
| 05000387/LER-2023-004-01, Manual Reactor Scram Due to Degraded Main Condenser Vacuum | Susquehanna | 26 August 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Feedwater
High Pressure Coolant Injection
Reactor Protection System
Emergency Diesel Generator
Main Steam Isolation Valve
Reactor Core Isolation Cooling
Reactor Pressure Vessel
Residual Heat Removal
Spray Pond
Emergency Core Cooling System
Safety Relief Valve
Main Condenser | |
| 05000373/LER-2024-004-01, Emergency Diesel Generator Auto-Start and Load Due to Loss of System Auxiliary Transformer | LaSalle | 22 August 2024 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Emergency Diesel Generator | Time of Discovery
Offsite Circuit |
| 05000316/LER-2024-003, Plant Shutdown Required by Technical Specifications Due to Reactor Coolant System Identified Leakage | Cook | 22 August 2024 | | Steam Generator
Reactor Coolant System
Auxiliary Feedwater | Packing leak
Probabilistic Risk Assessment
Operational leakage |
| 05000333/LER-2024-001-01, EDG Lube Oil Check Valve Bonnet Cap Leak Due to Failed Gasket | FitzPatrick | 21 August 2024 | 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Emergency Diesel Generator | Mission time
Temporary Leak Repair |
| 05000387/LER-2024-001-01, Main Steam Isolation Valve Leakage Due to Valve Body Seat Wear | Susquehanna | 21 August 2024 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Main Steam Isolation Valve
Main Steam Line
Main Steam | Local Leak Rate Testing |
| 05000530/LER-2024-001-01, Inoperable Boron Dilution Alarm System(Bdas) with Technical Specification Violation | Palo Verde | 21 August 2024 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Reactor Coolant System
Shutdown Cooling | |
| 05000339/LER-2024-001-01, Loss of Generator Field for 2J Eog During 2-PT-82.28 | North Anna | 20 August 2024 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Emergency Diesel Generator | |
| 05000318/LER-2024-001-01, Manual Reactor Trip Due to 22 Steam Generator Feed Pump Trip | Calvert Cliffs | 20 August 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Steam Generator
Feedwater
Reactor Protection System
Auxiliary Feedwater
Main Condenser | |
| 05000382/LER-2024-004, Automatic Reactor Trip Due to Lightning Strike | Waterford | 15 August 2024 | | Steam Generator
Reactor Coolant System
Reactor Protection System
Emergency Core Cooling System
Emergency Feedwater System | Safe Shutdown |
| 05000425/LER-2024-001, Manual Actuation of the Reactor Protection System Due to a Rod Control Fuse Opening Causing a Misaligned Shutdown Rod | Vogtle | 9 August 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Reactor Protection System | Safe Shutdown
Shutdown Margin |
| 05200026/LER-2024-001, Manual Reactor Protection System Actuation Due to Procedure Not Optimally Sequenced to Reset the Rapid Power Reduction Signal | Vogtle | 6 August 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(x) | Steam Generator
Reactor Coolant System
Feedwater
Reactor Protection System
Main Condenser
Control Rod | |
| 05000389/LER-2024-003, Unplanned Reactor Scram | Saint Lucie | 5 August 2024 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | | Loss of condenser vacuum |