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 |
|---|
| 05000397/LER-2025-001, Pressure Boundary Leakage Resulting in a Technical Specification Required Plant Shutdown, Degraded Condition, and Condition Prohibited by Technical Specifications | Columbia | 10 June 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 | Unanalyzed Condition
Grab sample
Pressure Boundary Leakage
Unidentified leakage |
| 05000382/LER-2025-003, Auxiliary Component Cooling Water Train Inoperable Resulting in a Condition Prohibited by Technical Specifications | Waterford | 9 June 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | Ultimate heat sink |
| 05000298/LER-2025-001, Inoperable Diesel Generator Jacket Water Pump Results in Condition Prohibited by Technical Specifications | Cooper | 6 June 2025 | | Emergency Diesel Generator | Safe Shutdown
Abnormal operational transient
Loss of Offsite Power
Offsite Circuit |
| 05000528/LER-2025-004, Train a Emergency Diesel Generator Emergency Stop with System Actuation | Palo Verde | 5 June 2025 | | Emergency Diesel Generator | |
| 05000458/LER-2025-001, Human Performance Error Results in Manual Reactor Trip | River Bend | 5 June 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Service water
Reactor Protection System | |
| 05000528/LER-2025-003, Specified System Actuation Due to Loss of Power (Lop)/Load Shed (LS) Signal | Palo Verde | 5 June 2025 | | Emergency Diesel Generator | |
| 05000254/LER-2025-004, Loss of Suppression Chamber Vacuum Breaker Safety Function Due to Configuration Control Error | Quad Cities | 4 June 2025 | 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
Reactor Pressure Vessel | Water Inventory Control |
| 05000263/LER-2024-002-01, Low Pressure Coolant Injection Inoperable Due to Motor Valve Failure | Monticello | 30 May 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 | Core Spray
Residual Heat Removal
Emergency Core Cooling System
Low Pressure Coolant Injection | Probabilistic Risk Assessment
Large early release frequency |
| 05000296/LER-2025-001-01, Automatic Reactor Scram Following Main Generator Trip | Browns Ferry | 29 May 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Reactor Protection System
Emergency Diesel Generator
Primary Containment Isolation System | |
| 05000382/LER-2025-002, Auxiliary Pressurizer Spray Train Inoperable Resulting in a Condition Prohibited by Technical Specifications | Waterford | 29 May 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) | Reactor Coolant System | Past operability |
| 05000339/LER-2025-001, Reactor Trip Breakers Opened Due to High Vibes on 2-RC-P-1B | North Anna | 28 May 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Reactor Protection System
Control Rod | |
| 05000366/LER-2025-002, A Emergency Diesel Generator Inoperable Due to Inadvertent Overspeed Trip | Hatch | 23 May 2025 | 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
Emergency Diesel Generator | Overspeed trip
Overspeed |
| 05000382/LER-2025-001, Inoperability of Startup Transformer a Results in a Condition Prohibited by Technical Specifications | Waterford | 23 May 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Emergency Diesel Generator | Safe Shutdown
Foreign Material Exclusion
Offsite Circuit
Skill of the craft |
| 05000364/LER-2025-002, Two Pressurizer Safety Valves Lift Pressure Outside of Technical Specifications Limits Due to Setpoint Drift | Farley | 23 May 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Reactor Coolant System
Emergency Core Cooling System | Time of Discovery |
| 05000251/LER-2025-001-01, Degraded Condition | Turkey Point | 23 May 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded | Reactor Coolant System | Boric Acid |
| 05000528/LER-2025-001, Unit 1 Loss of High Pressure Safety Injection Safety Function | Palo Verde | 22 May 2025 | | | |
| 05000440/LER-2025-001, Automatic Actuation of Division 3 Diesel Generator Resulting from Startup Transformer Testing | Perry | 21 May 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation
10 CFR 50.73(a)(2)(iv)(B)(8) | Service water
Emergency Diesel Generator
High Pressure Core Spray
Residual Heat Removal
Emergency Core Cooling System
Decay Heat Removal | Fuel cladding |
| 05000263/LER-2025-001, Automatic Reactor Scram on Low Water Level | Monticello | 16 May 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Feedwater
Reactor Protection System
Primary containment
Reactor Pressure Vessel
Circulating Water System | |
| 05000315/LER-2025-001, Two Main Steam Safety Valves Failed Setpoint Testing | Cook | 15 May 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Steam Generator
Main Steam Safety Valve | Probabilistic Risk Assessment
Corrosion bonding
Large early release frequency |
| 05000416/LER-2025-002, Automatic Emergency Diesel Generator Actuation Caused by Grid Transient | Grand Gulf | 13 May 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Emergency Diesel Generator | |
| 05000499/LER-2024-002-01, Two Control Room Envelope HVAC Trains Inoperable Resulting in a Condition That Could Have Prevented Fulfillment of a Safety Function | South Texas | 12 May 2025 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function | HVAC
Control Room Envelope | |
| 05000251/LER-2025-002, Emergency Diesel Generator Actuation | Turkey Point | 9 May 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Emergency Diesel Generator | Safe Shutdown
Loss of Offsite Power |
| 05000254/LER-2025-003, Main Steam Isolation Valves Local Leak Rate Test Exceed Technical Specification Limits | Quad Cities | 9 May 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Main Steam Isolation Valve
Primary containment
Main Steam Line
Main Steam | |
| 05000353/LER-2025-001, HPCI Valve Isolated During a Surveillance Test Due to a Degraded Test Connector | Limerick | 2 May 2025 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function | High Pressure Coolant Injection
Primary containment
Core Spray
Residual Heat Removal
Automatic Depressurization System
Emergency Core Cooling System | Test box |
| 05000324/LER-2025-001, Automatic Actuation of Containment Isolation Valves During Testing | Brunswick | 1 May 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Main Steam Isolation Valve
Primary Containment Isolation System
Primary containment
Main Condenser | |
| 05000296/LER-2024-004-01, Reactor Coolant System Pressure Boundary Leakage Identified from Recirculation System Small Bore Piping | Browns Ferry | 24 April 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Reactor Coolant System | Pressure Boundary Leakage
Unidentified leakage |
| 05000352/LER-2025-001, Bypass Leakage on the B Train of Standby Gas Treatment System HEPA Filters Exceeded Technical Specification Value | Limerick | 21 April 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Standby Gas Treatment System | |
| 05000269/LER-2025-001, Inoperability of Keowee Hydroelectric Unit Due to Legacy Deficiencies in Generator Exceiter Speed Switch Calibration Procedure Resulting in a Condition Prohibited by Technical Specifications | Oconee | 21 April 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Reactor Coolant System
Service water | Probabilistic Risk Assessment |
| 05000366/LER-2025-001, Primary Containment Inoperable Due to Exceeding Technical Specification Allowable Leakage Limits | Hatch | 17 April 2025 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded | Primary containment | Local Leak Rate Testing
Large early release frequency |
| 05000416/LER-2025-001, Manual Scram Due to Degraded Condenser Vacuum | Grand Gulf | 16 April 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Reactor Protection System
Emergency Diesel Generator
Control Rod | |
| 05000327/LER-2024-002-01, Treactor Trip Due to a Turbine Trip | Sequoyah | 9 April 2025 | 10 CFR 50.73(a)(2)(iv), System Actuation | Reactor Protection System
Auxiliary Feedwater | |
| 05000296/LER-2025-001, Automatic Reactor Scram Following Main Generator Trip | Browns Ferry | 9 April 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Reactor Protection System
Emergency Diesel Generator
Primary Containment Isolation System | |
| 05000327/LER-2024-001-01, Reactor Trip Due to a Turbine Trip | Sequoyah | 9 April 2025 | 10 CFR 50.73(a)(2)(iv), System Actuation | Reactor Protection System
Auxiliary Feedwater | |
| 05000335/LER-2025-001-01, Safety Injection Tank Above Technical Specifications Limit | Saint Lucie | 8 April 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | |
| 05000498/LER-2025-001, Two Inoperable Emergency Core Cooling System Trains Resulting in Potential Loss of Safety Function | South Texas | 7 April 2025 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function | HVAC
Emergency Core Cooling System
Control Room Envelope | |
| 05000395/LER-2025-001, (Vcsns), Manual Reactor Trip Due to Unisolable EHC Leak | Summer | 7 April 2025 | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | Feedwater
Main Turbine
Emergency Feedwater System | Through-Wall Leak |
| 05000412/LER-2025-001, Automatic Reactor Trip and Automatic Actuation of the Auxiliary Feedwater System Due to Loose Feedback Linkage on Feedwater Regulating Valve | Beaver Valley | 1 April 2025 | 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) | Steam Generator
Feedwater
Reactor Protection System
Auxiliary Feedwater
Main Steam | Large early release frequency |
| 05000413/LER-2025-001, Plant Shutdown Required by Technical Specifications Due to Unidentified Reactor Coolant System Leakage | Catawba | 31 March 2025 | 10 CFR 50.73(a)(1), Submit an LER
10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown | Reactor Coolant System | Aging Management
License Renewal
Pressure Boundary Leakage
Unidentified leakage
Operational leakage |
| 05000316/LER-2024-004-01, AB Emergency Diesel Generator Inoperable for Longer than Allowed by Technical Specifications | Cook | 27 March 2025 | 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
Emergency Diesel Generator | Mission time
Probabilistic Risk Assessment
Large early release frequency |
| 05000254/LER-2025-002, Control Room Emergency Ventilation Air Conditioning System Inoperable Due to Logic Issue | Quad Cities | 27 March 2025 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function | HVAC
Control Room Emergency Ventilation
Control Room Envelope | |
| 05000335/LER-2025-001, Safety Injection Tank Above Technical Specification Limits | Saint Lucie | 26 March 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | |
| 05000328/LER-2024-001-01, Reactor Trip Due to an Electrical Trouble Turbine Trip, Update Letter | Sequoyah | 26 March 2025 | 10 CFR 50.73(a)(2)(iv), System Actuation | Reactor Protection System
Auxiliary Feedwater | |
| 05000336/LER-2024-002-01, For Millstone, Unit 2, Two Main Steam Safety Valves Failed to Lift within the Acceptance Criteria Resulting in a Condition Prohibited by Technical Specifications | Millstone | 20 March 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Steam Generator
Main Steam Safety Valve
Decay Heat Removal
Control Rod
Main Steam | Loss of Offsite Power |
| 05000338/LER-2024-003-01, Loss of Offsite Power Train a Relay Failure During Surveillance Testing | North Anna | 18 March 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | Auxiliary Feedwater | Loss of Offsite Power |
| 05000390/LER-2025-002, Automatic Reactor Trip Due to Main Turbine Trip | Watts Bar | 18 March 2025 | | Feedwater
Reactor Protection System
Auxiliary Feedwater | |
| 05000328/LER-2025-001, Reactor Trip Breakers Opened Due to Group 2 of Control Rod Bank D Failing to Withdraw | Sequoyah | 11 March 2025 | 10 CFR 50.73(b)(3)(iv)(A) | Reactor Protection System
Control Rod | |
| 05000254/LER-2025-001, Technical Specification 3.6.4.2 Action Not Performed Due to Tagout Boundary Placement Error | Quad Cities | 7 March 2025 | | Secondary containment
Primary containment
Reactor Building Ventilation | |
| 05000250/LER-2024-003-01, Condition Prohibited by Technical Specifications | Turkey Point | 6 March 2025 | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | | |
| 05000390/LER-2025-001, Loss of the Control Room Emerency Air Temperature Control System Due to Chiller Oil Migration | Watts Bar | 3 March 2025 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function | Control Room Emergency Air Temperature Control System | |
| 05000440/LER-2024-004, Division 3 Diesel Generator Inoperable Due to Low Output Voltage Resulting in Loss of Safety Function | Perry | 24 February 2025 | 10 CFR 50.73(a)(2)(v), Loss of Safety Function | Reactor Core Isolation Cooling
High Pressure Core Spray | Probabilistic Risk Assessment
Fuel cladding |