NUREG-1022, Event Reporting Guidelines for 10 CFR 50.72 and 10 CFR 50.73

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Event Reporting Guidelines for 10 CFR 50.72 and 10 CFR 50.73.

Current edition is Revision 3.

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NUREG-1022 Rev 3 Summary document: XaatmhbJsiyOzO8r9FQbqtrczz3CnWZ39zPWEsm4/edit#

The information reported under 10 CFR 50.72 and 50.73 is used by the NRC staff in responding to emergencies, monitoring ongoing events, confirming licensing bases, studying potentially generic safety problems, assessing trends and patterns of operational experience, monitoring performance, identifying precursors of more significant events, and providing operational experience to the industry.


In 1983, partially in response to lessons from the Three Mile Island accident, the U.S. Nuclear Regulatory Commission (NRC) revised its immediate notification requirements via the emergency notification system (ENS) in 10 CFR 50.72 and modified and codified its written licensee event report (LER) system requirements in 10 CFR 50.73. The revision of 10 CFR 50.72 and the new 10 CFR 50.73 became effective on January 1, 1984. Together, they specified the types of events and conditions reportable to the NRC for emergency response and identifying plant-specific and generic safety issues. They have remained in effect since then with only minor modifications until early 2001.

10 CFR 50.72 - Immediate Report (ENS)

Section 50.72 provides for immediate notification requirements via the emergency notification system (ENS)3

  • [[ENS Notifications Made|List of ENS Notifications]]

10 CFR 50.73 - 60-Day Report (LER)

Section 50.73 provides for 60-day written licensee event reports (LERs).

  • [[:Category:LER|List of Licensee Event Reports (LER)]]


This section clarifies specific areas that are applicable to multiple reporting criteria or that historically appear to be subject to varied interpretations.

2.1 Engineering Judgment

The reportability of many events and conditions is self evident. However, the reportability of other events and conditions may not be readily apparent, and the use of engineering judgment is involved in determining reportability.

Engineering judgment may include either a documented engineering analysis or a judgment by a technically qualified individual, depending on the complexity, seriousness, and nature of the event or condition. A documented engineering analysis is not a requirement for all events or conditions, but it would be appropriate for particularly complex situations. In addition, although it is not required by the rule, it may be prudent to record in writing that a judgment was exercised by identifying the individual making the judgment, the date made, and briefly documenting the basis for this judgment. In any case, the staff considers that the use of engineering judgment implies a logical thought process that supports the judgment.

2.2 Differences in Tense between 10 CFR 50.72 and 50.73

The present tense is generally used in 10 CFR 50.72 because the event or condition generally would be ongoing at the time of reporting. The past tense is used in 10 CFR 50.73 because the event or condition is generally past when an LER is written. However, unless otherwise specified, events that occurred within 3 years of the date of discovery are reportable under 10 CFR 50.72 and 50.73 regardless of the plant mode or power level and regardless of the significance of the structure, system, or component (SSC) that initiated the event. Specific criteria in Section 3 of this report contain additional details for when tense, plant mode, power level, and significance of the SSC that initiated the event are relevant to reportability.

2.3 Reporting Multiple Events in a Single Report

More than one failure or event may be reported in a single ENS notification or LER if (1) the failures or events are related (i.e., they have the same general cause or consequences) and (2) they occurred during a single activity (e.g., a test program) over a reasonably short time (e.g., within 4 hours or 8 hours for ENS notifications, or within 60 days for LER reporting).

To the extent feasible, report failures that occurred within the first 60 days of discovery of the first failure in one LER. If appropriate, state in the LER text that a supplement to the LER will be submitted when the test program is completed. In the revised LER, include all of the failures, including those reported in the original LER (i.e., the revised LER should stand alone).

Generally, LERs are intended to address specific events and plant conditions. Thus, unrelated events or conditions should not be reported in one LER. Also, an LER revision should not be used to report subsequent failures of the same or like components that are the result of a different cause or for separate events or activities.

Unrelated failures or events should be reported as separate ENS notifications to be given unique ENS numbers by the NRC. However, multiple ENS notifications may be addressed in a single telephone call.

2.4 Deficiencies Discovered during Engineering Reviews or Inspections

As indicated in NUREG-1397, “An Assessment of Design Control Practices and Design Reconstitution Programs in the Nuclear Power Industry,” issued February 1991, Section 4.3.2, the reporting requirements specified in 10 CFR 50.9, “Completeness and Accuracy of Information,” 10 CFR 50.72, and 10 CFR 50.73 apply equally to discrepancies discovered during design document reconstitution programs, design-bases documentation reviews, and other similar engineering reviews. There is no basis for treating discrepancies discovered during such reviews differently from any other reportable item.

Licensees should evaluate the reportability of suspected but unsubstantiated discrepancies discovered during such a review program in the same manner as other potentially reportable items. See Section 2.5 for a discussion of reporting time limits and discovery dates.

2.5 Time Limits for Reporting

Reporting times in 10 CFR 50.72 are keyed to the occurrence of the event or condition, as described below. The present tense is generally used in 10 CFR 50.72 because the event or condition generally would be ongoing at the time of reporting. If a reportable event or condition is not on-going at the time of discovery, guidance on time limits for reporting under 10 CFR 50.73 at the end of this section may be used for determining the time of discovery for 10 CFR 50.72 reports.

In 10 CFR 50.72, the NRC requires an ENS notification within the following times:

  • Paragraph 50.72(a)(3) requires ENS notification of the declaration of an Emergency Class “immediately after notification of the appropriate State or local agencies and not later than one hour after the time the licensee declares one of the Emergency Classes.”
  • Paragraph 50.72(b)(1) requires ENS notification for one type of event “as soon as practical and in all cases within one hour of the occurrence of any deviation from the plant’s technical specifications authorized.”
  • Paragraph 50.72(b)(2) requires ENS notification for specific types of events and conditions “as soon as practical and in all cases, within four hours of the occurrence of any of the following.”
  • Paragraph 50.72(b)(3) requires ENS notification for specific types of events and conditions “as soon as practical and in all cases, within eight hours of the occurrence of any of the following.”

These 10 CFR 50.72 reporting times have some flexibility because a licensee needs to ensure that reporting does not interfere with plant operation. However, that does not mean that a licensee should automatically wait until close to the time limit expiration before reporting.

In 10 CFR 50.73, the NRC requires submittal of an LER “within 60 days after the discovery” of a reportable event. Many reportable events are discovered when they occur. However, if the event is discovered at some later time, the discovery date is when the reportability clock starts under 10 CFR 50.73.

The discovery date is generally the date when the event was discovered rather than the date when an evaluation of the event is completed. For example, if a technician sees a problem, but a delay occurs before an engineer or supervisor has a chance to review the situation, the discovery date (which starts the 60-day clock) is the date that the technician sees a problem.

However, in some cases, such as discovery of an existing but previously unrecognized condition, it may be necessary to undertake an evaluation in order to determine if an event or condition is reportable. If so, the guidance provided in Regulatory Issue Summary (RIS) 2005-20, Revision 1, “Revision to NRC Inspection Manual Part 9900 Technical Guidance, ‘Operability Determinations & Functionality Assessments for Resolution of Degraded or Nonconforming Conditions Adverse to Quality or Safety,’” dated April 16, 2008, which applies primarily to operability determinations, is appropriate for reportability determinations as well.

This guidance indicates that the evaluation should proceed on a time scale commensurate with the safety significance of the issue and that, whenever reasonable expectation no longer exists that the equipment in question is operable, or significant doubts begin to arise, appropriate actions, including reporting, should be taken.

2.6 Events Discussed with the NRC Staff

On occasion, some licensee personnel have erroneously believed that if a reportable event or condition had been discussed with the resident inspector or other NRC staff, there was no need to report under 10 CFR 50.72 and 50.73 because the NRC was aware of the situation. Some licensee personnel have also expressed a similar misunderstanding for cases in which the NRC staff identified a reportable event or condition to the licensee via inspection or assessment activities. Such conditions do not satisfy 10 CFR 50.72 and 50.73. The regulations in 10 CFR 50.72 and 50.73 specifically require a telephone notification via the ENS and/or submittal of a written LER for an event or condition that meets the criteria stated in those rules.

2.7 Voluntary Reporting

Information that does not meet the reporting criteria of 10 CFR 50.72 and 50.73 may be reportable under other requirements, such as 10 CFR 50.9, 20.2202, 20.2203, 50.36, 72.74, 72.216, 73.71, and 10 CFR Part 21, “Reporting of Defects and Noncompliance.” In particular, 10 CFR 50.9(b) states that “Each applicant or licensee shall notify the Commission of information identified by the applicant or licensee as having for the regulated activity a significant implication for public health and safety or common defense and security.” This applies to information that is not already required by other reporting or updating requirements. Notification must be made to the Administrator of the appropriate regional office within 2 working days of identifying the information. Reporting under 10 CFR 50.9, “Completeness and Accuracy of Information,” is required, not voluntary.[1] Voluntary reporting, as discussed in the following paragraphs, pertains to information of lesser significance than that described in 10 CFR 50.9(b).

Licensees are permitted and encouraged to report any event or condition that does not meet the criteria for required reporting, if the licensee believes that the event or condition might be of safety significance or of generic interest or concern. Reporting requirements aside, assurance of safe operation of all plants depends on accurate and complete reporting by each licensee of all events having potential safety significance. Instructions for voluntary ENS notifications and LERs are discussed in Sections 4.2.2 and 5.1.4 of this report.

The NRC staff encourages voluntary LERs rather than information letters for voluntary reporting. The LER format is preferable because it provides the information needed to support NRC review of the event and facilitates administrative processing, including data entry.

2.8 Retraction or Cancellation of Event Reports

An ENS notification may be retracted via a followup telephone call, as discussed further in Section 4.2.3 of this report. A retracted ENS report is retained in the ENS database, along with the retraction.

An LER may be canceled by letter as discussed further in Section 5.1.2 of this report. Canceled LERs are deleted from the LER database.

Sound, logical bases for the withdrawal should be communicated with the retraction or cancellation. (Example 3 in Section 3.2.4 of this report illustrates a case in which there were sound reasons for a retraction. The last event under Example 1 in Section 3.2.6 illustrates a case in which the reasons for retraction were not adequate.) For reports that were submitted as a result of an operability determination, the retraction or cancellation should discuss why the operability determination was revised, as well as its impact on the associated reporting criteria (e.g., system operability was never lost, the limiting condition for operation (LCO) was always met, completion times were never exceeded, etc). RIS 2005-20, Revision 1 provides guidance on operability determinations.

3. Specific Reporting Criterion

10 CFR 50.72

10 CFR 50.73


This section describes the ENS referenced in 10 CFR 50.72 and provides general and specific guidelines for ENS reporting.

4.1 Emergency Notification System

The NRC Operations Center is the nucleus of the ENS and has the capability to handle emergency communication needs. The NRC’s response to both emergencies and nonemergencies is coordinated in this communication center. The key NRC emergency communications personnel, the emergency officer (EO), regional duty officer (RDO), and the headquarters operations officer (HOO), are trained to notify appropriate NRC personnel and to focus appropriate NRC management attention on any significant event.

(1) Emergency Notification System Telephones Each commercial nuclear power reactor facility has ENS telephones. These telephones are located in each licensee’s control room, TSC, and EOF. A separate ENS line is installed at EOFs that are not on site.
(2) Health Physics Network Telephones The HPN is designed to provide health physics and environmental information to the NRC Operations Center in the event of an ongoing emergency. These telephones are installed in each licensee's TSC and EOF.
(3) Recording The NRC records all conversations with the NRC Operations Center. The recordings are saved for 1 month in case there is a public or private inquiry.
(4) Facsimile Transmission (Fax) Licensees occasionally fax an event notification into the NRC Operations Center on a commercial telephone line in conjunction with making an ENS notification. However, 10 CFR 50.72 requires that licensees notify the NRC Operations Center via the ENS;

therefore, licensees also must make an ENS notification.

4.2 General ENS Notification

4.2.1 Timeliness

The required timing for ENS reporting is spelled out in 10 CFR 50.72(a)(3), (b)(1), (b)(2), (b)(3), (c)(1), and (c)(2) as “immediate” and “as soon as practical and in all cases within one (or four or eight) hour(s)” of the occurrence of an event (depending on its significance and the need for prompt NRC action). The intent is to require licensees to make and act on reportability decisions in a timely manner so that ENS notifications are made to the NRC as soon as practical, keeping in mind the safety of the plant. See Section 2.5 for further discussion of reporting timeliness.

4.2.2 Voluntary Notifications

Licensees may make voluntary or courtesy ENS notifications about events or conditions in which the NRC may be interested. The NRC responds to any voluntary notification of an event or condition as its safety significance warrants, regardless of the licensee’s classification of the reporting requirement. If it is determined later that the event is reportable, the licensee can change the ENS notification to a required notification under the appropriate 10 CFR 50.72 reporting criterion.

4.2.3 ENS Notification Retraction

If a licensee makes a 10 CFR 50.72 ENS notification and later determines that the event or condition was not reportable, the licensee should call the NRC Operations Center on the ENS telephone to retract the notification and explain the rationale for that decision. There is no set time limit for ENS telephone retractions. However, because most retractions occur following completion of engineering and/or management review, it is expected that retractions would occur shortly after such review. A retracted ENS report is retained in the ENS database, along with the retraction. See Section 2.8 for further discussion of retractions.

4.2.4 ENS Event Notification Worksheet (NRC Form 361)

The ENS “Event Notification Worksheet” (NRC Form 361) provides the usual order of questions and discussion for easier communication and its use often enables a licensee to prepare answers for a more clear and complete notification. A clear ENS notification helps the HOO to understand the safety significance of the event. Licensees may obtain an event number and notification time from the HOO when the ENS notification is made. If an LER is required, the licensee may include this information in the LER to provide a cross-reference to the ENS notification, making the event easier to trace.

Licensees should use proper names for systems and components, as well as their alphanumeric identifications, during ENS notifications. Licensees should avoid using local jargon for plant components, areas, operations, and the like so that the HOO can quickly understand the situation and have fewer questions. In addition, others not familiar with the plant can more readily understand the situation.

Electronic versions of NRC Form 361 are available at the NRC public Web site at

4.3 Typical ENS Reporting Issues

At the time of an ENS notification, the NRC must independently assess the status of the reactor to determine if it is in a safe condition and expected to remain so. The HOO needs to understand the safety significance of each event to brief NRC management or initiate an NRC response. The HOO will be primarily concerned about the safety significance of the event, the current condition of the plant, and the possible near-term effects the event could have on plant safety. The HOO will attempt to obtain as complete a description as is available at the time of the notification of the event or condition, its causes, and its effects. Depending on the licensee’s description of the event, the HOO may be concerned about other related issues. The questions that licensees typically may be asked to discuss do not represent a requirement for reporting. These questions are of a nature to allow the HOO information to more fully understand the event and its safety significance and are not meant in any way to distract the licensee from more important issues.

The licensee's first responsibility during a transient is to stabilize the plant and keep it safe.

However, licensees should not delay in declaring an emergency class when conditions warrant because delaying the declaration can defeat the appropriate response to an emergency.

Because of the safety significance of a declared emergency, time is of the essence. The NRC needs to become aware of the situation as soon as practical to activate the NRC Operations Center and the appropriate NRC regional incident response center, as necessary, and to notify other Federal agencies.

The effectiveness of the NRC response during an event depends largely on complete and accurate reporting from the licensee. During an emergency, the appropriate regional incident response center and the NRC Operations Center become focal points for NRC action. Licensee actions during an emergency are monitored by the NRC to ensure that appropriate action is being taken to protect the health and safety of the public. When required, the NRC supports the licensee with technical analysis and coordinates logistics support. The NRC keeps other Federal agencies informed of the status of an incident and provides information to the media. In addition, the NRC assesses and, if necessary, confirms the appropriateness of actions recommended by the licensee to local and State authorities.

IN 85-80 indicates that it is the licensee’s responsibility to ensure that adequate personnel, knowledgeable about plant conditions and emergency plan implementing procedures, are available on shift to assist the shift supervisor to classify an emergency and activate the emergency plan, including making appropriate notifications, without interfering with plant operation. When 10 CFR 50.72 was published, the NRC made clear its intent in the Statements of Consideration that notifications on the ENS to the NRC Operations Center should be made by those knowledgeable of the event. If the description of any emergency is to be sufficiently accurate and timely to meet the intent of the NRC’s regulations, the personnel responsible for notification must be properly trained and sufficiently knowledgeable of the event to report it correctly. The NRC did not intend that notifications made under 10 CFR 50.72 would be made by those who did not understand the event that they are reporting.

ENS reportability evaluations should be concluded and the ENS notification made as soon as practical and in all cases within 1, 4, or 8 hours to meet 10 CFR 50.72. The Statements of Consideration noted that the 1-hour deadline is necessary if the NRC is to fulfill its responsibilities during and following the most serious events occurring at operating nuclear power plants without interfering with the operator’s ability to deal with an accident or transient in the first few critical minutes (48 FR 39041; August 29, 1983).


This section discusses the guidelines for preparing and submitting LERs. Section 5.1 addresses administrative requirements and provides guidelines for submittal; Section 5.2 addresses the requirements and guidelines for the LER content. Portions of the rule are quoted, followed by explanation, if necessary. Copies of the required “Licensee Event Report” form (NRC Form 366), “Licensee Event Report (LER) Continuation Sheet” (NRC Form 366A), and “Licensee Event Report (LER) Failure Continuation” form (NRC Form 366B) may be found at the NRC public Web site at

5.1 LER Reporting Guidelines

This section addresses administrative requirements and provides guidelines for submittal.

Topics addressed include submission of reports, forwarding letters, cancellation of LERs, report legibility, reports other than LERs that use LER forms, supplemental information, revised reports, and general instructions for completing LER forms.

5.1.1 Submission of LERs

§ 50.73(d)

“Submission of reports. Licensee Event Reports must be prepared on Form NRC 366 and submitted to the U.S. Nuclear Regulatory Commission, as specified in § 50.4.”

An LER is to be submitted (mailed) within 60 days of the discovery date. If a 60-day period ends on a Saturday, Sunday, or holiday, reports submitted on the first working day following the end of the 60 days are acceptable. 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.

5.1.2 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 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 database.

5.1.3 Report Legibility

§ 50.73(e)

“The reports and copies that licensees are required to submit to the Commission under the provisions of this section must be of sufficient quality to permit legible reproduction and micrographic processing.”

No further explanation is necessary.

5.1.4 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 5.2.7(6). Because not all requirements of 10 CFR 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.

5.1.5 Supplemental Information and Revised LERs

§ 50.73(c)

“The Commission may require the licensee to submit specific additional information beyond that required by paragraph (b) of this section if the Commission finds that supplemental material is necessary for complete understanding of any unusually complex or significant event. These requests for supplemental information will be made in writing and the licensee shall submit, as specified in § 50.4, the requested information as a supplement to the initial LER.”

This provision authorizes the NRC staff to require the licensee to submit specific supplemental information.

If an LER is incomplete at the time of original submittal or if it contains significant incorrect information of a technical nature, the licensee should use a revised report to provide the additional information or to correct technical errors discovered in the LER. Identify the revision to the original LER in the LER number as described in Section 5.2.7, Item (6).

The revision should be complete and should not contain only supplementary or revised information to the previous LER, because the revised LER will replace the previous report in the computer file. In addition, indicate in the text on the LER form the revised or supplementary information by placing a vertical line in the margin. If an LER mentions that an engineering study was being conducted, report the results of the study in a revised LER only if it would significantly change the reader’s perception of the course, significance, implications, or consequences of the event or if it results in substantial changes in the corrective action planned by the licensee.

Use revisions only to provide additional or corrected information about a reported event. Do not use a revision to report subsequent failures of the same or like component, except as permitted in 10 CFR 50.73. Some licensees have incorrectly used revisions to report new events that were discovered months after the original event because they were loosely related to the original event. These revisions had different event dates and discussed new, although similar, events. Report events of this type as new LERs and not as revisions to previous LERs.

5.1.6 Special Reports

There are a number of requirements in various sections of the TS that require reporting of operating experience that is not covered by 10 CFR 50.73. If LER forms are used to submit special reports, check the “Other” block in Item 11 of the form and type “Special Report” in the space immediately below the block. The provisions of 10 CFR 50.73(b) may not be applicable or appropriate in a special report. Develop the content of the report to best present the information associated with the situation being reported. In addition, if the LER form is used to submit a special report, use a report number from the sequence used for LERs.

If an event is reportable both under 10 CFR 50.73 and as a special report, check the block in Item 11 for the applicable section of 10 CFR 50.73 as well as the “Other” block for a special report. The content of the report should depend on the reportable situation.

5.1.7 Appendix J Reports (Containment Leak Rate Test Reports)

A licensee must perform containment integrated and local leak rate testing and report the results as required by Appendix J to 10 CFR Part 50. When the leak rate test identifies a situation reportable under 10 CFR 50.73 (see Section 3.2.4 of this report), submit an LER and include the results in a report under Appendix J to 10 CFR Part 50 by reference, if desired. The LER should address only the reportable situation, not the entire leak rate test.

5.1.8 10 CFR 73.71 Reports

Submit events or conditions that are reportable under 10 CFR 73.71, “Maintenance of Records, Making of Reports,” using the LER forms with the appropriate blocks in Item 11 checked. If the report contains Safeguards Information as defined in 10 CFR 73.21, “Protection of Safeguards Information: Performance Requirements,” the LER forms may still be used but should be appropriately marked in accordance with 10 CFR 73.21. Include safeguards and security information only in the narrative and not in the abstract. In addition, the text should clearly indicate the information that is safeguards or security information. Finally, the requirements of 10 CFR 73.21(g) must be met when transmitting Safeguards Information. For additional guidelines on 10 CFR 73.71 reporting, see Regulatory Guide 5.62, Revision 1, “Reporting of Safeguards Events,” issued November 1987; NUREG-1304, “Reporting of Safeguards Events,” issued February 1988; and Generic Letter 91-03, “Reporting of Safeguards Events,” dated March 6, 1991.

If the LER contains proprietary information, mark it appropriately in Item 17 (text) on the LER form. Include proprietary information only in the narrative and not in the abstract. In addition, indicate clearly in the narrative the information that is proprietary. Finally, the requirements of 10 CFR 2.790(b) must be met when transmitting proprietary information.

5.1.9 Availability of LER Forms

The NRC will provide LER forms (i.e., NRC Forms 366, 366A, and 366B) free of charge.

Copies may be obtained by writing to the NRC Records Management Branch, Office of the Chief Information Officer, U.S. Nuclear Regulatory Commission, Washington, DC 20555.

Electronic versions are also available at the NRC public Web site at

5.2 LER Content Requirements and Preparation Guidance

5.2.1 Optical Character Reader

To help reduce the number of errors incurred by the optical character reader used to read LER contents into NRC databases, the NRC suggests the following practices.

The staff suggests that you do not use underscore, do not use bold print, do not use italic print style, do not end any lines with a hyphen, and do not use paragraph indents. Instead, print copy single spaced, with a blank line between paragraphs.

The following are limitations on the use of symbols in the textual areas:

  • Spell out the word “degree.”
  • Use </= for “less than or equal to.”
  • Use >/= for “greater than or equal to.”
  • Use +/- for “plus or minus.”
  • Spell out all Greek letters.

Do not use exponents. A number should be either expressed as a decimal, spelled out, or, preferably, designated in terms of “E” (E field format). For example, 4.2x10-6 could be expressed as 4.2E-6, 0.0000042 or 4.2 x 10(-6).

Define all abbreviations and acronyms in both the text and the abstract and explain all component designators the first time they are used (e.g., the ESW pump 1-SW-P-1A).

5.2.2 Narrative Description or Text (NRC Form 366A, Item 17)

(1) General
§ 50.73(b)(2)(i)

The LER shall contain the following: “A clear, specific, narrative description of what occurred so that knowledgeable readers conversant with the design of commercial nuclear power plants, but not familiar with the details of a particular plant, can understand the complete event.” There is no prescribed format for the LER text; write the narrative in a format that most clearly describes the event. After the narrative is written, however, review the appropriate sections of 10 CFR 50.73(b) to make sure that applicable subjects have been adequately addressed. It is helpful to use headings to improve readability. For example, some LERs employ major headings such as event description, safety consequences, corrective actions, and previous similar events and subheadings such as initial conditions, dates and times, event classification, systems status, event or condition causes, failure modes, method of discovery, component information, immediate corrective actions, and actions to prevent recurrence.

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). Specific information that should be included, as appropriate, is described in 10 CFR 50.73(b)(2)(ii), (b)(3), (b)(4), and (b)(5) and separately in the following sections.

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 important for defining and understanding what happened and for determining the potential implications of the event.

Paraphrase pertinent sections of the latest submitted FSAR rather than referencing them because not all organizations or individuals have access to FSARs. Extensive crossreferencing would be excessively time consuming, considering the large number of LERs and large number of reviewers that read each LER. Ensure that each applicable 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.

§ 50.73(b)(2)(ii)(A)

The narrative description must include the following: “Plant operating conditions before the event.”

Describe the plant operating conditions such as power level or, if not at power, describe the mode, temperature, and pressure that existed before the event.

§ 50.73(b)(2)(ii)(B)

The narrative description must include the following: “Status of structures, components, or systems that were inoperable at the start of the event and that contributed to the event.”

If there were no SSCs that were inoperable at the start of the event and contributed to the event, so state. Otherwise, identify SSCs that were inoperable and contributed to the initiation or limited the mitigation of the event. This should include alternative mitigating SSCs that are a part of normal or emergency operating procedures that were or could have been used to mitigate, reduce the consequences of, or limit the safety implications of the event. Include the impact of support systems on mitigating systems that could have been used.

§ 50.73(b)(2)(ii)(C)

The narrative description must include the following: “Dates and approximate times of occurrences.”

For a transient or system actuation event, the event date and time are the date and time that the event actually occurred. If the event is a discovered condition for which the occurrence date is not known, the event date should be specified as the discovery date. However, a discussion of the best estimate of the event date and its basis should be provided in the narrative. For example, if a design deficiency was identified on March 27, 1997, that involved a component installed during refueling in the spring of 1986, and only the discovery date is known with certainty, the event date should be specified as the discovery date. A discussion should be provided that describes, based on the best information available, the most likely time that the design flaw was introduced into the component (e.g., by the manufacturer or by plant engineering prior to procurement). The length of time that the component was in service should also be provided (i.e., when it was installed).

Discuss both the discovery date and the event date if they differ. If an LER is not submitted within 60 days from the event date, explain the relationship between the event date, discovery date, and report date in the narrative. See Section 2.5 for further discussion of discovery date.

Give dates and approximate times for all major occurrences discussed in the LER (e.g., discoveries; immediate corrective actions; systems, components, or trains declared inoperable or operable; reactor trip; actuation and termination of equipment operation; and stable conditions achieved). In particular, for standby pumps and emergency generators, indicate the length of time of operation and any intermittent periods of shutdown or inoperability during the event. Include an estimate of the time and date of failure of systems, components, or trains if different from the time and date of discovery. A chronology may be used to clarify the timing of personnel and equipment actions.

For equipment that was inoperable at the start of the event, provide an estimate of the time the equipment became inoperable and the last time the equipment was demonstrated to be capable of performing its safety function. The licensee should provide the basis for this conclusion (e.g., a test was successfully run or the equipment was operating). For equipment that failed, provide the failure time and the last time the equipment was demonstrated to be capable of performing its safety function. The licensee should provide the basis for this conclusion (e.g., a test was performed or the equipment was operating).

Components such as valves and snubbers may be tested over a period of several weeks.

During this period, a number of inoperable similar components may be discovered.[2] In such cases, similar failures that are reportable and that are discovered during a single test program within the 60 days of discovery of the first failure may be reported as one LER. For similar failures that are reportable under 10 CFR 50.73 criteria and that are discovered during a single test program or activity, report all failures that occurred within the first 60 days of discovery of the first failure on one LER. However, the 60-day clock starts when the first reportable event is discovered. State in the LER text (and code the information in Items 14 and 15) that a supplement to the LER will be submitted when the test is completed. Submit a revision to the original LER when the test is completed. Include all of the failures, including those reported in the original LER, in the revised LER (i.e., the revised LER should stand alone).

(2) Failures and Errors
§ 50.73(b)(2)(ii)(D)

The narrative description must include the following: “The cause of each component or system failure or personnel error, if known.” Include the root cause(s) identified for each component or system failure (or fault) or personnel error. Contributing factors may be discussed as appropriate. For example, a valve stem breaking could have been caused by a limit switch that had been improperly adjusted during maintenance; in this case, the root cause might be determined to be personnel error and additional discussion could focus on the limit switch adjustment. If the personnel error is determined to have been caused by deficient procedures or inadequate personnel training, this should be explained.

If the cause of a failure cannot be readily determined and the investigation is continuing, the licensee should indicate what additional investigation is planned. A supplemental LER should be submitted following the additional investigation if substantial information is identified that would significantly change a reader’s perception of the course or consequences of the event, or if there are substantial changes in the corrective actions planned by the licensee.

§ 50.73(b)(2)(ii)(E)

The narrative description must include the following: “The failure mode, mechanism, and effect of each failed component, if known.” Include the failure mode, mechanism (immediate cause), and effect of each failed component in the narrative. The effect of the failure on safety systems and functions should be fully described. Identify the specific part that failed and the specific trains and systems rendered inoperable or degraded. Identify all dependent systems rendered inoperable or degraded.

Indicate whether redundant trains were operable and available.

If the equipment is degraded but not failed, the licensee should describe the degradation and its effects and indicate the basis for the conclusion that the equipment would still perform its intended function.

§ 50.73(b)(2)(ii)(F)

The narrative description must include the following: “The Energy Industry Identification System component function identifier and system name of each component or system referred to in the LER.

(1) The Energy Industry Identification System is defined in: IEEE Std 803-1983 (May 16, 1983) Recommended Practice for Unique Identification in Power Plants and Related Facilities--Principles and Definitions.
(2) IEEE Std 803-1983 has been approved for incorporation by reference by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
(3) A notice of any changes made to the material incorporated by reference will be published in the Federal Register. Copies may be obtained from the Institute of Electrical and Electronics Engineers, 445 Hoes Lane, P.O. Box 1331, Piscataway, NJ 08855-1331. IEEE Std 803-1983 is available for inspection at the NRC's Technical Library, which is located in the Two White Flint North Building, 11545 Rockville Pike, Rockville, Maryland 20852-2738; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to:

The system name may be either the full name (e.g., “reactor coolant system”) or the two-letter system code (such as “AB” for the RCS). However, when the name is long (e.g., low-pressure coolant injection system), the system code (e.g., BO) should be used. If the full names are used, the Energy Industry Identification System (EIIS) component function identifier and/or system identifier (i.e., the two-letter code) should be included in parentheses following the first reference to a component or system in the narrative. The component function identifiers and system identifiers need not be repeated with each subsequent reference to the same component or system.

If a component within the scope of the Equipment Performance and Information Exchange (EPIX) System is involved, the system and train designation should be consistent with the EIIS used in EPIX.

§ 50.73(b)(2)(ii)(G)

The narrative description must include the following specific information as appropriate for the particular event: “For failures of components with multiple functions, include a list of systems or secondary functions that were also affected.”

No further explanation is necessary.

§ 50.73(b)(2)(ii)(H)

The narrative description must include the following: “For failure that rendered a train of a safety system inoperable, an estimate of the elapsed time from the discovery of the failure until the train was returned to service.” No further explanation is necessary.

§ 50.73(b)(2)(ii)(I)

The narrative description must include the following: “The method of discovery of each component or system failure or procedural error.” Explain how each component failure, system failure, personnel error, or procedural deficiency was discovered. Examples include reviewing surveillance procedures or the results of surveillance tests, prestartup valve lineup check, performing quarterly maintenance, plant walkdown, and so forth.

§ 50.73(b)(2)(ii)(J)

The narrative description must include the following: “For each human performance related root cause, the licensee shall discuss the cause(s) and circumstances.”

Generally, the criteria of 10 CFR 50.73(b)(2)(i) require a clear, specific narrative so that knowledgeable readers can understand the complete event. Further, for each human performance-related root cause, the criterion of 10 CFR 50.73(b)(2)(ii)(J) requires a description of the cause(s) and circumstances. In order to support an understanding of human performance issues related to the event, the narrative should address the factors discussed below to the extent they apply.

(1) the cause(s), including any relation to the following areas:

(a) procedures, where errors may be due to missing procedures, procedures that are inadequate due to technical or human factors deficiencies, or that have not been maintained current
(b) training, where errors may be the result of a failure to provide training, having provided inadequate training, or as the result of training (such as simulator training or on-the-job training) that does not provide an environment comparable to that in the plant
(c) communications, where errors may be due to inadequate, untimely, misunderstood, or missing communication or be due to the quality of the communication equipment
(d) human-system interface, such as the size, shape, location, function, or content of displays, controls, equipment, or labels, as well as environmental issues such as lighting, temperature, noise, radiation, and work area layout
(e) supervision and oversight, where errors may be the result of inadequate command and control, work control, corrective actions, self-evaluation, staffing, task allocation, overtime, or schedule design
(f) fitness for duty, where errors may be due to the influence of any substance legal or illegal, or mental or physical impairment; e.g., mental stress, fatigue, or illness
(g) work practices such as briefings, logs, work packages, teamwork, decisionmaking, housekeeping, verification, awareness, or attention

(2) the circumstances, including the following:

(a) the personnel involved, whether they are contractor or utility personnel, whether or not they are licensed, and the department for which they work
(b) the work activity being performed and whether or not there were any time or situational pressures present
§ 50.73(b)(2)(ii)(L)

The narrative description must include the following: “The manufacturer and model number (or other identification) of each component that failed during the event.”

The manufacturer and model number (or other identification, such as type, size, or manufacture date) also should be given for each component found failed during the course of the event. An example of other identification could be (for a pipe rupture) size, schedule, or material composition.

(3) Safety System Responses
§ 50.73(b)(2)(ii)(K)

The narrative description must include the following: “Automatically and manually initiated safety system responses.”

The LER should include a discussion of each specific system that actuated or failed to actuate.

Do not limit the discussion to engineered safety features. Indicate whether or not the equipment operated successfully. For some systems, such as HPCI, RCIC, RHR, and AFW, the type of actuation may not be obvious. In those cases, indicate the specific equipment that actuated or should have actuated, by train, compatible with EPIX train definitions (e.g., AFW train B).

Indicate the mode of operation, such as injecting into the reactor vessel, recirculation, pressure control, and any subsequent mode of operation during the event.

5.2.3 Assessment of Safety Consequences

§ 50.73(b)(3)

The LER shall contain the following: “An assessment of the safety consequences and implications of the event. This assessment must include:

(i) The availability of systems or components that could have performed the same function as the components and systems that failed during the event, and
(ii) For events that occurred when the reactor was shutdown, the availability of systems or components that are needed to shutdown the reactor and maintain safe shutdown conditions, remove residual heat, control the release of radioactive material, or mitigate the consequences of an accident.”

Give a summary assessment of the actual and potential safety consequences and implications of the event, including the basis for submitting the report. Evaluate the event to the extent necessary to fully assess the safety consequences and safety margins associated with the event.

Include an assessment of the event under alternative conditions if the incident would have been more severe (e.g., the plant would have been in a condition not analyzed in its latest FSAR) under reasonable and credible alternative conditions, such as a different operating mode. For example, if an event occurred while the plant was at low power and the same event could have occurred at full power, which would have resulted in considerably more serious consequences, this alternative condition should be assessed and the consequences reported.

Reasonable and credible alternative conditions may include normal plant operating conditions, potential accident conditions, or additional component failures, depending on the event. Normal alternative operating conditions and off-normal conditions expected to occur during the life of the plant should be considered. The intent of this section is to obtain the result of the considerations that are typical in the conduct of routine operations, such as event reviews, not to require extraordinary studies.

For events that occurred when the reactor was shut down, discuss the availability of systems or components that are needed to shut down the reactor and maintain safe shutdown conditions, remove residual heat, control the release of radioactive material, or mitigate the consequences of an accident.

5.2.4 Corrective Actions

§ 50.73(b)(4)

The LER shall contain the following: “A description of any corrective actions planned as a result of the event, including those to reduce the probability of similar events occurring in the future.

Include whether the corrective action was or is planned to be implemented. Discuss repair or replacement actions as well as actions that will reduce the probability of a similar event occurring in the future. For example: “the pump was repaired and a discussion of the event was included in the training lectures.” Another example: “although no modification to the instrument was deemed necessary, a caution note was placed in the calibration procedure for the instrument before the step in which the event was initiated.”

In addition to a description of any corrective actions planned as a result of the event, describe corrective actions on similar or related components that were done, or are planned, as a direct result of the event. For example, if pump 1 failed during an event and required corrective maintenance and that same maintenance also was done on pump 2, so state.

If a study was conducted, and results are not available within the 60-day period, report the results of the study in a revised LER if they result in substantial changes in the corrective action planned. (See Section 5.1.5 for further discussion of submitting revised LERs.)

5.2.5 Previous Occurrences

§ 50.73(b)(5)

The LER shall contain the following: “Reference to any previous similar events at the same plant that are known to the licensee.” The term “previous occurrences” should include previous events or conditions that involved the same underlying concern or reason as this event, such as the same root cause, failure, or sequence of events. For infrequent events such as fires, a rather broad interpretation should be used (e.g., all fires and, certainly, all fires in the same building should be considered previous occurrences). For more frequent events, such as engineered safety feature actuations, a narrower definition may be used (e.g., only those scrams with the same root cause). The intent of the rule is to identify generic or recurring problems.

The licensee should use engineering judgment to decide how far back in time to go to present a reasonably complete picture of the current problem. The intent is to be able to see a pattern in recurring events, rather than to get a complete 10- or 20-year history of the system. If the event was a high-frequency type of event, 2 years back may be more than sufficient.

Include the LER number(s), if any, of previous similar events. Previous similar events are not necessarily limited to events reported in LERs. If no previous similar events are known, so state. If any earlier events, in retrospect, were significant in relation to the subject event, discuss why prior corrective action did not prevent recurrence.

5.2.6 Abstract (NRC Form 366, Item 16)

§ 50.73(b)(1)

The LER shall contain the following: “A brief abstract describing the major occurrences during the event, including all component or system failures that contributed to the event and significant corrective action taken or planned to prevent recurrence.”

Provide a brief abstract describing the major occurrences during the event, including all actual component or system failures that contributed to the event, all relevant operator errors or violations of procedures, the root cause(s) of the major occurrence(s), and the corrective action taken or planned for each root cause. If space does not permit describing failures, at least indicate whether or not failures occurred. Limit the abstract to 1,400 characters (including spaces), which is approximately 15 lines of single-spaced typewritten text. Do not use EIIS component function identifiers or the two-letter codes for system names in the abstract.

The abstract is typically included in the LER database to give users a brief description of the event to identify events of interest. Therefore, if space permits, provide the numbers of other LERs that reference similar events in the abstract.

As noted in Section 5.1.8, do not include safeguards, security, or proprietary information in the abstract.

5.2.7 Other Fields on the LER Form

(1) Facility Name (NRC Form 366, Item 1)

Enter the name of the facility (e.g., Indian Point, Unit 1) at which the event occurred. If the event involved more than one unit at a station, enter the name of the nuclear facility with the lowest nuclear unit number (e.g., Three Mile Island, Unit 1).

(2) Docket Number (NRC Form 366, Item 2)

Enter the docket number (in 8-digit format) assigned to the unit. For example, the docket number for Yankee-Rowe is 05000029. Note the use of zeros in this example.

(3) Page Number (NRC Form 366, Item 3)

Enter the total number of pages included (including figures and tables that are attached to Item 17 text) in the LER package. For continuation sheets, number the pages consecutively beginning with page 2. The LER form, including the abstract and other data, is prenumbered on the form as page 1 of _.

(4) Title (NRC Form 366, Item 4)

The title should include a concise description of the principal problem or issue associated with the event, the root cause, the result (why the event was required to be reported), and the link between them, if possible. It is often easier to form the title after writing the assessment of the event because the information is clearly at hand.

“Licensee Event Report” should not be used as a title. The title “Reactor Trip” is considered inadequate, because the root cause and the link between the root cause and the result are missing. The title “Personnel Error Causes Reactor Trip” is considered inadequate because of the innumerable ways in which a person could cause a reactor trip. “Technician Inadvertently Injected Signal Resulting in a Reactor Trip” would be a better title.

(5) Event Date (NRC Form 366, Item 5)

Enter the date on which the event occurred in the eight spaces provided. There are two spaces for the month, two for the day, and four for the year, in that order. Use leading zeros in the first and third spaces when appropriate. For example, June 1, 1987, would be properly entered as 06011987.

If the date on which the event occurred cannot be clearly defined, use the discovery date. See Section 2.5 of this report for further discussion of discovery date.

(6) Report Number (NRC Form 366, Item 6)

The LER number consists of three parts: (1) the four digits of the event year (based on event date), (2) the sequential report number, and (3) a revision number. The numbering system is shown in the diagram below; the event occurred in the year 1991, it was the 45th event of that year, and the submittal was the first revision to the original LER for that event.

Event Sequential Revision Year Report Number Number 1991 - 045 - 01 Event Year: Enter the four digits. The event year should be based on the event date (Item 4).

Sequential Report Number: As each reportable event is reported for a unit during the year, it is assigned a sequential number. For example, for the 15th and 33rd events to be reported in a given year at a given unit, enter 015 and 033, respectively, in the spaces provided. Follow the guidelines below to ensure consistency in the sequential numbering of reports.

  • Each unit should have its own set of sequential report numbers. Units at multiunit sites should not share a set of sequential report numbers.
  • The sequential number should begin with 001 for the first event that occurred in each calendar year, using leading zeros for sequential numbers less than 100.
  • For an event common to all units of a multiunit site, assign the sequential number to the lowest numbered nuclear unit.
  • If a sequential number was assigned to an event, and it was subsequently determined that the event was not reportable, a “hole” in the series of LER numbers would result.

The NRC would prefer that licensees reuse a sequential number rather than leave holes in the sequence. A sequential LER number may be reused even if the event date was later than subsequent reports.

If the licensee chooses not to reuse the number, write a brief letter to the NRC noting that “LER number xxx for docket 005000XXX will not be used.” Revision Number: The revision number of the original LER submitted is 00. The revision number for the first revision submitted should be 01. Subsequent revisions should be numbered sequentially (i.e., 02, 03, 04).

(7) Report Date (NRC Form 366, Item 7)

Enter the date the LER is submitted to the NRC in the eight spaces provided, as described in Section 5.2.7(5) above.

(8) Other Facilities (NRC Form 366, Item 8)

When a situation is discovered at one unit of a facility that applies to more than the one unit, submit a single LER. LER form Items 1, 2, 6, 9, and 10 should refer to the unit primarily affected or, if both units were affected approximately equally, to the lowest numbered nuclear unit.

The intent of the requirement is to name the facility in which the primary event occurred, whether or not that facility is the lowest numbered of the facilities involved. The automatic use of the lowest number should only apply to cases where both units are affected approximately equally. Item 8 only should indicate the other unit(s) affected. The abstract and the text should describe how the event affected all units.

Enter the facility name and unit number and docket number (see Sections 5.2.7(1) and 5.2.7(2) for format) of any other units at that site that were directly affected by the event (e.g., the event included shared components, the LER described a tornado that threatened both units of a twounit plant).

(9) Operating Mode (NRC Form 366, Item 9)

Enter the operating mode of the unit at the time of the event as defined in the plant’s TS in the single space provided. For plants that have operating modes such as hot shutdown, cold shutdown, and operating but do not have numerical operating modes (e.g., Mode 5), place the letter “N” in Item 9 and describe the operating mode in the text.

(10) Power Level (NRC Form 366, Item 10)

Enter the percent of licensed thermal power at which the reactor was operating when the event occurred. For shutdown conditions, enter 000. For all other operating conditions, enter the correct numerical value (estimate power level if it is not known precisely), using leading zeros as appropriate (e.g., 009 for 9-percent power). Significant deviations in the operating power in the balance of plant should be clarified in the text.

(11) Reporting Requirements (NRC Form 366, Item 11)

Check one or more blocks according to the reporting requirements that apply to the event. A single event can meet more than one reporting criterion. For example, if, as a result of sabotage, reportable under 10 CFR 73.71(b), a safety system failed to function, reportable under 10 CFR 50.73(a)(2)(v), and the net result was a release of radioactive material in a restricted area that exceeded the applicable license limit, reportable under 10 CFR 20.2203(a)(3)(i), prepare a single LER and check the three boxes for 10 CFR 73.71(b), 50.73(a)(2)(v), and 20.2203(a)(3)(i).

In addition, an event can be reportable as an LER even if it does not meet any of the criteria of 10 CFR 50.73. For example, a case of attempted sabotage (10 CFR 73.71(b)) that does not result in any consequences that meet the criteria in 10 CFR 50.73 can be reported using the “Other” block. Use the “Other” block if a reporting requirement other than those specified in Item 11 was met. Specifically describe this other reporting requirement in the space provided below the “Other” block and in the abstract and text.

(12) Licensee Contact (NRC Form 366, Item 12)
§ 50.73(b)(6)

The LER shall contain the following: “The name and telephone number of a person within the licensee’s organization who is knowledgeable about the event and can provide additional information concerning the event and the plant's characteristics.” Enter the name, position title, and work telephone number (including area code) of a person who can provide additional information and clarification for the event described in the LER.

(13) Component Failures (NRC Form 366, Item 13)

Enter the appropriate data for each component failure described in the event. A failure is defined as the termination of the ability of a component to perform its required function. Unannounced failures are not detected until the next test; announced failures are detected by any number of methods at the instant of occurrence.

If multiple components of the same type failed and all of the information required in Item 13 (i.e., cause, system, component, and so forth) was the same for each component, then only a single entry is required in Item 13. Clearly define the number of components that failed in the abstract and text.

The component information elements of this item are discussed below.

Cause: Enter the cause code as shown below. If more than one cause code is applicable, enter the cause code that most closely describes the root cause of the failure.

Code Classification and Definition
A - Personnel Error
is assigned to failures attributed to human errors. Classify errors made because written procedures were not followed or because personnel did not perform in accordance with accepted or approved practice as personnel errors. Do not include errors made as a result of following incorrect written procedures in this classification.
B - Design, Manufacturing, Construction/Installation
is assigned to failures reasonably attributed to the design, manufacture, construction, or installation of a system, component, or structure. For example, include failures that were traced to defective materials or components otherwise unable to meet the specified functional requirements or performance specifications in this classification.
C - External Cause
is assigned to failures attributed to natural phenomena. A typical example would be a failure resulting from a lightning strike, tornado, or flood. Also assign this classification to manmade external causes that originate off site (e.g., an industrial accident at a nearby industrial facility).
D - Defective Procedure is assigned to failures caused by inadequate or incomplete written procedures or instructions.
E - Management/Quality Assurance Deficiency
is assigned to failures caused by inadequate management oversight or management systems (e.g., major breakdowns in the licensee’s administrative controls, preventive maintenance program, surveillance program, or quality assurance controls; inadequate root cause determination; inadequate corrective action).
X Other
is assigned to failures for which the proximate cause cannot be identified or which cannot be assigned to one of the other classifications.
Enter the two-letter system code from Institute of Electrical and Electronics Engineers (IEEE) Standard 805-1984, “IEEE Recommended Practice for System Identification in Nuclear Power Plants and Related Facilities,” dated March 27, 1984. Copies may be obtained from the Institute of Electrical and Electronics Engineers, 445 Hoes Lane, P.O. Box 1331, Piscataway, NJ 08855-1331.
Enter the applicable component code from |IEEE Standard 803A-1983, “IEEE Recommended Practice for Unique Identification in Power Plants and Related Facilities—Component Function Identifiers.”]]
Component Manufacturer
Enter the four-character alphanumeric reference code. If the manufacturer is one used in EPIX, use the manufacturer’s name as it appears in EPIX.
Reportable to EPIX
Enter a “Y” if the failure is reportable to EPIX and an “N” if it is not reportable.

Include in the LER text and in Item 13 of the LER form any component failure involved in the event, not just components within the scope of EPIX or EIIS.

Failure Continuation Sheet (NRC Form 366B): If more than four failures need to be coded, use one or more of the failure continuation sheets (NRC Form 366B). Code the entries in Items 1, 2, 3, and 6 of the failure continuation sheet to match entries of these items on the initial page of the LER. Complete Item 13 in the same manner as Item 13 on the basic LER form. Do not repeat failures coded on the basic LER form on the failure continuation sheet. Place any failure continuation sheets after any text continuation sheets and include those sheets in the total number of pages for the LER.

(14) Supplemental Report (NRC Form 366, Item 14)

Check the “Yes” block if the licensee plans to submit a followup report. For example, if a failed component had been returned to the manufacturer for additional testing and the results of the test were not yet available when the LER was submitted, a followup report would be submitted.

(15) Expected Submission Date of Supplemental Report (NRC Form 366, Item 15)

Enter the expected date of submission of the supplemental LER, if applicable. See Section 5.2.7(5) for the proper date format. The expected submission date is a target/planning date; it is not a regulatory commitment.

(16) LER Text Continuation Sheet (NRC Form 366A)

Use one or more additional text continuation sheets of LER Form 366A to continue the narrative, if necessary. There is no limit on the number of continuation sheets that may be included.

Drawings, figures, tables, photographs, and other aids may be included with the narrative to help readers understand the event. If possible, provide the aids on the LER form (i.e., NRC Form 366A). In addition, care should be taken to ensure that drawings and photographs are of sufficient quality to permit legible reproduction and micrographic processing. Avoid oversized drawings (i.e., larger than 8.5 by 11 inches).

5.2.8 Obtaining LER Forms

The latest NRC forms may be found at the NRC public Web site at

External Links

  1. As indicated in the Statement of Considerations for 10 CFR 50.9, “A licensee cannot evade the rule by never 'finding' information to be significant. The fact that a licensee considers information to be significant can be established, for example, by the actions taken by the licensee to evaluate that information” (59 FR 49362;December 31, 1987).
  2. 16 Note that inoperable similar components might indicate common cause failures of independent trains or channels, which are reportable under 10 CFR 50.73(a)(2)(vii); see Section 3.2.8 for further discussion.