10 CFR 50.73(b)

10 CFR 50.73(b) are the LER content rules.

See also

• CFR base page: 10 CFR 50.73, Licensee Event Report System
• Licensee Event Report (LER)
• LER form: NRC Form 366, Licensee Event Report
• NRC guidance: NUREG-1022

10 CFR 50.73(b), Contents

(b) Contents. The Licensee Event Report shall contain:

(1) 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.

(2)(i) 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.

(ii) The narrative description must include the following specific information as appropriate for the particular event:

(A) Plant operating conditions before the event.

(B) Status of structures, components, or systems that were inoperable at the start of the event and that contributed to the event.

(C) Dates and approximate times of occurrences.

(D) The cause of each component or system failure or personnel error, if known.

(E) The failure mode, mechanism, and effect of each failed component, if known.

(F) 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: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

(G) For failures of components with multiple functions, include a list of systems or secondary functions that were also affected.

(H) 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.

(I) The method of discovery of each component or system failure or procedural error.

(J) For each human performance related root cause, the licensee shall discuss the cause(s) and circumstances.

(K) Automatically and manually initiated safety system responses.

(L) The manufacturer and model number (or other identification) of each component that failed during the event.

(3) 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.

(4) 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.

(5) Reference to any previous similar events at the same plant that are known to the licensee.

(6) 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.

NUREG-1022 Section 5 excerpts

§ 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. 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).

§ 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: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

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.

§ 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.

§ 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.

§ 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.)

§ 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.

§ 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.

§ 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.