**NRC INSPECTION MANUAL**	IRIB

INSPECTION MANUAL CHAPTER 0309

# REACTIVE INSPECTION DECISION BASIS FOR POWER REACTORS

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Issue Date: 	2	0309

Table of Contents0309-01	PURPOSE	10309-02	BACKGROUND	10309-03	RESPONSIBILITIES	1Figure 1: Flow Chart for AIT or IIT Decision-Making	30309-04	REQUIREMENTS	304.01	Initial Event Notification and Follow-up	304.02	Risk Significance	404.03	Risk Measures and Quantitative Criteria for Reactive Inspections	4Table 1: Reactor Safety Deterministic Screening Criteria for Risk Assessment	5Table 2: Event Response as a Function of CCDP	6Table 3: Event Response as a Function of CLERP	604.04	Deterministic Factors for Reactive Inspections	7Table 4: Reactor Safety Deterministic Criteria	8Table 5: Radiation Safety Deterministic Criteria	8Table 6: Security Deterministic Criteria	1104.05	Recommendation and Decision	1204.06	Documentation	1204.07	Inspection Charter	1304.08	Communications	1404.09	Allegations	140309-05	REFERENCES	14Exhibit 1: Additional Guidance and Examples	Ex1-1Enclosure 1: Decision Documentation for Reactive Inspection (Deterministic and Risk Criteria Analyzed)	Encl1-1Enclosure 2: Decision Documentation for Reactive Inspection and Examples (Deterministic-only Criteria Analyzed)	Encl2-1Attachment 1: Revision History for IMC 0309	Att1-1

Issue Date: 	i	0309

Issue Date: 12/14/23	2	0309

# 0309-01	PURPOSE

01.01	To provide amplifying direction and guidance to the Office of Nuclear Reactor Regulation (NRR) and the regional staff for implementing the requirements prescribed in Management Directive (MD) 8.3, “NRC Incident Investigation Program.”

01.02	To provide a detailed list of deterministic criteria that can be used on their own or in conjunction with a probabilistic risk assessment as a decision basis for implementing Incident Investigation Teams (IITs), Augmented Inspection Teams (AITs), and Special Inspections (SIs).

01.03	To provide guidance on the use of risk metrics and probabilistic risk assessment to inform the need for a reactive inspection.

01.04	To discuss the availability of various tools to communicate with internal and external stakeholders on event response and assessment.

01.05	To provide a sample format to use when documenting reactive inspection decisions.

# 0309-02	BACKGROUND

It is the policy of the U.S. Nuclear Regulatory Commission (NRC) to ensure that significant events involving reactor and materials facilities licensed by the NRC are investigated in a timely, objective, systematic, and technically sound manner; that the information pertaining to each event is documented; and that the cause or causes of each event are ascertained. MD 8.3 is the agency-level governing document for this Inspection Manual Chapter (IMC). MD 8.3 includes deterministic and risk criteria for determining the agency’s appropriate event response and delineates office-level responsibilities for significant event responses. A significant event is any radiological, safeguards, or other safety-related event at an NRC-licensed facility that poses an actual or significant potential hazard to public health and safety, property, or the environment. This IMC also refers to a significant event as an “event” or “incident.” Significant events include initiating events (e.g., complicated reactor trips) and significant degraded conditions. This IMC provides specific roles and responsibilities for the staff involved in the event response process as well as guidance for developing cooperative staff-level relationships among the participating offices. Inspection Procedure (IP) 71153, “Follow Up of Events and Notices of Enforcement Discretion,” is used to gather the information needed to evaluate events and to assess their significance. This information and the directions in this IMC are then used to make reactive inspection decisions. IP 93812, “Special Inspection,” and 93800, “Augmented Inspection Team,” provide implementing directions for reactive inspection responses. NUREG-1303, “Incident Investigation Manual,” details the procedures involved in conducting an IIT.

# 0309-03	RESPONSIBILITIES

03.01	Operating Experience Branch (IOEB)

IOEB is responsible for the initial NRR follow-up of significant events at power reactors and is the initial NRR point of contact to coordinate event evaluation. IOEB works with the regional offices and inspectors to develop event details. IOEB contacts appropriate technical branches and the project manager (PM) for support to address relevant technical and regulatory issues, including safety significance determinations. If an event or condition warrants headquarters involvement in the reactive inspection decision, IOEB participates in the decision-making process (see section 04.05).

03.02	Probabilistic Risk Assessment Operational Support and Maintenance Branch (APOB)

At the request of IOEB or the regional office, APOB evaluates the risk associated with significant events at power reactors. The APOB risk analyst should seek a consensus with the regional Senior Risk Analysts (SRAs) on the event’s risk significance so that regional and headquarters managers receive consistent risk insights. Differences between headquarters and regional risk assessments, that could affect the response decision, should be explained to the decision makers. APOB provides the risk input to NRR management through IOEB. If an event or condition warrants headquarters involvement in the reactive inspection decision, APOB participates in the decision-making process (see section 04.05).

03.03	Other Technical Branches/NRR

At the request of IOEB, the Division of Operating Reactor Licensing (DORL), or the regional offices, NRR technical branches provide technical support for resolving issues identified during follow-up of significant events.

03.04	Division of Operating Reactor Licensing (DORL)

The DORL PM keeps abreast of significant events at assigned power reactor plant(s) and provides logistical support for regional offices and other NRR staff during the short-term event response. The PM promptly alerts IOEB to potentially significant events. If an event or condition warrants consideration of an AIT or IIT, the PM provides logistical support by setting up a conference between headquarters and the regional office (see section 04.05).

03.05	Regional Staff

The regional staff formulates recommendations to their respective Regional Administrator (RA) regarding appropriate event response and places a completed MD 8.3 determination in the Agencywide Documents Access and Management System (ADAMS) once a decision is finalized. If an event or condition warrants consideration of an AIT or IIT, staff will participate in the decision-making process (see section 04.05). When the decision is made to launch a reactive inspection, the staff will develop an inspection charter and place it in ADAMS.

03.06	Division of Preparedness and Response/Incident Response Directorate (DPR/IRD)

DPR/IRD is part of the Office of Nuclear Security and Incident Response (NSIR). If an event or condition warrants consideration of an AIT or IIT, IRD will participate in the decision-making process (see section 04.05).

The flow of communication among the participating staff organizations and the decisionmaking points is depicted in figure 1.

Figure 1: Flow Chart for AIT or IIT Decision-Making

# 0309-04	REQUIREMENTS

## 04.01	Initial Event Notification and Follow-up

When NRR is notified of a potentially significant event, or an event with potential generic implications, IOEB will coordinate initial NRR event follow-up activities, working with the regional office to understand the significance and generic implications of the event. The DORL PM is kept informed of the event information and provides logistical support for further appropriate NRR event follow-up activities. IOEB requests assistance from NRR technical staff as needed. Regional staff may request technical support from NRR by contacting IOEB.

## 04.02	Risk Significance

Power reactor events are evaluated for risk significance when one or more of the deterministic criteria listed in table 1 are met. In NRR, APOB in coordination with the responsible regional office promptly evaluates the risk of events or degraded conditions when the risk estimate conducted by the regional SRA is ≥1E5 conditional core damage probability (CCDP) or ≥1E6 conditional large early release probability (CLERP), or when requested by the regional staff. In such cases, all currently available event or degradedconditionrelated risk information will be promptly provided to APOB for risk evaluation. APOB communicates with its regional counterparts (e.g., the regional SRAs) and IOEB to share pertinent risk information to reach a consensus on the risk significance of the event or degraded condition. The regional SRAs inform regional management of the risk significance, and APOB provides the NRR risk input and uncertainty estimates to NRR management, typically through IOEB. Additionally, the Office of Nuclear Regulatory Research can provide risk analysis support upon request.

## 04.03	Risk Measures and Quantitative Criteria for Reactive Inspections

a. Deterministic Screening. The purpose of this deterministic screening is to eliminate the need to perform a detailed risk assessment for events that are low risk and well understood. Appropriately managed plant configurations due solely to planned maintenance under applicable rules and regulations (e.g., Title 10 of the *Code of Federal Regulations* (10 CFR) 50.65(a)(4); 10 CFR 50.59, “Changes, tests, and experiments”; and technical specifications) need not be considered.

Table 1: Reactor Safety Deterministic Screening Criteria for Risk Assessment

b. Risk Assessment. Evaluate the risk of significant events or conditions at power reactors meeting any of the deterministic screening criteria in table 1, as follows: CCDP best reflects loss of defense in depth due to the event, regardless of whether the cause is deficient licensee performance. CCDP accounts for actual plant configuration, including equipment unavailable because of maintenance and testing. IMC 0609, “Significance Determination Process,” addresses CCDP determination. Although CCDP represents a fundamentally different concept for events than for degraded conditions that do not initiate an event, the same guidelines may be applied to both in order to assist management in its riskinformed decision-making.

The lack of complete event information at the time of the NRC response decision focuses attention on the uncertainty of influential assumptions and their effect on the risk significance. IP 71153 discusses inspector inputs to risk analyses that are needed to understand the risk significance. In determining risk significance of an event, NRC should assess the potential influence on risk of the following:

dominant core damage sequence(s)

level of confidence in failure/unavailability values assumed for the sequence(s)

influence on the CCDP estimate of contributing factors where the confidence level is low

Table 2 provides recommended event response thresholds as a function of CCDP. The overlap of options relative to CCDP levels provides the opportunity to select different inspection or investigation options on the basis of such factors as uncertainty of the risk estimate coupled with the deterministic insights. Risk insights should also be used in considering the number of inspectors, their expertise, and the areas of focus.

Table 2: Event Response as a Function of CCDP

In addition to core damage risk, NRC should assess whether degraded conditions could increase the likelihood of a large early release resulting from containment failure or containment bypass. For events or degraded conditions associated with containment performance or bypass, the risk of a large early release (e.g., the CLERP) is evaluated, if practical, in addition to CCDP. Table 3 lists appropriate reactive inspection thresholds as a function of CLERP.

Table 3: Event Response as a Function of CLERP

If the risk assessment is ≥1E-5 CCDP or ≥1E-6 CLERP, regional management will promptly contact NRR (IOEB), as coordination with headquarters will be necessary (see figure 1 and section 04.05).

In some cases, the adequacy of risk assessment models, assumptions, and uncertainties may make it difficult to numerically quantify risk. In such cases, recommendations should rely on the deterministic criteria and the NRC’s current understanding of the event and its causes.

## 04.04	Deterministic Factors for Reactive Inspections

In addition to the significant events at power reactors discussed in section 04.03, there are other significant events (related to reactor safety, radiation safety, or safeguards and security) that may occur at an NRC-licensed facility. The factors that cause these other types of incidents are not necessarily part of a licensee’s probabilistic risk assessment (PRA) model, and their risk significance may not be easily quantified. Therefore, the incidents must be examined using deterministic criteria, considering safety, margin, defense in depth, and additional factors when deciding on the appropriate level of reactive inspection. The NRC also considers additional factors such as openness, public interest, and public safety as appropriate when deciding whether to dispatch an IIT, AIT, or SI. These additional deterministic criteria are listed in section 04.05 (and in Enclosure 2). Tables 4, 5, and 6 list these additional deterministic criteria. They are organized by incident type (reactor safety, radiation safety, safeguards/security) and by the reactive inspection warranted.

For these criteria, no quantitative risk assessment is required, and meeting any one of the deterministic criteria is the basis for considering an IIT, AIT, or SI (as specified) informed by consideration of safety, margin, defense in depth, and additional factors.

Table 4: Reactor Safety Deterministic Criteria

Table 5: Radiation Safety Deterministic Criteria

Table 6: Security Deterministic Criteria

## 04.05	Recommendation and Decision

If the review of the event under sections 04.03 and 04.04 yields an SI, the RA will decide whether to initiate the SI. In this case, regional management may consult with NRR and NSIR but is not required to do so.

If the review of the event under section 4.03 and 04.04 yields an AIT recommendation or falls within the SI/AIT overlap region, the regional staff shall promptly contact IOEB and provide event details. IOEB will direct the DORL PM to coordinate a conference with representatives from the regional office, DORL, APOB, IOEB, and NSIR/DPR to discuss whether an SI or AIT is more appropriate. In such cases, the RA, in consultation with the NRR Office Director and NSIR Office Director, makes the final decision on whether to proceed with an SI or AIT.

If the review of the event under section 4.03 and 04.04 yields an IIT recommendation or falls within the AIT/IIT overlap region, the Directors of NRR and NSIR will consult with the RA and provide a recommendation to the Executive Director for Operations (EDO). In such cases, the EDO, in consultation with the RA, will make the ultimate decision on whether to proceed with an AIT or IIT.

The regional office will notify the licensee of its intentions once a final decision is made to launch an SI or AIT.

## 04.06	Documentation

Enclosure 1 provides a form for regional personnel to use when documenting their decision whether to pursue a reactive inspection based on evaluation of the deterministic and risk criteria in section 04.03. Enclosure 2 provides a form for regional personnel to use when documenting their decision whether to pursue a reactive inspection based on evaluation of the deterministic criteria in section 04.04. To fully document the basis for not performing a reactive inspection, both enclosures 1 and 2 should be completed. As noted in enclosure 2, the regions may customize the form to fit regional protocols, but the deterministic criteria should not be changed. The form, along with specific instructions for its completion by regional staff, should be included in regional office instructions or implementing procedures. Basic guidelines include:

As appropriate and known, describe the event or degraded conditions, apparent system interactions, operational responses, impacts on safety and safety functions, site conditions, and modes of operation in the Brief Description of the Significant Event or Degraded Condition section. Reference any event notifications received in response to the event or degraded condition.

If none of the deterministic criteria were met, provide sufficient detail to justify the conclusion in the criteria Remarks section as appropriate. Also, state that no deterministic criteria were met in the Response Decision section of the form.

If one or more of the deterministic criteria were met, provide sufficient detail to justify the conclusion in the criteria Remarks section. When applicable under section 04.03, request an SRA perform a risk assessment and document results in the Conditional Risk Assessment section of the form.

Avoid documenting a commitment to perform additional event-related inspection when the MD 8.3 evaluation determines no additional reactive inspection is warranted.

Additional guidance for when it may be appropriate to not perform an MD 8.3 evaluation as well as examples of completed MD 8.3 evaluations are included in exhibit 1.

After documenting the agency’s reactive inspection decision, its basis, and a sufficient response for each criterion, place the documented decision in ADAMS and profile using template “NRR123: Management Directive (MD) 8.3, Reactive Inspection Evaluation” (ML18233A547) generally no more than 7 calendar days after the event or discovery of the degraded condition. Submit the document to the Document Processing Center after it is either determined that the document is sensitive or, when non-sensitive, coincident with the publication of the associated inspection report documenting related inspection. [C1]

## 04.07	Inspection Charter

The purpose of the charter is to delineate the general scope of the reactive inspection and to facilitate fact gathering and understanding. Available risk insights and apparent causal indications should be used to develop the charter’s scope. The charter may reasonably include an examination of the conditions preceding the event, event chronology, system responses, human factors, safety culture, equipment performance, quality assurance, radiological considerations, safeguards considerations, event precursors, event response, operating experience, and safety or security impacts in determining the causes of the significant event and in support of appropriate agency follow-up actions. The charter should assess immediate corrective actions and compensatory measures taken to address immediate safety or security concerns. The charter should be consistent with the risk insights and the event’s complexity.

Reactive inspections are focused on fact-gathering and a thorough independent review of events. When the inspection is complete, the inspector should consider providing feedback to headquarters on any suggested changes to prevent or reduce the frequency of the significant events or enhance oversight processes.

The charter should not attempt to assess the adequacy of any longer-term corrective actions used to improve licensee performance and prevent recurrence of significant conditions, as these followup activities are addressed using supplemental or baseline inspections. Performing these activities during a reactive inspection may delay prompt dissemination of the facts and circumstances surrounding the significant event and impose an unwarranted regulatory burden on licensees.

For SIs and AITs, the inspection charter is generally communicated as an enclosure to a memorandum from the RA to the leader, with copies provided to the NRR office director, Office of Public Affairs (OPA), Regional Public Affairs Officer, affected licensee, and NSIR office director when related to security or emergency planning. The charter may be modified during a reactive inspection in consultation with management, if the inspection develops significant new information that warrants review.

## 04.08	Communications

Communication tools that are available to enhance the effectiveness and efficiency of the agency’s communications with its stakeholders. The NRC has developed the “Event Response and Assessment Communications Plan,” which is available in the ADAMS Main Library internal folder entitled “Communication Plans.”

The communication tools available for event or degraded condition response and assessment include the following:

a communications team

central tracking of controlled correspondence

a notification sequence for significant regulatory documents

formalized questions and answers for common and expected significant events for use by the OPA during initial event response

a dedicated web page for each event

If it is determined that a communications team is warranted, DORL typically plays the key NRR role in developing and coordinating the communications team and subsequent communications activities. Specific communication activity assignments are determined by the communications team. IOEB, the Regional Offices, and other NRR branches support such DORL activities, as needed. Communication activities typically continue beyond the initial phase of investigative response until their goals have been accomplished.

Reactive inspections may generate high public interest. The RA in consultation with the OPA, may elect to open a reactive inspection exit meeting to the public. Alternately, the RA may decide it is more appropriate to have a separate public meeting, press conference, or both in lieu of a public meeting with the licensee.

## 04.09	Allegations

If, during the course of evaluating events using this procedure, the inspector(s) suspect that there might be an element of willfulness or intentional wrongdoing, they will (1) prepare and submit an allegation receipt form to the appropriate regional office with the inspector(s) as the concerned individual(s), (2) inform the appropriate regional manager(s) of the suspicion, and (3) handle the potential willfulness or intentional wrongdoing in accordance with the allegation process. This should be done regardless of whether a reactive inspection is conducted.

# 0309-05	REFERENCES

“Event Response and Assessment Communications Plan,” October 3, 2000 (ML003774969)

IMC 0609, “Significance Determination Process”

IP 71153, “Follow Up of Events and Notices of Enforcement Discretion”

IP 93800, “Augmented Inspection Team”

IP 93812, “Special Inspection”

MD 8.2, “NRC Incident Response Program”

MD 8.3, “NRC Incident Investigation Program”

NUREG-1303, “Incident Investigation Manual”

END

Issue Date: 	1	0309

Issue Date: 12/14/23	1	0309

Exhibit 1: Additional Guidance and Examples

Below is a list of events and conditions that generally would not warrant an MD 8.3 evaluation unless they are exacerbated by other issues that contributed to those events and conditions or complexities that occurred because of those events and conditions:

1. Uncomplicated reactor trips or scrams (manual or auto).

2. Scaffolding found to have potentially impacted only a single safety related system operation.

3. Safety system instrumentation found out of calibration via periodic testing or surveillance.

4. Inadvertent discharge of Freon, fire water, carbon dioxide or Halon having no adverse impact on plant operations.

5. Tritium leaks found because of scheduled testing or investigation by the licensee.

6. Loss of spent fuel cooling with little or no pool temperature rise (delta of 15oF and highest temp below 140oF).

7. Balance of plant transients that do not result in a plant trip/scram.

8. Short-term losses of shutdown cooling/decay heat removal which were readily recovered (Less than 20 percent of Margin to Time to Boil).

9. Isolated surveillance testing failures (not readily known to be repetitive, generic, or common mode in nature).

10. Loss of secondary containment (BWR).

Examples of MD 8.3 determinations [C2]:

Search ADAMS for Document Type “MD 8.3 Reactive Inspection Evaluation”

Issue Date: 12/14/23	Ex1-1	0309

Enclosure 1: Decision Documentation for Reactive Inspection(Deterministic and Risk Criteria Analyzed)

Note:	The above tables are provided as examples only. The regions have discretion to modify these tables in their implementing procedures or office instructions.

Issue Date: 12/14/23	Encl1-1	0309

Enclosure 2: Decision Documentation for Reactive Inspection and Examples(Deterministic-only Criteria Analyzed)

Note:	The above tables are provided as examples only. The regions have discretion to modify these tables in their implementing procedures or office instructions.

Issue Date: 12/14/23	Encl2-1	0309

Attachment 1: Revision History for IMC 0309

Issue Date: 12/14/23	Att1-1	0309

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