IP 71111, Reactor Safety-Initiating Events, Mitigating Systems, Barrier Integrity
10-28-2011
https://www.nrc.gov/docs/ML1115/ML111511016.pdf
text
Issue Date: 10/28/11 - 1 - 71111
NRC INSPECTION MANUAL IRIB
INSPECTION PROCEDURE 71111
REACTOR SAFETYCINITIATING EVENTS,
MITIGATING SYSTEMS, BARRIER INTEGRITY
PROGRAM APPLICABILITY: 2515
71111-01 INSPECTION OBJECTIVE
To independently gather sufficient information by performing a minimum level of
baseline inspection to determine whether licensee performance meets the following
cornerstone objectives:
01.01 Initiating Events (I). To limit the frequency of those events that upset plant
stability and challenge critical safety functions, during a shutdown as well as power
operations.
01.02 Mitigating Systems (M). To ensure the availability, reliability, and capability of
systems that mitigate initiating events to prevent reactor accidents.
01.03 Barrier Integrity (B). To ensure that physical barriers protect the public from
radionuclide releases caused by accidents.
71111-02 INSPECTION REQUIREMENTS
02.01 Plan and perform inspections in accordance with the following attachments to
this procedure:
Attachment 01: Adverse Weather Protection (I,M)
Attachment 02: (Reserved)
Attachment 03: (Reserved)
Attachment 04: Equipment Alignment (I,M,B)
Attachment 05: Fire Protection (I,M)
Attachment 06: Flood Protection Measures (I,M)
Attachment 07: Heat Sink Performance (I,M)
Attachment 08: Inservice Inspection Activities (I,M,B)
Attachment 09: (Reserved)
Attachment 10: (Reserved)
Attachment 11: Licensed Operator Requalification Program (M,B)
Attachment 12: Maintenance Effectiveness (I,M,B)
Attachment 13: Maintenance Risk Assessments and Emergent Work Control (I,M,B)
Attachment 14: (Reserved)
Attachment 15: Operability Evaluations and Functionality Assessments (M,B)
Attachment 16: (Reserved)
Attachment 17: Evaluations of Changes, Tests, or Experiments and Permanent
Plant Modifications (I,M,B)
Attachment 18: Plant Modifications (I,M,B)
Attachment 19: Post Maintenance Testing (M)
Attachment 20: Refueling and Other Outage Activities (I,M,B)
Attachment 21: Component Design Bases Inspection (M)
Attachment 22: Surveillance Testing (M,B)
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Attachment 23: (Reserved)
The above listing indicates which cornerstones apply to each inspection procedure.
Findings from these inspections must be grouped by the inspector into the cornerstone
to which they apply (see inspection guidance tables in the procedures and cornerstone
charts in IMC 2515, Appendix A, Attachment 2 for guidance). Each finding must be
aligned with only one cornerstone following application of the significance determination
process (SDP) described in IMC 0609, to avoid double counting in assessing
performance.
02.02 In using the above inspection attachments, the inspector verifies that the
licensee has entered the identified problems in its corrective action program and verifies
effectiveness of corrective actions for a selected sample of related problems.
02.03 As they occur, review significant site specific Institute of Nuclear Power
Operations (INPO) and similar independent, third party evaluation reports in accordance
with OEDO Procedure – 0220, “Coordination with the Institute of Nuclear Power
Operations (INPO)” and document the review in accordance IMC 0612, “Power Reactor
Inspection Reports.”
71111-03 INSPECTION GUIDANCE
General Guidance
Applicable Performance Indicators:
The inspections conducted under this procedure provide information on licensee
performance in areas that are not measured by the following performance indicators
(PIs): unplanned scrams, unplanned power changes, and unplanned scrams with
complications (Initiating Events); safety system functional failures and mitigating system
performance indices (Mitigating Systems); and reactor coolant system (RCS) specific
activity and RCS identified leak rate (Barrier Integrity). In fulfilling the inspection
requirements of the attachments, the inspector needs to exercise care to not spend time
inspecting activities or characteristics that are already covered by a PI, although the PI
verification procedure IP 71151,”Performance Indicator Verification” does gather such
information.
Risk-Informed Inspection Planning:
This section provides guidance on the risk-informed aspect of planning the performance
based inspections in the baseline inspection program.
In accordance with NRC Commission Policy, a Arisk-informed@ approach to regulatory
decision-making represents a philosophy whereby Arisk insights@ are considered
together with other factors to establish requirements that better focus licensee and
regulatory attention on design and operational issues commensurate with their
importance to public health and safety. This Policy defines the term Arisk insights@ as
the results and findings that come from risk assessments. It is in this context that the
terms Arisk-informed@ and Arisk insights@ are used in the following discussion of riskinformed inspection planning and in the determination of what to inspect using a riskinformed approach.
Risk-informed inspection planning (i.e. the selection of risk-informed inspection
samples) is based on the following:
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$ Extracting risk insights from a risk model;
$ Using these insights to select structures, systems, components (SSCs), and activities
for inspection; and
$ Using insights from plant-specific and industry operational experience to add SSCs
into the inspection sample.
Frequently used risk insights that are normally available for inspection planning can be
obtained from Individual Plant Examinations (IPEs). If available, it is preferable to use
an updated plant-specific Probabilistic Risk Assessment (PRA) to extract risk insights.
The types of information that are normally available from the IPEs include:
$ lists of dominant accident sequences and their contribution to core damage frequency
(CDF) and large early release frequency (LERF),
$ lists of accident initiators, components, systems, and operator actions ranked by
importance measures, such as Risk Achievement Worth (RAW), Risk Reduction
Worth (RRW), Birnbaum, Fussell-Vesely (F-V) (in some PRAs importance measures,
such as system importance are not provided because system-level cutsets may not
have been determined),
$ lists of accident sequence cutsets and system level cutsets (can be deleted unless
the inspector wants to review the PRA model in detail), and
$ lists of potential severe-accident vulnerabilities.
These PRA insights are useful in selecting SSCs, but are only a first step in a riskinformed approach to inspection. As plant configurations change from on-line
maintenance or plant modifications, the relative importance of an SSC or an accident
sequence may change. Because plant risk changes dynamically from operational
activities (e.g., surveillance testing) in combination with ongoing maintenance,
inspection planning needs to be flexible and consider changes in SSC importance for
inspection priority.
In addition to the frequently used risk insights listed above, the following items are
considered general guidance for developing and using other risk insights throughout the
inspection process.
$ Inspectors should consider the inputs to the Significance Determination Process
(SDP) throughout the inspection process, both planning and implementation. For
example, the SDP screens as very low significance (green) inspection findings that
affect only one train of mitigating system for a single initiating event. Therefore,
inspectors should consider planning inspections that target combinations of SSCs
that are related within an accident sequence and affect more than one train.
$ Inspectors should consider the SDP during plant status tours (IMC 2515, Appendix D)
to identify potential SDP candidates (i.e., single train failure during testing), and plan
inspections to determine if the SDP Phase 1 screening criteria are satisfied.
$ Inspectors are encouraged to use resources in addition to the plant-specific IPEs.
Although the IPEs are generally the most valuable resource in extracting risk insights,
they have not been reviewed or approved by the NRC, and some licensees may not
be updating their IPEs. Therefore, inspectors may need to use other resources to
evaluate certain PRA assumptions regarding system success criteria or operator
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actions/human errors. Insights from industry operational experience can be an
excellent resource for planning and focusing inspections. Because many licensees
are maintaining updated plant-specific PRAs as Aliving PRAs,@ these PRAs should be
used when available.
$ Inspectors should review the site=s ARisk-Informed Inspection Notebook@ or “Plant
Risk Information eBook” issued by the NRC for use with the SDP as appropriate.
These notebooks provide site-specific information on pertinent core damage
scenarios and sequences, systems that perform mitigating functions, and the number
of trains required for each class of initiators.
Risk-informed inspection planning is expected to vary depending on the type of
inspection being conducted. Listed below are some examples of risk-informed
inspection planning techniques with some examples in capturing risk insights.
Refueling Outage Inspection Planning Example
Refueling and shutdown activities generally are periods of high activity with less
defense-in-depth because equipment is out of service and are potentially high risk
periods. The inspection attachment for refueling and outage activities and other
inspection procedures will be used to inspect during these periods. Inspections should
be planned before the outage and the planning should include the licensee=s outage
plan, schedule, and risk assessment. The inspection planning should identify the
following:
$ Major maintenance and modification activities during the refueling outage;
$ Periods of heightened risk in the outage risk profile including mid-loop configuration,
open containment configuration, electrical equipment outages, and switchyard
activities; and
$ Mitigating system availability and operator compensatory measures, including
temporary modifications, for maintaining key plant safety functions.
Using this information, the risk-informed inspection plan can be developed to evaluate
the effectiveness of the licensee=s program practices such as post-maintenance testing
for modifications that, if improperly installed or implemented, could affect the function of
mitigating system equipment, temporary modifications used as backup electrical power
supplies, and aligning electrical power supplies during switchyard activities.
In addition to the licensee=s outage risk assessment, inspectors are encouraged to use
other resources, including shutdown risk insights from similar plants and insights from
shutdown risk studies by the NRC (e.g., NUREG-1449, “Shutdown and Low Power
Operation at Commercial Nuclear Power Plants,@ and NUREG/CR-6093, “An Analysis of
Operational Experience During Low Power and Shutdown@).
Reactor Safety Cornerstone Team Inspection Planning Example
The baseline program includes four team inspections: fire protection, component design
bases, modifications/10 CFR 50.59, and problem identification and resolution. The
procedures for each of these inspections specifically require senior reactor analyst
(SRA) involvement before the inspection. The SRA will review the licensee=s IPE or
Individual Plant Examination of External Events (IPEEE) before the inspection and
provide risk insights to the inspection team.
Resident and Region-Based Inspection Examples
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Many of the inspections must be coordinated with the licensee=s schedule or specific
plant conditions that are not considered during the annual planning meeting. In these
cases, inspections should be planned by the inspectors using the licensee=s
maintenance and surveillance schedule, risk assessments, and the IPE. Inspectors
should determine when to conduct inspections based on the plant=s work scheduling
process but should also factor changes in plant conditions (i.e., emergent work) into the
inspection plan. During plant status tours, inspectors will gather real-time plant
information that should be used to alter the inspection plans accordingly. Inspection
planning should identify the following:
$ Periods of heightened risk from on-line maintenance that affects or could affect
mitigating systems, or could potentially cause an initiating event. Particular attention
should be given to activities that have increased potential for initiating a plant event or
transient when mitigating capability is decreased, such as switchyard maintenance
activities when an emergency diesel generator (EDG) or turbine-driven AFW pump is
unavailable;
$ Planned tests, including surveillance tests, post-modification tests, and postmaintenance tests; and
$ Planned on-line installation of modifications.
Using this information, the inspection plan can be developed to implement several
inspection attachments during one maintenance activity. For example, during
maintenance of an emergency diesel generator (EDG), the following items could be
inspected:
$ Verification that planned on-line maintenance is properly performed in accordance
with maintenance rule requirements (i.e., performing required risk assessments);
$ Hours of unavailability are properly captured under the maintenance rule and
performance indicators, and those hours are consistent with assumptions of
unavailability in the IPE (consistency between the IPE assumptions and actual plant
practices is important so that risk ranking and relative importance of the SSC is
accurately represented in the IPE);
$ Proper alignment or testing of another EDG train or other mitigating system train that
is important for a loss of offsite power event; and
$ Acceptability of post-maintenance testing of the EDG after maintenance.
These types of verifications would be performed using the maintenance rule
implementation, maintenance work risk assessment and emergent work, PI verification,
post-maintenance testing, and surveillance testing inspection procedures. If during EDG
maintenance, emergent work comes up or the weather turns bad, the inspectors should
alter the inspection plan to cover these inspectable areas because combinations of
degraded conditions tend to increase risk the most.
To manage progress in completing the baseline inspection program, the senior resident
inspector and regional Division of Reactor Projects (DRP) branch chief should review
each calendar quarter the completion status of the attachments to this procedure for
their assigned inspections.
Specific Guidance
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03.01 No specific guidance.
03.02 The inspector should use the guidance in IP 71152, AProblem Identification and
Resolution,@ and IMC 2515, Appendix A, when verifying the effectiveness of corrective
actions.
03.03 IMC 0612 provides guidance on documenting the NRC review of INPO
evaluations, accreditations reports, or other third party reviews. NRC personnel should
not take possession of INPO evaluation documents, make copies for NRC internal
distribution absent extraordinary circumstances, or use these documents to form a basis
for regulatory action. Inspectors should normally review hardcopies of INPO
evaluations on licensee-owned property outside of the Resident Inspector’s Office or
electronically using the licensee’s information system to preclude taking possession of
confidential commercial information. These restrictions do not apply to INPO Event
Reports (IER) or INPO Significant Event Evaluation and Information Network (SEE-IN)
reports, which are covered in the NRC/INPO Memorandum of Agreement and are
available on the NRC’s intranet.
71111-04 REFERENCES
OEDO Procedure – 0220, “Coordination with the Institute of Nuclear Power Operations
(INPO)” (http://www.internal.nrc.gov/oedo/procedures-guidance/)
IMC 0609, “Significance Determination Process”
IMC 0612, “Power Reactor Inspection Reports”
IMC 2515, Appendix A, “Risk-Informed Baseline Inspection Program”
IMC 2515, Appendix D, “Plant Status”
IP 71151,”Performance Indicator Verification”
IP 71152, AProblem Identification and Resolution@
NUREG-1449, “Shutdown and Low Power Operation at Commercial Nuclear Power
Plants@ (http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1449/)
NUREG/CR-6093, “An Analysis of Operational Experience during Low Power and
Shutdown@ (ML072410503)
Memorandum of Agreement between the Institute of Nuclear Power Operations and the
U.S. Nuclear Regulatory Commission, Effective Date: December 6, 2010
End
Issue Date: 10/28/11 Att1-1 71111
Attachment 1 – Revision History for IP 71111
Commitment
Tracking
Number
Issue Date Description of Change Training
Needed
Training
Completion
Date
Comment
Resolution
Accession
Number
04/03/00
CN 00-003
Initial Issue
N/A 12/11/00
CN 00-024
Revised to add requirements and guidance for
reviewing major INPO reports to satisfy EDO
Field Policy Manual on the topic. Guidance was
also added about using SDP, when applicable,
to evaluate the significance of INPO findings.
No change in IP resources or effort.
NO N/A N/A
N/A 05/06/03
CN 03-015
Revised to include pilot program procedure
attachments developed to consolidate baseline
inspection procedures. This pilot program will
be implemented at two power reactor sites in
each region for a period of one year.
NO N/A N/A
N/A 05/16/08
CN 08-015
This document is being revised to reflect
changes resulting from the 2007 ROP
Realignment, update the list of performance
indicators, and remove reference to a pilot
program that was conducted in 2003.
Completed 4 year historical CN search.
NO N/A N/A
N/A 10/28/11
CN 11-025
Added a reference to OEDO-0220 which
contains additional guidance and direction for
the review of INPO reports. Added additional
guidance related to protection of confidential
commercial information. This resolves
FF 71111-1674.
NO N/A ML112140265