sdp introduction: 'significance determination …the significance determination process."...

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SignificanceDetermination Process

Technical Training CenterChattanooga, Tennessee

Learning Objectives

" Given a scenario, use IMC-0612,Appendix B to determine if an issue hassufficient significance to warrant use ofthe significance determination process.

" Given a scenario, use IMC-0609,Appendix A, and a Phase 2 pre-solvedtable to determine the risk significance.


.Purpose of SDP

* The Significance DeterminationProcess (SDP) uses risk insights,where appropriate, to help the NRCinspectors and staff to determinethe safety significance ofinspection findings.


SDP Objectives* To characterize the significance of

an inspection finding for the NRClicensee performance assessmentprocess, using best available riskinsights as appropriate.

The SDP thus assigns a color to theinspection finding.


Exhibit 2: REACTOR OVERSIGHT PROCESS

Communications

Agency Response

Management Conference

Monitor Licensee Actionsr-- - ---------- ------.......... i NRC Rlati ActionsL ...........

- -- ... .....

Additional Regulatory Actions

Assessment Process

(Action Matrix)

Public Meetings

" Press Releases" NRC Web Site" PDR/ADAMS

Assessment ReportsInspection Plans

Inspection FindingsPerformance Indicators

Signi~fica

Enforcement

4i

Cornerstones of Safety

'nee Evaluations I Significance Evaluations

Significance Deterlnination Proces'S Performance Indicator Thresholds

mA A

A.A|, I

* i

* i

Supplemental Event ResponseInspections (SI/AIT/IIT) [

Inspections

A

-I

Generic Safety Risk InformedInspections Baseline Inspections

)k--------------------------- ---------------------------

Performance Indicators

Performance Indicators

r- I Performance Results in all 7 Cornerstones of Safety m


SDP Colors

GreenACDF

- very low safety significance.< 1E-6

White - low to moderate safety significance.1E-6 < ACDF < 1E-5

Yellow - substantial safety significance.1E-5 <ACDF < 1E-4

Red - high safety significance.1E-4 < ACDF


SDP Objectives(Continued)

" To provide all stakeholders an objectiveand common framework forcommunicating the potential safetysignificance of inspection findings.

" To provide a basis for assessmentand/or enforcement actions associatedwith an inspection finding.

" To provide the inspectors with plant-specific risk information for use in risk-informing the inspection program.


Types of SDPs

* At least one SDP supports eachcornerstone associated with thestrategic performance areasdefined in IMC 2515.

e The SDPs and related instructionsare found in IMC 0609.


Exhibit 1: REGULATORY FRAMEWORK

Cornerstones

SHUMAN -------- SAFETY CONSCIOUS WORK --------- PROBLEM --------PERFORMANCE ENVIRONMENT IDENTIFICATION AND

RESOLUTION

Cross-Cutting Areas


SDP ListingA. Significance Determination of

Reactor Inspection Findings forAt-Power Situations

B. Emergency Preparedness SDPC. Occupational Radiation Safety

SDPD. Public Radiation Safety SDPE. Physical Protection SDPF. Fire Protection SDP


SDP ListingG. Shutdown Safety SDPH. Containment Integrity SDPI. Operator Requal. Human

Performance SDPJ. SG Tube Integrity Findings SDPK. Maint. Risk Assess. & Risk

Management SDPM. Significance Determination

Process Using Qualitative CriteriaTechnical Training CenterChattanooga, Tennessee

Determining theSignificance of Reactor

Inspection Findings for At-Power Situations


Entry Conditions

* This SDP provides a simplified risk-informed framework to estimatethe increase in core damagefrequency during at-powersituations due to conditions whichcontribute to unintended risk.increases caused by de)Ocoimý


Deficient Performance

L_ VV(]., is an issue that isthe result of a licensee not meeting arequirement or standard where thecause was reasonably within thelicensee's ability to foresee and correct,and that should have been prevented. Aperformance deficiency can exist if alicensee fails to meet a self-imposedstandard or a standard required byregulation. IMC 0612.


Examples of DeficientPerformance

" Safety-related pump dischargevalve remained closed followingsurveillance testing.

* Debris left in safety-related tankfollowing maintenance activities.

" Failing to take proper correctiveaction when testing demonstrateda problem.


Entry Conditions (Cont'd)" Conditions which do not represent deficient

licensee performance are considered part ofthe acceptable plant risk and are notcandidates for SDP evaluation.

" Each Issue should be screened by using IMC0612, Appendix B, to determine whetherthe issue is more than a minor issue.

" If issue is not minor, then it is a candidatefor SDP evaluation.

" This SDP is not used for event evaluation.


Use Figure 1 and the questions listed below to determine if a finding has sufficientsignificance to warrant further analysis or documentation.

Figure 1

IMC 0612

Appendix B:

IssueScreening


see exception inSection 05.03

IMC-0612

Appendix BGreater

Yesl Figure 1App. E?

Greater

Minor

Yes


Issue

Performance DeficiencyQuestion

* Did the licensee fail to meet a requirementor standard, where the cause wasreasonably within the licensee's ability toforesee and correct and which shouldhave been prevented?

* A performance deficiency can exist if alicensee fails to meet a self-imposedstandard or a standard required byregulation.


Traditional EnforcementQuestions

* Does the issue have actual safetyconsequence (overexposure, excessiveradioactive release)?

* Does the issue have the potential forimpacting the NRC'Fs ability to performits regulatory function?

* Are there any willful aspects of theViolation?

Technical Training CenterChattanooga., Tennessee

Minor Questions* Could the issue be reasonably viewed as a

precursor to a significant event?* If left uncorrected, could the finding become a

more significant safety concern?• Does the finding relate to a performance

indicator that would have caused the PI toexceed a threshold?

* Is the finding associated with one of thecornerstone attributes listed at the end of thisattachment and does the finding affect theassociated cornerstone objective?

* 9 maintenance risk assessment and riskmanagement questions (not listed here).

Technical Training Center > Objectives Figure I

Chattanooga, Tennessee IJ>

Initiating Events

* Objective - to limit the likelihood ofthose events that upset plant stabilityand challenge critical safety functionsduring shutdown as well as poweroperations.

* Attributes: design control, protectionagainst external factors, configurationcontrol, equipment performance,procedure quality, and humanperformance.


Mitigating Systems

" Objective - to ensure the availability,reliability, and capability of systemsthat respond to initiating events toprevent undesirable consequences (i.e.,core damage).

* Attributes: design control, protectionagainst external factors, configurationcontrol, equipment performance,procedure quality, and humanperformance.


Barrier Integrity

" Objective - to provide reasonableassurance that physical design barriers(fuel cladding, RCS, and containment)protect the public from radionuclidereleases caused by accidents.

" Attributes: design control, configurationcontrol, procedure quality, humanF erformance, cladding performancecladding), RCS equipment and barrier

performance (RCS), and SSC and barrierperformance (containment).

Technical Training CenterChattanooga, Tennessee E

SDP Questions" Is the event associated with an increase in the

likelihood of an initiating event?" Is the finding associated with the operability,

availability, reliability, or function of a systemor train in a mitigating system?

" Is the finding associated with the integrity offuel cladding, the reactor coolant system,reactor containment, control room envelope,auxiliary building (PWR), or ... (BWR)?

" Is the finding associated with degradedconditions that could concurrently influence anymitigation equipment and an initiating event?


SDP Questions (cont'd)* Is the finding associated with or involve

impairment or degradation of a fireprotection feature?

" Is the finding associated with the spentfuel pool cooling system radiologicalbarrier?

" Is the finding associated with inadequate10 CFR 50.65(a)(4) risk assessment(quantitative only) and/or riskmanagement?


SDP Phases

* Phase 1 - Characterization and InitialScreening of Findings

Characterization of the finding and an initial screening oflow-significance findings for disposition by the licensee'scorrective action program.

* Phase 2- Risk Significance Estimation andJustification Using the Site Specific Risk-Informed Inspection Notebook and Pre-SolvedTable* Plant-specific estimation of the risk significance of an

inspection finding and development of the basis for thedetermination.


SDP Phases(Continued)

* Phase 3 - Risk SignificanceEstimation Using Any Risk BasisThat Departs from the Phase 1 orPhase 2 Processe Any departure from the guidance provided for

Phase 1 or 2 constitutes a Phase 3 analysis.Phase 3 analysis methods will utilize appropriatePRA techniques and rely on the expertise of NRCrisk analysts.


Determine Applicable Scenarios from Table 2.

* I T 1 1 7

TPCS AFW I EIHP FB HPR STATUS

Initiating EventLikelihood(Table 1)

Mitigation Capability- Table 41

2

3

OK

OK

CID

CD

CD

4

5

Plant name abbrev.: CALL


Table 3.X for each scenario

A Little Math

* If events A and B are independent,then the Pr(A and B) is:

Pr(A and B) - Pr(A) Pr(B)

* Logarithms

log AB logA + log BTechnical Training CenterChattanooga, Tennessee

SDP Tables* In IMC - 0609

-Table 4, Remaining Mitigation Capability Credit

- Table 51 Counting Rule Worksheet

* In Site Specific Workbook-Table 1, Categories of Initiating Events

- Table

- Table

21Initiators and Dependency

3.X1 Worksheets for required initiatingevent scenarios.


Example using notebook

TDAFWIssue


SDP Phase 2 Steps(IMC 0609, App. A, Att. 1)

Step 2.1.1: Check for the mostcurrent version of SDPNotebook and Pre-solvedWorksheet.

Step 2.1.2: Determine theexposure time.


1.1 Exposure Time

If the inception of the condition isunknown:- determine last successful demonstration of

functionality.

- Exposure time = (date discoveredinoperable - date of functionalitydemonstration)/2

- called t/2


SDP Phase 2 Steps(IMC 0609, App. A, Att. 1 cont'd)Step 2.1.3: Find the appropriate target for

the inspection finding in the pre-solvedtable.

Step 2.1.4: Determine the risk significanceof the inspection finding and thepotential risk contribution due to LargeEarly Release Frequency (LERF).


SDP Phase 2 StepsI[IMC 0609, App. A, Att. 1- conStep 2.1.5: Screen for the potential risk

contribution due to external events ifresults from Step 2.1.4 are Green andgreater than or equal to 1E-7.

t'd)

is


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