Success Criteria Development Technical Element Module

Overview

The Success Criteria Development (SC) technical element defines the minimum requirements that must be met by functions, systems, components, and human actions to prevent or mitigate a release for each modeled initiating event and event sequence. It aligns with RG 1.247’s objective for the success criteria PRA element: to determine the minimum requirements for each function (and ultimately the systems/components performing those functions) under the plant conditions represented in each sequence and plant operating state (POS).

This module provides structured types to document success criteria at multiple levels (overall/event-sequence-family, system, component, human actions), their technical bases, and the process documentation, uncertainties, and pre-operational assumptions required for traceability and peer review.

Purpose

1. Establish success requirements consistent with initiating event response and POS conditions
2. Trace success criteria to engineering analyses (thermal-hydraulic, structural, neutronics, radiation transport)
3. Capture system capacities, component performance requirements, and human action timing/feasibility
4. Document the process, model uncertainties, limitations, codes, and expert judgments used
5. Differentiate capability categories (e.g., realistic criteria for risk-significant sequences)
6. Provide structured inputs to Systems, HRA, Event Sequence Quantification, MST/RC, and Risk Integration

Structure

┌──────────────────────────────────────────────────────────────────────────────┐
│                       Success Criteria Development                           │
│                                                                              │
│  ┌─────────────────────┐  ┌──────────────────────────┐  ┌──────────────────┐ │
│  │  Criteria Levels     │  │ Technical Bases & Docs   │  │ Integration Hooks│ │
│  │                     │  │                          │  │                  │ │
│  │ - OverallSuccess... │  │ - ProcessDocumentation   │  │ - POS references │ │
│  │ - SystemSuccess...  │  │ - ModelUncertaintyDoc    │  │ - IE references  │ │
│  │ - ComponentSuccess..│  │ - PreOperationalAssumps  │  │ - Sequence refs  │ │
│  │ - HumanActionSuccess│  │ - PeerReview & Trace     │  │ - SuccessCriteriaIds │
│  └─────────────────────┘  └──────────────────────────┘  └──────────────────┘ │
│                                                                              │
│  ┌─────────────────────┐  ┌──────────────────────┐  ┌────────────────────┐  │
│  │  Analysis Types      │  │  Quant & Importance  │  │  Config & Version  │  │
│  │ - TH, Structural     │  │ - CC category flags  │  │ - VersionInfo      │  │
│  │ - Neutronic, RadTrans│  │ - Significance flags │  │ - Traceability     │  │
│  └─────────────────────┘  └──────────────────────┘  └────────────────────┘  │
└──────────────────────────────────────────────────────────────────────────────┘

Key Features

• Multiple levels of criteria: overall (sequence/family), system, component, and human action
• Engineering basis references and analysis-type classification (TH, structural, neutronic, radiation transport)
• System capacity and component performance requirements with basis
• Sequence, initiating event, and POS references for contextual applicability
• Capability category support (e.g., realistic criteria for risk-significant sequences)
• Process documentation (calculations, codes, limitations, expert judgment, grouped events treatment, digital, passive, shared systems)
• Model uncertainty and pre-operational assumption documentation
• Peer review and traceability structures

Core Components

• OverallSuccessCriteriaDefinition: Overall criteria for an event sequence or family with key safety functions and end-state parameters
• SystemSuccessCriteriaDefinition: Required capacities and dependencies per system with analysis references
• ComponentSuccessCriteriaDefinition: Component performance requirements and system linkage
• HumanActionSuccessCriteriaDefinition: Action description, timing basis, feasibility, and dependencies
• SuccessCriterion base types for consistent naming, descriptions, and references
• Documentation types: ProcessDocumentation, ModelUncertaintyDocumentation, PreOperationalAssumptionsDocumentation, PeerReviewDocumentation, and BaseTraceabilityDocumentation
• AnalysisType enum: TH/STRUCTURAL/NEUTRONIC/RADIATION_TRANSPORT/OTHER

See the schema source for full definitions: success-criteria-development.ts.

Integration with Other Technical Elements

Element	Interaction
Plant Operating States	Criteria reference POS conditions (decay heat, RCS config, barriers) to establish feasibility and minima
Initiating Event Analysis	Criteria scope ties to specific initiating events and sequence families
Event Sequence Analysis	Overall/system/component criteria referenced by sequences; end-state parameters aligned
Systems Analysis	Required capacities/performance inform system models and availability assumptions
Data Analysis	Parameter sources (e.g., pump curves, valve performance, success thresholds) trace to data/analyses
Human Reliability Analysis	Human action criteria provide timing and context for HRA quantification
Mechanistic Source Term / RC	Barrier protection criteria link to release category assumptions
Risk Integration	Criteria realism and significance flags inform capability categories and acceptance comparisons

Best Practices

Criteria Development

1. Align criteria with the most limiting POS and sequence conditions; record basis and conservatism
2. Use analysis-type tagging and cite calculations/codes with versions and limitations
3. Maintain direct references to sequences, initiating events, and POSs for traceability

System & Component Requirements

1. Quantify required capacities/performance with clear units and acceptance bands
2. Capture inter-system dependencies and functional success pathways
3. Keep criteria synchronized with system/failure modeling and success criteria IDs

Human Actions

1. Document timing windows, cues, procedures, and feasibility constraints
2. Coordinate with HRA for dependency and performance shaping factors
3. Validate consistency with POS instrumentation availability and access

Documentation & Reviews

1. Populate process documentation (SC-C1 a–k): end-state definitions, calculations, codes, limitations, expert judgment, mitigating systems, human action timing basis, grouped events, digital systems, passive safety, shared systems
2. Record model uncertainties (SC-C2) and pre-operational assumptions (SC-C3)
3. Track peer review findings and traceability with versioned references

Regulatory Compliance Alignment (RG 1.247)

RG 1.247 Expectation	Schema Support
Determine minimum requirements per function/system/component	Overall/System/ComponentSuccessCriteriaDefinition with capacities and performance
Realistic criteria for risk-significant sequences (capability categories)	usesRealisticCriteria, isRiskSignificant flags
Engineering basis, calculations, and codes documented	ProcessDocumentation (SC-C1 b–d)
Treatment of expert judgment	ProcessDocumentation.expertJudgmentUse (SC-C1 e)
Human action timing basis	ProcessDocumentation.humanActionTimingBasis (SC-C1 g); HumanActionSuccessCriteriaDefinition
Grouped events treatment and bounding	ProcessDocumentation.groupedEventsCriteria (SC-C1 h)
Digital and passive safety considerations	ProcessDocumentation.digitalSystemsCriteria, passiveSafetyCriteria (SC-C1 i–j)
Shared systems treatment	ProcessDocumentation.sharedSystemsCriteria (SC-C1 k)
Model uncertainty and pre-operational assumptions	ModelUncertaintyDocumentation (SC-C2), PreOperationalAssumptionsDocumentation (SC-C3)
Traceability and peer review	BaseTraceabilityDocumentation, PeerReviewDocumentation

Usage Workflow

1. Define overall criteria per event sequence/family with key safety functions and end-state parameters
2. Derive system capacities and component performance requirements from analyses; link references
3. Specify human action success criteria and timing basis
4. Complete process documentation (SC-C1 a–k), uncertainty (SC-C2), and pre-op assumptions (SC-C3)
5. Link criteria to sequences, initiating events, and POSs; update success criteria IDs in referencing modules
6. Review and iterate with Systems, HRA, and Event Sequence teams; update documentation and traceability

Additional Resources

• Detailed documentation: Success Criteria Development Documentation
• Schema source: success-criteria-development.ts
• Related: Event Sequence README, POS README

Glossary (Selected)

• Success Criteria: Minimum requirements for preventing or mitigating a release in a sequence context
• Capability Category: Quality level expectations (e.g., realism for risk-significant sequences)
• TH/Neutronic/Structural/Rad-Transport: Major analysis types used to derive criteria

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This README provides a regulatory-aligned summary of the Success Criteria Development technical element consistent with the style used across MEF modules.