System

{{entity:Nuclear Reactor Protection System}} interim QC session. The project has 166 requirements across 8 subsystems with 48 PART_OF relationships, 51 CONNECTS facts, and 149 trace links. Decomposition status remains in-progress — this is an interim QC triggered by the session counter, not a first-pass-complete gate review.

Findings

The critical finding was that 117 of 166 requirements (70.5%) lacked both --rationale and --verification attributes. These were all requirements created in sessions after the initial scaffolding: 37 subsystem requirements ({{sub:SUB-REQS-016}} through {{sub:SUB-REQS-053}}), 24 interface requirements ({{ifc:IFC-DEFS-011}} through {{ifc:IFC-DEFS-034}}), all 47 verification plan entries, and all 9 architecture decisions.

Lint reported 8 findings: 3 high (ontological mismatches), 1 medium (abstract metric), 4 low (classification ambiguity and missing “shall” keywords). The 56 requirements lacking “shall” are all ARC decisions and VER entries, which by nature are not SHALL statements — this is expected.

One duplicate requirement identified: {{sys:SYS-REQS-014}} is identical to {{sys:SYS-REQS-013}} (both specify the same 10 CFR 73.54 cyber security programme). Tagged as duplicate-of-SYS-REQS-013.

Orphan analysis: 9 orphans, all ARC-DECISIONS entries. Architecture decisions do not participate in the standard trace linksets (STK→SYS→SUB/IFC→VER), so these orphans are structurally expected.

VER coverage stands at 47 verification entries against 86 SUB+IFC requirements (55% coverage). All 34 IFC requirements have corresponding VER entries. The gap is in SUB requirements — only 13 of 52 have dedicated VER entries.

Corrections

Rationale backfill (117 updates): Every missing requirement received a specific engineering rationale. For performance requirements, rationale explains the derivation of numeric values and consequences of not meeting them (e.g., {{sub:SUB-REQS-016}} source range 6-decade coverage derives from subcritical-to-critical monitoring needs; {{sub:SUB-REQS-035}} 4-hour battery capacity from 10 CFR 50.63 station blackout coping). For safety requirements, rationale traces to the specific regulatory basis (IEEE 603 clauses, NRC GDCs, BTP 7-19). For interface requirements, rationale explains why specific cable types, signal standards, and isolation methods are used (e.g., {{ifc:IFC-DEFS-012}} mineral-insulated cable for in-containment radiation resistance).

Verification attributes set on all 117 previously unset requirements. Methods assigned: Test (majority), Analysis (ARC decisions, D3 and cyber assessments), Inspection (physical separation, penetration assembly, HSI reviews), Demonstration (breaker testing, overlap testing).

Lint acknowledgements: 2 findings acknowledged — {{entity:Nuclear Reactor Protection System}} correctly classified as abstract (distributed system, not single physical object), and “regulatory guide 1” correctly abstract (document, not equipment). {{entity:Containment Environment Monitor}} reclassified with detailed physical context ({{hex:54A53058}}) to address the third high-severity finding.

Duplicate tagged: {{sys:SYS-REQS-014}} marked duplicate-of-SYS-REQS-013.

flowchart TB
    NPS[Nuclear Reactor Protection System]
    RTS[Reactor Trip Subsystem]
    ESFAS[ESF Actuation System]
    NIS[Nuclear Instrumentation]
    PIS[Process Instrumentation]
    PAMS[Post-Accident Monitoring]
    PWR[Class 1E Power Supply]
    TSS[Test and Surveillance]
    CDS[Communication and Display]
    NPS --> RTS
    NPS --> ESFAS
    NPS --> NIS
    NPS --> PIS
    NPS --> PAMS
    NPS --> PWR
    NPS --> TSS
    NPS --> CDS
    NIS -->|flux signals| RTS
    NIS -->|flux signals| ESFAS
    PIS -->|process signals| RTS
    PIS -->|process signals| ESFAS
    PWR -->|125VDC/120VAC| RTS
    PWR -->|125VDC/120VAC| ESFAS
    TSS -->|test injection| RTS
    TSS -->|test injection| ESFAS
    CDS -->|display data| PAMS

Residual

• SUB verification gap: 39 of 52 subsystem requirements lack dedicated VER entries. The existing 47 VER entries cover all 34 IFC requirements plus 13 SUB requirements. Closing this gap requires ~39 additional VER entries — beyond single-session budget.
• Duplicate SYS-REQS-014: Tagged but not deleted (protocol prohibits overwriting prior-session work). Should be consolidated in a future session.
• CEM reclassification: Reclassified to {{hex:54A53058}} but the hex code did not change, suggesting the physical context was insufficient to flip the Physical Object trait. May need manual trait review.

Next

Continue decomposition (status remains in-progress). Priority for next session: resume subsystem decomposition work on any remaining subsystems not yet fully decomposed. The interim QC gap — missing SUB verification entries — should be addressed incrementally during decomposition sessions rather than in a dedicated batch. Next interim QC due at session 226.