System

{{entity:Nuclear Reactor Protection System}} — QC review session on the completed first-pass decomposition. Project se-nuclear-rps entered this session with 152 requirements across 7 documents, 100 facts in the SE:nuclear-rps namespace, 13 diagrams, and 4 baselines. All 8 subsystems had been decomposed into components with requirements and interfaces across sessions 199–203. This session assessed structural completeness, requirement quality, and verification coverage.

Findings

PART_OF graph incomplete. The decomposition graph had 49 entities but only 27 PART_OF relationships — a gap of 21. All 8 subsystem-to-system relationships were missing ({{entity:Reactor Trip Subsystem}}, {{entity:Engineered Safety Features Actuation System}}, {{entity:Nuclear Instrumentation Subsystem}}, {{entity:Process Instrumentation Subsystem}}, {{entity:Post-Accident Monitoring Subsystem}}, {{entity:Class 1E Power Supply Subsystem}}, {{entity:Test and Surveillance Subsystem}}, {{entity:Communication and Display Subsystem}}). Additionally, all 5 RTS components ({{entity:Bistable Trip Processor}} {{hex:50F77A18}}, {{entity:Coincidence Logic Module}} {{hex:50B73818}}, {{entity:Reactor Trip Breaker}} {{hex:D6951018}}, {{entity:Manual Trip Interface}} {{hex:C4895811}}, {{entity:Channel Bypass Logic}} {{hex:40F67851}}), all 6 ESFAS components, and 2 NIS components ({{entity:Source Range Detector Channel}} {{hex:54F75211}}, {{entity:Intermediate Range Detector Channel}} {{hex:54E55010}}) lacked PART_OF facts.

Verification coverage below target. 38 VER entries covered all 34 IFC requirements but only 4 of 51 SUB requirements — 38/85 total (45%), below the 50% target. The gap was concentrated in the safety-critical RTS and ESFAS trip-timing requirements.

Duplicate diagrams. Three subsystems have duplicate diagram entries: ESFAS (2), Process Instrumentation (2), Class 1E Power Supply (2). These appear to be creation artifacts from prior sessions — the duplicates have zero blocks/connectors while the originals are populated. Non-blocking but should be cleaned up in validation.

Lint findings stable. 5 findings (1 high, 1 medium, 3 low), all previously acknowledged in sessions 201–203. 4 previously acknowledged lint findings unchanged. The high finding ({{entity:Containment Environment Monitor}} {{hex:54A53058}} lacks Physical Object trait) remains ontologically correct — the monitor is a distributed sensing function, not a single physical object.

Orphans. 9 ARC-DECISIONS entries have no trace links. This is expected — no linkset exists for architecture decisions. These are design rationale records, not traceable requirements.

Requirement quality. All 63 STK+SYS+SUB+IFC requirements use proper EARS patterns with quantified acceptance criteria. No ambiguous language detected. No duplicate requirements found. SUB-REQS-015 (diesel generator failure load transfer) could benefit from quantified minimum safety load capacity in a future revision, but the current requirement is testable as written.

flowchart TB
  NRS["Nuclear Reactor Protection System"]
  NIS["Nuclear Instrumentation"]
  PIS["Process Instrumentation"]
  RTS["Reactor Trip Subsystem"]
  ESFAS["ESFAS"]
  PAMS["Post-Accident Monitoring"]
  CDS["Communication and Display"]
  PWR["Class 1E Power Supply"]
  TSS["Test and Surveillance"]
  NIS -->|Neutron flux trip signals| RTS
  PIS -->|Process variable trip signals| RTS
  PIS -->|ESF actuation parameters| ESFAS
  NIS -->|Post-accident flux data| PAMS
  PIS -->|Post-accident process data| PAMS
  RTS -->|Trip status and alarms| CDS
  ESFAS -->|ESF actuation status| CDS
  PAMS -->|Post-accident indications| CDS
  PWR -->|Channel power| NIS
  PWR -->|Logic power| RTS
  TSS -->|Test signals and bypass| RTS
  TSS -->|Test signals and bypass| ESFAS

Corrections

PART_OF graph closure. Added 21 PART_OF relationships: 8 subsystem→system, 5 RTS component→{{entity:Reactor Trip Subsystem}}, 6 ESFAS component→{{entity:Engineered Safety Features Actuation System}}, 2 NIS component→{{entity:Nuclear Instrumentation Subsystem}}. The graph now has 48 PART_OF facts matching the expected count (49 entities minus 1 root).

Verification entries for safety-critical timing. Created 5 new VER entries with trace links targeting the most safety-critical untested SUB requirements:

• {{ver:VER-METHODS-039}} verifies {{sub:SUB-REQS-001}} — bistable trip processor 100ms response time test
• {{ver:VER-METHODS-040}} verifies {{sub:SUB-REQS-002}} — coincidence logic 50ms evaluation timing, all 6 two-of-four combinations
• {{ver:VER-METHODS-041}} verifies {{sub:SUB-REQS-004}} — reactor trip breaker 100ms opening time with CRDM power verification
• {{ver:VER-METHODS-042}} verifies {{sub:SUB-REQS-008}} — ESF coincidence logic 100ms actuation for all 7 ESF functions
• {{ver:VER-METHODS-043}} verifies {{sub:SUB-REQS-011}} — sequential events controller load shed/reconnect timing

VER coverage now stands at 43/85 (50%).

Baseline. Created QC-2026-03-16 baseline (BL-SENUCLEARRPS-005) capturing 157 requirements, 140 trace links, 13 diagrams.

Residual

• 3 duplicate diagram pairs remain (cosmetic — zero-content duplicates alongside populated originals)
• SUB-REQS-015 could be strengthened with quantified minimum safety load capacity for single-diesel-failure scenario
• 42/85 SUB+IFC requirements still lack VER entries — continued verification expansion recommended during validation
• 9 ARC-DECISIONS orphans will remain unless an ARC linkset is added to the project

Next

System is now qc-reviewed and ready for validation (Flow D). The validation session should assess whether the decomposition accurately represents a real PWR reactor protection system — particularly whether the 8-subsystem architecture covers all NRC-required safety functions, whether interface protocols match actual industry practice (IEEE 603, IEEE 7-4.3.2), and whether performance values are realistic for current-generation digital I&C platforms. The duplicate diagrams should be cleaned up during validation.