System

The {{entity:Fusion Reactor Control System}} ({{hex:51F77B19}}) QC review, session 412. Project state at entry: 245 requirements, 248 trace links, 10 diagrams, 26 baselines. Status was qc-reviewed from session 393; this session performed an interim QC pass on 19 sessions of accumulated decomposition work, covering the full sub-subsystem decomposition of all 8 subsystems.

Findings

Orphan requirements — 11 identified, 0 remaining. The most significant structural gap: eleven requirements had no trace links, nine of which had null documentSlug (not assigned to any document section). The orphaned requirements were substantive: {{entity:safety arbiter}} 1oo2 redundancy ({{sub:SUB-REQ-085}}), the safe state operational definition ({{sub:SUB-REQ-084}}), MHD Mode Stabiliser NTM detection performance ({{sub:SUB-REQ-082}}), Disruption Prediction Engine validation dataset ({{sub:SUB-REQ-079}}), tritium regulatory compliance ({{sub:SUB-REQ-073}}, {{sub:SUB-REQ-086}}, {{sub:SUB-REQ-089}}), and physical housing specifications ({{sub:SUB-REQ-067}}, {{sub:SUB-REQ-068}}). All were reassigned to the subsystem-requirements document and traced to their parent SYS requirements.

Physical embodiment — 4 high-severity lint findings. The linter flagged {{hex:51F77B19}} (FRCS), {{hex:54F77218}} ({{entity:quench detection system}}), {{hex:55F53218}} ({{entity:pellet injection controller}}), and {{hex:002008B1}} ({{entity:safety arbiter}}) for lacking the {{trait:Physical Object}} trait while carrying physical constraints. Four new subsystem requirements created to establish formal physical boundaries: rackmounted IEEE 344-qualified enclosures for FRCS, radiation-hardened hardware within 10 m of superconducting coils for QDS, tritium-perimeter cabinet with C2 containment for PIC, and IEC 61513 Category A dedicated cabinet with point-to-point hardwiring for the Safety Arbiter.

Duplicate requirement — 1 deleted. SUB-REQ-098 ({{hex:71F77308}} DPMS RE detection, REQ-114) was a near-duplicate of SUB-REQ-097 (REQ-113), differing only in omitting synchrotron radiation monitoring alongside hard X-ray detection. Trace links re-pointed from REQ-114 to REQ-113 before deletion. REQ-116 (VER for RE detection) retained and linked to the correct subsystem requirement.

Biological/Biomimetic misclassification. The {{entity:disruption prediction engine}} carried the {{trait:Biological/Biomimetic}} trait because the LSTM architecture is computationally inspired by neural biology. Reclassified with explicit context noting it is a deterministic VHDL FPGA implementation in a nuclear I&C role — not a biological system. Lint finding 5 (no biocompatibility requirements) resolved by removing the classification basis.

Residual findings. The lint flags {{hex:51F77B19}}, {{hex:51F77A59}} ({{entity:emergency shutdown system}}), and {{hex:002008B1}} as Ethically Significant without corresponding requirements. For a nuclear fusion reactor control system, the ethical obligations are addressed through the SIL-3 safety case, IEC 61513 nuclear I&C qualification, and IAEA regulatory compliance requirements — not discrete ethical requirements. This is a legitimate ontological interpretation gap rather than a missing requirement category.

Corrections

Requirements assigned to subsystem-requirements document: SUB-REQ-067, 068, 073, 079, 082, 084, 085, 086, 089, SUB-REQ-097 (was REQ-113). Trace links created: {{sys:SYS-REQ-012}} → {{sub:SUB-REQ-029}} (ICRH arc protection), {{sys:SYS-REQ-002}} → REQ-113 (RE detection) and REQ-065 (DPE validation), {{sys:SYS-REQ-001}} → REQ-072 (MHD NTM detection), {{sys:SYS-REQ-004}} → REQ-089 (safe state definition), REQ-095 (IESS 1oo2), REQ-042 and REQ-099 (PIC tritium), {{sys:SYS-REQ-011}} → REQ-104 (tritium inventory safeguards), {{sys:SYS-REQ-009}} → REQ-036 and REQ-037 (FRCS and QDS physical housing). Physical embodiment requirements REQ-118 through REQ-121 created and traced to {{sys:SYS-REQ-009}} and {{sys:SYS-REQ-004}}.

Residual

Spray patterns on {{sys:SYS-REQ-004}} (≥26 links) and {{sys:SYS-REQ-001}} (≥15 links) remain. SYS-REQ-004 (SIL-3 SCRAM) genuinely cascades to every safety subsystem; all links carry explicit rationale. The Ethically Significant lint findings require human review to determine if additional governance or public-interest requirements belong in the STK document. The mode stabiliser abstract metric finding (lint 10) needs statistical confidence and sample-size annotations — deferred to next decomposition session.

Next

Project at 248 requirements, 263 trace links, 0 orphans. The decomposition is structurally sound. Validation session (Flow D) is the recommended next step: walk each ConOps scenario through the trace chain from STK through VER, verify the SIL-3 safety argument chain for each hazard identified in the concept phase, and check operating mode coverage for the burn, ramp-up, and disruption modes.

flowchart TB
  n0["Fusion Reactor Control System"]
  n1["Plasma Control System"]
  n2["Disruption Prediction and Mitigation System"]
  n3["Heating and Current Drive Control"]
  n4["Magnet Safety and Protection System"]
  n5["Fuel Injection and Burn Control"]
  n6["Plasma Diagnostics Integration System"]
  n7["Plant Control and I&C System"]
  n8["Interlock and Emergency Shutdown System"]
  n0 -->|contains| n1
  n0 -->|contains| n2
  n0 -->|contains| n3
  n0 -->|contains| n4
  n0 -->|contains| n5
  n0 -->|contains| n6
  n0 -->|contains| n7
  n0 -->|contains| n8