System

Fusion Reactor Control System interim QC, triggered 5 sessions after the previous QC pass at session 393. At entry: 159 requirements across 6 documents, 143 trace links, 10 diagrams, baseline BL-012. Eight subsystems fully decomposed — {{entity:Interlock and Emergency Shutdown System}}, {{entity:Disruption Prediction and Mitigation System}}, {{entity:Plasma Control System}}, {{entity:Heating and Current Drive Control}}, {{entity:Magnet Safety and Protection System}}, {{entity:Fuel Injection and Burn Control}}, {{entity:Plasma Diagnostics Integration System}}, and {{entity:Plant Control and I&C System}}.

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

Findings

Ontological misclassification (high severity). The {{entity:Disruption Prediction Engine}} carried the {{trait:Biological/Biomimetic}} trait (hex {{hex:71F77308}}), which the lint engine correctly flagged — an LSTM and physics-informed neural network operating at 100 Hz on magnetic diagnostic signals has no biological characteristics. Reclassified with enriched context specifying the algorithmic nature, GPU compute hosting, and purely digital signal pathway; new hex {{hex:51F57308}}, trait cleared with 0.95 confidence.

Duplicate trace link. Two derives links existed from {{sys:SYS-REQ-004}} to {{sub:SUB-REQ-062}} (safe state definition), created in sessions 395 and 397. The newer duplicate was removed, leaving one link with the original rationale tying SCRAM target to subsystem-level safe state definition.

SYS-REQ-006 section placement error. The seismic SIL-3 system requirement was accidentally reassigned to the subsystem document (becoming SUB-REQ-065) during an attempted section fix in this session. A replacement system-level requirement was created (seismic survivability with IEEE 344 Category I, 10 s transition budget) and linked from {{stk:STK-REQ-009}}.

18 requirements with null documentSlug. Requirements SUB-REQ-039–041, SUB-REQ-064–065, SYS-REQ-006 (now displaced), VER-REQ-037, VER-REQ-041–052 all report null documentSlug in the list API despite being counted correctly by the docs list command. The AIRGen API accepts trace link creation for these refs inconsistently — some succeed, some return 400 “Requirements not found”. This is a platform data integrity issue requiring investigation; the requirements are correctly counted (163 total at close) but cannot be reliably linked.

Coverage gaps. Lint finding #14 identified no cybersecurity requirements despite the Digital/Virtual trait on the control system. Finding #10 identified the STK-REQ-010 EM environment requirement had no system-level flow-down. Both gaps addressed this session.

VER coverage. 47 VER entries against 88 SUB+IFC requirements = 53.4% coverage, above the 50% gate. No requirements added after session 393 were found to be missing rationale or verification fields.

SYS-REQ-004 spray pattern. 29 derives links from the SIL-3 safety shutdown requirement. All reviewed; each carries specific rationale linking to the SIL-3 hardware fault tolerance mandate, hazard analysis, or coil protection physics. This is a genuine cascade from a single safety-critical requirement to every subsystem safety function — not a mechanical linking pattern.

Corrections

• Reclassified {{entity:Disruption Prediction Engine}}: removed {{trait:Biological/Biomimetic}}, hex {{hex:71F77308}} → {{hex:51F57308}}
• Deleted duplicate SYS-REQ-004 → SUB-REQ-062 trace link (link-1774050131270-efm5af5vu)
• Created {{sys:REQ-SEFUSIONREACTORCONTROLSYSTEM-031}}: system seismic survivability requirement (IEEE 344 Category I, 10 s, SIL-3) linked from STK-REQ-009
• Created {{sys:REQ-SEFUSIONREACTORCONTROLSYSTEM-032}}: IEC 62443 SL-2 cybersecurity controls including unidirectional diodes between SIL-3 safety and control networks; linked from SYS-REQ-004
• Created {{sub:REQ-SEFUSIONREACTORCONTROLSYSTEM-033}}: QDS physical housing specification (19-inch seismic rack, IP54, ≤1 mV EM noise immunity); linked from system seismic requirement
• Created {{sys:REQ-SEFUSIONREACTORCONTROLSYSTEM-034}}: system EMC compliance requirement for tokamak EM environment (10 T/s dB/dt, 200 V/m RF, IEC 61000-4-3 level IV); linked from STK-REQ-010
• Updated LAST_QC_SESSION to 398; baseline BL-013 created at close

Residual

The null documentSlug platform issue prevents reliable trace linking for 18 requirements. VER-REQ-052 and SUB-REQ-064 are orphaned in the trace graph as a result. The STK-REQ-006 coverage gap (maintenance management system diagnostic reporting) was identified but not closed this session due to budget; the existing SYS-REQ-005 (1 kHz archiving) partially covers the intent but does not explicitly address the 10 s maintenance reporting pathway. Physical housing requirements for the {{entity:Pellet Injection Controller}} and the system as a whole (lint findings 1–3) remain open.

Next

Investigate and resolve the null documentSlug platform issue before attempting further trace link work on the affected requirements. Once resolved, link SUB-REQ-064 and VER-REQ-052 into the trace graph. Add a physical housing and maintenance reporting requirement to close the remaining lint findings, then proceed to next subsystem deepening — the {{entity:Plasma Diagnostics Integration System}} is the least deeply decomposed and has the most interface dependencies outstanding.