System

QC review of {{entity:Radio Chemistry Laboratory for a UK Nuclear Dockyard}} (se-radiochem-lab), triggered by first-pass-complete status. The project contains 257 requirements across 12 subsystems, 100 decomposition facts, and 243 trace links. This is a full first-pass QC — the last interim QC was session 234.

Findings

The primary quality gap was missing rationale: 141 of 257 requirements lacked engineering justification (62 SUB, 29 IFC, 43 VER, 7 ARC). This is the most significant finding — over half the requirements had no recorded basis for their specified values or constraints. Verification attribute was missing from only 3 ARC entries (acceptable — architecture decisions are not testable requirements).

Verification coverage stood at 70/155 SUB+IFC requirements (45%), below the 50% target. All 51 IFC requirements had VER entries, but only 19 of 104 SUB requirements did.

Lint reported 5 findings (3 high, 2 low):

• High: “minute” and “modbus tcp” flagged as lacking Physical Object trait but referenced in physical constraints — both are false positives (time unit and protocol, not components)
• High: {{entity:Evaporation and Concentration Unit}} classified without Physical Object trait despite being physical equipment ({{hex:54D51219}})
• Low: Ontological ambiguity between {{entity:Ultra-Low-Background Liquid Scintillation Counter Array}} and {{entity:Area Gamma Dose Rate Monitoring Network}} (65% Jaccard, differing physical classification)
• Low: 82 requirements lack “shall” — these are the 12 ARC decisions and 70 VER entries, which by convention use descriptive rather than prescriptive language

Orphan analysis found 13/257 requirements unlinked: 12 ARC decisions (architecture decisions are not traced in the current linkset model) and {{sub:SUB-REQS-053}}, which is a confirmed duplicate of {{sub:SUB-REQS-051}} (already tagged duplicate-of-SUB-REQS-051).

Corrections

Rationale additions (36 requirements): Added engineering rationale to all safety-critical subsystem requirements across:

• {{entity:Hot Cell Facility}} ({{sub:SUB-REQS-001}} through {{sub:SUB-REQS-011}}): Shielding derivation from IRR17, manipulator payload basis, lead glass radiation browning, ventilation pressure cascade, HEPA DF basis, transfer port interlock safety case, dissolution chemistry basis, criticality detection redundancy, decontamination clearance levels, iodine adsorber performance, and safety interlock logic
• {{entity:Active Effluent Treatment Plant}} ({{sub:SUB-REQS-012}} through {{sub:SUB-REQS-023}}): Batch mode regulatory basis, evaporator VRF derivation, ion exchange DF for Cs-137, discharge valve closure timing, double containment regulatory basis, pH treatment range, online monitoring requirement, drum handling standards, sub-atmospheric evaporator rationale, cumulative discharge tracking, and bund construction requirements
• {{entity:Ventilation and Containment System}} ({{sub:SUB-REQS-024}} through {{sub:SUB-REQS-030}}): Supply air sizing, duty/standby fan safety justification, in-situ DOP testing standard, pressure cascade hierarchy, methyl iodide DF, stack monitoring sensitivity, and stack height dispersion modelling
• {{entity:Radiation Protection and Health Physics System}} ({{sub:SUB-REQS-034}}): Area gamma monitoring coverage
• {{entity:Alpha Spectrometry Laboratory}} ({{sub:SUB-REQS-076}} through {{sub:SUB-REQS-080}}): PIPS resolution for actinide peak separation, vacuum requirements, carousel capacity, peak deconvolution, dead time correction
• {{entity:Liquid Scintillation Counting Facility}} ({{sub:SUB-REQS-081}} through {{sub:SUB-REQS-087}}): Ultra-low background for tritium MDA, PSA capability, electrolytic enrichment factor, unattended counting capacity, fume cupboard containment, MDA calculation standard, dark adaptation
• {{entity:Sample Receipt and Preparation Laboratory}} ({{sub:SUB-REQS-052}}): Dose rate measurement at receipt

Verification entries (8 new): Created {{sub:VER-METHODS-071}} through {{sub:VER-METHODS-078}} covering biological shielding survey, ventilation pressure differential test, HEPA aerosol challenge, cell decontamination demonstration, double containment hydrostatic test, duty/standby fan changeover test, pressure cascade verification, and area gamma monitor calibration. All traced to their parent SUB requirements. VER coverage now 78/155 = 50.3%.

Lint corrections: Reclassified {{entity:Evaporation and Concentration Unit}} with explicit physical context. Acknowledged “minute” and “modbus tcp” findings as false positives (stored LINT_ACKNOWLEDGED facts).

Residual

105 requirements still lack rationale (mostly IFC and VER entries, plus remaining SUB requirements from Gamma Spectrometry, Solid Waste Management, and LIMS subsystems). The IFC rationale gap (29 reqs) and VER rationale gap (43 reqs) should be addressed during validation, prioritising safety-critical interfaces.

The confirmed duplicate {{sub:SUB-REQS-053}} remains in the dataset (protocol prohibits deleting prior-session requirements) but is tagged and excluded from coverage calculations.

The 2 low-severity lint findings (ontological ambiguity and “shall” keyword) are acknowledged but do not require corrective action — VER and ARC entries are intentionally descriptive.

flowchart TB
  n0["Radio Chemistry Laboratory"]
  n1["Sample Receipt and Preparation"]
  n2["Gamma Spectrometry Suite"]
  n3["Alpha Spectrometry Laboratory"]
  n4["Liquid Scintillation Counting"]
  n5["ICP-MS Analysis Suite"]
  n6["Radiochemical Separations"]
  n7["Hot Cell Facility"]
  n8["Ventilation and Containment"]
  n9["Active Effluent Treatment"]
  n10["Solid Waste Management"]
  n11["Radiation Protection"]
  n12["LIMS"]

  n0 --> n1
  n0 --> n2
  n0 --> n3
  n0 --> n4
  n0 --> n5
  n0 --> n6
  n0 --> n7
  n0 --> n8
  n0 --> n9
  n0 --> n10
  n0 --> n11
  n0 --> n12

Next

Status is now qc-reviewed — the next session should execute Flow D (Validation), assessing whether this decomposition accurately represents a real UK nuclear dockyard radiochemistry laboratory. Validation should prioritise: (1) checking whether the Hot Cell and Active Effluent requirements reflect current ONR/EA regulatory expectations, (2) verifying interface protocols are realistic for this class of facility, and (3) closing the remaining rationale gaps on IFC and VER entries as part of validation corrections.