System

Radio Chemistry Laboratory for a UK Nuclear Dockyard — decomposition in progress. This session addressed the two remaining undecomposed analytical measurement subsystems: the {{entity:Liquid Scintillation Counting Facility}} and the {{entity:ICP-MS Analysis Suite}}. Both were already referenced in CONNECTS facts from the {{entity:Extraction Chromatography Station}} but had no internal component structure, requirements, or interface definitions. Additionally, 38 missing PART_OF structural facts were repaired across all 12 subsystems. The project now holds 234 requirements, 83 PART_OF facts, and 52 CONNECTS relationships.

Decomposition

The {{entity:Liquid Scintillation Counting Facility}} was decomposed into five components reflecting the real measurement chain for beta-emitting radionuclides at a nuclear dockyard. The {{entity:Tritium Distillation and Electrolytic Enrichment System}} ({{hex:50951218}}) is the most distinctive element — SPE electrolytic enrichment provides the 20-50x concentration factor needed to achieve sub-Bq/L detection limits for tritium in groundwater, which is the key environmental compliance measurement for a submarine reactor maintenance facility. The {{entity:Ultra-Low-Background Liquid Scintillation Counter Array}} ({{hex:D6E71018}}) provides the counting platform with BGO guard detectors and <1 CPM background in the tritium window. The {{entity:Scintillation Cocktail and Vial Preparation Station}} ({{hex:C6841018}}), {{entity:Quench Correction and Calibration Standards Set}} ({{hex:C2843058}}), and {{entity:LSC Spectrum Analysis and MDA Calculation Software}} ({{hex:40A53158}}) complete the measurement chain from sample preparation through to LIMS-ready results.

The {{entity:ICP-MS Analysis Suite}} was decomposed into five components. The {{entity:Quadrupole ICP-MS with Collision Reaction Cell}} ({{hex:D4E53018}}) provides actinide isotopic analysis at sub-pg/mL detection limits — the critical capability for U-235/U-238 ratio measurement to distinguish natural uranium from enriched contamination. The {{entity:Clean Room Sample Preparation Enclosure}} ({{hex:D0851058}}) at ISO Class 5 ensures procedural blanks below 50 pg uranium, essential for measurements at these trace levels. The {{entity:ICP-MS Sample Introduction and Autosampler System}} ({{hex:D1C73018}}), {{entity:ICP-MS Calibration and Quality Control Standards Set}} ({{hex:C0843058}}), and {{entity:ICP-MS Data Processing and Isotope Ratio Software}} ({{hex:40A53B58}}) handle automated sample delivery, traceable calibration with IDMS capability, and GUM-compliant uncertainty budgets.

flowchart TB
  TD["Tritium Distillation and Enrichment"]
  CP["Cocktail and Vial Preparation"]
  CA["ULB LSC Counter Array"]
  QS["Quench Calibration Standards"]
  SW["LSC Analysis Software"]
  RL["Radiochem Separations Lab"]
  LM["LIMS"]
  TD -->|Enriched water samples| CP
  RL -->|Separated fractions| CP
  CP -->|Prepared counting vials| CA
  QS -->|Quench standards| CA
  CA -->|Raw spectra| SW
  SW -->|Activity results| LM

```mermaid
flowchart TB
  CR["Clean Room Enclosure"]
  SI["Sample Introduction"]
  MS["Quadrupole ICP-MS with CRC"]
  CS["Calibration Standards"]
  DP["Data Processing SW"]
  EC["Extraction Chromatography"]
  LM["LIMS"]
  EC -->|Separated actinide fractions| CR
  CR -->|Prepared solutions| SI
  CS -->|IDMS spike solutions| SI
  SI -->|Nebulised aerosol| MS
  MS -->|Raw mass spectra| DP
  DP -->|Isotope ratios and activities| LM

Analysis

Cross-domain comparison shows the {{entity:Ultra-Low-Background Liquid Scintillation Counter Array}} ({{hex:D6E71018}}) shares 31 of 32 traits with the {{entity:HPGe Detector Array}} ({{hex:D6E51018}}) at 97% Jaccard similarity — both are powered, observable, compositional radiation detection instruments with signal processing. The single trait difference is consistent with the HPGe’s cryogenic cooling requirement. This high similarity confirms the ontological coherence of the radiochem lab’s measurement instruments across detection modalities.

The architecture decisions for both subsystems reflect real constraints: LSC includes in-house tritium enrichment rather than outsourcing because the monthly regulatory reporting cycle and security classification of dockyard samples preclude external laboratory turnaround times ({{arc:ARC-DECISIONS-010}}). The ICP-MS uses a quadrupole with collision-reaction cell rather than sector-field because chemical separation via extraction chromatography resolves the U-238/Pu-239 mass overlap more cost-effectively than purchasing a high-resolution instrument ({{arc:ARC-DECISIONS-011}}).

Structural repair: all 12 subsystems now have PART_OF relationships to the main system entity, and all component-level PART_OF facts are in place — 83 total, up from 24 at session start. Lint reports 2 high-severity ontological mismatches (Modbus TCP and Evaporation Unit lacking Physical Object trait) which are pre-existing and ontologically defensible.

Requirements

Created 13 subsystem requirements ({{sub:SUB-REQS-081}} through {{sub:SUB-REQS-093}}): 7 for LSC covering counter background (<1 CPM), alpha/beta discrimination (<0.5% misclassification), tritium enrichment factor (>=20), sample capacity (600 vials), fume cupboard containment, ISO 11929 MDA calculation, and dark adaptation; 6 for ICP-MS covering U-238 sensitivity (>500 Mcps/ppm), abundance sensitivity (<1E-7), clean room blanks (<50 pg U), isotope ratio precision (<0.5% RSD), sample throughput with carryover control, and IDMS quantification.

Created 7 interface requirements ({{ifc:IFC-DEFS-041}} through {{ifc:IFC-DEFS-047}}): 4 for LSC defining the enrichment-to-preparation, counter-to-software, software-to-LIMS, and separations-to-LSC boundaries; 3 for ICP-MS defining chromatography-to-clean-room, instrument-to-software, and software-to-LIMS boundaries. All interface requirements traced to parent system requirements and all have corresponding verification entries.

Created 9 verification entries ({{ver:VER-METHODS-057}} through {{ver:VER-METHODS-065}}) — all 7 interface requirements have VER entries, plus 2 key subsystem requirements (counter background and tritium enrichment). VER coverage stands at 65/138 (47%) for SUB+IFC requirements.

Next

The radiochem lab now has 12 subsystems fully decomposed with structural facts, requirements, and interfaces. The next session should assess whether this constitutes first-pass completion — the LIMS subsystem may warrant decomposition into its own components (sample tracking, reporting, instrument integration modules) rather than remaining a monolithic entity. VER coverage needs to reach 50% — 4 more verification entries would cross the threshold. One orphaned requirement ({{sub:SUB-REQS-053}}) needs a trace link.