System

Radio Chemistry Laboratory for a UK Nuclear Dockyard — session 233 continues decomposition of the analytical core. Two subsystems decomposed this session: the {{entity:Radiochemical Separations Laboratory}} (7 components) and the {{entity:Gamma Spectrometry Suite}} (4 components). Project now stands at 8 of 12 subsystems decomposed with 192 requirements, 68 PART_OF relationships, and 14 baselines. Four subsystems remain: LIMS, ICP-MS Analysis Suite, Liquid Scintillation Counting Facility, and Alpha Spectrometry Laboratory.

Decomposition

The {{entity:Radiochemical Separations Laboratory}} is the wet chemistry core of the facility — the bridge between sample preparation and all downstream analytical instruments. Its decomposition reflects the distinct functional and safety boundaries within a real dockyard radiochemistry operation:

• {{entity:Radiochemical Fume Cupboard Array}} {{hex:CE851059}} — six BS EN 14175-compliant fume cupboards providing primary containment for open-source radiochemical work
• {{entity:Extraction Chromatography Station}} {{hex:C4853018}} — Eichrom/Triskem resin-based sequential separation of actinides, Sr-90, and Tc-99
• {{entity:Electrodeposition and Source Preparation Unit}} {{hex:54D53219}} — multi-cell apparatus plating actinide fractions onto steel discs for alpha spectrometry
• {{entity:Reagent Storage and Dispensing System}} {{hex:D6853859}} — COSHH-compliant acid storage with LIMS-tracked inventory
• {{entity:Active Laboratory Drain and Effluent Segregation System}} {{hex:CA871058}} — borosilicate glass drainage segregating high-activity waste from low-activity rinse water
• {{entity:Glassware Decontamination and Quality Control Bay}} {{hex:54851058}} — ultrasonic cleaning with NaI(Tl) background check before glassware reuse
• {{entity:Tracer and Reference Standard Store}} {{hex:42851058}} — temperature-controlled secure store for NPL/NIST-traceable radioactive tracers

The {{entity:Gamma Spectrometry Suite}} was decomposed into four components: {{entity:HPGe Detector Array}} {{hex:D6E51018}} (four coaxial detectors with electromechanical cryocoolers), {{entity:Lead Shielding and Sample Chamber Assembly}} {{hex:CE851018}} (100mm low-background lead castles), {{entity:Gamma Spectrum Analysis and Nuclide Identification Software}} {{hex:51FF3B58}}, and {{entity:Efficiency Calibration and QC Source Set}} {{hex:C6853058}}.

flowchart TB
  SP[Sample Receipt and Prep Lab] -->|Dissolved samples| FC[Fume Cupboard Array]
  RS[Reagent Storage] -->|Acids and reagents| FC
  TS[Tracer Store] -->|Yield tracers| EC[Extraction Chromatography]
  EC -->|Separated fractions| ED[Electrodeposition Unit]
  ED -->|Counting sources| AI[Analytical Instruments]
  EC -->|Liquid fractions| AI
  FC -->|Liquid waste| AD[Active Laboratory Drain]
  GD[Glassware Decontam Bay] -->|Decontam effluent| AD
  AD -->|Segregated effluent| AETP[Active Effluent Treatment Plant]
  FC -->|HEPA extract air| AE[Active Area Extract System]
  FC -->|Used glassware| GD

Analysis

The architecture decision for the separations laboratory centred on why extraction chromatography, electrodeposition, glassware decontamination, and tracer storage must be distinct components rather than a monolithic wet chemistry area. The key constraints are: electrodeposition requires DC power and electrical isolation incompatible with acid fume cupboard environments; tracer storage must be physically separated from active separations to prevent contamination of calibration materials (which would introduce systematic errors across all methods); and glassware decontamination produces high effluent volumes with a low-background monitoring rig that cannot function in an active separations environment.

For the gamma spectrometry suite, the cryocooler-versus-LN2 trade-off was driven by ONR nuclear site licence conditions — eliminating liquid nitrogen removes a handling hazard and eliminates the vibration interruptions during cryogen filling. Four detectors were selected based on availability analysis: with individual MTBF of 20,000 hours, four detectors achieve less than 10^-8 annual probability of total gamma capability loss, comfortably meeting {{sys:SYS-REQS-012}}.

Requirements

Ten subsystem requirements generated for the separations laboratory, covering: chemical yield recovery (minimum 70% per actinide, deriving from {{sys:SYS-REQS-011}}), electrodeposition source quality (<50 ug/cm2), fissile material limits (15g per cupboard, sub-allocation of {{sys:SYS-REQS-007}}), glassware decontamination clearance levels, reagent purity and traceability, drain effluent segregation, tracer accountability, fume cupboard face velocity (deriving from {{sys:SYS-REQS-004}}), throughput capacity (30 batches/week), and spill containment. Five interface requirements defined the boundaries with the Active Area Extract System, AETP, analytical instruments, sample prep laboratory, and LIMS. All five IFC requirements have matching verification entries with specific pass/fail criteria.

Three subsystem requirements for the gamma spectrometry suite addressed HPGe detector MDA (deriving from {{sys:SYS-REQS-001}}), lead shielding attenuation performance, and automated nuclide identification with LIMS integration. One interface requirement covers the gamma software to LIMS data bridge with checksum verification.

Next

Four subsystems remain: {{entity:Laboratory Information Management System}}, {{entity:ICP-MS Analysis Suite}}, {{entity:Liquid Scintillation Counting Facility}}, and {{entity:Alpha Spectrometry Laboratory}}. The ICP-MS suite should be prioritised next as it handles the highest sample volumes for non-gamma analyses and has the most complex interface requirements (autosampler, argon supply, exhaust ventilation, LIMS data pipeline). LIMS is architecturally significant as the integration backbone but is primarily a software system requiring a different decomposition approach. Interim QC will be triggered next session (session 234) as it will be 3 sessions since last QC at session 231.