Cyclotron SOP · TFIA-2 Air Sampler
A high-volume air sample is only as good as the run that produced it. This page is the eight-step run SOP, four worked examples of the dual-cartridge collection-efficiency cross-check, and the per-run release-record entry that lands in the AERB annual environmental report.
Run SOP — eight steps
Visual inspection of motor housing, filter holder integrity, vacuum-gauge zero, mains lead and earth bond. Any visible damage holds the run pending engineering. Pass-state signed into the run log.
Load a fresh 4-inch paper filter (gloved handling, unique filter ID logged). Load two fresh activated charcoal cartridges in series — front cartridge marked "F" or "1", back cartridge marked "B" or "2"; orientation locked. Crimp the holder seal to spec torque.
Power-on into a clean-stream geometry; verify vacuum-gauge reading matches the calibrated no-load value within tolerance. A drift outside tolerance indicates motor wear, leak in the filter holder, or instrument drift — escalate before sampling begins.
Position at the designated sample point (stack tap, hot-lab return, I-131 room mid-air). For isokinetic stack work, verify nozzle orientation against the flow direction. Pre-run timestamp captured.
Power-on; record vacuum-gauge readings at start, midpoint and end. Sustained gauge drift toward the loaded-filter end of the scale indicates the paper filter is loading; if drift crosses the changeout threshold mid-run, terminate and split the sample.
Power-off at planned end time (or at split point). Remove the filter and cartridges using gloves; package separately with run-ID labels carrying sampler ID, sample-point ID, start / end timestamps, total run time, vacuum-gauge log. Sign over to the counting lab.
Counting lab measures each item in the appropriate counter geometry — paper filter on the filter-disc position, each charcoal cartridge in the cartridge well. Per-isotope photopeak windows acquired against the calibration; per-item activity figures returned to the sample record.
Compute front-cartridge activity ÷ (front + back); document the per-run cartridge collection efficiency. Compute concentration: activity ÷ total volume sampled (gauge-rate × run time). Sign the per-run release-record entry; archive for the AERB annual report and routine inspection.
Cross-check arithmetic — four worked examples
Per-run collection efficiency = front-cartridge activity ÷ (front + back). Below ~99 % flags a marginal cartridge; below ~95 % rejects the sample because the per-run concentration figure becomes unreliable; below ~80 % indicates a clear breakthrough or channelling defect and escalates to a cartridge-lot review. Numbers below are illustrative — site IQ / OQ / PQ sets the per-isotope thresholds.
| Scenario | Front cartridge | Back cartridge | Efficiency | Action |
|---|---|---|---|---|
| Clean run — efficiency in spec | 12.4 Bq | 0.05 Bq (ND) | > 99.6 % | Accept — concentration computed from front cartridge; back ND confirms no breakthrough |
| Marginal — efficiency just in spec | 8.2 Bq | 0.07 Bq | 99.2 % | Accept with note — flag cartridge lot for retest of next batch; consider proactive cartridge change |
| Out of spec — breakthrough | 4.1 Bq | 0.6 Bq | 87.2 % | Reject sample — sum-of-cartridge concentration unreliable; rerun with new cartridge lot; escalate cartridge supply review |
| Channelling defect — symmetric | 2.3 Bq | 2.1 Bq | 52.3 % | Reject sample + reject cartridge lot — clear channelling failure; quarantine remaining cartridges and escalate to supplier |
Per-isotope thresholds and acceptance / rejection criteria are locked at site IQ / OQ / PQ against ANSI N13.1 / ANSI N42.18 and the AERB cyclotron-facility air-monitoring framework. The sampling lab maintains the acceptance criteria sheet and signs the per-run release-record entry against it.