What happened?  

Two Radiation Safety staff members were processing incoming radioactive materials shipments. During the task, one technician was clearing empty shipping boxes from the work area and inadvertently removed and disposed of a box still containing a Co-57 dose calibrator standard (5.55 mCi). When the error was discovered later that day, the Radiation Safety team conducted a recovery operation using a NaI detector and four technicians to locate the source within the facility dumpster. The source was recovered inside the lead pig in which it had been shipped, and no contamination was detected in the dumpster or surrounding area.

What was the cause? 

• Immediate cause: An unopened shipping box containing a 5.55 mCi Co-57 sealed source was removed from the receiving area with empty packaging and placed in the facility dumpster, because the technician clearing the area could not visually distinguish it from already-processed empty boxes.
• Underlying causes:
  • Full and empty shipping boxes were co-located on the same work surface with no physical or visual separation.
  • Boxes were not marked "source inside" or "cleared for disposal" at the relevant points in the workflow.
  • Housekeeping of empty packaging was performed during, rather than after, shipment processing.
  • No check-before-disposal verification step required confirmation that a box was empty before it left the receiving area.
  • The source had not yet been logged into inventory or transferred to its designated secure storage location at the time of disposal.
• Root cause: Gap in the receiving-area workflow and inventory-control procedure. Specifically, the SOP for receiving radioactive-materials shipments did not (a) enforce physical separation of in-process and disposal-ready packaging, (b) require source-in-hand to source-in-storage transfer before any housekeeping, (c) include a verify-empty step before any box leaves the receiving area, or (d) require real-time inventory reconciliation at the end of each shipment. This is a system-level workflow failure, not an individual performance failure.

How can incidents like this be prevented? 

• Eliminate the co-location of full and empty shipping packaging. Reconfigure the receiving workflow so that in-process shipments and empty packaging for disposal physically cannot share the same work surface. The simplest implementations:
  • A one-way receiving bench: shipments enter on one end, are opened, sources are transferred to storage, and only then is empty packaging moved to a separate disposal station (ideally in a different room or behind a barrier).
  • Separate receiving and disposal rooms entirely, where feasible.
• Eliminate the "clear empty boxes during active processing" step. Housekeeping for packaging materials occurs only after all shipments in the current session have been fully processed and their sources have been logged in storage. No mid-session disposal.
• Consider a vendor-side change: many radioactive materials suppliers will, upon request, use distinctively colored or marked outer packaging (e.g., a colored sticker, tape, or band) that remains on the box until the source is removed. If your supplier offers this, use it; if not, ask. Source-still-inside visual signaling at the supplier level is a substitution control, because it removes the reliance on receiver-side labeling. Proper labeling of empty and non-empty radioactive use items.
• Physical separation zones: use colored floor tape, a marked bin system, or a physical rack to designate three distinct areas on the receiving bench:
  • Incoming / unopened (source may be inside)
  • Opened / source removed, awaiting verification (verify-empty zone)
  • Cleared for disposal (empty, confirmed)
    Boxes move one-way through the zones and can only enter the disposal waste stream from the third zone.
• "Source inside" signaling on the box itself: as soon as a radioactive-materials box arrives, place a brightly colored "SOURCE INSIDE — DO NOT DISCARD" tag, sticker, or magnet on the outside. The tag is removed only after the source is transferred to storage, and the box has been visually verified as empty. This is a cheap, high-reliability engineering control.
• Lockable waste-area access control: the disposal dumpster or waste staging area should not be freely accessible from the receiving space during active processing. A locked or access-controlled waste stream (even as simple as a keyed bin in-room and a scheduled transfer to the main dumpster) prevents "accidental toss" events and shortens the recovery window if they do occur.
• Radiation detector at the disposal transition point: a benchtop NaI or GM detector positioned at the exit from the receiving area — or a portal-style detector — that surveys any box leaving for disposal. If a source is accidentally boxed, the detector catches it before the box leaves the room. This is standard in many nuclear medicine and radiopharmaceutical receiving areas. The fixed survey can be as simple as a handheld detector passed over each outgoing box as part of the verify-empty step.
• Storage lockers near the receiving bench: sources move directly from opening to logged storage in a secured, shielded location within arm's reach of the receiving bench. Travel distance between opening and storage is a known failure mode — the longer the path, the more likely a source is to be set down and forgotten.
• Revise the SOP for receiving radioactive-materials shipments to specify, in order:
  1. Shipment arrives; "SOURCE INSIDE" tag applied immediately on receipt.
  2. Package survey performed per regulatory requirements (external contamination, dose rate).
  3. Box opened on the receiving bench; source removed and transferred directly to designated secure storage.
  4. Source logged into inventory (activity, isotope, manufacturer, date, location).
  5. Box moved to verify-empty station; opened, inspected, inverted, confirmed empty.
  6. "SOURCE INSIDE" tag removed by a second person.
  7. Empty box moved to disposal staging.
  8. At the end of the workflow, disposal staging is cleared to the waste stream.
• Enforce the single-session rule: all shipments received in one session are fully processed (steps 1–6 above) before any empty packaging is cleared. No parallel disposal during active processing.
• Two-person verification at disposal transition: the person disposing of any packaging from the receiving area is not the same person who processed the shipment. The second person confirms the tag is removed (implying verify-empty was done). This is a simple, high-reliability administrative control against single-person error.
• Real-time inventory reconciliation: at the end of each receiving session, the day's shipping manifests are reconciled against the inventory log and the physical contents of storage before the area is released. A source that is on the manifest but not in storage is flagged immediately — ideally before the waste stream has left the building.
• Receipt-to-storage time limit: the SOP specifies a maximum interval (e.g., 15 minutes) between opening a box and the source being in secured storage. This prevents "set it down for a minute" situations.
• Training on the workflow, not on "being careful": the training for receiving personnel is about the steps and the physical zones, not general admonitions to pay attention. Frame the workflow itself as the control, and train to its specifics.
• Audit the workflow quarterly: observe an actual receiving session and check for zone discipline, tag use, verify-empty, and two-person disposal verification. Findings go to the Radiation Safety Committee / RSO.
• Update the license-required written procedures if this workflow is covered by your radioactive-materials license. Workflow changes should be reflected in the licensed procedures, not just in local practice.