Camera Takes a Fall Before the Day's Work
Loading at the shop at 05:30, a 35 Ci iridium-192 crank-out camera slides off the tailgate and lands on asphalt on its lock-ring end, a fall of about 3 ft. There is a visible dent beside the lock ring and a fresh paint crack. The crank turns smoothly, the lock ring rotates to the locked position, and the source has never been cranked out. Your survey meter, checked on its check source that morning, reads 60 mR/h on the dented surface, 12 mR/h at 1 m, and 1 mR/h at 3 m, with background elsewhere around the truck. An exposure job is scheduled two hours away, the crew is loaded, and the client is waiting. The camera's certificate of compliance and shipping papers are in the cab.
1. Interpret the survey readings. Do they show that the source is fully shielded, fully exposed, or something in between?
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Estimate what 'fully exposed' would look like. For 35 Ci of Ir-192, unshielded at 1 m: 0.48 × 35 / 1² = 16.8 R/h = 16,800 mR/h.
Compare with the reading: 12 mR/h ÷ 16,800 mR/h ≈ 0.0007, i.e. about 0.07% of an unshielded source. In equivalent terms the camera is behaving as though roughly 25 mCi of unshielded material were present.
What that tells you:
- It is not a source lying outside the shield - a fully exposed 35 Ci source at 1 m would be measured in tens of thousands of mR/h, and the inverse-square falloff from 12 to 1 mR/h between 1 m and 3 m is roughly consistent, so the field is small, not huge.
- It is not clean, either. A sound camera with the source properly seated should read near background at 1 m, and 60 mR/h at the dented surface is well above the camera's own baseline.
The honest conclusion is: you cannot certify the source is properly seated or that the shielding is intact, and the dent is at the lock ring - the exact feature that positions and retains the source. Small leakage or a slightly displaced source is consistent with these numbers, and 'small' is not a category you are allowed to accept without a basis.
2. Decide whether the camera goes on the truck, and whether the job runs today.
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The job does not run today. A camera with a fresh impact near the locking mechanism and readings above its normal baseline is out of service until the RSO authorizes return to service. Client schedule is not a factor in that decision; the crew's two-hour drive is a cost, not a reason.
Moving it is a separate question from using it. The external radiation numbers, on their face, sit inside the transport limits for a package: surface 60 mR/h is below the 200 mR/h surface limit, and the transport index at 1 m is about 12/10 = 1.2, below the limit of 10. That means the reading, by itself, would not block a shipment and would put the package in the Yellow-III label category (above the 1 mrem/h-at-1-m threshold for Yellow-II).
But the numbers are not the whole test. Impact damage raises two questions the readings do not answer:
- Can the source shift? The dent is beside the lock ring. If the source can move inside the shield, a truck ride turns a contained problem into an uncontrolled one.
- Is there removable contamination? A damaged camera and a source capsule that took an impact require a wipe test before anything goes into a cab.
Correct sequence: wipe test, survey the loaded configuration, RSO assessment of the damage against the certificate of compliance and the manufacturer's guidance, and - if it must move - movement under the RSO's direction with the package properly labeled and the vehicle placarded as required for Yellow-III. If there is any question of source movement, it moves in an approved overpack or not at all. A replacement camera goes out for the job.
3. Identify what should have prevented this and what the corrective actions should be.
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Immediate cause: the camera was not secured for transport. A 3 ft fall from a tailgate during loading is a handling failure, not bad luck.
System causes to look for:
- No written or enforced procedure for loading and securing the camera (chocks, tiedown, or a dedicated transport case) and no second-person check.
- Pre-job inspection performed at the destination rather than at the point of loading, so the drop was never tied to a documented inspection.
- No established baseline of what 'normal' shielded readings look like for this camera, which is why nobody could say immediately whether 12 mR/h at 1 m was high or expected.
Corrective actions:
- Secure the camera physically for transport; add the check to the pre-load checklist and require it be signed.
- Record baseline contact and 1 m readings for each camera at the last calibration/leak test and post them in the truck, so an abnormal reading is obvious in the field.
- Any impact above a defined threshold (for example, a drop of more than a few inches onto a hard surface) triggers automatic removal from service and RSO notification - no judgement call in the field.
- Wipe test and document before return to service, and obtain manufacturer or RSO authorization before it is used again.
- Brief the crews on the event so the next drop is reported instead of being quietly loaded.