To satisfy IAEA regulations for a Type B(M) package, irradiated fuel flasks must be demonstrated to withstand (without loss of containment or shielding function) all of the following severe accident scenarios:
| Test | Condition | What it Simulates |
|---|---|---|
| Drop test 1 | Free fall from 9 metres onto a flat, unyielding surface | High-speed road/rail accident impact |
| Drop test 2 | Free fall from 1 metre onto a spike (puncture bar) | Penetration by a sharp object in a crash |
| Fire test | 800 degrees C engulfing fire for 30 minutes | Sustained fire following a transport accident |
| Immersion test | Submerged in 15 metres of water for 8 hours | Submersion after a bridge collapse or marine accident |
These tests are performed sequentially on the same flask specimen, demonstrating that even after being dropped, punctured, burned, and submerged, the flask maintains its safety functions.
Key point for exams: These tests are very conservative. Real-world accidents are almost always less severe than the test conditions. Transport flask safety records worldwide are excellent --- there has never been a significant release of radioactivity from a properly certified transport flask in a transport accident.