Training Scenario for Radioactive source located in a parking lot.
1. Poor signal due to concrete pillars and vehicles between source and instrument
2. Poor signal due to concrete pillar immediately in front of instrument (high shielding)
3. Poor signal due to to concrete pillar despite distance from source
4. Possible signal as in line of sight of source however metal car body shielding source
5. Distance halved from point 4 so twice the potential dose to read better signal less metal in way
6. At point of source, simulated radiation seen through glass of tailgate, light clusters (plastic) and shuts
7. Poor signal due to shielding of metal body work on signal
8. Better signal due to halving of distance (Inverse square law)
9. Good signal through poorly shielded glass and plastic fittings
10. Full source exposure giving maximum signal
This exercise is an excellent way to introduce trainees to the complexity of Radiation Monitoring and particularly to reinforce the 3 major principles of safe monitoring
• TIME — The less time you spend near the radiation source, the lower your exposure will be.
• DISTANCE — The greater your distance from the source, the less your exposure will be.
Radiation exposure decreases with distance according to the inverse-square law. That is, if you triple your distance from the radiation source, your exposure will decrease by a factor of 9 (three squared).
· SHIELDING — External exposure to radiation can be partially blocked by the use of
shielding. Traditionally, shielding is made of lead or concrete. However, staying be hind vehicles, buildings, or other objects will also decrease exposure.
In this scenario the STS 913VR source is used. This source gives a 360 degree simulated radiation field which allows the source to be approached in any direction. Trainees should be encouraged to investigate the different shielding properties of the structure and vehicle. The hazards of rushing the monitoring can be shown by approaching from a shielded position (where there may be little or no signal) and then exposing the source by opening the trunk at which point the instrument will register immediately to full scale.
The signal strength can also be adjusted using the remote control to make the detection harder to achieve.