ASNT Industrial Radiography Radiation Safety Practice Test

If you have 88 Ci of Ir-192 (3256 GBq), where should you place your high radiation boundary knowing the R factor is 5.2 R (52 mSv)?

1. 50 ft (15.24 m)

2. 20 ft (6.1 m)

3. 68 ft (20.73 m)

4. 100 ft (30.48 m)

The correct answer is: 68 ft (20.73 m)

To determine the appropriate placement of the high radiation boundary for 88 Ci of Ir-192, one must consider both the activity of the isotope and the associated radiation dose. The R factor provides a measure of how much radiation exposure can be expected at various distances from the source. In this case, an R factor of 5.2 R (or 52 mSv) is indicative of the radiation levels that would necessitate establishing boundaries to ensure safety. When evaluating the options provided, the correct placement of the high radiation boundary is critical to protect individuals from excessive radiation exposure. The ideal distance must be calculated based on the R factor and the specific activity of iridium-192, accounting for how radiation intensity diminishes with distance. Placing the boundary at 68 feet (20.73 m) appropriately reflects the balance between safety and operational necessity. This distance is sufficient to keep radiation levels within acceptable limits, ensuring that individuals outside this boundary are not exposed to doses that could exceed regulatory safety standards for industrial radiography work. Using other distances, such as 50 ft, 20 ft, or 100 ft, could either expose individuals to more radiation than is safe or be unnecessarily conservative, respectively. The established R factor indicates that 68 feet