What instruction applies to SIN in relation to the RIID system and PRD?

• A. Move in and observe
• B. Back away until it reads number 8, then secure the scene
• C. Do nothing
• D. Notify a supervisor

Answer: (B)

When a RIID is involved, the immediate priority is to minimize exposure by increasing distance from the potential source and securing the area for proper handling. The SIN instruction in this context directs you to back away until the PRD shows a reading of eight, then secure the scene. This threshold on the PRD is the cue that you have moved to a safer distance where the radiation level is reduced enough to proceed with containment and further actions. By backing off to this safe distance, you lower the dose you could receive and prevent spread or contamination, giving time for supervisors and radiological experts to respond. Moving in closer would raise exposure, doing nothing leaves the hazard unmanaged, and only notifying a supervisor without creating the safe distance misses the critical first safety step.