An air sample collected by drawing a known volume of air through a Marinelli container is used to measure which form of contamination?

• A. Iodine
• B. Particulate
• C. Noble Gas
• D. Tritium

Answer: (C)

The key idea is that the Marinelli container is used to present a gas-phase sample to a gamma detector in a fixed geometry, which is ideal for counting airborne noble gas radionuclides. Noble gases remain in the gaseous state in air and don’t readily adhere to surfaces or form particulates, so drawing a known volume of air into a sealed Marinelli container allows those gamma-emitting gases to be counted directly. This makes the method well-suited for measuring contamination in the form of noble gases like xenon or krypton.

In contrast, iodine contamination is typically captured on charcoal and processed for counting, particulate contamination is captured on filters, and tritium is often measured in water or as a different chemical form that isn’t counted as a gas in a Marinelli setup. So the form that this air-sampling method targets is noble gases.