Unit 1.8

Question 1

What are the major sources of natural (background) radiation?

Answer 1

Radon is the biggest; others include Series radiation (Thorium, Neptunium, Uranium, Actinium), internal radiation (potassium-40), cosmic radiation.

Question 2

Decay of what atom creates radon, and how does it impose radiation damage?

Answer 2

U-238 decays in to Rn-222; it migrates into your house and is breathed in, giving internal alpha radiation. Radon (Rn-222) is the major contributor, but Thoron (Rn-220) also plays a role (Th-232 decay into Rn-220).

Question 3

Why are bananas terrible for you and you should never eat them?

Answer 3

K-40. This is mostly a joke.. but I seriously hate bananas.

Question 4

Name the major radioisotopes associated with the following common consumer items.
Pathway Lighting/Exit Signs
Watches
Tobacco
Smoke Detectors
Gas Mantles

Answer 4

Pathway Lighting/Exit Signs; H-3 (tritium)
Watches: Radium-226, Promethium-147
Tobacco: Smoking is 1/2 as bad as 420… so its the two 210 mass number elements; Pb-210, Po-210.
Smoke Detectors; Americium-241
Gas Mantles: Thorium-232 (which makes the Thoron (Rn-220) that we worry about with Radon).

Question 5

What is the average annual effective dose equivalent from all sources on the US population in 1987 (Report 94) and 2006 (Report 160)?

Answer 5

Report 94 (1987): 360mrem
Report 160 (2006): 620mrem.
Biggest difference in human dosing is medical use (imaging, nuclear medicine, etc).