Video Transcript
Which of the following would
produce a greater risk of radioactive contamination? (A) A very soft and crumbly
radioactive substance being rubbed against a very hard and tough nonradioactive
substance. Or (B) a very hard and tough
radioactive substance being rubbed against a very soft and crumbly nonradioactive
substance.
In order to answer this question,
let’s first remember that radioactive contamination occurs when unstable atoms from
a radioactive object are transferred to a different object. Next, we can consider a few
different scenarios with varied substances to decide which types of substances are
the most efficient at contaminating other substances. The two answer options discuss
soft, crumbly substances and hard, tough substances.
First, consider the example of a
piece of chalk and a chalkboard. A piece of chalk is soft and
crumbly, and a chalkboard is hard and tough. When a piece of chalk is rubbed
against a chalkboard, parts of it crumble off the chalk and are transferred to the
chalkboard.
Next, let’s think about sand and a
shovel. The shovel is hard and tough, and
the sand is soft and crumbly. Even if the shovel is used to dig
in the sand or rub against the sand, parts of the shovel will not rub off and
transfer to the sand.
The same principles apply to
radioactive materials and nonradioactive materials. Just like the chalk, if a
radioactive material is soft and crumbly, then it will easily transfer pieces to a
hard and tough surface, such as the chalkboard. And just like the shovel, if a
radioactive material is hard and tough, then it will not easily transfer pieces to a
soft and crumbly surface, such as the sand.
With this example, we can see that
the correct answer to the question is option (A). A very soft and crumbly radioactive
substance being rubbed against a very hard and tough nonradioactive substance
produces the greater risk of radioactive contamination.
