Hazards of Contamination and Irradiation

Section 1 of 6Two ways of being exposed

Feature	Irradiation	Contamination
What it is	Exposure to radiation from a source outside the object	Unwanted radioactive atoms getting onto or into an object
Does the object become radioactive?	No	Yes, because it now carries radioactive atoms
When does exposure stop?	When the source is removed or the object moves away	Only when the radioactive atoms are removed or have decayed
Typical protection	Distance, time limits, shielding	Sealed suits, gloves, masks, careful cleaning

Section 2 of 6Why contamination is worse

1Atoms stick or enter

• Atoms stick or enter Radioactive material may land on skin or be inhaled, swallowed or enter a wound.

2Source travels with you

• Source travels with you You cannot step away from it, so exposure continues for as long as the atoms stay in your body.

3Internal organs hit

• Internal organs hit Alpha emitters inside the body are especially harmful because the radiation is absorbed by the surrounding tissue.

4Cell damage

• Cell damage Ionising radiation can damage cells and DNA, leading to mutations and cancer.

Section 3 of 6Protecting people

Shielding

• Shielding Lead absorbs most radiation, so lead-lined aprons and screens reduce irradiation.
• A lead apron is worn during an X-ray to protect parts of the body not being imaged.

Airtight suits

• Airtight suits Workers where a radiation leak may have occurred wear sealed suits to stop radioactive atoms from getting on or into them.

Limit exposure

• Limit exposure Keeping a distance from sources and spending as little time near them as possible both lower the dose.

Section 4 of 6Case study: Chernobyl

Chernobyl, 1986

What happened

• What happened An explosion at the nuclear power plant in Ukraine released large amounts of radioactive material into the air.

Response

• Response Hundreds of thousands of people were evacuated to prevent them being contaminated.

Long-term effect

• Long-term effect An exclusion zone of about 2600 km² remains because radioactive contamination of the ground is still high.

Section 5 of 6Key terms

Term	Meaning
Irradiation	Exposing an object to radiation from a source, without the object itself becoming radioactive.
Contamination	The presence of unwanted radioactive atoms on or in an object or person.
Ionising radiation	Radiation that can remove electrons from atoms and damage living cells.
Shielding	A material, such as lead, that absorbs radiation to protect people.
Exclusion zone	A region that people may not enter because of high radiation levels.

Section 6 of 6Exam technique

1

Saying that an irradiated object becomes radioactive - only contamination makes something radioactive.

2

Assuming moving away from the source solves contamination; the radioactive atoms may still be on or in the body.

3

Writing that lead suits stop contamination; an airtight suit prevents atoms getting in, while lead absorbs radiation for irradiation.

4

Forgetting to mention DNA damage and cancer when asked about the hazard of radiation.