P4: Radiation for Life

Lesson 11:Uses of Radioisotopes

(part 1)

Lesson Objectives

• Identify sources of background radiation.

• Understand the use of alpha sources in smoke detectors.

• Understand how radioisotopes are used as industrial tracers

Success CriteriaGrade E Grade C Grade A

Recall the main sources of background radiation

Recall background radiation can come from man-made sources and waste products

Evaluate the relative significance of sources of background radiation

Recall industrial examples of the use of tracers

Describe how tracers are used in industry

Explain why gamma radiation is used in an industrial tracer

Recall that alpha sources are used in some smoke detectors

Explain how a smoke detector with an alpha source works

Key Words:

background radiation • cosmic rays • radioisotope • alpha • decay • tracer • gamma

Background radiation:

Granite rocks contain small amounts of radioactive uranium. When uranium decays it emits radon gas which is also radioactive. Wales, Devon, Cornwall. Lots of granite!!

Calculating background radiation

‘Radioactive Penetration’!

Demo!

Tracers

Radioisotopes are used as tracers in industry, research and medicine.

Tracers are used to: Detect leaks or blockages in underground pipes Find the routes of underground pipes Track dispersal of waste Monitor the uptake of fertilisers in plants Check for a blockage in a patient’s blood vessel

Locating a leak/blockage A very small amount of a suitable radioisotope is put

into the pipe A detector is passed along the ground above the path

of the pipe to track the progress of the radioisotope An increase in the activity is detected in the region of

the leak or blockage and little or no activity is detected after this point.

Smoke alarms contain a weak source of alpha radiation.

How can radiation detect a fire?

The alpha particles ionize the air.

If there is smoke present, it interacts with the ions produced by the alpha particles and ionization is reduced.

This means that less current is flowing through the air, which causes the alarm to sound.

α

α

smoke particle

Calculating background radiation(Higher)

Multiple-choice quiz

Success CriteriaGrade E Grade C Grade A

Recall the main sources of background radiation

Recall background radiation can come from man-made sources and waste products

Evaluate the relative significance of sources of background radiation

Recall industrial examples of the use of tracers

Describe how tracers are used in industry

Explain why gamma radiation is used in an industrial tracer

Recall that alpha sources are used in some smoke detectors

Explain how a smoke detector with an alpha source works

Key Words:

background radiation • cosmic rays • radioisotope • alpha • decay • tracer • gamma