Australia's Science Forum

Could anyone recommend the easiest and most cost effective way of testing radioacticve sources? I read they need to be tested every 5 years. I would hazard a guess that ours have never been tested.
Thanks
Carol

Hi Carolg,

You should be able to use your school's geiger counter to test the sources.
Save having to pay someone else to do it for you. You'll soon know if they've lost their oomph.

Cheers
Judy

Hi All,

Testing the Radioactive Sources may be a bit tricky in schools because of the Instrumentation used. Usually you would put the sources into a XRD or X-Ray Diffractor and fire X-Rays at it. But these instruments are worth Hunderds of thousands of dollars and are located at Uni.

The amount of Diffraction is then measured then the results come through. This will determine how much of the isotope has undertaken its natural Half-Life Breakdown.

But there is a simpler method, utilising the Geiger counter, fire each source at it for a given fixed time (this being 5 Minutes) then record the results. Keep these results in an Excel Spreadsheet and keep these results until next time you measure.

Measure these sources again the following year and also tabulate these results.

Begin by putting two sets of data into a graph and visually determine whether the Radioisotope is decaying or how long it is taking for the decay to take place.

Keep in mind that the following Isotopes have the Half-Life as indicated:

Americium 241 - Alpha emitter - 432 year Half-Life
Strontium 90 - Beta emitter - 28 year Half-Life
Cobalt 60 - Gamma emitter - 5.24 year Half-Life

For example;
If there was 1 gram of Strontium 90 in 28 years time there will be 0.5g of Strontium 90 and 0.5 grams of the more stable Yttrium 90.

The Isotope I have listed under-go decay at their Half-Lives and decay into more stable Isotopes which do not emit any radiation due to their stability, so all-in-all after their half life only half of each sample will be emitting radiation.

Names of the stable Isotopes after the Half-Life Decay:

Americium 241 Decays by half to Neptunium 237
Strontium 90 Decays by half to Yttrium 90
Cobalt 60 Decays by half to Nickel 60.

I hope this has been informative for you..

Robb......

In SA we are required to follow the National Health and Medical Research Council “Code of Practice for the Safe Use of Ionizing Radiation in Secondary Schools, (1986)’ This code includes the need for testing and says:

"10.2 The responsible teacher shall carry out a routine check, at intervals not exceeding five years, of the condition of each sealed source. The teacher shall also arrange for these checks following any event such as an accident or fire. which may reasonably be suspected of causing damage to the sources. Sources more than 10 years old should be wipe tested.

A wipe test is designed to ensure that the sealing of a radioactive source is not breaking down. It consists of wiping the surface of the source with a moist filter paper, placing the filter in a small plastic bag, and then submitting it to the statutory authority for assessment. Details to be included with each test shall identity the source tested and shall provide a return address for any reports."

In 2001 the appropriate ‘statutory authority’ was
The Radiation Section (att: graham Palmer)
Radiation Protection Branch
Dept of Human Services
P0 Box 6, R(JNDLE MALL SA 5000

NB: Samples can be sent by post.