Radiation reality check

November 24th, 2014

The Sydney Morning Herald has gone for the nuclear option today, claiming that the use of minute traces of radioactive isotopes under close supervision and strict approval is not being disclosed by gas developers in New South Wales.

The article reports the use of Caesium-137 (also referred to as Cesium-137 or CS-137) in density measuring devices – densitometers – that are used to monitor and measure various activities during the drilling and well completion processes.

It’s worth highlighting some facts about Caesium, the use of densitometers, and the strict licensing and safety measures in place while it is being used.


Caesium-137 is one of the most common radioisotopes used in industry.

Thousands of devices use caesium-137 for a range of applications:

  • Thickness Gauging – Caesium-137 is used in the measurement of light alloys, glass, plastics, and rubber for which beta sources are not suitable.
  • Oil Well Logging (OWL) – Caesium encapsulations are used to characterise rock strata during oil well logging applications such as wireline logging and logging while drilling.
  • Flow Gauging – Caesium and a detector are placed on opposite sides of the material to be measured. Gamma radiation transmitted through the sample is then directed related to the sample thickness.
  • Level Gauging – Cs-137 is used to monitor process fluids without making physical contact with package contents.
  • Medical – Gamma rays from Caesium are used in radiotherapy as a treatment for brachytherapy.

(Source: http://www.qsa-global.com/sources/industrial-isotopes/cesium-137.aspx)

CS-137 is used in minute amounts in sealed stainless steel capsules (sometimes referred to as encapsulated devices).


As the name suggests, densitometers measure the density of materials and fluids.

In the case of oil and gas production, a densitometer is used after a well is drilled to gather geological information.

Where a well is to be hydraulically fractured, a densitometer can be used to measure the density of fracturing fluids.

It’s important to note that at no time does CS-137 come in contact with fracturing fluid or ​any parts of the ground in the vicinity of a natural gas well – because of the strict controls under which it is used, and the containment devices that the material is held within.

The device is used by licensed technicians, and is removed from the well after the procedure is complete.

The typical amount of CS-137 is about the size of a headache tablet.

Licensing and safety measures

In NSW, the use of CS-137 is governed by the Radiation Safety Act and the Radiation Safety Regulations – with oversight and enforcement from the Environment Protection Authority (EPA).

Both the company and the individual technicians using the device are required to be licensed, and when not in use, the material is required to be securely stored in lead and concrete lined canisters.

According to the same Sydney Morning Herald article that raises ‘health concerns’, the NSW environmental regulator, Mark Gifford, says:

“The EPA is not aware of any incidents or accidents involving caesium-137 and CSG in NSW.”


The Sydney Morning Herald article reports – without question – the claims of anti-development activists about an alleged lack of disclosure by companies about the use of radioactive materials.

That claim is completely without foundation, and shows the level of research that activist groups don’t undertake before they rush to make unsubstantiated claims.

AGL’s statement about today’s claims can be read here, while the Santos statement is here.

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