Environmental Radiation

ANSTO monitors environmental gamma radiation at a station in Engadine, about 3km south-east of Lucas Heights, and the data are reported every 15 minutes. This environmental radiation is almost completely from natural background radiation, although ANSTO's controlled airborne discharges may occasionally be detectable. A range from 30 to 60 nGy/h was measured in ARPANSA's 2002 survey of natural background radiation near Engadine.

ANSTO uses environmental radiation data to evaluate atmospheric dispersion from its site at Lucas Heights.

• Gamma radiation is a penetrating form of short wavelength electromagnetic radiation, similar to x-rays.
• The environmental radiation graph (above) shows measurements in nanoGrays (nGy) which are units of absorbed radiation dose commonly used in environmental monitoring. A nanoGray is one billionth (one thousand millionth) of a Gray.
• "Spikes" in the environmental radiation graph (above) may occur during the regular calibration checks of the instrument that are needed to ensure accurate data. Gaps appearing in either graph are usually associated with delayed radio transmission of data from Engadine.
• A temporary rise in environmental gamma radiation is often detected when it rains. This occurs because rain affects the behaviour of naturally occurring radionuclides, such as the gas radon. These radionuclides can be absorbed by rain drops and temporarily concentrated near the ground. Also, radon naturally builds up in air spaces in the soil and can be released when rain soaks into the ground.

See a list of definitions and information on other types of radiation (e.g. alpha and beta particles) in our glossary of nuclear terms.