ARPANSA verification program 2022/2023

ARPANSA scientists independently verified radiation levels at the Australian Nuclear Science and Technology Organisation's (ANSTO) Lucas Heights site in October 2022. Verification samples of air filters, water and ground water taken according to the 2022-2023 sampling program were also analysed at ARPANSA’s radioanalytical laboratory.

ARPANSA’s results are consistent with ANSTO’s Monitoring Results. There were no detections above the minimum detectable activity (MDA) for samples analysed by in-situ gamma spectrometry for relevant radionuclides¹. Values at or below the MDA indicates they are indistinguishable from background radiation. If measurements indicated that radiation was detected above investigation levels, ARPANSA would investigate and take relevant regulatory actions.

The survey conducted by the ARPANSA team shows no indication of an abnormal release or significant change to the levels measured at the outset of the monitoring program, which began in 2019.

Verification samples

ARPANSA’s Radioanalytical Laboratory analysed duplicate samples of TC45 carbon cartridges from ANSTO’s emission stacks, ground water sample from the Little Forest Legacy site (LFLS) and water samples from the main disposal pipeline (MDP) Weir. 

Stack samples were analysed by HPGe gamma spectrometry for I-131. Comparison of the I-131 activities present in the filters at the time of measurement enables ARPANSA to assess the precision of ANSTO’s monitoring and detection systems and the ability to detect a release or emission above the notification level. The high precision and ability to detect a release is confirmed by each measurement being less than 0.001% of the notification level.

Water samples were analysed using liquid scintillation counting for tritium (LFLS) and for gross alpha and beta radioactivity (MDP Weir). Tritium infiltration into the groundwater is the most significant concern for the LFLS and is also the most plentiful waste product that was deposited at the site. All ARPANSA measurements for tritium were in good agreement with ANSTO results and were well below the World Health Organization (WHO) drinking water guidance level for tritium (10,000 becquerels per litre). Gross alpha and beta analysis is a screening procedure to assess whether further specific analyses are required. The results from both laboratories using liquid scintillation counting (LSC) are well below the screening level of 0.5 Bq/L and provide confidence that no transport or migration of alpha or beta-emitting radionuclides has occurred from the ANSTO site.

Results for Tritium concentrations found in groundwater samples*:

^{*WHO drinking water guideline value for tritium is 10,000 Bq/L.
**95% CI where k=2.}

Conclusion

Overall, results showed:

• no detectable gamma radiation from radioisotopes of interest at the time of sampling
• all water measurements were below the drinking water guidelines values
• stack sample measurements were well below notification levels
• analysis of duplicate/verification samples were in agreement with ANSTO’s results

These results indicate that ANSTO’s operation at Lucas Heights has negligible impact on the environment. The public’s exposure to radiation at Lucas Heights is no more than at any other location where only background radiation is present. ARPANSA will continue to monitor and verify ANSTO’s environmental management as part of our ongoing regulatory oversight. 

¹ Radionuclides of interest for off-site in-situ gamma spectrometry are Co-60, Mo-99, Tc-99m, I-123, I-131, I-132, I-133, Cs-137