26 Sep 2022

Application of Non-Parametric Control Charts (Statistical Process Control) to radioxenon distribution at International Monitoring System stations of the CTBTO

Out-of-control shifting of a physical phenomenon © http://eng.sut.ac.th/mae/maeweb/sites/default/files/Ch5%20Methods%20and%20Philosophy%20of%20Statistical%20Process%20Control.pdf
Out-of-control shifting of a physical phenomenon © http://eng.sut.ac.th/mae/maeweb/sites/default/files/Ch5%20Methods%20and%20Philosophy%20of%20Statistical%20Process%20Control.pdf

The detection of atmospheric radioxenon activity concentrations plays a key role in understanding radioactive emissions from nuclear power plants and medical isotope production facilities. Among all possible fission products Noble Gas isotopes, namely 131mXe, 133mXe, 133Xe and 135Xe, generally known as radioxenon, are of particular interest since they are periodically released in the atmosphere by civil sources as medical isotope production facilities, nuclear power plants and nuclear research reactors.

Xe-133 activity concentrations measured at IMS MNX45 station; mean assessments and variance assessments, using the RSP non-parametric method and comparison with the IDC method © R. Gualdi, Studio statistico non-parametrico delle misure di radioxeno per la verifica del Trattato per l’abolizione totale dei Test nucleari (CTBT), Master’s degree thesis, University of Bologna, 2020
Xe-133 activity concentrations measured at IMS MNX45 station; mean assessments and variance assessments, using the RSP non-parametric method and comparison with the IDC method © R. Gualdi, Studio statistico non-parametrico delle misure di radioxeno per la verifica del Trattato per l’abolizione totale dei Test nucleari (CTBT), Master’s degree thesis, University of Bologna, 2020

Making conclusions about a n unexpected release of radioxenon is a very complex task. The Comprehensive Test Ban Treaty Organization (CTBTO) has envisioned for its verification purpose the realization of a network of monitoring station worldwide, that is almost completed. We have tried to properly characterize both the radioxenon atmospheric background levels and the possible anomalous radioxenon values that are larger than the average atmospheric background level for each active station of the International Monitoring System of the CTBTO. With this aim we have used and compared several statistical inference-based non-parametric distribution-free methods  (not based on particular distributional assumptions). They can be used on a stream of single observations (no subgroups), can be able to estimate the presence of change points in the process location and/or process scale, can work with a desired false alarm probability, or a given ARL(H0), can offer some post-signal diagnostics to properly interpret the results.

Xe-133 activity concentrations measured at IMS SEX63 station; mean assessments and variance assessments, performed using the RSP non-parametric method and comparison with the IDC method  © R. Gualdi, Studio statistico non-parametrico delle misure di radioxeno per la verifica del Trattato per l’abolizione totale dei Test nucleari (CTBT), Master’s degree thesis, University of Bologna, 2020
Xe-133 activity concentrations measured at IMS SEX63 station; mean assessments and variance assessments, performed using the RSP non-parametric method and comparison with the IDC method  © R. Gualdi, Studio statistico non-parametrico delle misure di radioxeno per la verifica del Trattato per l’abolizione totale dei Test nucleari (CTBT), Master’s degree thesis, University of Bologna, 2020

 

Contact

Giuseppe Ottaviano
ENEA
giuseppe.ottaviano@enea.it