A Bayesian method with empirically fitted priors for the evaluation of environmental radioactivity: application to low-level radioxenon measurements

Abstract

To cite this version:Isabelle Rivals, Clément Fabbri, Guillaume Euvrard, Xavier Blanchard. A Bayesian method with empirically fitted priors for the evaluation of environmental radioactivity: application to low-level radioxenon measurements. Journal of Radioanalytical and Nuclear Chemistry, Springer Verlag, 2012, 292 (1) Corresponding author: Isabelle RivalsAbstract The decision that a given detection level corresponds to the effective presence of a radionuclide is still widely made on the basis of a classic hypothesis test. However, the classic framework suffers several drawbacks, such as the conceptual and practical impossibility to provide a probability of zero radioactivity, and confidence intervals for the true activity level that are likely to contain negative and hence meaningless values. The Bayesian framework being potentially able to overcome these drawbacks, several attempts have recently been made to apply it to this decision problem. Here, we present a new Bayesian method that, unlike the previous ones, presents two major advantages together. First, it provides an estimate of the probability of no radioactivity, as well as physically meaningful point and interval estimates for the true radioactivity level. Second, whereas Bayesian approaches are often controversial because of the arbitrary choice of the priors they use, the proposed method permits to estimate the parameters of the prior density of radioactivity by fitting its marginal distribution to previously recorded activity data. The new scheme is first mathematically developed. Then, it is applied to the detection of radioxenon isotopes in noble gas measurement stations of the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty.

A Reliable Absolute and Relative Bayesian Method for Nuclear Decommissioning: Low-Level Radioactivity Detection With Gamma-Ray Spectrometry

“…Such results paved the way to an implementation of the Bayesian approach for xenon detection. Rivals et al (2012) [13] developed a Bayesian method using specific priors for the detection of radioxenon isotopes in noble gas measurement stations of the International Monitoring System (also related to the Comprehensive Nuclear-Test-Ban Treaty Organization). Results showed that the detection capability benefited from the estimation of the radioactivity prior density probability, the confidence interval for the true radioactivity level, and the probability of no radioactivity being present.…”