Determination of correction factors for alpha activity measurements in the environment (conditions of high dust loading)

Geryes, Tony; Monsanglant-Louvet, Céline

doi:10.1093/rpd/ncq451

Cited by 6 publications

(3 citation statements)

References 4 publications

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“…Beta emissions of 210 Pb cannot be directly measured because of their energies that are too low, so that 210 Pb is measured via 210 Bi one month after sampling when both isotopes have reached radioactive equilibrium [21]. Radionuclide activities on filter samples were determined by subtracting the detector background (electronic noise and some unblocked cosmic rays) and by taking into account the detector efficiency and an attenuation factor for alpha particles [25]. Initial activities at the time of sampling were then retrieved by fitting radioactive decay trend during the one-month period of analysis by using classical radioactivity laws.…”

Section: Field Description and Sampling Techniquesmentioning

confidence: 99%

A New Degassing Model to Infer Magma Dynamics from Radioactive Disequilibria in Volcanic Plumes

et al. 2018

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Pb within gas bubbles en route to the surface. Theoretical short-lived radioactive disequilibria in volcanic gases predicted by this new model differ from those produced by the former models and better match the values we measured in the plume during the 2015 campaign. A Monte Carlo-like simulation based on variable parameters characterising the degassing process (magma residence time in the degassing reservoir, gas transfer time, Rn-Pb-Bi-Po volatilities, magma volatile content) suggests that short-lived disequilibria in volcanic gases may be of use to infer both magma dynamics and degassing kinetics beneath Mount Etna, and in general at basaltic volcanoes. However, this simulation emphasizes the need for accurately determined input parameters in order to produce unambiguous results, allowing sharp characterisation of degassing processes.

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Section: Field Description and Sampling Techniquesmentioning

confidence: 99%

A New Degassing Model to Infer Magma Dynamics from Radioactive Disequilibria in Volcanic Plumes

et al. 2018

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“…On the other hand, mass measurements show a large amount of collected non-radioactive aerosols. Experiments have been conducted by several authors to appreciate the effect of the aerosol mass deposit on the nuclear measurement (Bartlett and Walker 1996; Geryes and Monsanglant-Louvet 2011; Hogue et al 2018; Hoover and Newton 1998; Huang et al 2002; Moore et al 1993; Seiler et al 1988). The experiments showed the influence of the amount of material on the nuclear, especially alpha, measurement, which is significantly degraded, and the result given by the CAM got worse with the aerosol mass accumulation on the sampling filter.…”

Section: Introductionmentioning

confidence: 99%

Impact of the Coarse Indoor Non-radioactive Aerosols on the Background Radon Progenies’ Compensation of a Continuous Air Monitor

et al. 2022

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This paper addresses the problem of false positive alarm when using a continuous air monitor (CAM) in decommissioning sites of nuclear facilities. CAMs are used to measure airborne activity and play an important role in the radiation protection of workers likely to be exposed to radioactive aerosols. Monitors usually sample aerosols on a membrane filter. Radioactive particles sampled are detected through the alpha and beta decays that they emit. These latter ionizing particles are measured online by spectrometry thanks to a Passivated Implanted Planar Silicon detector (PIPS). Alpha and beta decays, in this context, come mainly from the natural radon progeny ( 218 Po, 214 Pb, and so on) and, in the case of radioactive contamination, also from artificial radionuclides such as 239 Pu or 137 Cs. The aim of the CAM is to alert the workers when the artificial airborne activity occurs, always considering the presence of a variable background due to the natural particulate airborne activity. The CAM-specific algorithm considers this background dynamically and continuously, often by using a constant parameter. However, non-radioactive aerosols are also sampled on the membrane filter. These latter make the discrimination more difficult as they lead to the deterioration of the alpha-energy spectrum. In this paper, the effect of coarse non-radioactive aerosols on the CAM response is highlighted with four aerosol size-distributions. The evolution of the background is characterized as a function of the aerosol mass sampled, with the example of a simple algorithm. Thus, in this paper, results show a positive correlation of the background with the aerosol mass sampled by the CAM. In addition, results highlight at least two different evolutionary trends according to the aerosol size distribution. An explanation of these evolutions is given by considering the penetration profile of the natural radioactive aerosols in the granular deposit above the CAM filter. The main consequence of these results is that the background could not be considered as proportional to radon progeny as it is currently used.

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“…This is unfortunately the problem with an aerosol (1 to 10 g/cm 3 ) in air (1 mg/cm 3 ). However, this method has been successfully used for radioactive aerosol simulation inside a filter [20], where the filter has been represented by various layers. However, we cannot design as precisely as presented before the placement of radioactivity inside the deposit, except through macroparameters characterizing the aerosol deposit distribution.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of a CAM-Measured Spectra Influenced by Coarse Aerosol

Dougniaux¹,

Soerjady²,

Ankrah³

et al. 2022

Atmosphere

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In nuclear facilities, the mandatory atmosphere surveillance is operated by Continuous Air Monitors. This standalone instrument is designed to measure the airborne aerosol activity concentration and to trig an alarm signal when a predetermined activity concentration is exceeded. However, a rapid resuspension event of coarse aerosol leads to a measurement error: the airborne aerosol activity concentration is over-evaluated. Prior results have shown that the coarse aerosol deposit disturbs the background evaluation for the radioactivity measurement. The interactions between radioactive aerosols (with radon daughters) and coarse non-radioactive aerosols have to be investigated by running together aerosol models and nuclear simulations. Therefore, this paper investigates different ways to represent an aerosol deposit in numerical simulations. We developed two numerical aerosol deposit models that we integrated into Geant4, a tool for the simulation of the passage of radiations through matter, and then compared these to experimental results. The simplest model was discarded, and by using the second model, we managed to correctly frame our simulation results as an experimental measurement: an aerosol has been correctly considered in a nuclear simulation. By combining theory, simulations, and experimentations on both aerosol science and nuclear physics, this research will be able to improve the comprehension of monitors’ behaviour in delicate situations and, more broadly, the filtration of aerosols using radioactivity.

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Determination of correction factors for alpha activity measurements in the environment (conditions of high dust loading)

Cited by 6 publications

References 4 publications

A New Degassing Model to Infer Magma Dynamics from Radioactive Disequilibria in Volcanic Plumes

A New Degassing Model to Infer Magma Dynamics from Radioactive Disequilibria in Volcanic Plumes

Impact of the Coarse Indoor Non-radioactive Aerosols on the Background Radon Progenies’ Compensation of a Continuous Air Monitor

Numerical Simulation of a CAM-Measured Spectra Influenced by Coarse Aerosol

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