Thomas Frosio

All Publications

• Radiation Physics commissioning of LCLS-II superconducting Linac. Gun and cryomodules commissioning NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT Frosio, T., Allan, J., Blaha, J., Brogognia, H., Rokny, S., Leitner, M., Aderhold, S., Bai, M., Littleton, S. 2026; 1086

  View details for DOI 10.1016/j.nima.2026.171340

  View details for Web of Science ID 001685006900001

• Transfer functions for <i>Q_A </i>/<i>Q_B </i> international regulatory limits for the safe transport of radioactive materials JOURNAL OF RADIOLOGICAL PROTECTION Frosio, T., Thomas, S., Endres, J., Eberhardt, H., Louis, B., Cabianca, T., Brown, I., Foster, M., Menaa, N., Bertreix, P. 2024; 44 (3)

  Abstract

  This paper presents a proposed revision of the International Atomic Energy Agency transport regulations, related to theA1andA2limit values used to determine the radioactive transport classification. Based on the 'Qsystem', a novel methodology was introduced to deriveQAandQBvalues related to scenarios involving external exposure from a distant source. These values are key parameters that respectively represent the total effective dose and total equivalent dose to the skin, from all primary and secondary particles contributing to radiation exposure. The International Working Group (WGA1/A2) is established and associated with the TRANSSC Technical Expert Group on Radiation Protection. A review of theA1andA2values is performed in response to identified limitations within the existingQsystem. The followed approach is based on Monte Carlo simulations that enabled the development of transfer functions aimed at reducing computational time and increasing the flexibility of dose evaluations for any radionuclide with known particle emission spectra. This method allows updating theQAandQBvalues to account for future data evolutions (decay data, fluence-to-dose conversion coefficients) and standardizing the calculation of regulation limits across all referenced radionuclides and scenarios related to external exposure. The transfer functions are established using three Monte Carlo simulation codes-FLUKA, Geant4, and MCNP-and address the previous limitations of the 'Qsystem', reflecting the latest International Commission for Radiation Protection recommendations and improvements in calculation techniques. The results of the WG show consistent agreement across the codes, with minor discrepancies observed at low primary energies due to statistical uncertainties and different handling of stopping power for electrons/positrons in the codes. This revised approach aligns with current standards and recommendations, ensuring that the radiological consequences of transport accidents are acceptable for the newA1andA2limits from a radiological protection perspective.

  View details for DOI 10.1088/1361-6498/ad6453

  View details for Web of Science ID 001278271100001

  View details for PubMedID 39019049

• Skin dose contamination conversion coefficients. Benchmark with three simulation codes JOURNAL OF RADIOLOGICAL PROTECTION Frosio, T., Bertreix, P., Menaa, N., Thomas, S., Eberhardt, H., Endres, J. 2022; 42 (1)

  Abstract

  Handling of radioactive material by operators can lead to contamination at the surface of the skin in case of an accident. The quantification of the dose received by the skin due to a contamination scenario is performed by means of dedicated dose coefficients as it is the case for other radiation protection dose quantities described in the literature. However, most available coefficients do not match realistic scenarios according to state-of-the-art of science and technology. Therefore, this work deals with dedicated dose conversion factors for skin contamination. Since there is an increasing demand on dose coefficients in general, these specific coefficients can be used for various calculations in radiation protection. In this work a method to evaluate such coefficients for the skin contamination dose related to photons, electrons, positrons, alpha and neutron particles is proposed. The coefficients are generated using Monte-Carlo simulations with three well established calculation codes (FLUKA, MCNP, and GEANT4). The results of the various codes are compared against each other for benchmarking purposes. The new dose coefficients allow the computation of the skin received dose, in the case of skin contamination scenario of an individual, taking into account the decay radiation of the radionuclides of interest. To benchmark the quantity derived here, comparisons of radionuclide contamination doses to the skin using the VARSKIN code available in the literature are performed with the results of this work.

  View details for DOI 10.1088/1361-6498/ac3bc4

  View details for Web of Science ID 000743699600001

  View details for PubMedID 34801994

• Calculation and benchmark of fluence-to-local skin equivalent dose coefficients for neutrons with FLUKA, MCNP, and GEANT4 Monte-Carlo codes JOURNAL OF RADIOLOGICAL PROTECTION Frosio, T., Bertreix, P., Menaa, N., Thomas, S. 2021; 41 (3): 564-578

  Abstract

  Dose equivalent limits for single organs are recommended by the ICRP (International Commission for the Radiological Protection publication 103). These limits do not lend themselves to be measured. They are assessed by convoluting conversion factors with particle fluences. The Fluence-to-Dose conversion factors are tabulated in the ICRP literature. They allow assessing the organ dose of interest using numerical simulations. In particular, the literature lacks the knowledge of local skin equivalent dose (LSD) coefficients for neutrons. In this article, we compute such values for neutron energies ranging from 1 meV to 15 MeV. We use FLUKA, MCNP and GEANT4 Radiation transport Monte-Carlo simulation codes to perform the calculations. A comparison between these three codes is performed. These calculated values are important for radiation protection studies and radiotherapy applications.

  View details for DOI 10.1088/1361-6498/ac057e

  View details for Web of Science ID 000686338200001

  View details for PubMedID 34038896

• Photons fluence to local skin Dose coefficients and benchmark with three Monte-Carlo codes. Application to the computation of radioactive material transport limits APPLIED RADIATION AND ISOTOPES Frosio, T., Bertreix, P., Menaa, N., Thomas, S., Eberhardt, H., Endres, J. 2021; 176: 109892

  Abstract

  Fluence to Local Skin Dose Conversion Coefficients (LSD-CC) are radiological protection quantities used for external radiation exposures which allow the conversion of particle fluences into local skin equivalent dose. The International Commission on Radiological Protection published LSD-CC for electrons with an energy range from 10 keV to 10 MeV. However, the literature does not address these radiation protection quantities for all particle types, in particular for photons. In this article, computed LSD-CC values for photons are presented which enrich the literature and are of interest for the radiation protection community. As an example for an application of the use of the computed LSD-CC values, the IAEA A1/A2 working group, which supports the review of the international regulation related to the transport of radioactive material, has decided to estimate the dose to the skin using such coefficients. In this publication, LSD-CC for photons are computed and benchmarked using GEANT4, FLUKA and MCNP. In addition, the FLUKA Monte-Carlo calculation code is used to compute the LSD-CC values for electrons and positrons to compare with existing data in the literature and validate the presented models. As one application of these LSD-CC values, the transfer functions for calculating the IAEA A-values are determined using the LSD-CC and are compared to a one-step direct calculation method.

  View details for DOI 10.1016/j.apradiso.2021.109892

  View details for Web of Science ID 000691275800009

  View details for PubMedID 34418729

• Qualification of the activities measured by gamma spectrometry on unitary items of intermediate-level radioactive waste from particle accelerators APPLIED RADIATION AND ISOTOPES Dyrcz, P., Frosio, T., Menaa, N., Magistris, M., Theis, C. 2021; 167: 109431

  Abstract

  In the frame of maintenance, upgrade and dismantling activities, activated equipment are removed from the accelerator complex and require characterization in view of their disposal as radioactive waste. The characterization process consists of a series of radiation measurements, complemented by analytical studies, which quantify the activity of radionuclides inside an object. A fraction of the radioactive waste produced at CERN presents contact dose-rates higher than 100 μSv/h, and can therefore be classified as LILW Waste ("Low and intermediate level radioactive waste"). These objects, due to the activation mechanisms, are often subject to large activity heterogeneities. The quantification of gamma-emitting radionuclides is typically performed by gamma spectrometry, under the assumption of homogeneous distributions of activity within an object. However, this assumption can lead to underestimating the activity value of such radionuclides. In this article we perform a gamma spectrometry qualification in order to quantify the impact of assuming homogenous distribution.

  View details for DOI 10.1016/j.apradiso.2020.109431

  View details for Web of Science ID 000596040000012

  View details for PubMedID 33011515

• Qualification of gamma spectrometry measurement for the radiological characterization of mixed VLLW cables in particle accelerators APPLIED RADIATION AND ISOTOPES Rimlinger, M., Frosio, T., Menaa, N., Magistris, M., Theis, C. 2020; 166: 109419

  Abstract

  In the framework of maintenance activities in particle accelerators, such as upgrades and dismantling, a large number of activated equipment are removed from the accelerator complex and require characterization in view of their disposal as radioactive waste. In particular, cables can be of different types. This feature induces variations of the efficiency calibration curves due to the variation of the material composition, source distribution and density. Hence, quantifying the activities of the gamma-emitting radionuclides can be quite challenging for mixed cables. In this article, we propose a new qualification methodology, based on gamma spectrometry, in order to assess the activity results uncertainties of gamma-emitting radionuclides. This new methodology is developed to define the envelop efficiency calibration curves and allows for the establishment of more accurate activity values with their corresponding uncertainties.

  View details for DOI 10.1016/j.apradiso.2020.109419

  View details for Web of Science ID 000589093400071

  View details for PubMedID 32980765

• An enhanced characterization process for the elimination of very low level radioactive waste in particle accelerators APPLIED RADIATION AND ISOTOPES Frosio, T., Bertreix, P., Magistris, M., Menaa, N., Michaud, R., Rimlinger, M., Theis, C., Ulrici, L., Zaffora, B. 2020; 166: 109312

  Abstract

  The elimination of very low level waste towards the French national repository requires their radiological characterization to estimate the radionuclide inventory and the associated activities within a waste package. Such characterization is performed by means of activation calculations and measurements. Two elimination projects have been identified at CERN, to dispose of bulk metallic waste and cables activated in the CERN accelerator complex. Based on the experience gained over the last 4 years, we develop a large scale elimination process to dispose of such types of activated equipment. A program for quality controls has therefore been developed through a novel software tool whose purpose is to compute the radiological data required by the repository for the acceptance of the waste as well as performing quality controls.

  View details for DOI 10.1016/j.apradiso.2020.109312

  View details for Web of Science ID 000589093400013

  View details for PubMedID 32871509

• Generation of low-energy neutrons cross-sections for the Monte Carlo code FLUKA and the deterministic code ActiWiz APPLIED RADIATION AND ISOTOPES Frosio, T., Magistris, M., Theis, C., Vincke, H. 2020; 166: 109352

  Abstract

  Activation of material is of interest for waste treatment and hazard assessment. In particular, activation of printed circuit can lead to the production of radionuclides at an isomeric state, for example, coming from silver. In particle accelerators, the production of silver isomeric states mainly come from low energy neutrons, below 20 MeV. The quantification of activation and associated doses at CERN is based on the FLUKA and ActiWiz codes. In the FLUKA release 2011.2c, all branching ratios for isomer production were set at 50% by default. The present work provides a set of nuclide- and energy-dependent branching ratios, extracted from the library EAF-2010. In the ActiWiz release 3.3, the library JEFF3.1.1 was used for low energy neutron cross-sections. This study provides a new set of neutron cross-sections extracted from JEFF3.3, ENDFB/VIII.0 and EAF-2010 for future update of ActiWiz.

  View details for DOI 10.1016/j.apradiso.2020.109352

  View details for Web of Science ID 000589093400033

  View details for PubMedID 32836164

• Classification of radiological objects at the exit of accelerators with a dose-rate constraint APPLIED RADIATION AND ISOTOPES Frosio, T., Dumont, G., Froeschl, R., Iliopoulou, E., Magistris, M., Menaa, N., Roesler, S., Theis, C., Vincke, H., Vincke, H. 2020; 165: 109303

  Abstract

  Maintenance activities and operations of high-energy particle accelerators can lead to the collection of radioactive equipment as well as waste materials. In order to ensure their proper classification as radioactive or non-radioactive, one has to quantify the activities of radionuclides produced. According to the regulatory requirements in Switzerland, these activities need to be compared with nuclide-specific clearance limits. In particular, a new set of clearance limits was introduced by the Swiss authorities in January 2018, leading to more conservative values for a number of relevant radionuclides. We describe in this paper a new methodology based on dose-rate measurements to classify potentially radioactive objects at the exit of the CERN accelerator complex. This methodology concerns the specific material compositions typically found at CERN and takes into account the latest clearance limits introduced by the Swiss authorities.

  View details for DOI 10.1016/j.apradiso.2020.109303

  View details for Web of Science ID 000568698100010

  View details for PubMedID 32771870

• On the holistic validation of electronic materials compound for irradiation study-Experimental and calculated results JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY Frosio, T., Menaa, N., Magistris, M., Theis, C. 2020; 326 (1): 11-24

  View details for DOI 10.1007/s10967-020-07334-y

  View details for Web of Science ID 000559227200006

• New methodology for in -situ classification of radiological items with a clearance monitor system NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT Frosio, T., Menaa, N., Dumont, G., Aberle, F. 2020; 966

  View details for Web of Science ID 000531581900007

• Radiological characterization of large electromagnets in view of their elimination as very low-level wastes NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT Frosio, T., Magistris, M., Menaa, N., Michaud, R., Rimlinger, M., Theis, C. 2020; 959

  View details for DOI 10.1016/j.nima.2020.163493

  View details for Web of Science ID 000518368800031

• A novel technique for the optimization and reduction of gamma spectroscopy geometry uncertainties APPLIED RADIATION AND ISOTOPES Frosio, T., Menaa, N., Bertreix, P., Rimlinger, M., Theis, C. 2020; 156: 108953

  Abstract

  Material activation can sometimes cause large heterogeneities in the distribution of radioactivity (hotspots). Moreover, the sample geometry parameters are not always well known. When performing gamma-spectroscopy to quantify the radionuclide inventory in activated materials, often predefined models are used to represent the sample geometry (dimensions, source-to-detector distance, material type) and their activity distribution, for efficiency calibration. This simplification causes uncertainties of the efficiency curves associated with the model and consequently, to the activity results. In this paper, we develop a new approach, based on ISOCS/LabSOCS to quantify and reduce uncertainties originating from the geometry model. The theory is described in this document and an experimental case is discussed.

  View details for DOI 10.1016/j.apradiso.2019.108953

  View details for Web of Science ID 000514754100036

  View details for PubMedID 31734031

• Computation of Radioactive Material Transport Limits Within A1/A2 Working Group at IAEA TRANSSC IEEE ACCESS Frosio, T., Bertreix, P., Theis, C., Donjoux, Y., Cabianca, T., Brown, I., Foster, M., Endres, J., Eberhardt, H., Hayakawa, N., Louis, B., Thomas, S., Bez, J. 2020; 8: 29040-29054

  View details for DOI 10.1109/ACCESS.2020.2971352

  View details for Web of Science ID 000525401500063

• A new gamma spectroscopy methodology based on probabilistic uncertainty estimation and conservative approach APPLIED RADIATION AND ISOTOPES Frosio, T., Menaa, N., Duchemin, C., Riggaz, N., Theis, C. 2020; 155: 108929

  Abstract

  The gamma spectroscopy technique is commonly used in many applications to evaluate the activity of gamma emitters in a given sample. This assessment of activity is of particular interest for the disposal of radioactive waste or for clearance purposes. However, for these specific applications, one needs to show that the evaluated activities are reasonably conservative. This paper shows an application of a methodology developed to quantify the efficiency calibration curve uncertainties originating from a test case sample and its associated geometry modelling. Therefore, the effects of enclosing geometries on the activity measurement results are discussed. The purpose is to provide an example of uncertainty analysis for an approach that could be applied to other studies in which a conservative estimation of the activity is required.

  View details for DOI 10.1016/j.apradiso.2019.108929

  View details for Web of Science ID 000502882400016

  View details for PubMedID 31675542

• Spectrum and Yield to Dose Conversion Coefficients for Beta Skin Doses Linked to the Q System HEALTH PHYSICS Frosio, T., Bertreix, P., Koster, U., Theis, C., Magistris, M. 2019; 116 (5): 607-618

  Abstract

  Monte Carlo simulations are a state-of-the-art method to calculate dose coefficients and could be used with the Q system for radioactive material packaging. These simulations often take a long time to converge with sufficient precision. Furthermore, if multiple sources have to be taken into account, many weeks of calculations may be needed. In order to reduce the calculation time, this paper proposes a new method based on a transfer function to instantly compute Q values associated with beta skin doses. The method developed in this paper can be applied to compute beta skin dose and easily could be extended to other particles and different depths in organs with various kinds of shielding configurations between source and target.

  View details for DOI 10.1097/HP.0000000000000986

  View details for Web of Science ID 000463601000005

  View details for PubMedID 30908318

  View details for PubMedCentralID PMC6571186

• Extension of Bayesian inference for multi-experimental and coupled problem in neutronics - a revisit of the theoretical approach EPJ NUCLEAR SCIENCES & TECHNOLOGIES Frosio, T., Bonaccorsi, T., Blaise, P. 2018; 4

  View details for DOI 10.1051/epjn/2018046

  View details for Web of Science ID 000447945400001

• Impact of correlations between core configurations for the evaluation of nuclear data uncertainty propagation for reactivity EPJ NUCLEAR SCIENCES & TECHNOLOGIES Frosio, T., Blaise, P., Bonaccorsi, T. 2017; 3

  View details for DOI 10.1051/epjn/2016039

  View details for Web of Science ID 000397453300001

• Manufacturing Data Uncertainties Propagation Method in Burn-Up Problems SCIENCE AND TECHNOLOGY OF NUCLEAR INSTALLATIONS Frosio, T., Bonaccorsi, T., Blaise, P. 2017; 2017

  View details for DOI 10.1155/2017/7275346

  View details for Web of Science ID 000394031000001

• Fission yields and cross section uncertainty propagation in Boltzmann/Bateman coupled problems: Global and local parameters analysis with a focus on MTR ANNALS OF NUCLEAR ENERGY Frosio, T., Bonaccorsi, T., Blaise, P. 2016; 98: 43-60

  View details for DOI 10.1016/j.anucene.2016.07.025

  View details for Web of Science ID 000383820400006

• Nuclear data uncertainties propagation methods in Boltzmann/Bateman coupled problems: Application to reactivity in MTR ANNALS OF NUCLEAR ENERGY Frosio, T., Bonaccorsi, T., Blaise, P. 2016; 90: 303-317

  View details for DOI 10.1016/j.anucene.2015.12.010

  View details for Web of Science ID 000370106200030

• Simulation of the core flowering End-of-life test realized on PHENIX reactor Prulhiere, G., Fontaine, B., Frosio, T. edited by Caruge, D., Calvin, C., Diop, C. M., Malvagi, F., Trama, J. C. E D P SCIENCES. 2014

  View details for DOI 10.1051/snamc/201401403

  View details for Web of Science ID 000408930200028