Analysis of the comparison of in situ measurements made on biological shielding of the BR3 nuclear reactor

INSIDER (Improved Nuclear SIte characterization for waste minimization in D&D operations under constrained EnviRonment) was a European project funded under the H2020-EURATOM programme and launched in June 2017. The project was coordinated by the French Commissariat a l'energie atomique et aux energies alternatives (CEA), it had a total duration of 4 years and covered a budget of 4 Meuro. INSIDER's work was performed by 5 technical working groups (WG) which brought together 18 institutions from 10 countries, leading to a total of 68 participating researchers. The objective of the project was to optimise the radiological characterisation of nuclear installations in constrained environments in order to obtain an accurate estimate of the content of contaminated materials as well as to optimise the quantity of contaminated materials to be treated as waste. The focus of this paper is on the statistical analysis of an interteam comparison of measurement results (dose rate, total gamma measurement, and gamma spectrometry) made in situ at the BR3 reactor, Belgium.The authors would like to thank the participants in the comparison: Fernando Legarda and Raquel Idoeta from Basque Country University (UPV/EHU Spain), Jesús Ruiz from TECNATOM (Spain), SCK-CEN (Belgium), Peter Volgyesi from MTA-EK (Hun- garia), Polina Otiougova from PSI (Switzerland), Lousai Leong from MIRION (France), Axel Klix from KIT (Germany)

Radiological characterisation in view of nuclear reactor decommissioning: On-site benchmarking exercise of a biological shield

[EN] Nearly all decommissioning and dismantling (D&D) projects are steered by the characterisation of the plant being dismantled. This radiological characterisation is a complex process that is updated and modified during the course of the D&D. One of the tools for carrying out this characterisation is the performance of in-situ measurements. There is a wide variety of equipment and methodologies used to carry out on-site measurements, depending on the environment in which they are to be carried out and also on the specific objectives of the measurements and the financial and personnel resources available. The extent to which measurements carried out with different types of equipment or methodologies providing comparable results can be crucial in view of the D&D strategy development and the decision-making process. This paper concerns an on-site benchmarking exercise carried out at the activated biological shield of Belgian Reactor 3 (BR3). This activity allows comparison and validation of characterisation methodologies and different equipment used as well as future interpretation of final results in terms of uncertainties and sensitivities. This paper describes the measurements and results from the analysis of this exercise. Other aspects of this exercise will be reported in separate papers. This paper provides an overview of the on-site benchmarking exercise, outlines the participating organisations and the measurement equipment used for total gamma, dose rate and gamma spectrometry measurements and finally, results obtained and their interpretations are discussed for each type of measurement as a function of detector type. Regarding the dose measurements, results obtained by using a large variety of equipment are very consistent. In view of mapping the inner surface of the biological shield the most appropriate equipment tested might be the organic scintillator, the BGO or even the ionisation chamber. In addition, for mapping this surface, the most appropriate total gamma equipment tested might be the LaBr3(Ce), the thick organic scintillator or the BGO. These measurements can only be used as a secondary parameter in a relative way. Results for the gamma spectrometry are very consistent for all the equipment used and the main parameters to be determined.INSIDER is a EU Horizon 2020 project and received funding from the Euratom Research and Training Programme 2014–2018 under grant agreement No 755554

Propriétés spectroscopiques, photophysiques et photochimiques des clusters trinucléaires de palladium et platine du type M₃ (PPh₂CH₂PPh₂)₃ (µ₃CO) (X)₂, X=CF₃CO₂ ̄ ou PF₆ ̄

Ce mémoire traite des clusters trinucléaires de palladium et de platine du type (M₃ (PPh₂CH₂PPh₂)₃ (µ₃CO)) (X)₂, X ̄=CF₃CO₂ ̄, ou PF₆ ̄. Il comporte trois parties principales. La première traite de la théorie de base nécessaire à la compréhension dudléveloppement qui suit, la deuxième évoque les différents travaux et résultats connus à ce jour, concernant les composés le palladium et de platine, notamment les clusters trinucléaires qui nous intéressent. Dans une troisième partie, La synthèse d'un nouveau composé, caractérisé cristallographiquement, sera exposée (Pd₃(PPh₂CH₂PPh₂)₃ (µ₃CO))(PF₆)(CF₃C0₂) - 2CH₃COCH₃. Puis, une approche de la spectroscopie et de la photophysique de ces clusters est exposée aboutissant à une détermination de certaines constantes physiques (durée de vie, rendement quantique...) concernant ces composés. Des calculs du type EHMO visant à confirmer les résultats expérimentaux obtenus sont faits. Enfin, la photochimie de ces clusters essentiellement en présence de gaz tels l'oxygène, l'hydrogène, le monoxyde de carbone et le dioxyde de carbone, ainsi que les nombreuses difficultés rencontrées quant à la mise en oeuvre du montage de photochimie sont développées

Propriétés spectroscopiques, photophysiques et photochimiques des clusters trinucléaires de palladium et platine du type M? (PPh?CH?PPh?)? (µ?CO) (X)?, X=CF?CO? ? ou PF? ?

Ce mémoire traite des clusters trinucléaires de palladium et de platine du type (M? (PPh?CH?PPh?)? (µ?CO)) (X)?, X ?=CF?CO? ?, ou PF? ?. Il comporte trois parties principales. La première traite de la théorie de base nécessaire à la compréhension dudléveloppement qui suit, la deuxième évoque les différents travaux et résultats connus à ce jour, concernant les composés le palladium et de platine, notamment les clusters trinucléaires qui nous intéressent. Dans une troisième partie, La synthèse d'un nouveau composé, caractérisé cristallographiquement, sera exposée (Pd?(PPh?CH?PPh?)? (µ?CO))(PF?)(CF?C0?) - 2CH?COCH?. Puis, une approche de la spectroscopie et de la photophysique de ces clusters est exposée aboutissant à une détermination de certaines constantes physiques (durée de vie, rendement quantique...) concernant ces composés. Des calculs du type EHMO visant à confirmer les résultats expérimentaux obtenus sont faits. Enfin, la photochimie de ces clusters essentiellement en présence de gaz tels l'oxygène, l'hydrogène, le monoxyde de carbone et le dioxyde de carbone, ainsi que les nombreuses difficultés rencontrées quant à la mise en oeuvre du montage de photochimie sont développées

New approaches for interlaboratory comparisons analysis using dark uncertainty applied to radioactive materials

International audienceIn order to further improve the management of contaminated materials in nuclear facilities subject to a decommissioning programme, as well as during post-accidental site remediation and clearance, the definition and selection of the most appropriate intervention scenarios producing well-characterized radioactive waste for which storage and disposal routes are clearly identified is needed.As a step towards this accomplishment, we propose a methodology for the organization and analysis of coordinated interlaboratory comparisons (ILC) for the performance assessment and the uncertainty evaluation of available measurement techniques (methods and tools) of radioactive materials. This methodology is new for this type of comparison and demonstrated on the BR3 (Belgian Reactor 3, Belgian Nuclear Research Center, Mol) case study from the H2020 INSIDER project (2017-2021), for which barium 133, cobalt 60 and europium 152 are analysed with gamma spectroscopy in ILC, based either on irradiated concrete from the BR3 bioshield or from spiked concrete certified reference material (CRM).On one hand, we show the advantage of organizing ILC on CRM for a more reliable uncertainty evaluation taking bias into account following ISO 21748:2017. But using CRM may be impossible due to their scarcity or too costly for performance assessment thus limiting the use of CRM in ILC in practice.On the other hand, we show that for performance evaluation and monitoring, ILC can be alternately performed on reference materials provided that laboratories' uncertainties are reported and the most appropriate analysis of data is performed using dark uncertainty (excess variance) in the presence of inconsistent data

Preliminary analysis of the on-site comparisons at BR3

International audienceIn order to estimate the measurement method performance of teams and laboratories in the INSIDER project, WP6 is organizing several interlaboratory comparisons on real and synthetic samples (certified reference materials). The first comparison in chronological order was carried out on in situ measurements made on BR3 activated concrete (Bioshield) in Mol (Belgium). This talk presents the preliminary results of the in situ comparison made by the WP5 teams

A comparison between Bayesian and ordinary kriging based on validation criteria: application to radiological characterisation

In decommissioning projects of nuclear facilities, the radiological characterisation step aims to estimate the quantity and spatial distribution of different radionuclides. To carry out the estimation, measurements are performed on site to obtain preliminary information. The usual industrial practice consists in applying spatial interpolation tools (as the ordinary kriging method) on these data to predict the value of interest for the contamination (radionuclide concentration, radioactivity, etc.) at unobserved positions. This paper questions the ordinary kriging tool on the well-known problem of the overoptimistic prediction variances due to not taking into account uncertainties on the estimation of the kriging parameters (variance and range). To overcome this issue, the practical use of the Bayesian kriging method, where the model parameters are considered as random variables, is deepened. The usefulness of Bayesian kriging, whilst comparing its performance to that of ordinary kriging, is demonstrated in the small data context (which is often the case in decommissioning projects). This result is obtained via several numerical tests on different toy models, and using complementary validation criteria: the predictivity coefficient (Q²), the Predictive Variance Adequacy (PVA), the $\alpha$-Confidence Interval plot (and its associated Mean Squared Error alpha (MSEalpha)), and the Predictive Interval Adequacy (PIA). The latter is a new criterion adapted to the Bayesian kriging results. Finally, the same comparison is performed on a real dataset coming from the decommissioning project of the CEA Marcoule G3 reactor. It illustrates the practical interest of Bayesian kriging in industrial radiological characterisation

Accurate determination of plutonium by Controlled Potential Coulometry: uncertainty evaluation by the Monte Carlo Method approach

International audienceThe accurate determination of plutonium (Pu) mass fraction in nuclear materials is essential to nuclear matter accountancy and international safeguard programs. Controlled-Potential Coulometry (CPC) is one of the best available analytical methods to perform such measurements. The implementation of CPC at the Nuclear Matter Metrological Laboratory of the French Atomic Energy Commission is described as well as the evaluation of measurement uncertainty using two approaches: the guide to the expression of uncertainty in measurement, and the Monte Carlo Method. The uncertainty values determined are compared to the international target values published by the International Atomic Energy Agency