Methodologies for an improved prediction of the isotopic content in high burnup samples. Application to Vandellos-II reactor core

Fuel cycles are designed with the aim of obtaining the highest amount of energy possible. Since higher burnup values are reached, it is necessary to improve our disposal designs, traditionally based on the conservative assumption that they contain fresh fuel. The criticality calculations involved must consider burnup by making the most of the experimental and computational capabilities developed, respectively, to measure and predict the isotopic content of the spent nuclear fuel. These high burnup scenarios encourage a review of the computational tools to find out possible weaknesses in the nuclear data libraries, in the methodologies applied and their applicability range. Experimental measurements of the spent nuclear fuel provide the perfect framework to benchmark the most well-known and established codes, both in the industry and academic research activity. For the present paper, SCALE 6.0/TRITON and MONTEBURNS 2.0 have been chosen to follow the isotopic content of four samples irradiated in the Spanish Vandellós-II pressurized water reactor up to burnup values ranging from 40 GWd/MTU to 75 GWd/MTU. By comparison with the experimental data reported for these samples, we can probe the applicability of these codes to deal with high burnup problems. We have developed new computational tools within MONTENBURNS 2.0. They make possible to handle an irradiation history that includes geometrical and positional changes of the samples within the reactor core. This paper describes the irradiation scenario against which the mentioned codes and our capabilities are to be benchmarked

Analysis of Different Uncertainty Activation Cross Section Data Libraries for LWR, ads and demo Neutron Spectra

This work is aimed to present the main differences of nuclear data uncertainties among three different nuclear data libraries: EAF-2007, EAF-2010 and SCALE-6.0, under different neutron spectra: LWR, ADS and DEMO (fusion

Solubility of gases in fluoroorganic alcohols. Part III. Solubilities of several non-polar gases in water¿+¿1, 1, 1, 3, 3, 3-hexafluoropropan-2-ol at 298.15¿K and 101.33¿kPa

Solubilities of the non-polar gases H2, N2, O2, CH4, C2H6, C2H4, CF4, SF6, and CO2 in the mixture (water + 1, 1, 1, 3, 3, 3-hexafluoropropan-2-ol) at the temperature of 298.15 K and 101.33 kPa partial pressure of gas are reported. A polynomial dependence of the solubilities on the molar fraction of the binary liquid mixture is found. The Henry''s constants at the vapor pressure of water, the standard changes in the Gibbs energy for the solution process and for the solvation process, and the so-called excess Henry''s constant are calculated. The results have been compared with those obtained by Scaled Particle Theory (SPT). A method to compare the solubility of a gas in different liquids is proposed and applied to 2, 2, 2-trifluoroethanol and 1, 1, 1, 3, 3, 3-hexafluoropropan-2-ol

Niche evolution reveals disparate signatures of speciation in the ‘great speciator’ (white‐eyes, Aves: Zosterops )

ACKNOWLEDGEMENTS J.O.E. and L.L. coordinated and secured project funding with the support from J.S.C.; we thank AT Peterson and CH Graham and two reviewers for critical feedback on earlier stages of the manuscript. The project was funded by the Research Foundation – Flanders (FWO; 1527918N & G042318N). J.O.E. received additional funds by an FWO Postdoctoral Fellowship (12G4317N). The authors declare no conflict of interest. No permits were needed to conduct the re- search presented here. DATA AVAILABILITY STATEMENT All data are available from open source platforms. Raw GBIF.org occurrence data used for this work (as accessed on 21st October 2016) can be accessed through GBIF Occurrence Download http://doi.org/10.15468/dl.erwqs6. We have deposited the prepared data used for this work on FigShare accessible through https://doi.org/10.6084/m9.figshare.13042031.v1 as well as R scripts for data analysis in a GitHub repository accessible through https://github.com/JOEngler/ZostiNicheEvol.Peer reviewedPublisher PD

Isotopic uncertainty assessment due to nuclear data uncertainties in high-burnup samples.

The accurate prediction of the spent nuclear fuel content is essential for its safe and optimized transportation, storage and management. This isotopic evolution can be predicted using powerful codes and methodologies throughout irradiation as well as cooling time periods. However, in order to have a realistic confidence level in the prediction of spent fuel isotopic content, it is desirable to determine how uncertainties affect isotopic prediction calculations by quantifying their associated uncertainties

Branched-chain ignition in strained mixing layers

Abstract. The time-dependent evolution of the radical pool in an initially inert hydrogen-air counterflow mixing layer subject to variable strain is investigated analytically. Although the initial chemistry description contains three different chain carriers, namely, H, O and OH, it is shown that the ignition problem can be accurately described in terms of a single radical-pool variable that incorporates steady-state assumptions for the radicals O and OH. Use of this non-standard procedure reduces the problem to the integration of a single conservation equation, whose solution depends on the existing Damkohler number A, defined as the ratio of the diffusion time across the mixing layer to the characteristic branching time. Ignition takes place when A remains predominantly above a critical value of the order of unity. The exponentially growing radical pool, which extends across the mixing layer, can be described analytically by separation of variables in configurations with a slowly varying strain rate, providing a solution that is used to investigate the parametric dependences of the ignition time. Weakly strained solutions are studied separately by addressing the asymptotic limit of large Damkohler numbers. It is seen that the reaction zone then becomes a thin layer of relative thickness A- 1 ' 4 centred at the location where the branching rate is maximum. The analysis employs asymptotic expansions in decreasing powers of A for the shape and for the exponential growth rate of the radical pool. The accurate description of the solution necessitates computation of three terms in the asymptotic expansion for the growth rate, yielding predictions for the ignition time that remain accurate even for values of A of the order of unity

Isotopic prediction simulations applied to high burnup samples irradiated in VANDELLÓS-II Reactor core

Isotopic content assessment has a paramount importance for safety and storage reasons. During the latest years, a great variety of codes have been developed to perform transport and decay calculations, but only those that couple both in an iterative manner achieve an accurate prediction of the final isotopic content of irradiated fuels. Needless to say, them all are supposed to pass the test of the comparison of their predictions against the corresponding experimental measures

Uncertainty assessment methodologies applied to Tritium production in fusion lithium breeding blankets

- Need of Tritium production - Neutronic objectives - The Frascati experiment - Measurements of Tritium activit

A Comparison of Sensitivity/Uncertainty Methodologies for the Tritium Production in the HFTM/IFMIF Specimen Cells and measurements in Tritium activity in HCLL TBM mock-up LiPb

The prediction of the tritium production is required for handling procedures of samples, safety&maintenance and licensing of the International Fusion Materials Irradiation Facility (IFMIF)