Advances in Carcinogenic Metal Toxicity and Potential Molecular Markers

Metal compounds such as arsenic, cadmium, chromium, cobalt, lead, mercury, and nickel are classified as carcinogens affecting human health through occupational and environmental exposure. However, the underlying mechanisms involved in tumor formation are not well clarified. Interference of metal homeostasis may result in oxidative stress which represents an imbalance between production of free radicals and the system’s ability to readily detoxify reactive intermediates. This event consequently causes DNA damage, lipid peroxidation, protein modification, and possibly symptomatic effects for various diseases including cancer. This review discusses predominant modes of action and numerous molecular markers. Attention is paid to metal-induced generation of free radicals, the phenomenon of oxidative stress, damage to DNA, lipid, and proteins, responsive signal transduction pathways with major roles in cell growth and development, and roles of antioxidant enzymatic and DNA repair systems. Interaction of non-enzymatic antioxidants (carotenoids, flavonoids, glutathione, selenium, vitamin C, vitamin E, and others) with cellular oxidative stress markers (catalase, glutathione peroxidase, and superoxide dismutase) as well as certain regulatory factors, including AP-1, NF-κB, Ref-1, and p53 is also reviewed. Dysregulation of protective pathways, including cellular antioxidant network against free radicals as well as DNA repair deficiency is related to oncogenic stimulation. These observations provide evidence that emerging oxidative stress-responsive regulatory factors and DNA repair proteins are putative predictive factors for tumor initiation and progression

Study of D2O/H2O-cooled thorium-fueled PWR-like SMR cores using the KNACK toolbox: conversion and safety assessment

International audienceBased on SMURE (Serpent2/MCNP Utility) and NDM (Nodal Drift Method for time-dependent diffusion), a full set of academic methods named KNACK (Knack of Nodal Approach to Core Kinetics) has been used for the design of 600 MWth D2O/H2O-cooled thorium-fueled SMR (Small Modular Reactor) cores. Three types of lattice, with 17x17, 19x19 or 21x21 PWR-like FAs (Fuel Assemblies), have been considered. After initial fissile zoning for power flattening, full core burnup calculations with D2O/H2O Spectral Shift Control have been performed at HFP (Hot Full Power) for the comparison of conversion performance. Temperature dependences of diffusion data have been implemented within a thermal lumped model for safety. A simple criterion, on coolant temperatures only, has finally been used for the comparative analysis of Rod Ejection Accidents (REA) from HZP (Hot Zero Power)

Study of D2O/H2O-cooled thorium-fueled PWR-like SMR cores using the KNACK toolbox: conversion and safety assessment

International audienceBased on SMURE (Serpent2/MCNP Utility) and NDM (Nodal Drift Method for time-dependent diffusion), a full set of academic methods named KNACK (Knack of Nodal Approach to Core Kinetics) has been used for the design of 600 MWth D2O/H2O-cooled thorium-fueled SMR (Small Modular Reactor) cores. Three types of lattice, with 17x17, 19x19 or 21x21 PWR-like FAs (Fuel Assemblies), have been considered. After initial fissile zoning for power flattening, full core burnup calculations with D2O/H2O Spectral Shift Control have been performed at HFP (Hot Full Power) for the comparison of conversion performance. Temperature dependences of diffusion data have been implemented within a thermal lumped model for safety. A simple criterion, on coolant temperatures only, has finally been used for the comparative analysis of Rod Ejection Accidents (REA) from HZP (Hot Zero Power)

Investigation of fission product isomeric ratios and angular momenta of 132^{132}Sn populated in the 241^{241}Pu(nth_{th},f) reaction

International audienceDuring an experimental campaign performed at the LOHENGRIN recoil spectrometer of the Institut Laue-Langevin (ILL), a kinetic energy dependence of 132Sn fission product isomeric ratio (IR) has been measured by inducing thermal fission of 241Pu. The IRs are deduced using gamma ray spectrometry in coincidence with the ionisation chamber. To interpret these data, we use the FIFRELIN Monte-Carlo code to simulate the de-excitation of the fission fragments. Combining the IRs with the FIFRELIN calculations, the angular momentum distribution with kinetic energy of the doubly magic nucleus of 132Sn was deduced. This will be compared with the angular momentum distribution obtained for the reaction 235U(nth,f) for 132Sn

Investigation of fission product isomeric ratios and angular momenta of

During an experimental campaign performed at the LOHENGRIN recoil spectrometer of the Institut Laue-Langevin (ILL), a kinetic energy dependence of 132Sn fission product isomeric ratio (IR) has been measured by inducing thermal fission of 241Pu. The IRs are deduced using gamma ray spectrometry in coincidence with the ionisation chamber. To interpret these data, we use the FIFRELIN Monte-Carlo code to simulate the de-excitation of the fission fragments. Combining the IRs with the FIFRELIN calculations, the angular momentum distribution with kinetic energy of the doubly magic nucleus of 132Sn was deduced. This will be compared with the angular momentum distribution obtained for the reaction 235U(nth,f) for 132Sn

Development of a Gas Filled Magnet spectrometer within the FIPPS project

communication - http://hal.in2p3.fr/in2p3-01171185International audienceThe Fission Product Prompt γγ-ray Spectrometer, FIPPS, is under development to enable prompt γγ-ray spectroscopy correlated with fission fragment identification. This will open new possibilities in the study of fission and of nuclear structure of neutron rich nuclei. FIPPS will consist of an array of γγ and neutron detectors coupled with a fission fragment filter. The chosen solution for the filter is a Gas Filled Magnet (GFM). Both experimental and modeling work was performed in order to extract the key parameters of such a device and design the future GFM of the FIPPS project. Experiments performed with a GFM behind the LOHENGRIN spectrometer demonstrated the capability of additional beam purification

Theoretical investigation of fission fragment kinetic energy distributions in the symmetric mass region for 233U(nth,f)

Fission yields are essential for nuclear reactor studies (decay heat, fuel inventory…) and constitute also one of the main observables needed to improve our understanding of the fission process. The symmetric mass region is of particular interest due to various intriguing properties of the fission fragments already reported in the literature : inversion of the nuclear charge polarization, large width of the fission fragment kinetic energy distribution, strong change of the prompt neutron multiplicity, etc. Recently, measurements of fission yields and kinetic energy distributions in the symmetric mass region were achieved at the LOHENGRIN mass spectrometer of the Institut Laue-Langevin (ILL). This experimental work is challenging due to the low counting rate and the appearance of contaminant masses, leading to pronounced components in the fission fragment kinetic energy distribution. Despite removing the undesirable contributions, the fission fragment kinetic energy distributions still show two components, indicating that the fission process could be modal. To go further and better characterize these components a comparison between our experimental data and Monte Carlo calculations (FIFRELIN code) simulating the de-excitation of the fission fragments for different fission channels will be presented and discussed

MURMUR: a new low-noise experiment for the search of neutron-hidden neutron transitions in the context of braneworld scenarios

International audience{MURMUR is a new passing-through-walls neutron experiment installed near the BR2 nuclear reactor at the Belgian Nuclear Research Center (SCK$\cdot$CEN, Mol, Belgium) and designed to search neutron interbrane transitions in the context of braneworld scenarios. In such scenarios, our visible Universe could be a 3-brane embedded in a multidimensional space-time, called the bulk, which could contain some other invisible adjacent 3-branes. Theoretical works have shown that the existence of hidden braneworlds can be experimentally tested thanks to neutron exchanges between braneworlds. A neutron $n$ in our visible brane can be converted into a hidden neutron $n'$ -- propagating in a hidden braneworld -- when scattered by a nucleus with a cross section $\sigma \big( n \rightarrow n'\big) \sim \sigma_E \big(n \rightarrow n \big) \times p$, where $\sigma_E$ is the usual elastic cross-section and $p$ the neutron swapping probability. Hidden neutrons could thus be generated in the moderator of the BR2 nuclear reactor where a high neutron flux undergoes many elastic scatterings. This hidden neutron flux could be free to travel out of the biological shielding of the reactor up to a matrix made of lead, acting as an antenna, which makes possible to regenerate hidden neutrons into visible ones thanks to reverse swapping. These regenerated neutrons can be detected thanks to a neutron detector placed inside the lead block. The MURMUR experimental setup is described, as well as the included upgrades compared to the first experiment of this kind carried out at the ILL (Grenoble, France) in 2015. The first results of MURMUR are introduced and discussed, and some upcoming improvements of the experimental setup are introduced

Development of a Gas Filled Magnet spectrometer within the FIPPS project

International audienceThe accurate knowledge of the fission product properties of actinides is important for the studies of innovative nuclear fuel cycles and also for the understanding of the fission process. Until now fission models cannot predict the fission yields with an acceptable accuracy. A collaboration between LPSC (Laboratoire de PhysiqueSubatomique et de Cosmologie), ILL (Institut Laue-Langevin) and CEA (Commissariat à l’Energie Atomique et aux Energies Alternatives) is pursuing a measurement program performed at the LOHENGRIN spectrometer at ILL (Grenoble, France) that is dedicated to the thorough characterization of fission yields in mass A, nuclear charge Z, kinetic energy Ek and spin J. To assess this last quantity, so far only an indirect method through isomeric ratio measurements has been used at the LOHENGRIN spectrometer.Nevertheless the evaluation of the fission fragment spin distributions can be done also directly via the measurement of prompt neutron and γ spectra per isotope. The FIPPS (FIssion Product Prompt γ-ray Spectroscopy) project at ILL aims at combining a powerful γ ray detection array with a gas-filled recoil separator for one of the fission products. The combined spectrometer will give access to new nuclear spectroscopy information of neutron-rich nuclides by tagging the complementary fragment and new insight into the fission process via combined measurements of mass A, nuclear charge Z, kinetic energy Ek and excited states.To optimize the design of the gas-filled separator in terms of acceptance and resolving power, we performed preparatory experiments using the second dipole magnet of the LOHENGRIN fission fragment separator. Using mass and energy separated fission fragment beams we studied the transmission, energy acceptance, energy loss and resolving power in A and Z with helium and nitrogen gas filling at pressures ranging from 2 mbar to 40 mbar. For instance, with the given magnet properties the best separation was reached with He at pressures around 40 mbar, corresponding to an overall energy loss of 50% in the gas. In parallel we developed a Monte Carlo simulation code to reproduce the obtained results. This code is now used for the detailed design of the gas-filled separator of the FIPPS project. In this talk experimental and simulation results will be presented along with the current status of the FIPPS project

Determination of neutron-induced fission fragment spin distribution after neutron evaporation

International audienceNuclear fission consists of splitting a nucleus into smaller nuclei. Several observablesare available to study the fission process such as fission yields orfission fragment angular momentum. Currently, fission models cannot predictall the observables with an acceptable accuracy for nuclear fuel cyclestudies for instance. Improvement of fission models is an important issue forthe knowledge of the process itself and for the applications. In this work, wetake an interest in fission fragment angular momentum distribution. Isomericratios (IRs) are a common observable giving access to investigate these distributions.We measured accurate IRs for 88Br, 132Sn and 132Te with the fissionfragment separator LOHENGRIN and developed a new analysis method toassess the mean value and uncertainty of the IR. An evaluation of the angularmomentum distribution of 132Sn was also performed with the FIFFRELINcode