[en] Interim, centralized, engineered (dry cask) storage facilities for USA light water power reactor spent nuclear fuel (SNF) should be implemented to complement and to offer much needed flexibility while the Nuclear Regulatory Commission is funded to complete its evaluation of the Yucca Mountain License and to subject it to public hearings. The interim sites should use the credo reproduced in Table 1 [Bunn, M., 2001. Interim Storage of Spent Nuclear Fuel. Harvard University and University of Tokyo] and involve both the industry and government. The sites will help settle the 50 pending lawsuits against the government and the $11 billion of potential additional liabilities for SNF delay damages if Yucca Mountain does not being operation in 2020 [DOE, 2008a. Report to Congress on the Demonstration of the Interim Storage of Spent Nuclear Fuel from Decommissioned Nuclear Power Stations (December)]. Under the developing consensus to proceed with closed fuel cycles, it will be necessary to develop SNF separation facilities with stringent requirements upon separation processes and upon generation of only highly resistant waste forms. The location of such facilities at the interim storage sites would offer great benefits to those sites and assure their long term viability by returning them to their original status. The switch from once-through to closed fuel cycle will require extensive time and development work as illustrated in 'The Path to Sustainable Nuclear Energy' [DOE, 2005. The Path to Sustainable Nuclear Energy. Basic and Applied Research Opportunities for Advanced Fuel Cycles. DOE (September)]. A carefully crafted long term program, funded for at least 5 years, managed by a strong joint government-industry team, and subjected to regular independent reviews should be considered to assure the program stability and success. The new uncertainty about Yucca Mountain role raises two key issues: (a) what to do with the weapons and other high level government wastes committed to be moved to Yucca Mountain by specified dates? And (b) can the $13.6 billion invested at Yucca Mountain be salvaged if the NRC approves the license submittal and the opposition relents after contentious hearings? Or will it take contingent actions, or, a switch to a partial closed fuel cycle with its reduced risks and earlier timing of their peak risk value? Only time will tell if any of these alternates will be acceptable but, they all reinforce the need for interim storage for commercial SNF. If the decision is to go to a new repository one wonders whether the time has not come to change the safety evaluation process for geological repositories by characterizing two to three sites and subjecting them to an arbitrary release of the fission products in the HLW to be stored and considering the forms of some of the HLW to reduce their peak risks. It would allow the proper choice to be made among the selected sites and to have a basis for convincing the local committee to accept the repository location. It may even decide whether the CONFU fuel assembly [MIT, 2006. Implications of alternative strategies for transition to sustainable fuel cycles. Nucl. Sci. Eng., 154 (September)] for pressurized water reactors can be accommodated in a once-through fuel cycle as suggested by Levy [Levy, S., 2008. Yucca backup plan. Nucl. Eng. Int., 24-28]. A similar configuration is possible in boiling water reactors.

[en] We have measured the electronic transitions of a lead phthalocyanine thin film by means of optical absorption and reflection electron energy loss spectroscopy in the range from 1 to 20 eV. We compare the optical absorption spectrum with the loss spectra and discuss their similarity. We identify the loss structures and we report a new absorption band at 10 eV. In addition we report that the inelastic electron scattering from the lower energy π→π* transition and from the C-H stretching vibrational mode show energy-dependent structure, characteristic of resonance scattering via temporary negative ion states

[en] We have investigated the effect of hydrogen interaction with silicene monolayer and multilayer films grown on Ag(111) by means of scanning tunneling microscopy, low energy diffraction and high-resolution electron energy loss spectroscopy. On monolayer silicene, we demonstrate that the recently reported hydrogenated γ-(3 × 3) is indeed observed, but is found often in coexistence with the usual “flower” pattern of the clean silicene-(3 × 3), also labeled α-(3 × 3). In the vibrational spectra, features related to Si−H vibrational modes show shifts towards lower energies as compared to hydrogenated Si surfaces. This substantial bond softening is indicative of a partial charge filling of the bonding or anti-bonding orbitals of the Si−H bonds as compared to Si(111)−H. Indirectly, this is an evidence of the hybridization of monolayer silicene with the Ag(111) substrate. At multilayer coverage, the situation is clearly different. Indeed, hydrogen strongly perturbs the √3 × √3 reconstruction of the multilayer film, leading to its local dissolution and to the formation of protrusions due to clustering of atoms. The vibrational spectrum of the √3 × √3 silicene closely resembles that of a highly hydrogenated Si surfaces, with the simultaneous presence of Si−H, Si−H₂ and Si−H₃ bonds.

[en] At monolayer coverage, silicene on Ag(1 1 1) may present different structural phases depending on the growth conditions. At multilayer coverage, only one structural phase has been reported: the (√3×√3)R30^∘ phase. However, no link between the structural arrangement of the monolayer and that of the multilayer has been addressed. In this paper, reporting experimental work based on low-energy electron diffraction and scanning tunneling microscopy, we focus on the structural aspects of a multilayer film of silicene. We demonstrate that it exhibits one structural arrangement, namely the (√3×√3)R30^∘ form, but with different domain orientations resulting from the structural properties of the initial wetting monolayer. (paper)

[en] Radiolabelled somatostatin analogues have been used in diagnostic and therapeutic nuclear medicine to treat cancerous tumours. Lanreotide, a cyclic octapeptide, β-naphthyl-peptide, with antiproliferative action on human small cell lung carcinoma was ¹⁸⁸Re labelled and characterised, and its biodistribution was studied in mice. Molecular modelling indicates that the lipophilic radiopharmaceutical might be an oxo-rhenium (V) penta-coordinated complex. The implanted human cervical tumour of epidermoid origin was positive for cytokeratins and Vimentin. Uptake of ¹⁸⁸Re-labelled peptide in the implanted tumour in athymic mice was 6.2±2.9% and was rapidly cleared via the hepatobiliary system. ¹⁸⁸Re-β-naphthyl-peptide might be a potential therapeutic agent

[en] For comprehensive quality control measurements in diagnostic radiography, ionization chambers and semiconductor-based dosimeters are used. Semiconductor dosimeters are easy to handle, and they provide several quantities of interest with one exposure. However, their inherent energy dependence of their response is influenced by the radiation quality and more pronounced than for ionization chambers. Therefore, multiple compensation methods, based on the radiation quality, are developed by the manufacturers. To ensure the quality of dose measurements, it is essential that every dosimeter used for this purpose is calibrated regularly. It shall be possible to perform this calibration independent from the manufacturer in a local Secondary Standards Dosimetry Laboratory (SSDL).

[en] Two-dimensional elemental topological insulators including silicene, germanene and stanene are currently the hottest topics in condensed matter physics. We first review the recent progress on electronic and topological properties of their monolayers from a fundamental viewpoint. Next, we describe their experimental realizations by epitaxial growth and their actual physical properties. We start with the description of the topological nature of generic Dirac systems and then apply it to silicene by introducing the spin and valley degrees of freedom. Based on them, we classify all topological insulators in the general honeycomb system. We discuss topological electronics based on honeycomb systems. We introduce the topological Kirchhoff law, which is a conservation law of topological edge states. A field effect topological transistor is proposed based on the topological edge states. We show that the conductance is quantized even in the presence of random distributed impurities. Monolayer topological insulators will be a key for future topological electronics and spin-valleytronics. The outstanding example of the realization of such monolayer Si, Ge and Sn novel artificial allotropes is the canonical 3 × 3 reconstructed epitaxial silicene phase grown in situ under ultra-high vacuum on the silver (111) surface. Its realization in 2012 has preceded the synthesis of germanene, followed by that of stanene, respectively on Au(111) and Bi₂Te₃ substrates. Further growth of Si and Ge over monolayer epitaxial silicene and germanene leads to layered thin films displaying Dirac fermion characteristics. Amazingly, Si deposition onto Ag(110) templates yields massively parallel, pentasilicene-like nanoribbons, a novel form of one-dimensional silicon. Field Effect Transistors have been already fabricated both with single and multi-layer silicene channels, clearly demonstrating potential applications in electronics of silicene and such related materials, which are directly compatible with the current, ubiquitous, Si-based technology. Finally, enticing prospects are outlined.

[en] Raman microscopy is one of the methods that could be used for future post-mortem analyses of samples extracted from ITER plasma facing components. This study shows that this technique is useful for studying tungsten-based materials containing impurities including oxides and nitrides. Here, we apply pulsed laser deposition and DC argon glow discharges to produce tungsten-containing synthetic films (compact, and porous), and nanoparticles, and investigate the influence of their morphology on the measured Raman spectra. The amounts of oxygen and/or nitrogen in the films are also investigated. Comparative data are obtained via x-ray Photoelectron Spectroscopy, Atomic Force Microscopy, Electron Microscopies (Scanning and Transmission), Energy Dispersive x-ray spectroscopy, and Time-of-Flight Elastic Recoil Detection Analysis. The power density of the laser beam used to perform the Raman microscopy is varied by up to 4 orders of magnitude (0.01–20 mW μm⁻²) so as to investigate the thermal stability of films and nanoparticles. As a first result, we give evidence that Raman microscopy is sensitive enough to detect surface native oxides. Secondly, more tungsten oxides are detected in porous materials and nanoparticles than in compact films, and the intensities of the Raman band correlate to their oxygen content. Thirdly, the thermal stability of these films (i.e. structural and chemical modification under laser heating) is poor when compact films contain a sufficiently large amount of nitrogen. This finding suggests that nitrogen can be substituted by oxygen during Raman laser induced heating occurring in ambient air. Finally, our methodology can be used to rapidly characterize the morphology and chemistry of the samples analyzed, and also to create oxides at the micrometer scale. (paper)