Office of Nuclear Energy

A novel sulfurated telechelic bis(methacrylate) monomer was synthesized and evaluated for its potential use in photopolymerization to yield gel polymer electrolytes (GPEs). The difunctional monomer was obtained via a two-step synthesis by the radical bismonoaddition of telechelic sulfurated dithiol onto allyl alcohol followed by the methacrylation of the resulting diol. It was prepared in 60% overall yield and thoroughly characterized by FTIR, Raman, and NMR spectroscopies. Several photopolymerizable formulations were then proposed by combining telechelic bis(methacrylate) with sodium bis(fluorosulfonyl)imide and tetraethylene glycol dimethyl ether. Upon UV initiation, a series of soft GPE films of various thicknesses were obtained and analyzed by FTIR spectroscopy. Their physicochemical, thermal, and preliminary electrochemical properties were then systematically studied. The resulting GPEs exhibit very low glass transition temperatures (−80 to −40 °C) and high electrical conductivity (1.2 × 10–4 S·cm–1) at room temperature, with electrochemical stability up to 4.5 V vs. Na+/Na. Sodium plating-stripping experiments in Na/GPE/Na symmetric cells show stable polarization voltage curves with no significant fluctuations, indicating homogeneous sodium deposition and dissolution up to a current density of 0.2 mA/cm2. These preliminary and promising results support the potential application of the developed GPEs in sodium batteries.

A key parameter in analyzing the performance of an integrated waste management system (IWMS) architecture for the disposition of spent nuclear fuel (SNF) is the SNF receipt rate from reactor and other custodian sites. Receipt rate in this paper means how much SNF is accepted per year for transport in the IWMS from such sites. Introducing one or more federal consolidated storage facilities (CSFs) into the IWMS architecture can potentially accelerate the receipt rate profile over time relative to system architectures without a CSF. This raises the question of what an optimal SNF receipt rate profile for an IWMS architecture might be in view of practical constraints and desired system performance attributes and associated metrics. This paper describes a sensitivity study on SNF receipt rates and the associated results for a selected set of IWMS scenarios aimed at informing near-term planning for storage capabilities and transportation assets. Two different strategies for CSF operation while awaiting availability of a disposal system to receive SNF are compared: one that relatively quickly fills an initial CSF and then idles the transportation system; and another that aims for more continuous use of transportation assets and receipt capabilities at the CSF. This study examines cost considerations and other factors, such as the timing of clearing reactor sites of SNF, efficient use of capital assets, and some other metrics that might be important to a CSF host community. Based on the analysis, an initial approach is presented that targets a continuous receipt strategy while maintaining the flexibility to step up receipt capabilities to a reasonable degree when needed and beneficial, within overall system constraints.

Solar photovoltaic (PV) electricity is considered to be an important source of electricity generation in the quest for net-zero carbon emissions. However, the growth of solar electricity is creating both increased material demands and increased greenhouse gas (GHG) emissions from silicon and PV manufacturing (also referred to as embodied GHG emissions of solar electricity). Here we analyze the silicon and solar PV supply chain for the United States (U.S.) market and find that the embodied GHG emissions of solar PV panel materials (such as silicon), manufacture, logistics, and installation in the U.S. given the current supply chain are 36 g CO2e kWh−1 of solar electricity generated. Eighty-five percent of the embodied GHG emissions are from PV panel production processes in China and other Asia–Pacific countries. Moving the silicon and PV manufacturing to the U.S. would reduce the embodied GHG emissions of solar electricity by 16% from its current level, primarily because of the lower GHG emission intensity of the U.S. electrical grid and the lower GHG emissions for aluminum electrolysis in North America. Future scenario analysis shows that by 2030, with the U.S. PV domestic supply chain and its decarbonized grid electricity and aluminum production, as well as improving PV conversion efficiency, the embodied GHG emissions of solar electricity in the U.S. will be reduced to 21 g CO2e kWh−1.

A new experiment collects data, since November 2019, at a depth of 210 m.w.e. in the Callio Lab in the Pyhasalmi mine in Finland. The setup, called NEMESIS (New Emma MEasurementS Including neutronS), incorporates infrastructure from the EMMA experiment with neutron and large-area plastic scintillator detectors. The experiment’s primary aim is to combine muon tracking with position-sensitive neutron detection to measure precision yields, multiplicities, and lateral distributions of high-multiplicity neutron events induced by cosmic muons in various materials. The data are relevant for background evaluation of the deep-underground searches for Dark Matter (DM), neutrino-less double beta decay, etc. Preliminary analysis revealed anomalies in muon-suppressed neutron multiplicity spectra collected during a 344-day run (live time) with a 565 kg Pb target. The spectra, otherwise well described by an exponential fit, show three peaks at high multiplicities. Although still at a low statistical significance, these small excesses match the outcome of an earlier measurement. The nature of the anomalies remains unclear, but, in principle, they may be a signature of self-annihilation of a WIMP with a mass close to 13 GeV/c2. With that assumption, the expected cross-section would be around 10−42 cm2 for Spin-Dependent or 10−46 cm2 for Spin Independent interactions. We propose verifying this hypothesis with an upgraded NEMESIS experiment, able to collect an order of magnitude more data than this measurement. Based on the statistical uncertainty, analysis of the event rate indicates that cross-section limits for DM mass range of approximately 3-40 GeV/c2 can be investigated with such a setup.

La mise en place des instruments de régulation s’appuie sur une conception de la propriété marquée dès le début par une perspective d’exclusion et de discrimination. Celle-ci se décline sur plusieurs registres (statut personnel, origine, couleur, richesse), qui peuvent être mobilisés ensemble ou successivement. Parmi les processus mis en jeu pour assurer ces exclusions, figure en bonne place une véritable fabrique de l’altérité qui distingue les colons, jugés seuls légitimes dans leur aspira...

As part of the Nuclear Innovation: Clean Energy Future initiative, this report describes flexibility in nuclear systems, the value it can bring, and international experiences surrounding flexible nuclear energy. Flexible nuclear energy for this report is defined as “The ability of nuclear energy generation to economically provide energy services at the time and location they are needed by end-users. These energy services can include both electric and non-electric applications utilizing both traditional nuclear power plants and advanced integrated systems.” Flexibility in nuclear systems is enabled by three main mechanisms: core ramping, integrated energy systems with multiple byproducts, and thermal storage. The value of this flexibility on a $\$$/MW and a $\$$/MWh basis can be estimated through a combination of physics and economics modeling. International agencies describe their experiences in operating flexible nuclear systems and describe their plans for increasing nuclear flexibility in a clean energy system, likely with a high penetration of variable renewable energy.

Book review: Jean-Noël Aletti, Il Gesù di Luca (Epifania della Parola; Bologna: Dehoniane 2012)

Chronic verbal retrieval deficits have been noted in traumatic brain injury (TBI), but no U.S. Food and Drug Administration-approved interventions are available. The present study investigated whether 10 sessions of 20 min of 1 mA anodal high-definition transcranial direct current stimulation (HD-tDCS) targeting pre-supplementary motor area/dorsal anterior cingulate cortex (preSMA/dACC) compared with sham HD-tDCS would improve verbal retrieval deficits in TBI patients. Improvements in verbal retrieval processes were observed up to 8 weeks post-treatment. Thus, potential dysfunction to verbal retrieval circuitry in TBI appears amenable to remediation through electromodulation with HD tDCS to the preSMA/dACC. Although further studies clarifying mechanisms by which tDCS brought about these improvements will likely inform refinements in the application of this therapeutic technique, the findings suggest the efficacy of using HD-tDCS to target other systems vulnerable to TBI to improve functioning.