Reprocessing vs direct disposal of used nuclear fuels: The environmental impacts of future scenarios for the UK

The UK recently switched from a “nominal” twice-through cycle - whereby used nuclear fuels were reprocessed, but uranium and plutonium were not routinely reintroduced in the fuel cycle – to a once-through cycle, where used nuclear fuels are stored pending disposal. However, it is also the current strategy to keep other options open, including a twice-through cycle based on a different chemical separation process from the conventional PUREX. This article presents a comprehensive Life Cycle Assessment study of future scenarios for the back-end of the UK nuclear fuel cycle that aims at informing policy- and decision-makers. The study considers the direct disposal approach and four reprocessing scenarios envisaging different strategies for disposal and/or reuse of reprocessed uranium and plutonium, and adopts a consequential approach including only short-term effects. These primarily represent reductions in demand for uranium mining due to recycling of uranium and plutonium, and are modelled upon identification of a marginal technology. Several marginal technologies are explored because of the uncertainty regarding the actual response of the market. Results of the study show that recycling of uranium, but especially of plutonium is of paramount importance because of the avoided burdens associated with production of nuclear fuel from mined uranium. The reprocessing scenarios envisaging reprocessing of used nuclear fuels and recycling of both plutonium and uranium represent the most favourable options. The direct disposal approach may be advantageous only in terms of radiological impacts depending on the marginal technology chosen

The environmental impacts of reprocessing used nuclear fuels: A UK case study

Historically the UK implemented a “nominal” twice-through cycle whereby used nuclear fuels were reprocessed, but uranium and plutonium were not recycled: they were stored pending a future decision by the UK Government. However, the policy for managing higher activity wastes is clear: it envisages their disposal in a Geological Disposal Facility. Consultations for siting a repository - which were suspended in 2013 - have recently restarted, but the repository will not be available for several decades at the earliest. This article presents a comprehensive LCA study on the historical UK approach for managing used nuclear fuels and the UK Government policy for disposal of higher activity wastes. The underpinning purpose is to inform policy and decision-makers concerned with decisions on the future of the UK nuclear fuel cycle. The study relies on a combination of operational data from the Sellafield site – the industrial complex home to the UK reprocessing plants - and literature data on the GDF, and on a number of assumptions regarding the GDF design and disposal of higher activity wastes. The results reveal that a great proportion of the environmental impacts can be linked to two specific causes: indirect burdens from production of uranyl nitrate, which is used to separate plutonium from uranium, and copper, proposed in one scenario to be used as the outer layer of the disposal canister for High Level Waste. The results also demonstrate that the carbon intensity of the management of used nuclear fuels is practically negligible when compared with results from other LCA studies that cover the entire fuel cycle

Headwater Influences on Downstream Water Quality

We investigated the influence of riparian and whole watershed land use as a function of stream size on surface water chemistry and assessed regional variation in these relationships. Sixty-eight watersheds in four level III U.S. EPA ecoregions in eastern Kansas were selected as study sites. Riparian land cover and watershed land use were quantified for the entire watershed, and by Strahler order. Multiple regression analyses using riparian land cover classifications as independent variables explained among-site variation in water chemistry parameters, particularly total nitrogen (41%), nitrate (61%), and total phosphorus (63%) concentrations. Whole watershed land use explained slightly less variance, but riparian and whole watershed land use were so tightly correlated that it was difficult to separate their effects. Water chemistry parameters sampled in downstream reaches were most closely correlated with riparian land cover adjacent to the smallest (first-order) streams of watersheds or land use in the entire watershed, with riparian zones immediately upstream of sampling sites offering less explanatory power as stream size increased. Interestingly, headwater effects were evident even at times when these small streams were unlikely to be flowing. Relationships were similar among ecoregions, indicating that land use characteristics were most responsible for water quality variation among watersheds. These findings suggest that nonpoint pollution control strategies should consider the influence of small upland streams and protection of downstream riparian zones alone is not sufficient to protect water quality

Phase I study of TP300 in patients with advanced solid tumors with pharmacokinetic, pharmacogenetic and pharmacodynamic analyses

Background: A Phase I dose escalation first in man study assessed maximum tolerated dose (MTD), dose-limiting toxicity (DLT) and recommended Phase II dose of TP300, a water soluble prodrug of the Topo-1 inhibitor TP3076, and active metabolite, TP3011. <p/>Methods: Eligible patients with refractory advanced solid tumors, adequate performance status, haematologic, renal, and hepatic function. TP300 was given as a 1-hour i.v. infusion 3-weekly and pharmacokinetic (PK) profiles of TP300, TP3076 and TP3011 were analysed. Polymorphisms in CYP2D6, AOX1 and UGT1A1 were studied and DNA strand-breaks measured in peripheral blood mononuclear cells (PBMCs). <p/>Results: 32 patients received TP300 at 1, 2, 4, 6, 8, 10, 12 mg/m2. MTD was 10 mg/m2; DLTs at 12 (2/4 patients) and 10 mg/m2 (3/12) included thrombocytopenia and febrile neutropenia; diarrhea was uncommon. Six patients (five had received irinotecan), had stable disease for 1.5-5 months. TP3076 showed dose proportionality in AUC and Cmax from 1--10 mg/m2. Genetic polymorphisms had no apparent influence on exposure. DNA strand-breaks were detected after TP300 infusion. <p/>Conclusions: TP300 had predictable hematologic toxicity, and diarrhea was uncommon. AUC at MTD is substantially greater than for SN38. TP3076 and TP3011 are equi-potent with SN38, suggesting a PK advantage

Approximation of hindered zonal settling rates for flocculated inorganic/organic composite suspensions in inertial flow conditions

Inorganic/organic composite nuclear wastes have poor settling properties which hinder major UK decommissioning operations. Improving the settling properties of these wastes and the accurate prediction of settling rates is therefore key. However, constricted access and limited monitoring capability in radioactive environments limits the use of primary material, necessitating the use of surrogate test materials. Herein, an organic laden nuclear waste test material was characterised by examining the surface chemistry, morphology and settling behaviour. A large molecular weight polyacrylamide polymer was deployed to aggregate the organic laden nuclear waste test material. The polyacrylamide successfully flocculated the test material, increasing the zonal settling rate and decreasing the turbidity by one and two orders of magnitude respectively at optimum polymer dose conditions. Whilst displaying steric stabilisation beyond the performance maxima, reductions in flocculant performance were small with no indication of permanent stabilisation at five times the optimum dose. To mitigate risk, it is critical to understand the dynamics of the settling process. Given the porous, fractal nature of the agglomerates, fractal modified hindered settling models were assessed in order to improve predictions at low solids concentrations. In particular, predictive models using drag coefficients compatible with creeping and inertia flow regimes were utilised in tandem with structural and size data to quantify the impact of neglecting inertia drag as favoured by previous literature. It was found that at low solids concentrations, the inter-particulate spacing was significant and that inertial flow conditions were integral considerations to achieve close first-order approximations of zonal settling rate

Emotional Sentence Annotation Helps Predict Fiction Genre

Fiction, a prime form of entertainment, has evolved into multiple genres which one can broadly attribute to different forms of stories. In this paper, we examine the hypothesis that works of fiction can be characterised by the emotions they portray. To investigate this hypothesis, we use the work of fictions in the Project Gutenberg and we attribute basic emotional content to each individual sentence using Ekman’s model. A time-smoothed version of the emotional content for each basic emotion is used to train extremely randomized trees. We show through 10-fold Cross-Validation that the emotional content of each work of fiction can help identify each genre with significantly higher probability than random. We also show that the most important differentiator between genre novels is fear

Social patterning in grip strength and in its association with age; A cross sectional analysis using the UK Household Longitudinal Study (UKHLS)

Background: Grip strength in early adulthood and midlife is an important predictor of disability, morbidity and mortality in later life. Understanding social patterning in grip strength at different life stages could improve insight into inequalities in age-related decline and when in the life course interventions could prevent the emergence of inequalities. Methods: Using United Kingdom Household Longitudinal Study (UKHLS) data on 19,292 people aged 16 to 99, fractional polynomial models were fitted to identify which function of age best described its association with grip strength. Linear regressions were used to establish whether socio-economic position (SEP), as measured by maternal education, highest educational qualification and income, was associated with grip strength. To test whether the association between age and grip strength was modified by SEP, interactions between SEP and the age terms were added. Differentiation was used to identify the age at which grip strength was highest for men and women and predicted levels of grip strength at peak were compared. Results: SEP is significantly associated with grip strength on all SEP measures, except education for men. Grip strength is highest at a younger age, and less strong for all measures of disadvantage for women and most measures for men. Interaction terms were not statistically significant indicating that the association between age and grip strength was not modified by SEP. Grip strength peak was 29.3 kg at age 33 for women with disadvantaged childhood SEP compared with 30.2 kg at age 35 for women with advantaged childhood SEP. Conclusion: The SEP differences in age and level of peak grip strength could be indicative of decline in muscle strength beginning earlier and from a lower base for disadvantaged groups. This could impact on the capacity for healthy ageing for those with disadvantaged SEP

A coastal vulnerability assessment for planning climate resilient infrastructure

publisher: Elsevier articletitle: A coastal vulnerability assessment for planning climate resilient infrastructure journaltitle: Ocean & Coastal Management articlelink: https://doi.org/10.1016/j.ocecoaman.2018.06.007 content_type: article copyright: © 2018 The Authors. Published by Elsevier Ltd

Heterologous expression screens in Nicotiana benthamiana identify a candidate effector of the wheat Yellow Rust Pathogen that associates with processing bodies

Rust fungal pathogens of wheat (Triticum spp.) affect crop yields worldwide. The molecular mechanisms underlying the virulence of these pathogens remain elusive, due to the limited availability of suitable molecular genetic research tools. Notably, the inability to perform high-throughput analyses of candidate virulence proteins (also known as effectors) impairs progress. We previously established a pipeline for the fast-forward screens of rust fungal candidate effectors in the model plant Nicotiana benthamiana. This pipeline involves selecting candidate effectors in silico and performing cell biology and protein-protein interaction assays in planta to gain insight into the putative functions of candidate effectors. In this study, we used this pipeline to identify and characterize sixteen candidate effectors from the wheat yellow rust fungal pathogen Puccinia striiformis f sp tritici. Nine candidate effectors targeted a specific plant subcellular compartment or protein complex, providing valuable information on their putative functions in plant cells. One candidate effector, PST02549, accumulated in processing bodies (P-bodies), protein complexes involved in mRNA decapping, degradation, and storage. PST02549 also associates with the P-body-resident ENHANCER OF mRNA DECAPPING PROTEIN 4 (EDC4) from N. benthamiana and wheat. We propose that P-bodies are a novel plant cell compartment targeted by pathogen effectors