High-resolution radiation mapping to investigate FDNPP derived contaminant migration

AbstractAs of March 2016, five years will have passed since the earthquake and ensuing tsunami that crippled the Fukushima Daiichi Nuclear Power Plant on Japan’s eastern coast, resulting in the explosive release of significant quantities of radioactive material. Over this period, significant time and resource has been expended on both the study of the contamination as well as its remediation from the affected environments. Presented in this work is a high-spatial resolution foot-based radiation mapping study using gamma-spectrometry at a site in the contaminated Iitate Village; conducted at different times, seventeen months apart. The specific site selected for this work was one in which consistent uniform agriculture was observed across its entire extent. From these surveys, obtained from along the main northwest trending line of the fallout plume, it was possible to determine the rate of reduction in the levels of contamination around the site attributable to the natural decay of the radiocesium, remediation efforts or material transport. Results from the work suggest that neither the natural decay of radiocesium nor its downward migration through the soil horizons were responsible for the decline in measured activity levels across the site, with the mobilisation of contaminant species likely adhered to soil particulate and the subsequent fluvial transport responsible for the measurable reduction in activity. This transport of contaminant via fluvial methods has already well studied implications for the input of contaminant material entering the neighbouring Pacific Ocean, as well as the deposition of material along rivers within previously decontaminated areas

Imperfect Detectors in Linear Optical Quantum Computers

We discuss the effects of imperfect photon detectors suffering from loss and noise on the reliability of linear optical quantum computers. We show that for a given detector efficiency, there is a maximum achievable success probability, and that increasing the number of ancillary photons and detectors used for one controlled sign flip gate beyond a critical point will decrease the probability that the computer will function correctly. We have also performed simulations of some small logic gates and estimate the efficiency and noise levels required for the linear optical quantum computer to function properly.Comment: 13 pages, 5 figure

The effect of common groundwater anions on the aqueous corrosion of zero-valent iron nanoparticles and associated removal of aqueous copper and zinc

This work has investigated the influence of common groundwater anions (Cl-, NO3-, SO42- and HCO3-) on the corrosion behaviour and associated removal of copper (Cu) and zinc (Zn) ions onto nanoscale zero-valent iron particles (nZVI). After 16 week exposure to solutions containing each anion at 10 mM concentrations, nZVI was observed to corrode into different iron (hydr)oxide phases (determined using XRD), depending upon the anion present: HNO3- produced goethite particles; NO3- produced predominantly magnetite/maghemite particles; both SO42- and Cl- produced a mixture of phases, including magnetite/maghemite, lepidocrocite and goethite. For solutions containing the different anions and 0.3 mM concentrations of Cu or Zn, near-total metal removal onto nZVI was recorded in the initial stages of the reaction (e.g. <24 hrs) for all systems tested. However, when Cl- and SO42- were also present significant subsequent desorption was recorded and attributed to the influence of anionic pitting corrosion. In contrast, no Cu or Zn desorption was recorded for batch systems containing NO3-, which was attributed to the enmeshment of Cu or Zn in a mixed-valent iron oxide shell. Results herein therefore demonstrate that NO3- could be utilised alongside nZVI to improve its long-term performance for in situ water treatment applications

Observations of Hunter-Schreger Bands

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66575/2/10.1177_00220345560350052201.pd

Structural effects in UO2 thin films irradiated with fission-energy Xe ions

Uranium dioxide thin films have been successfully grown on LSAT (Al10La3O51Sr14Ta7) substrates by reactive magnetron sputtering. Irradiation by 92 MeV 129Xe23+ ions to simulate fission damage that occurs within nuclear fuels caused microstructural and crystallographic changes. Initially flat and continuous thin films were produced by magnetron sputtering with a root mean square roughness of 0.35 nm determined by AFM. After irradiation, this roughness increased to 60–70 nm, with the films developing discrete microstructural features: small grains (∼3 μm), along with larger circular (up to 40 μm) and linear formations with non-uniform composition according to the SEM, AFM and EDX results. The irradiation caused significant restructuring of the UO2 films that was manifested in significant film-substrate mixing, observed through EDX analysis. Diffusion of Al from the substrate into the film in unirradiated samples was also observed

Structural effects in UO2 thin films irradiated with U ions

This work presents the results of a detailed structural characterisation of irradiated and unirradiated single crystal thin films of UO2. Thin films of UO2 were produced by reactive magnetron sputtering onto (0 0 1), (1 1 0) and (1 1 1) single crystal yttria-stabilised zirconia (YSZ) substrates. Half of the samples were irradiated with 110 MeV 238U31+ ions to fluences of 5 × 1010, 5 × 1011 and 5 × 1012 ions/cm2 to induce radiation damage, with the remainder kept for reference measurements. It was observed that as-produced UO2 films adopted the crystallographic orientation of their YSZ substrates. The irradiation fluences used in this study however, were not sufficient to cause any permanent change in the crystalline nature of UO2. It has been demonstrated that the effect of epitaxial re-crystallisation of the induced radiation damage can be quantified in terms of kernel average misorientation (KAM) and different crystallographic orientations of UO2 respond differently to ion irradiation

A multilevel neo-institutional analysis of infection prevention and control in English hospitals: coerced safety culture change?

Despite committed policy, regulative and professional efforts on healthcare safety, little is known about how such macro-interventions permeate organisations and shape culture over time. Informed by neo-institutional theory, we examined how inter-organisational influences shaped safety practices and inter-subjective meanings following efforts for coerced culture change. We traced macro-influences from 2000 to 2015 in infection prevention and control (IPC). Safety perceptions and meanings were inductively analysed from 130 in-depth qualitative interviews with senior- and middle-level managers from 30 English hospitals. A total of 869 institutional interventions were identified; 69% had a regulative component. In this context of forced implementation of safety practices, staff experienced inherent tensions concerning the scope of safety, their ability to be open and prioritisation of external mandates over local need. These tensions stemmed from conflicts among three co-existing institutional logics prevalent in the NHS. In response to requests for change, staff flexibly drew from a repertoire of cognitive, material and symbolic resources within and outside their organisations. They crafted 'strategies of action', guided by a situated assessment of first-hand practice experiences complementing collective evaluations of interventions such as 'pragmatic', 'sensible' and also 'legitimate'. Macro-institutional forces exerted influence either directly on individuals or indirectly by enriching the organisational cultural repertoire

Structural effects in UO₂ thin films irradiated with U ions

AbstractThis work presents the results of a detailed structural characterisation of irradiated and unirradiated single crystal thin films of UO2. Thin films of UO2 were produced by reactive magnetron sputtering onto (001), (110) and (111) single crystal yttria-stabilised zirconia (YSZ) substrates. Half of the samples were irradiated with 110MeV 238U31+ ions to fluences of 5×1010, 5×1011 and 5×1012ions/cm2 to induce radiation damage, with the remainder kept for reference measurements. It was observed that as-produced UO2 films adopted the crystallographic orientation of their YSZ substrates. The irradiation fluences used in this study however, were not sufficient to cause any permanent change in the crystalline nature of UO2. It has been demonstrated that the effect of epitaxial re-crystallisation of the induced radiation damage can be quantified in terms of kernel average misorientation (KAM) and different crystallographic orientations of UO2 respond differently to ion irradiation