► One of the design options in the UK envisages very deep borehole disposal where the host granite can be partially melted and then recrystallised. ► The acoustic emission was detected from the ...melting and solidification of natural granite in conditions simulating very deep borehole disposal. ► The cumulative number of signals, their durations and frequencies were monitored. ► Acoustic emission from the granite was also studied in part by monitoring phase transformation on heating and cooling of quartz.
Acoustic emission (AE) signals resulting from the melting and solidification of natural granite were monitored and analysed. The experimental work was conducted in laboratory conditions simulating very deep borehole disposal (DBD) of high level wastes such as sealed radioactive sources (SRS) or spent nuclear fuel (SNF). The cumulative number of signals, their durations and frequencies were the main characteristics of the monitored processes. The recorded AE could be associated with the complex changes in volume and shape of the constituent minerals associated with solid–liquid and solid–solid phase transformations within the granite. AE from the granite was also studied in part by monitoring phase transformation on heating and cooling of quartz.
The construction sector has one of the worst occupational health and safety records in Europe. Of all construction tasks, formwork activities are associated with a high frequency of accidents and ...injuries.
This paper presents an investigation of the activities and related safety risks present in vertical formwork for in-situ concrete construction in the civil engineering sector.
Using the methodology of staticized groups, twelve activities and ten safety risks were identified and validated by experts. Every safety risk identified in this manner was quantified for each activity using binary methodology according to the frequency and severity scales developed in prior research. A panel of experts was selected according to the relevant literature on staticized groups.
The results obtained show that the activities with the highest risk in vertical formwork tasks are: Plumbing and leveling of forms, cutting of material, handling materials with cranes, and climbing or descending ladders. The most dangerous health and safety risks detected were falls from height, cutting and overexertion.
The research findings provide construction practitioners with further evidence of the hazardous activities associated with concrete formwork construction and a starting point for targeting worker health and safety programmes.
Major and trace element data for the Tertiary, Shiant Isles Main Sill, NW Scotland, are used to discuss its complex internal differentiation. Vertical sections through the sill exhibit sharp breaks ...in chemistry that coincide with changes in texture, grain size and mineralogy. These breaks are paired, top and bottom, and correspond to the boundaries of intrusive units, confirming a four-phase multiple-intrusion model based on field relations, petrography, mineralogy and isotopes. Whole-rock chemistry is consistent with this model and necessitates only minor revisions to the intrusive and differentiation mechanisms previously proposed. The rocks contain strongly zoned minerals (e.g. olivine Fo70–5, clinopyroxene Mg# = 75–5, plagioclase An75–5) indicating almost perfect fractional crystallization, but whole-rock compositions do not show such extreme variations. Thus, while residual liquids became highly evolved in situ, they mainly became trapped within the crystal network and did not undergo wholesale inward migration. Some inward (mainly upward) concentration of residual liquids did occur to form a ‘sandwich horizon’, but the more volatile-rich, late-stage liquids that did not crystallize in situ appear to have migrated to higher levels in the sill to form pegmatitic horizons. Parental liquid compositions are modelled for the intrusive units and it is concluded that the original parent magma formed by partial melting of upper mantle that was more depleted in LREE than the sources of most Scottish Tertiary basaltic rocks. Incompatible trace elements in the picrodolerite–crinanite intrusive unit support isotope evidence that its parent magma was contaminated by crustal material. Attempts to reconcile the chemical characteristics of the sill with a recently proposed petrogenetic model based on a single intrusion of magma differentiated by novel, but controversial, processes fail comprehensively. It is predicted that the complex petrogenetic history of the Shiant Isles sill is not unusual and could become the model for other large (>50 m thick) sills.
Pathology Related to Chronic Arsenic Exposure Centeno, Jose A.; Mullick, Florabel G.; Martinez, Leonor ...
Environmental health perspectives,
10/2002, Volume:
110, Issue:
suppl 5
Journal Article
Peer reviewed
Open access
Millions now suffer the effects of chronic arseniasis related to environmental arsenic exposure. The biological mechanisms responsible for arsenic-induced toxicity and especially chronic effects, ...including cancer, are not well known. The U.S. Armed Forces Institute of Pathology (AFIP) is participating in an international research effort to improve this understanding by the development of the International Tissue and Tumor Repository for Chronic Arsenosis (ITTRCA). The ITTRCA obtains, archives, and makes available for research purposes, tissues from subjects exposed to arsenic. We provide here a short overview of arsenic-induced pathology, briefly describe arsenic-induced lesions in the skin and liver, and present five case reports from the ITTRCA. Arsenic-induced skin pathology includes hyperkeratosis, pigmentation changes, Bowen disease, squamous cell carcinoma, and basal cell carcinomas. A unique spectrum of skin lesions, known as arsenical keratosis, is rather characteristic of chronic arseniasis. Bowen disease, or squamous cell carcinoma in situ of the skin, has been well documented as a consequence of arsenical exposure. A spectrum of liver lesions has also been attributed to chronic arseniasis. Of these, hepatocellular carcinoma, angiosarcoma, cirrhosis, and hepatoportal sclerosis have been associated with arsenic exposure. We present case reports that relate to these health conditions, namely, squamous cell carcinoma, basal cell carcinoma, and Bowen disease of the skin and hepatocellular carcinoma and angiosarcoma of the liver. Four patients had been treated with arsenical medications for such conditions as asthma, psoriasis, and syphilis, and one case occurred in a boy chronically exposed to arsenic in drinking water.
Deep borehole disposal (DBD) is emerging as a viable alternative to mined repositories for many forms of highly radioactive waste. It is geologically safer, more secure, less environmentally ...disruptive and potentially more cost‐effective. All high‐level wastes generate heat leading to elevated temperatures in and around the disposal. In some versions of DBD this heat is an essential part of the disposal while in others it affects the performances of materials and waste forms and can threaten the success of the disposal. Different versions of DBD are outlined, for all of which it is essential to predict the distribution of temperature with time. A generic physical model is established and a mathematical model set up involving the transient conductive heat flow differential equation for a cylindrical source term with realistic decay. This equation is solved using the method of Finite Differences. A Fortran computer code (GRANITE) has been developed for the model in the context of DBD and validated against theoretical and other benchmarks. The limitations of the model, code, input parameters and data used are discussed and it is concluded that the model provides a satisfactory basis for predicting temperatures in DBD. Examples of applications to some DBD scenarios are given and it is shown that the results are essential to the design strategy of the DBD versions, geometric details and choice of materials used. Without such modeling it would be impossible to progress DBD of nuclear wastes; something that is now being given serious consideration in several countries.
This overview paper draws together findings from previous focus group research and studies of 100 individual construction accidents. Pursuing issues raised by the focus groups, the accident studies ...collected qualitative information on the circumstances of each incident and the causal influences involved. Site based data collection entailed interviews with accident-involved personnel and their supervisor or manager, inspection of the accident location, and review of appropriate documentation. Relevant issues from the site investigations were then followed up with off-site stakeholders, including designers, manufacturers and suppliers. Levels of involvement of key factors in the accidents were: problems arising from workers or the work team (70% of accidents), workplace issues (49%), shortcomings with equipment (including PPE) (56%), problems with suitability and condition of materials (27%), and deficiencies with risk management (84%). Employing an ergonomics systems approach, a model is proposed, indicating the manner in which originating managerial, design and cultural factors shape the circumstances found in the work place, giving rise to the acts and conditions which, in turn, lead to accidents. It is argued that attention to the originating influences will be necessary for sustained improvement in construction safety to be achieved.
Waste actinides, including plutonium, present a long-term management problem and a serious security issue. Immobilisation in mineral or ceramic waste forms for interim storage is a widely proposed ...first step. The safest, most secure geological disposal for Pu is in very deep boreholes and we propose that the key step to combination of these immobilisation and disposal concepts is encapsulation of the waste form in cylinders of recrystallized granite. We discuss the underpinning science, focusing on experimental work, and consider implementation. Finally, we present and discuss analyses of zircon, UO2 and Ce-doped cubic zirconia from high pressure and temperature experiments in granitic melts that demonstrate the viability of this solution and that actinides can be isolated from the environment for millions, maybe hundreds of millions, of years.
This paper discusses the need for interface management within construction, with particular reference to building facade interfaces. It categorizes the three different types of interface ...management-physical, contractual, and organizational. The implication of interface management in construction contracting is discussed; it is explained how the U.K. procurement trends have changed, affecting the interface management within projects. U.K. cladding procurement is very fragmented, and the paper maps the development of a typical cladding system showing the complexities of interface management. Finally, the paper discusses CladdISS, a U.K. government funded research project to develop a standardized strategy for the design and management of window and cladding interfaces. It explains the principles of CladdISS with reference to process maps, action plans, management strategy, bibliography, advice on standards, materials, maintenance, joints, movement, and tolerances. This will enable strategies to be developed to avoid the endemic interface problems occurring on-site. It will also guide the management of the interfaces throughout the project.
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