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Robotic wall scabbling, in vacuum (En-vac robotic wall scabbler)
Brief description of the technology The Robotic Wall Scabbling through aspiration (EWS - En-vac Robotic Wall Scabbler) is made-up of a distance-controlled scabbler unit, especially developed for the flat surfaces of walls and floors (Figure A; Figure B). ERWS adheres to the surface of the wall because of the aspiration in the tight chamber of the scabbling unit. Also, the aspiration system has the role to prevent dust infiltration and residues from the work surface during the scabbling process. The scabbling unit is sustained by a safety system and can move on the surface of the floors, walls and ceilings by some wheels which are individually controlled by engines. The complete ERWS system is composed of a robot which performs the scabbling, a recycling unit, a filter and an aspiration unit (DOE 2001). ERWS has the capacity to decontaminate deeper then the base technologies. The ERWS scabbling process is provided with steel filings or with iron shot. The aspiration unit sustains the robot on the wall, holds and transports the resulted wastes from the scabbling process. The recyclable and residual scabbling materials are transmitted to the recycling unit through an aspiration tube. The residues resulted from the scabbling process are processed through a recycling unit, a filter and an aspiration unit, all of them, separated from the robot. The recycling unit assures the permanent supply with abrasive particles through a tube. Target contaminants ERWS is aimed to remove the contaminants from the painted surfaces of concrete walls and floors. Similarly to other physical decontamination technologies, ERWS removes the paint and concrete layers containing the contaminants. Applicable materials and surface characteristics This technology is specific to flat, painted, concrete and steel carbon surfaces and is not applicable to uncovered metals, plastic materials, wood and surfaces with complex geometries. Waste streams and waste management related aspects The primary wastes, generated in the ERWS process, are represented by a steam of concrete and paint fragments, which contain small amounts of particles on the basis of which the scabbling is made. The particles the scabbling is made with, are recycled for about 10 times, representing in their turn, a small part of the total quantity of wastes. The wastes are automatically collected by the aspiration system. The scabbling recyclable particles are separated in the recycling system; the scabbling particles that cannot be recycled are stored in collector recipients in order to be evacuated. The special aspects of wastes discharge are specific to each case, depending on the detected radio nuclides and the presence of different materials in the paint. The secondary wastes are represented by personnel protection equipment. In the case of ERWS technology there are no specific requirements especially dedicated to the treatment and deposal of wastes or other aspects connected to their management. Performance status In March 2000 an experiment was conducted in order to establish the performance data and costs of the ERWS technology in a Test Area North (TAN) belonging to Idaho National Laboratory (INL) of DOE. The experiment consisted in the decontamination and removal of paint and/or concrete from the walls of the unit. In the experiment, the ERWS robot scabbling performances were compared to these of the manual conventional, scabbling units with abrasive materials. The experimental study was made on a wall with a surface of 5,7 m2 (60 ft2). The time for initializing the ERWS process was 3 hours and the effective period for the actual scabbling of the surface was 36 minutes. Comparative to the conventional technology, the ERWS scabbling was 5 times faster and much deeper. Because the scabbling was made in a closed circuit, there were no scabbling fragments on the floor and no air contamination was detected. The final filter of the aspiration unit retained 99,999% of the particles bigger than 1 micron, evacuated in the system. After the experiment, the whole ERWS system was decontaminated. The safety aspects associated to ERWS are represented by the risk of flaws into the electrical part of the robot. This risk can be reduced through the actions taken by the safety engineer. The risks associated to the use of ERWS technology are acceptable for the population. ERWS is a mature technology that has demonstrated its performances throughout the development of the experimental study from INL. The robot operation needs no special qualification; still, the ERWS system user needs training in operating the equipment. According to the opinion of the operators, employing this technology, a large surface was scabblered a lot easier and faster compared to the conventional technology. It was noticed that anchoring points are necessary for supporting the equipment in case of loss of electric power supply. Cost estimation of the decontamination technique, resulted after the soft simulation For the cost estimation of this decontamination technique, simulations were performed/executed, using ProVision 6.1.1. Program, Monte Carlo mathematical method. The work procedures specific to this decontamination process were taken into account and the WorkFlow model was used, based on the following basic components:
The workflow referring to the robotic scabbling of the walls, in vacuum environment (En-vac Robotic Wall Scabbler) was presented in Figure C. Generating the reports resulted after the simulation
This report (Table A) displays in a matrix, the individual decomposition involved the scenario of the simulated workflow. In this way, thus after the running of a simulation, the direct and indirect costs and those specific to the resources, can be explicitly reflected in such a report. The results on the lines reflect the cost values that are implied by each cost element, filled with the corresponding percentages for each generative activity. At the same time, there is a total line which sums up the individual registered values. Thus, the report presents in interaction, activities and elements of cost, the common values representing for each cost element, the engaged value by each activity.
Similar to the cost distribution table, the costs table (Table B) displays in a matrix, the individual costs decomposition, resulted after the simulation of the workflow scenario. This report presents, in interaction, the activities grouped on the components (actors) that operate them and the cost elements, the intersection values presenting for each activity the cost generated by the correspondent cost element. The costs at activity level are presented also as totals at component (actor) level, on a reserved line in this respect.
The report about the use of resources (Table C), displays in a matrix the decomposition of individual costs resulted after the stimulation of the workflow scenario. The table lines present the values of working time used by each resource (organization/role/consumed system in the execution of the activity) and the percentages correspondent to the respective lucrative activities. The table columns are used to show the time activity, two out of these being reserved as to comprise the timesheets for each resource and in the end to totalize it.
The staff activity report (Table D) displays in a matrix the decomposition of individual costs resulted after the simulation of the workflow scenario. The lines of the table reflect the specific timesheets for each role correspondent to the activities carried out and at the same time, the right involvement percentage. The first line used for summing up the column values, allowing thus the visualization of the total consumed time for each employee.
The cost chart (Figure D) represents a visual report of the costs in a scenario, costs resulted after simulation. Thus, with the help of this type of chart, the direct, indirect costs and those related to resources, for each activity in the simulated workflow, are considered. Axis X of the Cost Chart, displays all the component activities of the simulated scenario, split into cost categories (direct, indirect and resource related). The co-ordinate Y commensurate the levels attained by the cost elements on the preceding co-ordinate.
The Cost Distribution Chart (Figure E), represents a visual presentation form of costs distribution in a simulation scenario. We can follow the level attained by each of the cost elements (direct, indirect or resources generated). Axis X presents each cost element involved in the simulated scenario. Axis Y allows the evaluation of the levels attained by these cost elements. The values of these costs are displayed in segments, correspondent to the level of each activity in the simulated flow.
Following to the workflow, the Resource Utilization Chart (Figure F), allows the visualization of the individual efforts of the involved resources, efforts measured in working hours. (A resource can be represented by an organization, role or system used for the operativeness of the scenario’s activities). Axis X is an inventory of all the implied resources in the scenario, while axis Y allows the measurement of the working time. This working time is displayed for each activity implied in the process in order to visually estimate the percentage of each resource involvement.
The Staffing Chart (Figure G) presents visually the sum of resources consumed by each activity, estimated as total working hours. (The resource may be represented by an organization, role or system utilized to create the operativeness of the scenario’s activities). The axis X enables the inventory of all activities which compose the simulated workflow scenario, while the axis Y is used in measuring the total time for each previously inventoried activity. The total time is segmented in percentages according to the implied resources in the correspondent activities.
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