Various international and national bodies such as the International Atomic Energy Agency, the European Commission, the US Nuclear Regulatory Commission have put forward proposals or guidance documents to regulate the "clearance" from regulatory control of very low level radioactive material, in order to allow its recycling as a material management practice. All these proposals are based on predicted scenarios for subsequent utilisation of the released materials. The calculation models used in these scenarios tend to utilise conservative data regarding exposure times and dose uptake as well as other assumptions as a safeguard against uncertainties.None of these models has ever been validated by comparison with the actual real life practice of recycling. An international project was organised in order to validate some of the assumptions made in these calculation models, and, thereby, better assess the radiological consequences of recycling on a practical large scale.The validation was proposed to be carried out by comparing the results of dose measurements during a chain of recycling operations to dose values calculated for the same operations using the (US) RESRAD-RECYCLE and the (French) CERISE programmes. The operations were to cover all recycling activities, including the receipt of contaminated scrap at the radiologically controlled melting facility, its segmentation and melting, transport of released ingots to a manufacturing industry for use with other scrap as feed material and production of industrial products (rolls).The project was initiated by the Swedish Radiation Protection Institute and was a co-operation between authorities, research institutes and commercial companies from Sweden, France, USA and Belgium.A first phase of melting of contaminated scrap at Studsvik, release of ingots and transport to Åkers was carried out. The ingots were re-melted along with other (uncontaminated) scrap at Åkers to be used for manufacturing rolls. The doses to workers were measured at Studsvik, Åkers and during ingot transport. Dose calculations were made in parallel with these operations using the RESRAD-RECYCLE and CERISE programmes. However, the results of these calculations could not be compared with the corresponding values of doses taken by workers, because all of the doses were below the limit of detection.Due to this fact, a second phase was executed involving the segmenting and melting of a 3.4 t stainless steel fuel rack with an estimated activity concentration of over 150 Bq/g, mostly Co-60. The fuel rack was melted for volume reduction in the Studsvik facility in the middle of January 2001, in the presence of project team including the dose modellers, who then made code calculations to estimate the dose uptake of the workers.All personnel involved in the project operations were equipped with electronic (display) dosimeters. The measurements showed that segmenting was the work operation that gave the highest dose, almost 65 % of the total dose incurred, while melting itself accounted for only abou...
Hydrogen Peroxide (H 2 O 2 ) bipropellant rocket engines have been in use since the 1950's in launch vehicles, sounding rockets, and as RATO (Rocket Assisted TakeOff) units for aircraft. Often, these engines function at a low chamber pressure using pressure-fed propellants, open-cycle turbo-pumps, or low-pressure closed-cycle turbo-pumps. As a result, hydrogen peroxide bipropellant rocket engines have generally had limited performance relative to other engine architectures. Modern advances in high-pressure catalyst bed design at Purdue's Zucrow Research Laboratories as well as select use of transpiration cooling have made it possible to improve upon prior art by operating with a high-performance closedcycle pump arrangement at high chamber pressure (3200 psia). This leads to higher specific impulse, lower weight, and smaller engine components. The following report describes a design study for the injector, combustion chamber, and nozzle assembly associated with a small, 5,000 lbf thrust engine using this high-pressure cycle concept with 90% hydrogen peroxide and RP-1 propellants. Engine cycle design, chamber sizing, cooling selection and analysis, performance analysis, and structural design and analysis are all discussed. While many elements of the engine design require additional development prior to manufacturing, this study shows that very high-pressure closed-cycle hydrogen peroxide bipropellant engines should be feasible. Nomenclaturea = char depth b = empirical coefficient C p = specific heat D = diameter G = mass flux h = heat transfer coefficient = mass flow MR = mass ratio MW = molecular weight n = empirical coefficient P = pressure St = Stanton number t = time T = temperature u = flow velocity w = empirical coefficient = expansion ratio = density
Gas stove is one of the most common and basic domestic appliances found in any home in the subcontinent. It is the foremost article used for cooking at home, and thus necessitates interaction with it by the users in a significant way. Despite the advent of more advanced devices like the microwave oven or the induction cooktop, a traditional gas stove reigns supreme in the lives of homemakers. Therefore, an endeavor was undertaken to design a product that would improve the usage and performance of a gas stove, by way of alleviating the general problems faced by users in its operation. Design thinking strategies had been followed throughout the stages of the product development, beginning with a customer survey to understand the desirable needs, followed by translating them into tangible target specifications for the product to achieve, and finally using the ideation techniques to develop the concepts into feasible product. The morphological method of concept generation yielded possible concepts aimed towards a solution, which were evaluated by following the analysis techniques of Forced Decision (FD) and Decision Alternative Ratio Evaluation (DARE). The filtered concept was then subjected to product architecture design, where it was given an efficient physical form by using the Computer Aided Design (CAD) software SolidWorks, and lastly, the parametric design result was evaluated by means of various Design For Excellence (DFX) guidelines. The product turned out to be an appendage to the existing stove, that would shield the flame and provide efficient operation along with enhanced safety and ease of use, as validated by DFX principles and a Computational Fluid Dynamics (CFD) study to gauge its performance in relation to that of a standalone gas stove. This paper comprises of expositions of all the aforementioned processes as carried out, along with the final result, and pertinent analyses.
Disposal of waste is an important issue faced by sanitation agencies, especially in India, where the volume of waste generated has been increasing rapidly over the last few years. According to the Ministry of Housing and Urban Affairs, as of January 2020, 147,613 metric tonnes (MT) of solid waste is generated per day in the country. Part of the waste that is expunged on a daily basis from homes, is food and other kitchen waste, which are biodegradable or compostable. In rural areas, such waste is disposed of in landfills, such that they get decomposed to form compost that is used as manure for crops. But this is not feasible in large cities where empty land, as well as the time required for waste to get converted into compost, is in short supply. Composting is a proven method to reduce the volume of waste, to almost 15-20% of its original amount. Therefore, this work is focused on designing an electric composter that could decompose waste artificially, and is compact, efficient, odourless, and easy to operate. This product can thus manage biodegradable waste at the source of its generation, and effectively supplant the wastebasket in a kitchen by occupying no greater space than the latter. The yield of compost would also provide nutritive natural fertilizer to homes wherein kitchen gardens or terrace farms have been set up, as well as promote the creation of the same wherever space is available. In this paper, the important parameters involved in the design of composter, including geometry parameters and the ones of operational significance such as speed and number of blades of agitator and bin temperature, have been discussed thoroughly, along with providing an understanding of the processes and considerations necessitated.
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