Direct use of this fine DU-oxide has two limitations. First, concretes depend on their coarse aggregates to carry compressive stresses. If the shielding is not required to provide compressive strength, as in some cask designs, this untreated DUO2 powder still cannot be used to form even a low-strength, fine grout because of its chemical reactivity.
Therefore, the raw DUO2 must be treated and formed for use in stable high-strength concretes. Therefore, they made it possible to make very stable, high-strength concretes with over three times the density of standard construction concretes. This DUAGG process coupled with cask manufacturing is evaluated for its economic and technical viability in the subsequent sections. This study analyzed the project as if it were a stand-alone project; however, it was not intended to be a life-cycle cost analysis. The capital cost includes engineering design, equipment costs and installation, start up, and management.
Because the study does not include preoperational, decontamination, decommissioning, and closure costs, it cannot be considered a complete life-cycle cost analysis. However, the purpose of this analysis is to establish the potential viability of the DUAGG process as a private commercial venture. Too this end, we created a preconceptual baseline production plant equipment and layout described in Fig. Therefore, the equipment, site support facilities, and plant layout were also based on this production capacity.
Capital and operating costs for the United States were determined based on the unit-operations of the equipment used in the flowsheet, the layout of the plant, and the labor requirements. Most of the equipment can be readily obtained off- the-shelf from national vendors.
Conversely, DUCRETE may permit casks to contain more spent fuel assemblies at lower maximum temperatures within current volume and weight limits.
Table 2. Figure 7 illustrates the cask manufacturing processes. This preliminary estimate was not intended to establish the life-cycle cost of a cask manufacturing project.
Online shopping from a great selection at Books Store. Radiation Shielding Using Depleted Uranium Oxide in Nonmetallic Matrices of DU oxide (DUO 2) that could be used in nonmetallic matrix dry-storage casks.
Therefore, a complete study of the life duration of the plant has not been a part of this analysis. However, this study does include a baseline case and variations on the production cost due to changes in labor costs and other economic parameters of interest. The final product consists of SNF casks that are transportable and can be used for storage. In the future, a potential exists for the cask to be used for disposal purposes at the repository. The cask facility will receive prefabricated inner and outer cylinders, lids, and covers for the casks.
It was assumed that 3 days would be necessary 1 shift per day to completely produce one cask. This production rate established the size of the equipment needed to implement the production schedule as well as the site support facilities and the plant layout. Based on the unit-operations equipment used in the flowsheet, the layout of the plant, the labor requirements, and the capital and operating costs were determined. Table 3 summarizes the operating cost for the baseline case.
At the end of each exposure period, the vessels in which the samples were leached were cooled to room temperature and opened. The quantities leached were compared to the initial content of a DUAGG pellet to determine the degree of corrosion of the aggregate surfaces. The extent of surface corrosion, alteration, and formation of secondary minerals was used to indicate the potential for aggregate-paste interactions in DUCRETE concretes.
In order to determine whether any deleterious phases were formed, the surfaces of the samples at 2, 3, 6 and 13 months of exposure were examined by SEM equipped with EDX. The observations made indicate that except for the samples kept in deionized DI water Fig. The images at the surface of the sample made with back-scattered electrons BSE allow the average atomic number of each particle to be determined: the DU particles that have a high average Z will be seen as white on a BSE image.
However, for the samples cured in NaOH or in cement pore solution, the BSE images do not show as many white areas, confirming that the surface is covered by crystal growth. The samples kept in DI water show some erosion of the surface, with a crystalline phase containing large amounts of titanium.
This titanium phase, probably resembling rutile, is more resistant to leaching than the other basalt phases and appeared unaltered even after the other basalt phases were leached out. Of the chemicals that produce the basalt phase, aluminum and silicon are the elements that leach the most in the cement pore water, and this is even more striking in the 1 N NaOH solution. Both of these solutions are very basic, with pH above The amount leached is higher for NaOH and increased with the temperature and time of exposure. This consists of sintered DUO 2 particles with a silicate-based coating that covers the surfaces and fills the spaces between the grains, acting as an oxygen barrier, as well as corrosion and leach resistance.
DUAGG has a density up to 8. Also, DUCRETE presents environmentally friendly properties; the table below shows the effectiveness of converting depleted uranium into concrete, since potential leaching is decreased in a high order.
DU is a result of the enrichment of uranium for use in nuclear power generation and other fields. The UO 2 is then dried, crushed, and milled into a uniform sediment. After processing, DUCRETE composite may be used in container vessels, shielding structures, and containment storage areas, all of which can be used to store radioactive waste; the primary implementation of this material is within a dry cask storage system for high level waste HLW and spent nuclear fuel SNF.
Cask systems made from DUCRETE are smaller and lighter in weight than casks made from conventional materials, such as traditional concrete. Analysis has shown that DUCRETE is more cost effective than conventional materials; the cost for the production of casks made with DUCRETE is low when compared with other shielding materials such as steel , lead and DU metal, since less material is required as a consequence of a higher density.
Since DUCRETE is a low level radioactive composite, its relatively expensive disposal could decrease the cost effectiveness of such systems. Portland cement Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar and non-specialty grout. It was developed from other types of hydraulic lime in England in the mid 19th century, originates from limestone , it is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinker , grinding the clinker, adding 2 to 3 percent of gypsum.
Several types of Portland cement are available; the most common, called ordinary Portland cement, is grey, but white Portland cement is available. Its name is derived from its similarity to Portland stone , quarried on the Isle of Portland in Dorset, England , it was named by Joseph Aspdin who obtained a patent for it in However, his son William Aspdin is regarded as the inventor of "modern" Portland cement due to his developments in the s.
Portland cement is caustic, so it can cause chemical burns; the powder can cause irritation or, with severe exposure, lung cancer, can contain some hazardous components, such as crystalline silica and hexavalent chromium. Environmental concerns are the high energy consumption required to mine and transport the cement, the related air pollution, including the release of greenhouse gases, dioxin , NOx, SO2, particulates.
There are several ongoing researches targeting a suitable replacement of Portland cement by supplementary cementitious materials; the low cost and widespread availability of the limestone and other naturally-occurring materials used in Portland cement make it one of the lowest-cost materials used over the last century.
Concrete produced from Portland cement is one of the world's most versatile construction materials. Portland cement was developed from natural cements made in Britain beginning in the middle of the 18th century, its name is derived from its similarity to Portland stone, a type of building stone quarried on the Isle of Portland in Dorset, England.
The development of modern Portland cement began in , when John Smeaton experimented with combinations of different limestones and additives, including trass and pozzolanas, relating to the planned construction of a lighthouse, now known as Smeaton's Tower.
In the late 18th century, Roman cement was patented in by James Parker. Roman cement became popular, but was replaced by Portland cement in the s. In , James Frost produced a cement. James Frost is reported to have erected a manufactory for making of an artificial cement in Vicat's cement is an artificial hydraulic lime, is considered the'principal forerunner' of Portland cement; the name Portland cement is recorded in a directory published in being associated with a William Lockwood and others.
In his cement patent, Joseph Aspdin called his invention "Portland cement" because of the its resemblance to Portland stone. However, Aspdin's cement was nothing like modern Portland cement, but was a first step in the development of modern Portland cement, has been called a'proto-Portland cement'. William Aspdin had left his father's company. In the 's William Aspdin accidentally, produced calcium silicates which are a middle step in the development of Portland cement.
In , William Aspdin further improved his cement. In , he moved to Germany , where he was involved in cement making. William Aspdin made what could be called'meso-Portland cement'. Isaac Charles Johnson further refined the production of'meso-Portland cement', claimed to be the real father of Portland cement. John Grant of the Metropolitan Board of Works in set out requirements for cement to be used in the London sewer project; this became a specification for Portland cement.
The next development in the manufacture of Portland cement was the introduction of the rotary kiln, patented by Frederick Ransome in and ; the Hoffmann'endless' kiln , said to give'perfect control over combustion' was tested in , showed the process produced a better grade of cement. This cement was made at the Portland Cementfabrik Stern at Stettin , the first to use a Hoffmann kiln.. Portland cement had been imported into the United States from Germany and England , in the s and s, it was being produced by Eagle Portland cement near Kalamazoo , in , the first Portland cement was produced in the Coplay Cement Company Kilns under the direction of David O.
Saylor in Coplay, Pennsylvania. By the early 20th century, American-made Portland cement had displaced most of the imported Portland cement. ASTM C defines Portland cement as'hydraulic cement produced by pulverizing clinkers which consist of hydraulic calcium silicates containing one or more of the forms of calcium sulfate as an inter ground addition'; the European Standard EN uses the following definition: Portland cement clinker is a hydraulic material which shall consist of at l.
Gamma ray A gamma ray or gamma radiation, is a penetrating electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves and so imparts the highest photon energy. Paul Villard , a French chemist and physicist , discovered gamma radiation in while studying radiation emitted by radium. In , Ernest Rutherford named this radiation gamma rays based on their strong penetration of matter.
Very-high-energy gamma rays in the — TeV range have been observed from sources such as the Cygnus X-3 microquasar. Natural sources of gamma rays originating on Earth are as a result of radioactive decay and secondary radiation from atmospheric interactions with cosmic ray particles. However there are other rare natural sources, such as terrestrial gamma-ray flashes, that produce gamma rays from electron action upon the nucleus.