Reflector material

The moderator material and optimum sizes, the extraction channel configuration, as well as the converter and reflector material and sizes, were determined using the MCNP-4B code and the steepest descent method to attain a maximum flux density of thenual neutrons at the position of an object to be studied. The calculated data were experimentally verified, which showed good agreement. 

Jorgensen, G. and Rangaprasad, G., Ultraviolet Reflector Materials for Solar Detoxification of Hazardous Waste, SERI/TP-257-4418, SERI, Golden, CO, 1991. 

Listed in Table II are the reflective film materials undergoing outdoor exposure testing at DSET. Typical results for coupon testing of these materials are shown in Figures 9 and 10. Also shown are data from coupons cut from an uncoated aluminized polyester reflector supported in a Tedlar enclosure that was exposed in northeastern Oregon. Of the reflector material candidates studied, only the coated, silverized, stabilized polyester (OCLI) maintained its specular reflectivity for 18 months on EMMA (equivalent of 12 years). All reflective films showed severe reduction in mechanical properties. 

Table II Reflector Materials Undergoing Exposure Testing at DSET...

Figure 9. Typical Reflector Material Optical Data.

Figure 10. Typical Reflector Material Mechanical Data.

LIST the five essential requirements for reflector material in a thermal reactor. 

During the selection and application of materials used for construction of a nuclear facility, many different material properties and factors must be considered depending upon the requirements for each specific application. Generally, these consist of both non-fuel reactor materials, used for structural and component construction, and fuel materials. This chapter discusses some of the considerations used in the selection process for plant materials including material properties, fuel, fuel cladding, reflector material, control materials, and shielding materials. 

A reflector gets its name from the fact that neutrons leaving the reactor core hit the reflector and are returned to the core. The primary consideration for selecting a reflector material is its nuclear properties. The essential requirements for reflector material used in a thermal reactor are ... 

Figure 19.9 shows a sketch of such reflectors. The materials and the shape of the reflector determines its efficiency. Reflector materials must have high reflectivity, resist corrosion, heat and moisture, and be easily cleaned. They must also maintain the high reflectivity over a long period of time. 

VII.3. The criticality section of the SAR for a transportation package should include a description of the packaging and its contents. This description should focus on the package dimensions and material components that can influence reactivity (e.g. fissile material inventory and placement, neutron absorber material and placement, reflector materials) rather than structural information such as bolt placement, trunnions, etc. Engineering drawings and design descriptions should be invoked to specify the details of manufactured components. 

Material surveillance activities may include irradiation of material coupons in normal operation conditions (e.g. reactor tank materials such as aluminium or reflector materials such as graphite or beryllium). These coupons can then be removed for testing without disturbing the component material itself. 

FIGURE 4 Cross-sectional profiles of ideal trough concentrators generalized for absorbers of different shapes. In practice the reflectors are usually truncated to about half their full height to save reflector material with only negligible loss of concentration. Such designs have come to be called compound parabolic concept raters, or CPCs. 

All assembled arrays were three-dimensional, having an equal number of units ahmg the three directions of the array. Each cylinder was supported in an array, with its axis vertical, by a 1.6-mm-thick aluminum plate positioned in space stainless-steel rods of 5-mm dlam. The reflector material surrounding an array cylinders was polyethylene (p - 0.93 g/cm ), used in a 15.2-cm thickness only and located from the perlidieral cylinders of the array ( distance equal to one-half the surface separation between cylinders. The center-toeenterspacing of the units in 8- and 27-Unit arrays for both the reflected and the unreflected conditimis are presented in Table n. 

Several measurements of critical or near-critical reflected plutonium assemblies have been reported for a variety of reflector materials.Although these provide a reasoiable estimate of the critical mass to be ej ected for a water-reflected metal sphere, a direct measurement was considered worthwhile. 

Compaaltion and Atom Densities of Experimental Fuel and Reflector Material... 

In those relations, u(m) is a limiting surface density (g - crii ) m is the unreflected critical mass in the geometry of the unit n is N c is a constant characterizing the geometry ot center spaced units and equals 0.55 C2 is a constant dependent on the type of fissile material and is Influenced by the unit shape, by (he array shape, and by the array reflector material. 

The honeycomb critical assembly is a universal split table machine containing a 1.83-m ( ft>cubical matrix of 76-mm (3 in.)-square aluminum tub It is deagned to serve as a flexible system for initial mbckup studies for basic critical parameter investigations. Fuel inventory consists of various Assile species such as 330 kg of O.OS-mm-thick U(93) foils with widths and lengths appropriate to the aluminum matrix tubes. Control and safety rods utilize sections of the core or reflector materials for their flmction and major disassembly is provided by the movable section of the table. Honeycomb is presently stacked with a UOrMo (core). Be (reflector) mockup of a space powa reactor. 

On the picture obtained results of the GB concentration determination in the chamber are presented. Separated signals were collected scanned in time and corresponds to changes of concentration in the chamber. For specifying the minimum detectable concentration, the dependence of the signal on concentration was determined. The minimrun detectable concentration corresponds to the value of C X L = 40.8 mg.m. m. The presented value limits detection from the point of view of minimum amount of agent present at the beam path. The second limitation is minimum detectable signal after reflection from a natural reflector. From flie measurement results there was computed the value corresponds to the maximum distance for the terrain reflector for which the detection can be realized. This value is 3650 m. The presented value can be changing in dependence on the natural reflector material and atmospheric conditions. 

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