Copper reflectors

Table I shows the compositions of the cores studied, denoted as core 5, Pu A S, Pu B-5, and Pu C- The latter three cores had central zones containing plutonium surrounded by a core 5 driver region. All the cores were surrounded by a thick copper reflector.

Beryllium is added to copper to produce an alloy with greatly increased wear resistance it is used for current-carrying springs and non-sparking safety tools. It is also used as a neutron moderator and reflector in nuclear reactors. Much magnesium is used to prepare light nieial allo>s. other uses include the extraction of titanium (p. 370) and in the removal of oxygen and sulphur from steels calcium finds a similar use. 

Gold is classed as a heavy, noble metal located just below copper and silver in group 11 of the periodic table. Gold is a good conductor of electricity as well as an excellent heat reflector of infrared radiation, which makes it an efircient thin coating on glass in skyscrapers to reflect the heat of sunhght. 

Focusing collectors are usually cast acrylic Fresnel lenses, or mirrors of aluminized polyester film in frames of aluminum. These reflectors are either enclosed in a bubble of poly(vinyl fluoride) film, or under polycarbonate glazing, which may be covered with a fluorocarbon film to reduce the reflectivity. The absorbers for active systems are copper or aluminum since the temperatures are too high (325—370°C) for plastics. The frames, however, can be molded ABS, high density polyethylene or polyurethane, either solid or structural foam. Polybutylene or chlorinated PVC can be used for piping hot water, and tanks can be made of either reinforced polyester or blow- or rotational-molded, high density polyethylene (12—15). 

Silver is an excellent conductor of heat and electricity and a good reflector of light. It is relatively immune to oxidation but becomes tarnished by exposure to sulfur compounds in exceedingly small concentrations. It is an excellent electroplating metal and can also be deposited in thin films by evaporation. In Dewar flasks and other vacuum glassware, it is deposited from an aqueous medium by the Brashear process. Silver is an excellent brazing material and an important constituent of silver solder. The term silver is often applied to alloys of silver with copper for example Sterling silver contains 7.5 percent copper. Fine silver is 99.9+ percent silver. 

Berylliiun Beryl (BesAbSieOis) Electrolysis of fused BeCB or reduction of BeF2 with magnesiiun Alloy with copper Highly X-ray permeable Nuclear reflector/moderator... 

Use Structural material in space technology moderator and reflector of neutrons in nuclear reactors source of neutrons when bombarded with a-parti-cles special windows for X ray tubes in gyroscopes, computer parts, inertial guidance systems additive in solid-propellant rocket fuels beryllium-copper alloys. 

USE Source of neutrons when bombarded with alpha particles according to the equation jBe + JHe J C + jn This yields about 30 neutrons per million alpha particles. Also as neutron reflector and neutron moderator in nuclear reactors. In beryllium copper and beryllium aluminum alloys (by direct reduction of beryllium oxide with carbon in the presence of Cu nr Al). In radio tube parts. In aerospace structures. In inertial guidance systems. 

Speculum metal (Latin speculum, a mirror) or white bronze contains 2 of copper and i of tin. It is whiter even than tin, extremely brittle, and takes a high polish. It was used in Roman days for making mirrors and in more recent times found application in reflectors for telescopes. Later it was, of course, replaced by the well-known silvering process (p. 116). 

Steel clamping frames should be nickel-copper-chrome-plated to reflect heat to sheet edges. After 6 months use, consider replacing side and back reflectors in order to regain 4 to 8 percent efficiency. 

Precaution Flamm. solid powd. mod. fire hazard as powd. or dust or when exposed to flame si. explosion hazard as dust incompat. with halocarbons reacts incandescently with fluorine and chlorine reacts with Li, P Hazardous Decomp. Prods. Heated to decomp, in air, emits very toxic fumes of BeO NFPA Health 3, Flammability 1, Reactivity 0 Uses Structural material in space technology moderator In nuclear reactors source of neutrons windows for x-ray tubes in gyroscopes, computer parts, inertial guidance systems additive in solid-propellant rocket fuels beryllium-copper alloys aircraft brakes neutron reflectors... 

The converter consists of 1,536 pairs of thermopiles made of silicon-germanium alloy (Si 85% by mass, Ge 15% by mass) with n- and p-conductivity. Each module of 16 thermopiles is mounted on the inner surface of the hermetically sealed steel vessel. To provide for a good contact on the reactor heating, each module is pressed on the reflector by gas bellows elements. On the hot side, the keyboard consists of molybdenum plates, on the cold one - of copper bridges. To prevent an electric contact (shorting), insulating plates of beryllium oxide are used on the hot and cold sides. The excess heat is removed from the reactor-converter by shaped enamel-coated copper fins with an emissivity of at least 0.9 (O Fig. 59.2). 

Beryllium is used commercially in three major forms as a pure metal, as an alloy with other metals, and as a ceramic. The favorable mechanical properties of beryllium, e.g., its specific stiffness, have made it a major component for certain aerospace applications in satellites and spacecraft. As a modulator and reflector of neutrons, beryllium is of interest in fusion reactions and for nuclear devices that have defense applications. When a small amount of beryllium is added to copper, the desirable properties of copper (i.e., thermal and electrical conductivity) are kept but the material is considerably stronger. The superior thermal conductivity of beryllium oxide ceramics has made the product useful for circuit boards and laser tubes. A more complete discussion of the applications of beryllium was recently reviewed [2]. 

Data for foe 3 HtPu U fuel are shown in Fig. 2. fo these assemblies foe poison plates were located in the fuel parallel to and 6.01 in. from foe bottom reflector. As would be eiqiected, since copper and cadmium are l Mc-ally thermal-neut absorbers, their effect on the critical size c foe 30 HtPu-pV foel is much greater than on the faster 3 H Pu4-U fueL b foe more thermal foel, a i-in.-folck idate of Cu-Cd increased the critical height by about 20% this same pbte caused only a 4% increase in foe critical height of foe 3 H Pu4>U fueled assembly having foe same cross-section dimensions. 

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