Aluminum principal characteristics

A detailed report on the CP-5 reactor is given in the Atomic Energy Commission document Research Reactors a few of its principal characteristics are summarized here. The reactor core proper is an upright cylinder of D2O 2 ft high and 2 ft in diameter in which are immersed MTR-type aluminum fuel elements (see Fig. 5.28). The sides and bottom of the core are reflected by 2 ft of D2O, and this region in turn is surrounded by 2 ft of graphite. The top of the core is reflected by 2J ft of D2O alone. The fuel elements, of which there are 16, consist of boxlike arrays of fuel plates fabricated of a uranium-aluminum alloy, composed of 17.5 per cent aluminum and 82.5 per cent uranium. For computational purposes we will assume that the volume fraction of aluminum in the core is Vax = 0.0688 and that of D2O, Vdio = 0.914. The reactor was designed to produce 1,000 kw of heat, and at this power level the temperature of the D2O is 49 C. 

The principal characteristic that distinguishes the Group 3A elements from the rest of the representative elements is the existence of electron-deficient compounds. You may recall earlier references, in this book and elsewhere, to compounds of this type. It is not unusual for boron, aluminum, gallium, and occasionally beryllium and lithium to form compounds in which the metal is surrounded by less than an octet of electrons. One should of course be wary of such phrases as electron-deficient. It seems to imply that there is something wrong with such compounds. In fact, it is... 

Filter aids should have low bulk density to minimize settling and aid good distribution on a filter-medium surface that may not be horizontal. They should also be porous and capable of forming a porous cake to minimize flow resistance, and they must be chemically inert to the filtrate. These characteristics are all found in the two most popular commercial filter aids diatomaceous silica (also called diatomite, or diatomaceous earth), which is an almost pure silica prepared from deposits of diatom skeletons and expanded perhte, particles of puffed lava that are principally aluminum alkali siheate. Cellulosic fibers (ground wood pulp) are sometimes used when siliceous materials cannot be used but are much more compressible. The use of other less effective aids (e.g., carbon and gypsum) may be justified in special cases. Sometimes a combination or carbon and diatomaceous silica permits adsorption in addition to filter-aid performance. Various other materials, such as salt, fine sand, starch, and precipitated calcium carbonate, are employed in specific industries where they represent either waste material or inexpensive alternatives to conventional filter aids. 

In the trace-element data, the first principal component accounts for over 50% of the variance. Aluminum and most other elements correlate positively with the first principal component, a pattern consistent with simple dilution (22,23) - in this case, by quartz sand temper. In contrast, the second principal component (accounting for an additional 15% of the variance) represents the heavy mineral sand component (Ti, Hf, Zr), which negatively covaries with cobalt, manganese, antimony, and arsenic. The Qo and Qm clays from the lowlands are broadly similar in composition (Figure 5). The Qc deposit differs significantly, i.e., the low PC2 scores indicate high concentrations of the characteristic of heavy mineral sands (Ti, Hf, Zr). The Qk and Tp samples span range of composition, but are represented by only 2 samples each. 

Origins. Most of the radioactive waste at SRP originates in the two separations plants, although some waste is produced in the reactor areas, laboratories, and peripheral installations. The principal processes used in the separations plants have been the Purex and the HM processes, but others have been used to process a variety of fuel and target elements. The Purex process recovers and purifies uranium and plutonium from neutron-irradiated natural uranium. The HM process recovers enriched uranium from uranium—aluminum alloys used as fuel in SRP reactors. Other processes that have been used include recovery of and thorium (from neutron-irradiated thorium), recovery of Np and Pu, separation of higher actinide elements from irradiated plutonium, and recovery of enriched uranium from stainless-steel-clad fuel elements from power reactors. Each of these processes produces a characteristic waste. 

Al—Cu—Mg. The first precipitation hardenable alloy was an Al—Cu—Mg alloy. There is a ternary eutectic at 508 0, and there are nine binary and five ternary intermetallic phases. For aluminum-rich alloys, only four phases are encountered in addition to the aluminum soUd solution (Table 18). Several commercial alloys are based on the age hardening characteristics of the metastable precursors of 0 or S-phase, principally 0 or S. Hardening by T- and p-phases is not very effective. Alloys of greatest age hardenabiUty have compositions near the Cu Mg ratio of the S-phase. Additions of about 0.12% Mg to alloys containing as much as 6% Cu, however, significantly increase strength by refining the 0 precipitate. 

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