Plant MaterialsDOE-HDBK-1017/2-93REACTOR USE OF ALUMINUMREACTOR USE OF ALUMINUMAluminum is a favorite material for applications in tritium production and reactorplants. This chapter discusses the applications of aluminum in a reactor plant.EO 1.27STATE the applications and the property that makes aluminumideally suited for use in reactors operating at:a.Low kilowatt power b.Low temperature ranges.c.Moderate temperature rangeEO 1.28STATE why aluminum is undesirable in high temperature powerreactors.ApplicationsAluminum, with its low cost, low thermal neutron absorption, and freedom from corrosion at lowtemperature, is ideally suited for use in research or training reactors in the low kilowatt powerand low temperature operating ranges.Aluminum, usually in the relatively pure (greater than 99.0%) 2S (or 1100) form, has beenextensively used as a reactor structural material and for fuel cladding and other purposes notinvolving exposure to very high temperatures.Aluminum with its low neutron capture cross section (0.24 barns) is the preferred claddingmaterial for pressurized and boiling water reactors operating in the moderate temperature range.Aluminum, in the form of an APM alloy, is generally used as a fuel-element cladding in organic-moderated reactors. Aluminum has also been employed in gas-cooled reactors operating at lowor moderately high temperatures. Generally, at high temperatures, the relative low strength andpoor corrosion properties of aluminum make it unsuitable as a structural material in powerreactors due to hydrogen generation. The high temperature strength and corrosion properties ofaluminum can be increased by alloying, but only at the expense of a higher neutron capture crosssection.In water, corrosion limits the use of aluminum to temperatures near 100C, unless specialprecautions are taken. In air, corrosion limits its use to temperatures slightly over 300C.Failure is caused by pitting of the otherwise protective Al(OH)3 film. The presence of chloridesalts and of some other metals that form strong galvanic couples (for example, copper) canpromote pitting. Rev. 0Page 49MS-05
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