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Mold design is an art. Numerous design techniques are used to ensure that the casting obtained from a mold is sound. Normally, the designer uses a trial—and—error method to perfect his mold. If detects in the casting are discovered, he changes the design and casts another part. As the size and complexity of the mold increase, how-ever, this approach becomes economically unfeasible, especially when> — the cost of the metal to be cast is high. ~.t thc L ~ c ~l~n ~ c Sci=tifi ~ L~bc:atcry, it is cftcn ~cc—c... ~ essary to cast parts of uranium, gold or other metals that are rare,.. and/or of high chemical and isotopic purity. Uranium parts are cast • _~~j in zirconium—oxide—coated graphite molds which are relatively expen— sive to fabricate. Also of significance is the recovery cost; i.e., the cost ~ repurify the extra metal after the casting has been ma—chined. ~ese costs are important in two ways. First, they providemotivation to design better molds so that soucd castings can be ob— tam ed with less waste. Second, they prevent the use of the ordinary trial—and—error method of mold design. ~~ ~ This paper presents-e.~*—efforts to determine a system toevaluate mold designs using computer simulations. Although~~~~report ~~~~~~--~ ~ ~ the mold design for a thin—walled uranium hemisphere, the system isapplicable to virtually any shape mold. • D D