critical mass

critical mass: see chain reaction.

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critical mass

Minimum amount of a given fissionable material necessary to achieve a self-sustaining nuclear chain reaction under specified conditions. Critical mass depends on several factors, including the kind of fissionable material used, its concentration and purity, and the composition and geometry of the surrounding reaction system.

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critical mass [′krid·ə·kəl ′mas]

(nucleonics)

The mass of fissionable material of a particular shape that is just sufficient to sustain a nuclear chain reaction.

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critical mass - In physics, the minimum amount of fissionable material required to sustain a chain reaction. Of a software product, describes a condition of the software such that fixing one bug introduces one plus epsilon bugs. (This malady has many causes: creeping featurism, ports to too many disparate environments, poor initial design, etc.) When software achieves critical mass, it can never be fixed; it can only be discarded and rewritten.