English Dictionary

delayed criticality

名詞

不可算名詞 通常

(nuclear physics) The point at which the prompt neutrons and delayed neutrons produced by a nuclear fission chain reaction, taken together, are just sufficient to sustain the chain reaction (the state of being delayed critical); in this state, changes in reaction power occur slowly, allowing the reaction to be controlled on human timescales, due to the relatively long time delay associated with the emission of the delayed neutrons necessary to maintain the chain reaction.

日本語の意味

核物理学において、即発中性子と遅延中性子の合計が、核分裂連鎖反応を維持するのにちょうど十分な状態を指す。 / この状態では、核反応の出力が緩やかに変化し、比較的長い遅延時間によって制御が可能となる。

The reactor operators carefully adjusted control rod positions to avoid reaching delayed criticality during the fuel-loading operation.

炉の運転員は、燃料装填作業中に遅延臨界に達しないように制御棒の位置を慎重に調整した。

意味（1）

(nuclear physics) The point at which the prompt neutrons and delayed neutrons produced by a nuclear fission chain reaction, taken together, are just sufficient to sustain the chain reaction (the state of being delayed critical); in this state, changes in reaction power occur slowly, allowing the reaction to be controlled on human timescales, due to the relatively long time delay associated with the emission of the delayed neutrons necessary to maintain the chain reaction.

Although nearly all neutrons produced by fission are emitted as soon as the atom splits (within 10-14 sec or so), a very small proportion of neutrons (0.65% for U-235, 0.25% for Pu-239) are emitted by fission fragments with delays of up to a few minutes. In delayed criticality these neutrons are required to maintain the chain reaction. These long delays mean that power level changes can only occur slowly. All nuclear reactors operate in a state of delayed criticality.

delayed criticalities （ plural ）