应通过系统设计使发生上述具有潜在严重放射后果的事故的或然率非常小。
The probability of accidents with potentially serious radiological consequences referred to above shall be kept extremely small by virtue of the design of the system.
研究了平均速度与事故危险性、速度离散度与事故率以及速度与事故严重性的关系；提出了加强速度管理，控制交通流平均速度和减小相邻路段的速度差值的对策。
In order to find the relationship between speed and accident, and to reduce the loss of the accidents caused by speed, they were deliberately studied.
原子能委员会把假想的反应事故分为1级（小事故最大发生率）至9级（最严重事故最小发生率）。
The AEC had classified hypothetical reactor accidents from Class 1 (trivial incidents with high occurrence probability) to Class 9 (ultimate severity with occurrence highly unlikely).
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