The allowable stress levels to which the actual stress levels are compared are based on empirical findings for the material involved .
对所使用的材料来说,与实际应力比较的容许应力是以实验研究结果为基础的。
Soon after the explosion , the radiation level outside the reactor became elevated to 1015 microsievert -- the equivalent of being exposed to the maximum allowable level for a full year in a single day .