Above 450 , the formation of low density u ( al , si ) 3 phase , together with the release of the impurity gas and fragmentation of u3si2 particles , will cause fuel meat to swell , al matrix to crack and u3si2 particles to invade to clad . as a result , the thickness of the meat increased , the thickness of clad decreased and the deformation of fuel plates increased , and the leakage probability of the radioactive mass increased reasonably 同时，由于芯体膨胀及铀硅颗粒碎裂的综合作用，使u _ 3si _ 2颗粒向包壳侵入，最终使燃料板芯体厚度增加较大，芯体及燃料的体积也显著增加，包壳厚度减薄；高温将加速芯体u _ 3si _ 2颗粒碎裂、芯体开裂、包壳以及燃料板变形，从而使燃料芯体与包壳脱开，最终可能导致放射性物质泄漏。
The frequency of concrete strength testing is determined by the quantity of concrete used for a structure . a pre - cast mould is filled with concrete and , upon curing , soaked in water for 28 days before delivering to a laboratory for the " crushing " test . the compressive force needed to break the concrete represents the strength of the concrete 在建筑过程中，建造商要按地盘中使用石屎数量的多寡，去?定测试石屎强度的次数，测试时建造商需要在预制的铸模内倒满石屎，待它凝固后浸在水里二十八日，再运往实验室进行测试，看看需要用几大的力量才能把它压碎，这个令石屎碎裂的力度就是石屎的强度。
The frequency of concrete strength testing is determined by the quantity of concrete used for a structure . a pre - cast mould is filled with concrete and , upon curing , soaked in water for 28 days before delivering to a laboratory for the " crushing " test . the compressive force needed to break the concrete represents the strength of the concrete 在建筑过程中，建造商要按地盘中使用石屎数量的多寡，去定测试石屎强度的次数，测试时建造商需要在预制的铸模内倒满石屎，待它凝固后浸在水里二十八日，再运往实验室进行测试，看看需要用几大的力量才能把它压碎，这个令石屎碎裂的力度就是石屎的强度。
