191 混凝土作为中子屏蔽
Concrete as a neutron shield
（https://www.nuclear-power.com/）
混凝土作为中子屏蔽
The most commonly used neutron shielding in many nuclear science and engineering sectors is the shield of concrete. Concrete is also hydrogen-containing material, but unlike water, the concrete has a higher density (suitable for secondary gamma shielding) and does not need any maintenance. Because concrete is a mixture of several different materials, its composition is not constant. So when referring to concrete as a neutron shielding material, the material used in its composition should be told correctly. Generally, concrete is divided into “ordinary” concrete and “heavy” concrete. Heavy concrete uses heavy natural aggregates such as barites (barium sulfate) or magnetite or manufactured aggregates such as iron, steel balls, steel punch, or other additives. As a result of these additives, heavy concrete has a higher density than ordinary concrete (~2300 kg/m3). Very heavy concrete can achieve density up to 5,900 kg/m3 with iron additives or up to 8900 kg/m3 with lead additives. Heavy concrete provides very effective protection against neutrons.
在许多核科学和工程行业最常用的中子屏蔽是混凝土屏蔽。混凝土也是含氢材料，但与水不同，混凝土具有更高的密度（适用于二次伽马屏蔽），且不需要任何维护。由于混凝土是几种不同材料的混合物，其成分不是恒定的。因此，当涉及混凝土作为中子屏蔽材料时，应正确告知其成分中使用的材料。一般来说，混凝土分为“普通”混凝土和“重型”混凝土。重型混凝土使用诸如重晶石（硫酸钡）或磁铁矿等的重型天然粒料，或者诸如铁、钢球、钢冲子或其他添加剂等的人造粒料。由于这些添加剂，重型混凝土的密度高于普通混凝土（约2300 kg/m^3）。使用铁添加剂时，超重型混凝土的密度可达5900 kg/m^3，使用铅添加剂时，密度可达8900 kg/m^3。重型混凝土提供了非常有效的中子防护。
注：
（以下内容来自百度百科）
混凝土
因混凝土具有如下特点，所以常用作屏蔽材料。
（a）含有适当量的为屏蔽中子以及γ射线所必要的物质；
混凝土
（b）假如需要的话，还可以把某种元素、物质混入其中；
（c）成形、加工容易，还能作成形状复杂的屏蔽体，
（d）具有结构体所必需的强度和耐用性；
（e）与其他屏蔽材料相比，价格便宜。
（待续）
,
