核质量是中子质量的11倍（核言碎语280）

核质量是中子质量的11倍（核言碎语280）①Primary Source of Neutrons. The primary source of neutrons does not need to be irradiated to produce neutrons. These sources can be used especially in the case of a first core (i.e. a core consisting of fresh fuel only). The primary source of neutrons is based on the spontaneous fission reaction. The most commonly used spontaneous fission source is the radioactive isotope californium-252. Cf-252

194 外源中子和外部中子源

Source Neutrons and External Source of Neutrons

（https://www.nuclear-power.com/）

外源中子和外部中子源

• External Source of Neutrons. Sometimes source neutrons must be artificially added to the system. An external source of neutrons contains a material that emits neutrons and cladding to provide a barrier between the reactor coolant and the material. External sources are usually loaded directly into the reactor core (e.g. guide thimble tubes).
• 外部中子源。有时外源中子必须人工添加到系统中。外部中子源包含发射中子的材料，以在反应堆冷却剂和材料之间提供屏障的包壳。外部源通常直接加载到反应堆堆芯中（例如导向套管）。

①Primary Source of Neutrons. The primary source of neutrons does not need to be irradiated to produce neutrons. These sources can be used especially in the case of a first core (i.e. a core consisting of fresh fuel only). The primary source of neutrons is based on the spontaneous fission reaction. The most commonly used spontaneous fission source is the radioactive isotope californium-252. Cf-252 and other spontaneous fission neutron sources are produced by irradiating uranium or another transuranic element in a nuclear reactor where neutrons are absorbed in the starting material and its subsequent reaction products transmuting the starting material into the SF isotope. (α n) reactions can also be used to produce neutrons. The bombardment of beryllium by α-particles leads to the production of neutrons by the following exothermic reaction: 4He 9Be→12C n 5.7 MeV. This reaction yields a weak source of neutrons with an energy spectrum resembling that from a fission source and is used nowadays in portable neutron sources. Radium plutonium or americium can be used as an α-emitter.

①初级中子源。初级中子源不需要辐照来产生中子。尤其在首次堆芯（即仅由新燃料组成的堆芯）的情况下，可以使用这些源。初级中子源是基于自发裂变反应。最常用的自发裂变源是放射性同位素锎-252。Cf-252和其他自发裂变中子源是通过辐照核反应堆中的铀或其他超铀元素产生的，在此中子被原材料及其后续反应产物吸收，将原材料转化为SF同位素。（α，n）反应也可以用来产生中子。α粒子轰击铍导致通过以下放热反应产生中子：⁴He ⁹Be→¹²C n 5.7 MeV。该反应产生的中子源较弱，其能谱与裂变源的能谱相似，目前用于便携式中子源。镭、钚或镅可用作α发射体。

（待续）