Alpha phase uranium has a density of 19g/cm3 and a thermal conductivity which varies from 25W/mk at 25oc to 42W/mk at 665oC The transition from alpha to the beta phase takes place at 665oc and is accompanied by dimensional changes in crystalline structure of the uranium, expansion along one axis and contraction along the others. Mae b相的转变发生在665c,并伴随铀晶体结构尺寸变化,沿一个轴伸长,另一个轴 缩短。 To avoid distortion due to these anisotropic dimensional changes 665oC is considered to be the maximum operating temperature of uranium.为了防止 由于各向异性尺寸变化所造成的变形,665°c被认为是金属)铀的最高工作温度。 Metallic uranium is also very susceptible to radiation damage which produces dimensional changes and swelling above about450.金属铀也 非常容易受到辐照损伤,在大约450c以上产生尺寸变化和肿胀 Consequently high burnups of metallic uranium fuel are not possible n the British gascooled Magnox Reactors, which are the principal users of this type fuel, the burnup is limited to about3500MWdt.在主要采用这种燃料 的英国美诺克斯气冷堆中,其燃耗被局限在3500MWd/tAlpha phase uranium has a density of 19g/cm3 and a thermal conductivity which varies from 25W/mK at 25oC to 42W/mK at 665oC. The transition from alpha to the beta phase takes place at 665oC and is accompanied by dimensional changes in crystalline structure of the uranium, expansion along one axis and contraction along the others. 从a到 b相的转变发生在665oC，并伴随铀晶体结构尺寸变化，沿一个轴伸长，另一个轴 缩短。 To avoid distortion due to these anisotropic dimensional changes 665oC is considered to be the maximum operating temperature of uranium. 为了防止 由于各向异性尺寸变化所造成的变形，665oC被认为是(金属)铀的最高工作温度。 Metallic uranium is also very susceptible to radiation damage which produces dimensional changes and swelling above about 450oC. 金属铀也 非常容易受到辐照损伤，在大约450oC以上产生尺寸变化和肿胀。 Consequently high burnups of metallic uranium fuel are not possible. In the British gascooled Magnox Reactors, which are the principal users of this type fuel, the burnup is limited to about 3500MWd/t. 在主要采用这种燃料 的英国美诺克斯气冷堆中，其燃耗被局限在3500MWd/t