元素周期系的“时空限制”

本文从“时”“空”两个方面讨论了元素周期系的界限。铀后元素是不稳定的,随着原子序数的增加,半衰期迅速变短,作为不稳定核的存在受到可测时间的限制,可测时间的理论极限应是强相互作用时间10~(-23)秒。铀后元素最长寿同位素的半衰期τ(年)与原子序数Z有近似线性关系lgτ=-1.173Z+116.7,由此得出不稳定核存在的时间限制是Z=125;空间限制是Z=131～153。“时”“空”限制基本相一致,使得有理由认为周期系的极限界限在第八周期。     

Characteristics of nuclear and fossil energy wastes

Summary The radionuclides and toxic metals in transuranic, low-level radioactive coal combustion, and coal conversion wastes are summarized. These wastes also contain a variety of organic compounds, some of which can support indigenous microbial activity resulting in solubilization or stabilization of toxic metals and radionuclides.     

Microbial dissolution and stabilization of toxic metals and radionuclides in mixed wastes

Summary Microbial activity in mixed wastes can have an appreciable effect on the dissolution or precipitation of toxic metals and radionuclides. Fundamental information on microbial dissolution and stabilization (immobilization) of toxic metals and radionuclides, in particular actinides and fission products, in nuclear wastes under various microbial process conditions, e.g., aerobic, denitrifying, iron-reducing, fermentative, sulfate-reducing, and methanogenic conditions is very limited. Microbial transformations of typical waste components such as metal oxides, metal coprecipitates, naturally occurring minerals, and metal organic complexes are reviewed. Such information can be useful in the development of 1) predictive models on the fate and long-term transport of toxic metals and radionuclides from waste disposal sites, and 2) biotechnological applications of waste treatment leading to volume reduction and stabilization as wall as recovery and recycling of radionuclides and toxic metals.     

元素周期系界限问题研究

本文以四个立论为基础对原子的存在提出“空间限制”和“时间限制”概念。从“空间限制”考虑,原子存在的界限是Z=131-153号元素;从“时间限制”考虑,原子存在的界限是Z=125号元素,由此认为周期系界限的大体范围是在Z=125-131号元素。     

球床高温气冷堆闭式循环特性

从提高天然铀利用率和改进废物管理方面考虑,研究球床高温气冷堆乏燃料中铀钚的再利用和不同闭式燃料循环的特性。在250MW热功率球床模块式高温气冷堆示范电站铀钚循环的乏燃料中提取铀和钚为核燃料,设计了PuO2和混合氧化物(MOX)燃料元件,将新设计的燃料元件重新装入与示范电站有同样结构和尺寸的堆芯,分别形成纯钚燃料循环和MOX燃料循环。还研究了基于轻水堆级钚的燃料循环。采用了高温气冷堆物理设计程序VSOP,研究了高温气冷堆不同闭式循环的燃料利用和超铀元素焚烧特性。不同闭式循环钚消耗率分别为50%、46%和71%,天然铀的电利用率分别提高了6%、8%和20%。结果表明:高温气冷堆闭式燃料循环能有效焚烧钚同位素,适度提高天然铀的利用率。