光化学法锂同位素分离中化学反应速率常数测量

氢气与锂蒸气的化学反应速率常数是激光化学法锂同位素分离过程的一个重要参数。本文以可调谐半导体激光器为工具,通过监测锂原子蒸气对光的吸收测量原子蒸气密度的相对变化,建立了一种测量该速率常数的方法。在光化学锂同位素分离的典型条件下测得化学反应速率常数为9.0×10^-22 m³/s。该数值对于未来锂同位素分离装置中激光照射时间和氢气密度等参数的选择具有重要指导意义。     

钠水反应试验系统大泄漏钠水反应压力分布计算分析

本文采用一维大泄漏钠水反应分析程序LLEAK，计算和分析了大泄漏钠水反应工况下压力在钠水反应试验系统F204内的分布特性。结果表明：试验系统在水泄漏量为57 g/s、钠循环流量为10 m³/h和20 m³/h的工况下，泄漏点压力峰值仅为0.92 MPa，反应器出入口的爆破片均无动作，为保证系统压力处于较低水平，应考虑将爆破片动作整定值从1.0 MPa调低至0.8 MPa；试验系统在水泄漏量为290 g/s时系统压力峰值达到了1.4 MPa，为满足设备安全性，系统全环路的设备应至少能承受2.0 MPa的压力；在较大水泄漏量时，随钠循环流量的增大，将降低钠水反应对缓冲罐压力的影响；在较小水泄漏量时，随钠循环流量的增大，将恶化钠水反应对缓冲罐压力的影响。     

钠水反应试验系统中小泄漏钠水反应氢气分布特性

蒸汽发生器是钠冷快堆的关键设备之一，其传热管破裂引发的钠水反应会产生大量氢气及热量，危害钠冷快堆的安全运行。本文基于VOF多相流模型，在钠水反应试验系统内开展中小泄漏钠水反应工况的数值分析，获得了高压反应釜内氢气在钠水反应下的三维空间分布特性和迁移特性。结果表明：高压反应釜内氢气的迁移特性受钠液流速影响，氢气在整个循环环路的迁移特性主要受水泄漏量控制。通过设置灵敏度为0.005 ppm的氢计，获得了环路不同区域检测到氢气的最快特征时间。     

Acoustic Detection for Small-Leak Sodium-Water Reaction

Characteristics of acoustic signal produced by sodium-water reaction due to steam injection and by Ar gas injection into sodium were experimentally investigated. Acoustic signal was measured by using Kistler 808A and 815A5 accelerometers. Root mean square (RMS) measurements and frequency analysis of the signal were conducted.

The RMS measurements could detect a small water leakage into sodium, as small as 0.07 g/sec, in the present loop. The peaks in a frequency spectrum were caused by the natural vibration of a rod on which the acoustic transducer was mounted.

The RMS was approximately proportional to the one-third power of the steam leak rate and increased to some extent with the ambient sodium temperature. RMS values, both for sodium-water reaction and Ar gas injection, were about the same order of magnitude, when the data were plotted against the volumetric flow rates of steam and Ar gas.     

Reaction between Plutonium Dioxide and Graphite

The formation of PuC_1-x and Pu₂C₃ by heating a powdered mixture of PuO₂ and graphite was studied in the temperature range of 1,000°–1,350°C under reduced pressure. The reactions were pursued thermogravimetry, X-ray and chemical analyses.

The reaction rates for the formation of PuC_1-x and Pu₂C₃ obey the surface reaction law, the apparent activation energies of carburization being 102 and 105kcal/mol, respectively. In the reaction between PuO₂ and graphite, Pu₂C₃ is formed directly, and PuC_1-x is formed in turn therefrom. When the carbides are heated continuously above 1,450°C, appreciable weight loss takes place, which could be attributed to evaporation of Pu from the carbides.