控制棒水压驱动步升过程流动阻力影响分析

控制棒水压驱动系统（CRHDS）是清华大学为NHR200发明的新型内置式控制棒驱动系统。组合阀是驱动系统关键的流量控制部件,其流动阻力对控制棒水压驱动机构的步进性能有重要影响。本文完成了驱动机构不同流动阻力工况步升过程性能试验,建立了驱动机构水压缸步升过程理论模型,得到了水压缸步升过程关键性能参数的动态变化曲线,理论结果与试验结果符合很好。在此基础上,利用模型分析了热态工况驱动机构水压缸变流阻步升动态过程。结果表明：随着流动阻力的增大,步升平均速度逐渐减小,步升时间、步升后压力迟滞时间和步升过程总时间均增大。研究成果为CRHDS组合阀流动阻力的设计和优化奠定基础。     

内陆核电厂放射性液态流出物排放浓度限值的初步研究

本文简要探讨了内陆核电厂放射性液态流出物排放浓度限值确定的方法和依据。通过计算,给出了对于滨河、滨湖或滨水库厂址,系统排放口处除3H、14C外其他放射性核素的总排放浓度上限值为100Bq／L,且总排放口下游1km处受纳水体中总β放射性浓度不得超过1Bq／L,3H浓度不得超过100Bq／L的排放浓度要求。     

竖直窄矩形通道内弹状流中液膜特性研究

气液两相弹状流广泛存在于工程领域,弹状流中液膜特性对弹状流模型的建立具有重要意义。为此利用高速摄像系统,对竖直窄矩形通道(3.25 mm×40 mm)内弹状流中液膜进行了可视化研究。实验中发现窄矩形通道中气弹左右两侧窄边液膜厚度不等且存在波动,但其对两侧液膜速度影响较小,两侧液膜速度相等。液膜脱离厚度主要受两相流速及气弹长度影响。液膜脱离速度随液相折算速度增加而增大;在低液相流速时,随气相折算速度增加而减小;当液相流速≥1.204 m/s时,液膜不下落,液膜脱离速度随气相速度变化较小,主要受液相流速影响。     

环形通道内钠流动起始沸腾壁面过热度实验研究

对环形通道内金属钠起始沸腾壁面过热度进行实验研究。实验段长800 mm,环形通道外径10 mm,内径6 mm。电加热元件最高热流密度为846 kW/m²,进口过冷度为63.1～287.8 ℃,质量流量为7.2～122.0 kg/h,系统压力为0.85～28.79 kPa。实验结果表明,起始沸腾壁面过热度随热流密度和进口过冷度的增加而升高,随质量流量和系统压力的增加而降低。拟合得到了关于起始沸腾壁面过热度的半经验关系式,关系式计算结果与实验数据符合良好。     

压水堆核电厂液态流出物排放量统计方法研究

本文主要针对压水堆核电厂液态流出物排放的除³H和¹⁴C外的其余核素,从监测核素的种类、核素的探测限,以及小于探测限测量结果的统计等方面,比较分析我国与欧美国家的取样监测和统计要求,提出合理可行的改进建议,以更好反映我国运行压水堆核电厂液态流出物的排放现状。     

Solidification of Spent Ion Exchange Resin Using New Cementitious Material, (II)

When using cement solidification for spent ion exchange resin, resin content in the waste form is typically controlled below 20vol%. This is because the waste forms crack and deteriorate in water at higher resin contents. The deterioration mechanism and its preventive measures were investigated in this study.

Swelling pressure of the resin was experimentally measured for various waste forms. The resin in the waste form tended to swell under a water immersion condition and tensile stress was exerted on the cement matrix. The stress value changed in the region of 1.5~5.5 MP a depending on such factors as resin content and its type. The waste form was deteriorated in water when the tensile stress was higher than the tensile strength of the cement. These results suggested that the deterioration could be prevented by increasing the tensile strength of cement. A fiber reinforced cement was developed for which tensile strength was almost doubled (~7MP a) by adding 10 wt% steel fiber to the cement. This prevented deterioration and allowed the resin content to be increased from 20 to 42 Vol%     

Response Functions of Phoswich-Type Neutron Detector for High-Energy Cosmic Ray Neutron Measurement

A phoswich-type neutron detector was developed in order to measure high-energy cosmic ray neutron spectra in aircraft. The neutron detector consists of an EJ309 organic liquid scintillator that is 121.7mm in diameter and 121.7mm in length and is covered with a 15mm thick EJ299-13 outer plastic scintillator. The neutron response functions of the detector are required for the unfolding method to obtain the energy spectrum. The neutron response functions were created based on MCNPX simulations using an anticoincidence mode with the experimental light-output correlations with particle energies, uniformity of light collection and energy resolutions. The light-output correlation with particle energy, the uniformity of light collection and the energy resolutions were evaluated based on experiments. Measurements of neutron response functions were performed using four quasi-monoenergetic neutron beams from 40 to 80 MeV p-Li reactions to verify the calculated results. The calculated response functions show good agreement with the measurements. The angular response of the phoswich detector was confirmed to be isotropic from the calculation. The photon response functions of the detector were also calculated and agreed well with the measurements for 6.129MeV photons. Neutron and photon response matrices were created up to 300 and 50 MeV, respectively, over a wide energy range for experimental flights.     

化学发光的探测及其消除

化学发光是由化学反应而引起的光子发射,这一反应,可能涉及出现在闪烁溶液、溶解样品的试剂或者样品本身中的杂质。对多数研究者来说,只需要准确测定单纯由样品的放射性标记物所引起的计数,而化学发光带来很多麻烦,特别是对计数率低、又不好作预置处理的样品,化学发光会引起很大的误差。     

天然蒸发池技术处理低水平放射性废液的发展概况

天然蒸发池技术是利用太阳能对放射性废液中多余水分蒸发、去除的一种处理方法。由于其对运行设施要求简单,不需要过多的日常维护,并具有对低放射性废液净化系数较高、处理量大、节能等特点,因此天然蒸发池技术成为一种较为常用的低放射性废液处理方法。然而,天然蒸发池的运行设施占地面积较大,需要日照时间较长,该方法的应用受到一定限制。本文通过国内外具体实例和经验,介绍了天然蒸发池技术的改进及应用情况。