D2O isotope effects on hydrolysis and ionization equilibria in high-temperature water

D2O 同位素对高温水中水解和电离平衡的影响

• 批准号: 322862-2005
• 负责人: Tremaine, Peter
• 金额: $ 4.37万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=361579
• 关键词: D2O; isotope; effects; hydrolysis; ionization

CANDU reactors are a uniquely Canadian steam-generation technology in that their design is based on the use of heavy water in a closed loop to transfer heat from the reactor core to the steam generator.   The pH of the heavy water in this "primary coolant system" is tightly controlled to minimize the effects of corrosion and radioactive transport.  Optimizing primary coolant chemistry requires detailled models for the chemical behaviour of metal oxides, dissolved gases and pH-control additives at temperatures as high as 300°C, using data determined in light water systems.  The methods now used to correct these models for the differences between chemical equilibrium constants in light-water and heavy-water systems are based only on room temperature studies. This proposal is for a definitive laboratory study to provide fundamental data and understanding for the difference in equilibrium constants between H2O and D2O, for simple acids and bases at the extreme temperatures and pressures encountered in nuclear reactors (250 to 300°C and 10 MPa).  High precision measurements of chemical equilibrium constants will be made in H2O and D2O under identical conditions, using state-of-the-art instruments, constructed of inert materials to withstand the corrosive conditions that exist in high temperature water.  Only  a few such instruments exist worldwide. The results will be used to develop an improved practical model for estimating the magnitude of D2O isotope effects on metal hydrolysis and metal oxide solubility, under CANDU operating conditions. The project will contribute to research aimed at extending the lifetime of existing reactors  by providing criteria for optimizing primary circuit pH to reduce feeder tube thinning.  It will make a long term contribution to Canada's leadership role in heavy water technology by providing a fundamental understanding of D2Oisotope effects on chemical equilibria under extreme conditions of temperature and pressure.

CANDU反应堆是加拿大独特的蒸汽发生技术，其设计基于在闭环中使用重水将热量从反应堆堆芯传递到蒸汽发生器。 “一回路冷却剂系统”中重水的pH值受到严格控制，以最大限度地减少腐蚀和放射性迁移的影响。优化一回路冷却剂化学特性需要详细的模型，以了解金属氧化物、溶解气体和pH控制添加剂在高达300°C的温度下的化学行为，本文用轻水体系测定的数据，对模型中轻水和重水体系化学平衡常数的差异进行了修正。水系统仅基于室温研究。本建议是一项确定性的实验室研究，为核反应堆中遇到的极端温度和压力下简单酸和碱的H2O和D2O之间的平衡常数差异提供基本数据和理解（250至300°C和10 MPa）。将在相同条件下在H2O和D2O中进行化学平衡常数的高精度测量，使用最先进的仪器，由惰性材料制成，可以承受高温水中存在的腐蚀性条件。全世界只有少数这样的仪器。结果将被用来开发一个改进的实用模型，用于估计D2O同位素对金属水解和金属氧化物溶解度的影响程度，在CANDU运行条件下。该项目将为延长现有反应堆寿命的研究作出贡献，提供优化一回路pH值的标准，以减少进料管变薄，并将为加拿大在重水技术方面的领导作用作出长期贡献，提供关于D2O同位素对极端温度和压力条件下化学平衡的影响的基本认识。