Chemistry in near-critical and supercritical water for the generation IV CANDU reactor concept

“第四代”CANDU反应堆是一种新型的、极其节能的先进反应堆的概念设计，将于2025年投入使用。第四代概念将产生温度高达625°C的超临界水，用于发电、氢气和区域供热。使用超临界水将热量从反应堆堆芯输送到涡轮机，将产生比当前CANDU设计中使用的水化学条件更为极端的水化学条件，CANDU设计的工作温度为250至310°C。第四代CANDU概念的长期可行性取决于设计人员预测和控制水化学的能力，以最大限度地减少放射性核素传输和微妙的腐蚀影响。该提案为一个合作项目寻求资金，该项目将使用特拉华大学开发的最先进的电导系统，现在转移到圭尔夫，以确定在近临界和超临界条件下（300至400°C， 30 MPa）简单酸、碱和金属盐的电离和结合常数。电导仪是一种非常专业的高精度设备，是北美仅有的两种具有这种能力的仪器之一。该项目包括升级和校准设备，以改善超临界区域的操作，测量与第四代蒸汽发生器化学相关的几种酸、碱和盐，以及开发方程来预测这些极端条件下水性物质的行为。这项关于第四代反应堆概念的竞争前研究将提高北美在国际竞争中的有效性，以生产与加拿大的专业知识和CANDU经验相匹配的第四代反应堆。短期的好处是：(1)对SCWR化学基础的基本理解；(2)为近临界和超临界系统的基础研究提供仪器。如果该反应堆在北美开发，其长期效益是制造技术的领先地位，温室气体的显著减少，以及与44%的效率和氢气热电联产相关的能源节约。

The "Generation IV" CANDU reactor is a conceptual design for a novel, extremely energy-efficient  advanced reactor that would come on line in 2025.  The Gen IV concept would produce super-critical water at temperatures as high as 625°C to generate electricity, hydrogen and district heating.   The use of super-critical water to carry heat from the reactor core to the turbine will generate much more extreme water chemistry conditions than those used in current CANDU design, which operates from 250 to 310°C.  The long term viability of the Gen IV CANDU concept depends on the ability of designers to predict and control water chemistry to minimize radionuclide transport and subtle corrosion effects. This proposal seeks funding for a collaborative project that will use a state-of-the-art conductance system, developed at the University of Delaware and now moved to Guelph, to determine ionization and association constants for simple acids, bases and metal salts under near-critical and super-critical conditions (300 to 400°C, and 30 MPa).  The conductance apparatus is an extremely specialized piece of high-precision equipment, one of only two instruments with this capability in North America.  The project includes the upgrading and calibration of the equipment for improved operation in the supercritical region, measurements on several acids, bases and salts relevant to Gen IV steam generator chemistry, and the development of equations to predict the behaviour of aqueous species under these extreme conditions.  This pre-competitive research on Gen IV reactor concept, will advance North American effectiveness in the international competition to produce a Gen IV reactor compatible with Canada's expertise and CANDU experience. The short term benefits are (i)fundamental understanding of SCWR chemistry fundamentals and (ii) instrumentation for basic research on near-critical and super-critical systems. Long term benefits are the leadership in manufacturing technology if the reactor is developed in North America, significant reduction in green house gases,  and the energy savings associated with 44% efficiency and the co-generation of hydrogen.