Reaction Kinetics in Supercritical Water as Probed with Muonium

我们建议使用Muon自旋光谱来研究在超临界水冷却核反应堆(SCWR)所设想的所有温度和压力范围内过热水中的化学反应。在这样的实验中，我们使用Mu(Mu)作为氢原子(H)的替代品；从化学上讲，Mu可以被视为H的轻同位素。不列颠哥伦比亚省温哥华的TRIUMF是世界上仅有的四个适合进行此类工作的地点之一。在GenIV项目的第一阶段，我们扩展了我们之前在过热水中双分子反应的Mu衰变动力学的工作：在临界点以下，随着温度的升高，速率常数呈现出一个宽泛的极大值，然后在可压缩性极大值处出现一个急剧的极小值。设计和制造了一种新的靶室，可以将研究扩展到650℃。在恒压(例如25兆帕)下，水的密度从300℃的亚临界液体下降到650℃的超临界流体的十倍。我们将特别关注H与水的反应，因为这是高温下氢气的主要来源，也是SCWR化学控制策略制定的关键反应。

We propose to use muon spin spectroscopy to study chemical reactions in superheated water over the full range of temperatures and pressures envisaged for a supercritical-water-cooled nuclear reactor (SCWR). In such experiments we use muonium (Mu) as a surrogate for atomic hydrogen (H); chemically Mu can be viewed as a light isotope of H. TRIUMF, in Vancouver B.C., is one of only four locations in the world with intense muon beams suitable for such work. In phase I of the GenIV project we extended our previous work on Mu decay kinetics of bimolecular reactions in superheated water: rate constants exhibit a broad maximum with increasing temperature below the critical point, followed by a sharp minimum at the compressibility maximum. A new target cell has been designed and fabricated to extend studies to 650°C. At constant pressure (e.g. 25 MPa) the density of water falls by a factor of ten from the subcritical liquid at 300°C to the supercritical fluid at 650°C. We will pay particular attention to the reaction of H with water, since this is the major source of hydrogen gas at high temperature, and is a key reaction for the development of a chemistry control strategy for the SCWR.