Reaction Kinetics in Supercritical Water as Probed with Muonium

我们建议使用介子自旋光谱来研究超临界水冷核反应堆（SCWR）在所有温度和压力范围内的过热水中的化学反应。在这类实验中，我们用μ (Mu)代替氢原子(H)；在化学上，Mu可以被视为h的轻同位素。加拿大温哥华的TRIUMF是世界上仅有的四个适合进行这种工作的强介子束的地点之一。在GenIV项目的第一阶段，我们扩展了之前在过热水中双分子反应的Mu衰变动力学方面的工作：速率常数在临界点以下随着温度的升高而呈现出广泛的最大值，随后在可压缩性最大值处急剧最小。设计和制造了一种新的靶细胞，可以将研究范围扩展到650°C。在恒定压力下（例如25兆帕），水的密度从300°C的亚临界液体下降到650°C的超临界流体，下降了十倍。我们将特别关注氢与水的反应，因为这是高温下氢气的主要来源，也是SCWR化学控制策略发展的关键反应。

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.