1 IAPWS – CNC Computer Simulations of Supercritical Aqueous Fluids and Particle Formation Processes Lead Researcher: Svishchev, Igor (Trent University) Co-investigators: Plugatyr, Andriy Nahtigal, Istok

2 Outline 1. Supercritical water research at Trent University experimental work - flow reactor computer modeling team expertise 2. Particle formation processes in supercritical water 3. CANDU SCWR chemistry project

3 Supercritical Water Test Facility Andriy Plugatyr and Igor M. Svishchev (Supercritical Water Research Lab, Trent University)

4 Methodology – flow injection “Hot” zone A. Plugatyr and I. M. Svishchev, “Residence time distribution measurements and flow modeling in a supercritical water oxidation Reactor: Application of transfer function concept”, J. Supercrit. Fluids 44 (1), 31 (2008)

5 Flow injection under SCW conditions A. Plugatyr and I. M. Svishchev, J. Supercrit. Fluids, 44 (1), 31 (2008) Impulse/response experiments: Hydrodynamic behavior of flow-through reactor systems - Residence Time Distribution (RTD) measurements Binary diffusion coefficients - Taylor dispersion technique Kinetics measurements Taylor dispersion experiment u - fluid velocity, d - diameter of diffusion tube and D 12 - binary diffusion coefficient

6 Experiments vs. Modeling A. Plugatyr, “Molecular Dynamics simulations and flow injection studies of hydrothermal fluids”, Ph.D. Thesis (Queen’s U., 2009). Binary diffusion coefficient of phenol in aqueous solution T, KP, MPa a,Pa sa,Pa s ReD exptl. × 10 9, m 2 /s     1.94 Flow parameters and measured diffusion coefficient of phenol

7 Molecular Dynamics simulations Molecular Dynamics simulation of ion pair formation in SCW System: 1000 H 2 O + 1 NaCl; T= 673 K and  = 0.3 g/cm3 Nahtigal I., Zasetsky A.Y. and Svishchev I.M., J. Phys. Chem. B, 112, (2008).

8 Equation of state - simulations Plugatyr A. and Svishchev I.M., Fluid Phase Equilibria 277, 145 (2009). P  T surface for the SPC/E water Red dots represent simulation results Reference EOS by Wagner and Span Accurate short reference equation (16 coefficients) Can be fitted to a restricted data set Correct behavior of derivatives Works for mixtures

9 Equation of state - simulations Plugatyr A. and Svishchev I.M., Fluid Phase Equilibria 277, 145 (2009). Compressibility maximum of supercritical water Gas-like fluid Liquid-like fluid

10 Particle formation in SCW “Metastable” electrolyte solution Amorphous salt hydrate particles Cluster-cluster fusions, 1 ns “Critical” nuclei, 0.25 ns Nucleation begins Molecular Dynamics simulation of SrCl 2 - H 2 O mixture at 673 K and 0.17 g/cm 3 Svishchev I.M., Nahtigal I. and Zasetsky A.Y., J. Phys. Chem. C, 112, (2008).

11 Particle nucleation rate Cluster growth – decay curves System: NaCl-H 2 O (5.1 wt% salt) T=673 K and =0.17 g/cm 3 Critical NaCl cluster N* = 22 Particle nucleation rate J = 1.19 x cm -3 s -1 Classical nucleation theory J = 1/t V  (delay time)

12 Particle structure Amorphous ! Post-critical NaCl cluster (salt hydrate particle) formed in supercritical water Nahtigal I., Zasetsky A.Y. and Svishchev I.M., J. Phys. Chem. B, 112, (2008). Ion - ion separations Charged clusters Crystal

13 Hydrolysis in SCW Amorphous NaCl cluster formed in supercritical water with hydroxide localized to subsurface regions Nahtigal I. and Svishchev I.M., J. Phys. Chem. B, (in press). Free acid (HCl) is in SCW phase mNaCl(s) + nH 2 O  HCl + (m-1)NaCl · NaOH(s) + (n-1)H 2 O OH - HCl

14 Quenched cluster products Svishchev I.M. and Nahtigal I., J. Supercrit. Fluids (in press). Plates and ridged plates (NaCl) 32 (NaCl) 9 (NaCl) 18 (NaCl) 8 Rods (NaCl) 10 Cubes (NaCl) 16 Cubic morphology Boron nitride morphology Wurtzite morphology (NaCl) 7 (NaCl) 3 Non-cubic Low temperature quench to T = 298 K and  = g/cm 3

15 Dynamics of clusters Vibrational density of states Shape control ? Cube Plate (NaCl) 32

16 CANDU SCWR Chemistry Project  DO consumption (O 2 and H 2 O 2 oxidation) rates for select DO scavengers, up to 25 MPa and 650°C – to develop chemistry control strategies under oxygenated supercritical conditions in a CANDU SCWR  Effect of H 2 O 2 on corrosion and speciation in SCW  A kinetic model to estimate the residual levels of oxygen and the degradation by- products in the SCWR pressure tube and downstream of reactor core  Particle formation rates in a SCWR coolant (NaCl, Fe(OH) 2, ZrO(OH) 2, etc.) – to estimate potential particle (corrosion product) deposition on in-core and out-core surfaces