Three Dimensional Numerical Simulation of a Full Scale CANDU Reactor Moderator to Study Temperature Fluctuations

Authors: A. Sarchami, N. Ashgriz, M. Kwee

Abstract:

Threedimensional numerical simulations are conducted on a full scale CANDU Moderator and Transient variations of the temperature and velocity distributions inside the tank are determined. The results show that the flow and temperature distributions inside the moderator tank are three dimensional and no symmetry plane can be identified.Competition between the upward moving buoyancy driven flows and the downward moving momentum driven flows, results in the formation of circulation zones. The moderator tank operates in the buoyancy driven mode and any small disturbances in the flow or temperature makes the system unstable and asymmetric. Different types of temperature fluctuations are noted inside the tank: (i) large amplitude are at the boundaries between the hot and cold (ii) low amplitude are in the core of the tank (iii) high frequency fluctuations are in the regions with high velocities and (iv) low frequency fluctuations are in the regions with lower velocities.

Keywords: Bruce, Fluctuations, Numerical, Temperature, Thermal hydraulics

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1078955

References:

[1] D. Koroyannakis, R.D. Hepworth, and G. Hendrie, "An Experimental Study of Combined Natural and Forced Convection Flow in a Cylindrical Tank", AECL Report, TDVI-382, 1983.
[2] C. Yoon, B. W. Rhee, H. T. Kim, J. H. Park, B. J. Min, "Moderator analysis of Wolsong units 2/3/4 for the 35% reactor inlet header break with a loss of emergency core cooling injection" Journal of Nuclear Science and Technology 43 (5), 505-513, 2006.
[3] S. O. Yu, M. Kim, H. J. H. J. Kim, "Analysis of fluid flow and heat transfer inside Calandria vessel of CANDU-6 reactor using CFD", Nuclear Engineering and Technology 37 (6), 575-586, 2005.
[4] H. F. Khartabil, W. W. Inch, J. Szymanski, D. Novog, V. Tavasoli, J. Mackinnon, "Three-dimensional moderator circulation experimental program for validation of CFD code MODTURC_CLAS. In: 21st CNS Nuclear Simulation Symposium", Ottawa, Canada, 2000.