Dr. J. C. Luxat

Professor and NSERC/UNENE Industrial Research Chair in Nuclear Safety Analysis
Department of Engineering Physics

McMaster University
1280 Main Street West, Hamilton
Ontario, Canada  L8S 4L7

office: JHE/A326
email: luxatj@mcmaster.ca
voice:  (905) 525-9140 x 24670
fax:    (905) 528-5406

B.Sc.(Eng.) (Cape Town), M.Sc. (Cape Town), Ph.D. (Windsor), P.Eng., Nuclear Safety, Nuclear Engineering, Thermalhydraulics, Reactor Physics

Research Interests

Nuclear Safety Analysis Methodology
Best estimate models of physical processes, best estimate plant states, and most probable system configurations and failure events provide the most realistic representation of plant behaviour and consequences during accidents. Deviations from these best estimate conditions can and will occur, resulting in uncertainty in the outcome of a best estimate analysis. In order to quantify the variability and uncertainty in the outcome of an accident, it is necessary to identify and characterize the components contributing to uncertainty and evaluate their impact on safety consequences. A primary objective is to define, through the use of an integrated probabilistic approach, the ranges of key plant parameters that assure that safety limits are met at a prescribed level of probability and confidence.

Research in this area investigates approaches to propagation of time-dependent variability and uncertainty in plant response during accidents using dynamic sensitivity analysis and quasilinearization methods. Of particular interest is the representation of nonlinear bifurcation behaviour within a framework of quasilinearized sensitivity analysis since this allows time-dependent solutions for multiple-parameter variations to be generated from a limited set of detailed computer simulations obtained from best estimate computer codes.

Experimental Studies in Nuclear Safety Thermalhydraulics
Boiling heat transfer from cylindrical nuclear fuel elements and fuel channel calandria tubes is an important process in CANDU reactor accidents. Specifically, changes in heat transfer regimes from nucleate boiling to film boiling influence both the operational safety margins and integrity of components during accidents.

Research in this area investigates fundamental aspects of limiting heat transfer processes in two-phase systems. The major focus is on investigating the fundamental processes of vapour bubble nucleation and transport from the walls of horizontal cylindrical heated tubes. This will be used to improve understanding of heat transfer limitations during transitions in boiling regimes and vapour formation during rapid depressurization of hot fluids.

Theoretical Modelling Studies in Nuclear Safety Thermalhydraulics
Demonstrating the integrity of engineered barriers to fission product release is one primary objective of nuclear safety analysis. Where heat transfer to fluids occurs across an engineered barrier to fission product release - such as at the metal cladding (sheath) of a nuclear fuel element or at the pressure tube/calandria tubes of a fuel channel - a transition to a more limiting heat transfer regime (e.g. transition from nucleate boiling to film boiling) invariably poses a challenge to the integrity of the barrier. Additionally, transition from the film boiling regime to the nucleate boiling regime through the quenching process, in which a rapid increase in heat transfer and concomitant rapid reduction in the temperature of the wall occurs, is of importance in limiting the time during which integrity of a barrier is subject to challenge.

Research in this area is focused on mechanistic modelling of near-field processes including vapour bubble nucleation and transport processes and associated local heat transfer processes, such as conduction in metal walls and turbulent boundary layer convection, as they influence development and spread of vapour film patches (drypatches) on horizontal heated cylinders. Similarly, fundamental theoretical mechanistic modelling of the complementary transition from stable film boiling back to nucleate boiling (often referred to as the “quench” process) are being investigated.

 

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Selected Recent Publications

J.C.Luxat, “Analytical Evaluation of Probabilistic Safety Margins”, Proc. 25th CNS Annual Conf., Toronto, Ontario, June 2004.

J.C.Luxat, “Historical Perspective of the Design Basis in Canada”, OECD/CSNI/CNRA Workshop on Redefining Large Break LOCA, Zurich, Switzerland, June 2003.

D.W. Dormuth, P.J. Ingham and J.C.Luxat, “Application of Heirarchical, Two-Tiered Scaling Method to Channel Coolant Voiding in CANDU Reactors”, Proc. ANS Winter Meeting, Washington D.C., November 17-21, 2002.

J.C.Luxat, “Fuel Behaviour During A Power Pulse: A Review and Assessment of Reactivity Initiated Accident (RIA) Test Data”, Proc. 23rd CNS Annual Conf., Toronto, Ontario, June 2002.

J.C.Luxat, “Mechanistic Modeling of Heat Transfer Processes Governing Pressure Tube-To-Calandria Tube Contact and Fuel Channel Failure”, Proc. 23rd CNS Annual Conf., Toronto, Ontario, June 2002.
A. Popescu, J. Pascoe and J.C. Luxat , “Modifications of ACAP for Use in Accuracy Assessment of Safety Analysis Software at OPG”, Proc. 23rd CNS Annual Conf., Toronto, Ontario, June 2002.
J.C.Luxat and R. Huget, “Prototype Application Of Best Estimate And Uncertainty Safety Analysis Methodology to Large LOCA Analysis”, Proc. 22nd CNS Annual Conf., Toronto, Ontario, June 2001.

R. Huget, J.C.Luxat and D.K. Lau, “Application Of Best Estimate And Uncertainty Safety Analysis Methodology to Loss of Flow Events at Ontario Power Generation’s Darlington Nuclear Generating Station”, Proc. 22nd CNS Annual Conf., Toronto, Ontario, June 2001.

J.C.Luxat, “Review and Assessment Of Heavy Water Transport Properties For Accident Analysis At High Temperature Conditions”, Proc. 22nd CNS Annual Conf., Toronto, Ontario, June 2001.

J.C. Luxat, R.G Huget and F. Tran, “Development and Application of Ontario Power Generation’s Best Estimate Nuclear Safety Analysis Methodology”, Proc. ANS Topical Meeting on Best Estimate Methods (BE-2000), Washington DC, November, 2000.

J.C.Luxat, “Safety Analysis Technology: Evolution, Revolution and the Drive to Regain Margin”, Proc. 21st CNS Annual Conf., Toronto, Ontario, June 2000 (also CNS Bulletin, Vol. 21, No. 2, August 2000).

J.C. Luxat, W. Kupferschmidt, P.D. Thompson and M-A Petrilli, “The Industry Standard Toolset (IST) of Codes for CANDU Safety Analysis”, Proc. OECD/CSNI Workshop: Advanced Thermal-Hydraulic And Neutronic Codes: Current And Future Applications, Barcelona, Spain, April 10-13, 2000.

J. Pascoe, B.H. McDonald, J.C. Luxat, D.J. Richards and B. Rouben, “Qualification Programs for Computer Codes Used for Safety & Transient Analysis in Canada”, Proc. OECD/CSNI Workshop: Advanced Thermal-Hydraulic And Neutronic Codes: Current And Future Applications, Barcelona, Spain, April 10-13, 2000.

J.C. Luxat, V. Snell, M-A Petrilli and P.D. Thompson, “Implementation of Common Industry Safety Analysis Codes”, Proc. 20th CNS Annual Conf., Montreal, Quebec, May30 – June 2, 1999.

P. Boczar, A. Dastur, K. Dormuth, A. Lee, D. Meneley, D. Pendergast, J.C. Luxat, “Global Warming and Sustainable Energy Supply with CANDU Nuclear Power Systems”, Progress in Nuclear Energy, Vol. 32, No. 3/4, pp 297-304, 1998.

D.J. Richards, V.S. Krishnan and J..C. Luxat, “Best-Estimate Methods in CANDU Reactor LOCA Analysis”, Proc. OECD/NEA/CSNAI Seminar on Utilization of Best Estimate Methodology in Safety Analysis, Ankara, Turkey, 1998.

P.J. Ingham, J.C. Luxat, A.J. Melnyk and T.V. Sanderson, “Natural Circulation in an Integral CANDU Test Facility”, IAEA T/C Mtg. On Experimental Tests and Qualification of Analytical Methods to Address Thermohydraulic Phenomena in Advanced Water Cooled Reactors, Villigen, Switzerland, September 14-17, 1998.

A.Gloaguen, J.C. Luxat, W. Thomas, S. Izumi, A.S. Polyakov, R. Dodds, M. Bunn, L. Koch and N. Zarimpas, “Present Status and Environmental Implications of the Different Fuel Cycles – Key Issue Paper No. 2”, Proc. IAEA Int. Symp. on Nuclear Fuel Cycle and Reactor Strategy: Adjusting to New Realities, Vienna, Austria, June 3-6, 1997.

Boczar, P.G. , J.R. Hopkins, H. Feinroth and J.C. Luxat, “Plutonium Disposition in CANDU”, Proc. IAEA Technical Meeting on Recycling of Plutonium and Uranium in Water Reactor Fuels, Windermere, U.K. July 1995.