Thermomechanics of Nuclear Fuel

Garant předmětu:

Lecturer:

Tutor:

Supervisor:

Department of Nuclear Reactors

Synopsis:

In this course students are particularly introduced to thermomechanics of nuclear fuel. The first part is dedicated to the construction of fuel for various types of reactors and brief characteristics of used materials (fuel, cladding and construction materials). The main part of this course covers the detailed analysis of basic thermomechanical attributes of fuel within the scope of irradiation to the maximum burn-up. We go through and then carefully evaluate every physical model describing thermal and mechanical attributes of fuel rods as a complex and also as their parts (fuel, gap fuel-cladding, cladding). Finally there is a review with brief description and principles of numeric codes which are determined for thermomechanics fuel calculations.

Requirements:

17THN2, 17TERR

Syllabus of lectures:

1. Construction of fuel assemblies

Time range: 2 lectures

Introduction to thermomechanics of nuclear fuel, construction and detailed description of fuel assemblies for reactors: PWR, VVER, BWR, CANDU, VHTR, FBR. The main attention is focused to geometric and material characteristic of fuel, however in brief are described also its main operating conditions. Advanced types of nuclear fuel and development trends are also parts of overview.

2. Thermophysical properties of fuel

Time range: 2 lectures

Heat generation in fuel pellets, detailed description of thermophysical properties of fuel and critical review of their models with focus on UO2 a MOX fuel, they are described: thermal conductivity coefficient and its changes with burn-up, specific heat and density and processes, which have influence on it.

3. Mechanical behaviour of fuel

Time range: 1 lecture

Determination of basic terms, materials of fuel pellets, behaviour of fuel in nuclear reactor, deformation mechanisms (cracking, relocation, swelling, ?) and their models, grow of RIM on fuel boundary, fission gas release.

4. Thermophysical properties of cladding

Time range: 1 lecture

Detailed description of thermophysical properties of cladding and critical review of their models. Attention is focused on thermal conductivity coefficient and specific heat. High attention is focused on oxide layer grow, models of its grow speed and its thermophysical properties.

5. Mechanical behaviour of cladding

Time range: 1 lecture

Mechanical properties of cladding materials, deformation mechanisms (elastic, plastic, creep, irradiation grow), influence of oxide layer, influence of irradiation on mechanical properties.

6. Heat transfer in gap fuel-cladding

Time range: 2 lectures

Definition and description of heat transfer coefficient in gap fuel-cladding, physical phenomena which have influence on them and their changes during burn-up, models and their critical review.

7. Interaction fuel-clading

Time range: 1 lecture

Mechanical and chemical interaction fuel-cladding, gap closure, models of contact, modelling of interaction, growth of interlayer, PCI/PCMI

8. Termomechanical codes for modelling of fuel rod behaviour

Time range: 1 lecture

Basic structure, geometric simplification, thermal models, stress-deformation models, codes overview, input data, output data, comparison with experiments.

9. Fuel behaviour at design accidents

Time range: 1 lecture

Process of LOCA, process of accident with introduced reactivity, cladding bump, fuel pellets fragmentation, possibilities of fuel melting, cladding oxidation, transient phenomena, types of cladding disturbance.

10. Safety criteria of nuclear fuel

Time range: 1 lecture

Requirements on safety operation, design and operational limits, thermal, mechanic and corrosion criteria, experimental verification, role of thermomechanicof nuclear fuel in licensing process, thermomechanic analyses in safety report.

Syllabus of tutorials:

Creation of input file for code FEMAXI-6, calculations and discussion of results.

Study Objective:

knowledge: knowledge of basic phenomena and processes in fuel rod during burn-up in reactor at nominal and abnormal operation and design accidents, influence of this phenomena on thermomechanical properties and temperature fields in fuel.

Abilities: orientation in issue, thermomechanical calculation of fuel

Study materials:

Key references:

D. R. Olander: Fundamental aspects of nuclear reactor fuel elements, Report No. TID-26711-P1, Technical Information Center, Office of Public Affairs, Energy Research and Development Administration, Oak Ridge, TN USA, 1976

Bailly H., Ménessier D., Prunier C.: The Nuclear Fuel of Pressurized Water Reactors and Fast Reactors, Design and Behaviour, Lavoisier Publ. Inc., 1999

Suzuki M., Saitou H.: Light Water Reactor Fuel Analysis Code FEMAXI-6, JAERI, 2005

Recommended references:

Berna, G. A.; Beyer, C. E.; Lanning, D. D.: FRAPCON-3: A Computer Code for the Calculation of Steady-State, Thermal-Mechanical Behavior of Oxide Fuel Rods for High Burnups, Pacific Northwest National Laboratory, Richland, 1997

Lanning, D.D., Beyer, C,.E., Painter, C.L.: FRAPCON-3: Modifications to Fuel Rod Material Properties and Performance Models for High-Burnup Aplication, Pacific Northwest National Laboratory, Richland, 1997

Hagrman, D.T. at all: SCDAP/RELAP5/MOD3.1 Code Manual Volume IV: MATPRO -- A Library of Materials Properties for Light-Water-Reactor Accident Analysis, Idaho National Engineering Laboratory EGandG Idaho, Inc., Idaho Falls, 1993

Carbajo, J.J., Yoder, G.L., Popov, S.G., Ivanov, V.K.: A Review of the Thermophysical Properties of MOX and UO2 Fuels, Journal of Nuclear Materials 299, 181-198, 2001

Media and tools:

PC classroom, codes: FEMAXI-6 and Cosmos/M

Note:

Further information:

No time-table has been prepared for this course

The course is a part of the following study plans: