KAIST Hee Cheon NO Nuclear System/Hydrogen Lab. Chapter 3: Fuel Thermal Analysis Hee Cheon NO Nuclear System/Hydrogen Lab. KAIST

Contents 3.1 Basic heat transport modes 3.1.1 conduction heat transport 3.1.2 convective heat transport 3.1.3 radiation heat transport 3.2 Fuel irradiation effects 3.2.1 Fission gas release 3.2.2 Thermal expansion, densification, swelling 3.2.3 Clad creepdown and lift-off 3.2.4 Fuel-cladding interaction 3.2.5 Fuel failure mechanisms   3.3 Fuel thermal analysis 3.3.1 Fuel pellet thermal analysis 3.3.2 Fuel cladding thermal analysis 3.3.3 Fuel gas gap thermal analysis 3.3.4 Heat transfer in the fluid channel

3.1 Basic heat transport models Conduction heat transport

3.1 Basic heat transport models Convection heat transport heat transfer coefficient

3.1 Basic heat transport models Radiation heat transport Black medium: emissivility=1; perfect emiiter and absorber Grey medium(practical medium): emissivility<1

3.2 Fuel irradiation effects

3.2 Fuel irradiation effects Fission gas release: recoil & knockout

3.2 Fuel irradiation effects open tunnel network Fission gas release: diffusion mechanism

3.2 Fuel irradiation effects Fission gas release: grain size effect

3.2 Fuel irradiation effects Thermal expansion

3.2 Fuel irradiation effects Densification and swelling

3.2 Fuel irradiation effects Clad creepdown and lift-off creep: long-term transient deformation given load

3.2 Fuel irradiation effects Fuel-cladding interaction

3.2 Fuel irradiation effects Fuel failure mechanism

3.2 Fuel irradiation effects Fuel failure mechanism

3.3 Fuel thermal analysis Example of fuel temperature radial distribution in fuel pellet

3.3 Fuel thermal analysis Fuel thermal analysis Fouling is the accumulation of unwanted material on solid surfaces to the detriment of function. The fouling material can consist of either living organisms (biofouling) or a non-living substance (inorganic or organic). Other terms used in the literature to describe fouling include: deposit formation, encrustation, crudding, deposition, scaling, scale formation, slagging, and sludge formation.

3.3 Fuel thermal analysis Fuel pellet thermal analysis: Fuel cladding thermal analysis:

3.3 Fuel thermal analysis Fuel gas gap thermal analysis(open gap):

3.3 Fuel thermal analysis Fuel gas gap thermal analysis(closed gap): Meyer's hardness: H=force/contact area=mean contact pressure normal to surface of the indent; contact area~1/load; high Meyer's hardness means less plastic deformation which increases contact area;p/H~contact area

3.3 Fuel thermal analysis coolant T with cosine power profile:

3.3 Fuel thermal analysis cladding T for subcooled non-boiling cladding T for subcooled boiling: Jens-Lottes correlation

CHF concept 3.3 Fuel thermal analysis  

CHF correlation(W-3) 3.3 Fuel thermal analysis  

HW#3: Chapter 3: Probelms 4, 5