  Monte Carlo simulations show similarity on radial distributions of power and
isotopic concentrations at any effective full power depletion time among five
kinds of fuel-cladding combinations with the same cycle length, including the
normal UO2-zircaloy combination, the candidate Accident Tolerant Fuel (ATF)
UO2/U3Si2-FeCrAl combination, and three kinds of candidate ATF U3Si2-FeCrAl
combinations. An analytical formula f(x,s) including the fuel exposure (s) and
the relative radial (x) is proposed to describe the radial properties for all
five kinds of fuel-cladding combinations. f(x,s) has the form of the second
order polynomial term of s with the exponential type of coefficients depending
on x. It is shown that the suggested function f(x,s) gives a nice description
on the simulation data with rather small deviations and can immediately provide
radial distribution of power, burnup, and isotopic concentrations of 235U,
238U, 239Pu, and 241Pu at any fuel exposure and relative radius. It is useful
to discuss the fuel temperature through the present analytical formula. The
realistic radial power distribution gives flatter radial temperature
distribution compared with the uniform power distribution. Because of the
different thermal conductivities of fuels and claddings and the different
thicknesses of claddings, the present discussed five kinds of fuel-cladding
combinations have different radial temperature distributions, although their
radial power distributions are quite similar. The present work provides an
analytical formula to describe the radial properties of the ATF which is
expected to be helpful for further neutronic and multi-physics coupling
studies.
