Vol.:(0123456789)
International Journal of Thermophysics (2020) 41:111
https://doi.org/10.1007/s10765-020-02689-6
1 3
Evaluation of Structural and Thermal Properties
of Ce
1‑y
Gd
y
O
2‑x
Solid Solution
Pham Van Mao
1,2
· Tatsumi Arima
1
· Yaohiro Inagaki
1
· Kazuya Idemitsu
1
Received: 15 May 2020 / Accepted: 3 June 2020
© Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract
In the present study, the systematic evaluation of thermal properties was performed
for CeO
2
–Gd
2
O
3
(Gd
2
O
3
= 0–15 wt%) samples. Gd
2
O
3
doping into CeO
2
reduced
the grain size of CeO
2
–Gd
2
O
3
solid solution and caused the expansion of the lat-
tice parameter. The thermal conductivity of CeO
2
–Gd
2
O
3
solid solutions decreased
with increasing Gd
2
O
3
content and decreased with temperature up to nearly 900 K,
though the decreasing rates became smaller at a higher temperature. The values of
the thermal conductivity were mostly attributed to phonon mean free path which
decreased due to the Umklapp processes at high temperatures and reduced by pho-
non scattering due to Gd dopants and oxygen vacancies at low temperatures. The
phonon scattering caused by grain boundaries, and chemical impurities can be
neglected, and the isotope efect is considered to be small.
Keywords Burnable poisons · CeO
2
· Lattice imperfections · Phonon mean free
path · Thermal conductivity · UO
2
1 Introduction
Currently, burnable poison fuels such as (U,Gd)O
2-x
and (U,Er)O
2-x
are widely used
in the light water reactors, especially in the case of the pressurized water reactors
[1, 2]. The light water reactors use gadolinia (Gd
2
O
3
) or erbia (Er
2
O
3
) mixed with
the UO
2
dispersed into the fuel pellets in several fuel rods of each fuel assembly.
These materials help to control the initial reactivity, to spread the distribution of
core power by keeping uniform power distribution throughout much of the core life,
to increase fuel burnup, to prolong the refueling cycle length, to reduce the number
* Pham Van Mao
maopv@nucl.kyushu-u.ac.jp
1
Department of Applied Quantum Physics and Nuclear Engineering, Faculty of Engineering,
Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
2
Vietnam Electricity (EVN), No. 11 Cua Bac Street, Truc Bach Ward, Ba Dinh District, Hanoi,
Vietnam