The Use of Th in HTR: State of the Art and Implementation in Th/Pu Fuel Cycles

Table 2

(Pu-Th)O₂ fuel general characteristics in accordance with PUMA Project [10, 11].

Description	Value
Fuel pebble
Fuel pebble outer radius	3.0 cm
Thickness of fuel free zone	0.5 cm
Total heavy metal loading per fuel pebble	2.0 g
Matrix density	1.74 g/cm^3
Packing fraction in pebble bed	61%
Coated particle
Kernel Coating Material	C/C/SiC/C
Layer thickness	90/40/35/40 𝜇m
Layer densities	1.05/1.90/3.18/1.90 g/cm^3
Fuel kernel
Fuel kernel diameter	200 micron
Kernel material type	(Pu-Th)O2.0
Th-oxide density	9.55 g/cm^3 (95% TD) [13]
Pu-oxide density	10.89 g/cm^3 (95% TD) [12]