Assessment of ³He Release from Uranium Tritide Bed Considering Cyclic Operation Using Empirical Models

Abstract

In this study, the amount of ³He release from a tritium-loaded depleted uranium bed considering long-term operation in the fusion fuel cycle is assessed using empirical models. Several works are surveyed to investigate the trend of ³He released from uranium tritide. The model for ³He release is developed consisting of two parts, i.e., the natural release model and the heating release model, based on experimental studies. The natural release model is validated by applying it to experimental data. The model is applied to cyclic and long-term operation scenarios to assess the amount of ³He in the headspace of the metal tritide bed. The results show that the ³He release after long-term maintenance can be significant and must be separated from tritium before supply to the fuel cycle. During plasma operation and short maintenance, it is shown that the ³He release is less significant, but further requirement consideration is needed for the ³He separation process.

Keywords:

• Helium-3 release
• tritium
• depleted uranium
• empirical model
• cyclic operation

Nomenclature

$\mathit{a}$	=	= midpoint of natural release function (day)
$\mathit{b}$	=	= regressed parameter for heating release
$\mathit{c}$	=	= midpoint of logistic function
$\dot{G}$	=	= 3He generation rate (mol/day)
$\mathit{I}$	=	= amount of 3He retention in uranium (mol)
$\mathit{K}$	=	= capacity limitation
$\mathit{N}$	=	= target logistic function
$R_h$	=	= amount of 3He heating release (mol)
${\dot{R}}_{\mathit{n}}$	=	= 3He natural release rate (mol/day)
$\mathit{r}$	=	= logistic growth rate
$T_0$	=	= initial amount of tritium (mol)
$\mathit{t}$	=	= time (day)
$U_{\mathit{eff}}$	=	= effective amount of uranium tritide (mol)

Greek

$\mathit{\alpha }$	=	= regressed parameter for heating release
$\mathit{\lambda }$	=	= decay constant (day−1)

Acknowledgments

This work was supported by the Research and Development program through Korea Institute of Fusion Energy funded by the Ministry of Science & ICT, of Korea (IF2228-1).

Disclosure Statement

No potential conflict of interest was reported by the authors.