Stabilization of Uranium Nitride by Aluminum and Chromium Doping
Typ
Examensarbete för masterexamen
Program
Publicerad
2020
Författare
Axhage, Einar
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Uranium nitride is a promising accident tolerant fuel (ATF) candidate as it
has great uranium density and thermal conductivity. The main downside is
its inherent weakness to oxidation in mainly water and steam. In this work,
uranium nitride was synthesized with 20% of total molar metal content as varying
amounts of aluminum and chromium. The material was investigated in terms
of oxidation performance and microstructure in order to asses the suitability of
said dopants as an approach of stabilization. The material was synthesized as
microspheres via the internal sol-gel process and carbothermal reduction at 1550 °C.
Aluminum caused a change in microstructure and made the material more porous,
which was believed to be the main reason why aluminum reduced oxidation
performance during thermogravimetric analysis. This change was attributed to the
tendency of aluminum to collect along the grain boundaries, potentially weakening
grain adhesion. Only when chromium alone was added the oxidation temperature
was increased. Added chromium not only caused caused cracking due to the release
of gasses, but also surface formations due to the limited solubility of chromium in
uranium nitride.
Beskrivning
Ämne/nyckelord
LWR , UN , ATF , sol gel , chromium , aluminum , doping , microsphere