This project takes a pivotal first step on the path to developing a commercial thorium-plutonium light water reactor (LWR) fuel. This fuel-type is assessed to offer numerous fuel-cycle advantages, and will be commercially attractive as uranium prices and waste-management costs continue to rise. It is the fastest path toward exploiting thorium as a new fuel for electricity production. The commercialization path requires demonstration that the new fuel performs well - and safely - under LWR operating co nditions.The test reactor operated by IFE in Halden is a world leader in performing trial irradiations in simulated LWR conditions and so is ideally suited to acquiring the body of behavioural data needed for the thorium-plutonium fuel ceramic.Precisi on 'online' measurements will be made: (i) the temperature of the fuel operating at normal power levels, (ii) dimensional changes of the fuel pellets and cladding, (iii) internal rod pressure due to the release of fission gases from the fuel pellet. Pos t-irradiation examination will include sophisticated measurements of fuel pellet material properties, including: fission product distribution and thermal conductivity. Collectively, the suite of data will be extremely valuable since it will be used: (i ) in the approval for further necessary irradiations of the fuel in commercial LWR/s, and (ii) in building predictive thermo-mechanical computer codes.Ultimately this ongoing work will enable Thor Energy (& partners) to offer safety assurance services t o customers for new thorium-plutonium LWR fuels that it designs. There is a large potential revenue derivable from such work - given nuclear fuel growth and technology projections.The commercial qualification for thorium-plutonium LWR fuel is, however, dependent on the availability of reliable physical measurements of how the fuel behaves in LWR conditions. Now is the time to collect this data -using IFE's unique capabilities.