Oil consumption in a refinery is ∼6% of the production, which indicates a great interest in the use of nuclear heat to save oil. A high-temperature reactor (HTR) was designed to be used in an existing refinery in France having a crude oil through-put of 20 Tg/yr. The HTR produces only one part of the process heat, which is distributed by hot helium in a localized part of the refinery to decrease the length of helium ducts. The present boiler is kept in operation and is running at 30% capacity to have steam and electricity available in case of reactor shutdown. With a 1000 MW of thermal energy reactor, the amount of fuel conserved is 500 Gg/yr. The studies have shown that it was technically possible to use an HTR to provide a large part of the energy. However, economic calculations lead to a prime cost of conserved crude oil of almost twice the existing price. This situation could change if the cost of the crude oil increases significantly.