From Shale and Sands Oil Recovery LLC via PRNewswire:
The method, invented by Thomas O’Brien (Shale and Sands Oil Recovery LLC), utilizes a high temperature nuclear reactor since the output temperature is over 500 degrees Celsius. The types of reactors that produce this heat level are liquid metal-cooled reactors (which use negligible water to operate) and high temperature gas-cooled reactors. With this level of heat production, supercritical material, such as small amounts of water, can be injected into the shale formation initially causing a much higher degree of permeability then forming a reservoir of crude oil that can be pumped from the formation using conventional drilling methods. Thomas O’Brien, a geoscientist with over 30 years of experience and expertise, developed the method by studying and working in the reservoir analysis area then on the use of supercritical materials in concert with experts on oil shale.
Here’s the lowdown on liquid metal-cooled reactors from Wikipedia. From the article:
Disadvantages include difficulties associated with inspection and repair of a reactor immersed in opaque molten metal, and depending on the choice of metal, corrosion and/or production of radioactive activation products may be an issue.
More nuclear coverage here and here. More oil shale coverage here and here.