It is a generic high-pressure vessel that allows for insertion of smaller reactors of various designs for use in studying high-pressure reaction phenomena. The vessel has an inner diameter of 0.46 m (18 inches), a length of 1.2 m (48 inches), and was designed to be flexible, with an extensive array of ports, including 11 small ports (2″ diameter) and 3 larger ports (6″ diameter) for access to allow gas feeds, purges and heaters to internal reactors, electrical and thermocouple feed-throughs, product sampling, and other utilities such as hydraulic loading or strain monitoring. The vessel has been certified for operation up to 1500 psi at a shell temperature of 300 °C. Internal reactors can be designed to operate at higher temperatures at pressure, as long as the outer vessel does not exceed the 300 °C limit. Past projects include simulation of underground thermal treatment of coal seams to produce synthetic natural gas and liquid products (using internal pyrolysis reactor temperatures up to 600 °C) and in-situ pyrolysis of large oil shale cores. The latter experiments combined pyrolysis with axial loadings up to 10,000 lbf.