GOTHIC™ has been developed and maintained over 30+ years by NAS Engineering, Inc. (formerly Numerical Applications, Inc.). It has been used for the design, licensing, safety and operating analysis of nuclear power plant systems including primary system, containment, and equipment performance. GOTHIC includes the necessary modeling capabilities to represent the piping, reactor vessel, and components of the reactor coolant system.

Numerical Advisory Solutions, Inc. is the developer of the GOTHIC computer code and is the holder of the exclusive license to distribute sublicenses of the GOTHIC code and maintain, modify, and support the GOTHIC code for EPRI.

GOTHIC is a descendant of the COBRA-TF and COBRA-NC codes developed at Battelle, Pacific Northwest National Laboratory (PNNL), primarily for transient analysis for the core and vessel of a nuclear reactor. The FATHOMS code, developed at Numerical Applications, Inc. (NAI), was based on COBRA-NC and extended the range of applicability to allow the analysis of containment buildings and later evolved into GOTHIC. See the below flowchart for a representation of the code development and code relationships.