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A high temperature steady-state in-pile experiment was developed to simulate prototypical nuclear thermal propulsion conditions in addition to serve as a validation tool for radiative heat transfer computational methods. The experimental development of the test apparatus involved scaling the device to a larger heated region from a previous smaller out-of-pile prototype. A series of tests and investigations were conducted to replicate the smaller out-of-pile system's success of achieving 2500 K. However, limitations within the larger assembly were identified. The larger assembly can reliably generate usable temperature levels from room temperature up to those exceeding 1300 K. The larger system is achieving temperatures over 2500 K, but these are localized and unable to be monitored in the current design. Due to the limitations of the current heater, it is recommended that the apparatus be redesigned to utilize a heating element similar to that used during Project POODLE in the 1960s. However, the achieved temperature levels are still suitable for testing various components considered for a nuclear thermal rocket. Various in-pile experiments have been performed to test materials and instrumentation relevant to nuclear thermal rocket systems. This temperature level also provides sufficient thermal energy for radiative heat transfer studies. The experimental results were used to compare leading thermal modeling software packages and various solution methods. The experiment was compared against COMSOL and ANSYS. Within COMSOL the radiation view factors were calculated using the hemi-cube and the ray shooting solution methods. These were also compared against ANSYS, which utilized the hemi-cube view factor solution method.