Regulatory Guide (RG) 1.190 provides the basis for the U.S. Nuclear Regulatory Committee (NRC) to review any nuclear reactor vessel fluence calculation work that has been submitted to the committee. RG 1.190 intends to ensure the accuracy and reliability of the neutron fluence determination required by general design criteria related to the reactor coolant pressure boundary. RG 1.190 describes methods and assumptions acceptable to the NRC staff for determining the pressure vessel neutron fluence. RAPTOR-M3G (which stands for rapid parallel transport of radiation—multiple three-dimensional geometries) is a three-dimensional parallel discrete ordinates transport code that has been developed by Westinghouse Electric Company LLC Radiation Engineering Analysis group that can be used for commercial reactor vessel fluence production work. However, in order for RAPTOR-M3G to be accepted by NRC to perform fluence calculation for a pressurized water reactor fleet, a generic methodology qualification and uncertainty estimates must be performed. The methods qualification consists of three parts: (1) the analytical uncertainty analysis, (2) the comparison with benchmarks and operating reactor measurements, and (3) the estimate of uncertainty in the calculated fluence. This paper describes how RAPTOR-M3G 3D parallel discrete ordinates code was qualified per RG 1.190.