International design regulations can be used to test and design a reactor pressure vessel. These codes give engineers proactive steps that can be taken to prevent any major catastrophes. Through the use of the ANSYS finite element program, this project examines the efficacy of the elastic-plastic limit based design approaches of the primary International Design Codes (ASME and BS). For the analysis, a standard pressurized water reactor (PWR) with a 300 MW capacity was chosen. SA-508 Gr.3 Cl.1, a nuclear grade steel, was utilized as the RPV material in the comparison. It has been determined that the design by analysis approach can be utilized to eliminate the needless caution that results from using the design by rule approach, which is covered in BS-5500 section 3. This study suggests that by applying the design by analysis approach as outlined in the ASME code, the maximum allowed pressure of the RPV may be increased by up to 26.37%.