Design optimization of a closure head for a PWR reactor pressure vessel

In this paper, design optimization of the closure head for PWR reactor pressure vessel has been performed. The RPV closure head mainly consist of hemispherical head with openings for CRDM and QUICKLOC nozzles, and head flange with holes for closure studs. Thickness of the head and height of the flange have been optimized by employing response surface optimization methodology through design of experiments technique. The effect of thickness of head and height of flange on the stress intensity distribution of the closure head in the presence of openings were studied in order to explore the best design under the guidelines of the ASME code. The underdesigning (compromise of the Tresca yield criterion) and over-designing (compromise of the fracture toughness) of the closure head are controlled in a novel way through detailed stress analysis.