Reactor pressure vessel welding process

Surveillance test materials are prepared from the actual materials used in fabricating the beltline region of the reactor pressure vessel. The test materials are processed so that they are representative of the materials in the completed reactor vessel. Specimens are prepared from three metallurgically different materials, including base metal, weld metal and heat-affected zone (HAZ) material. 

A. The material used to manufacture the flywheel of the reactor coolant pump motor will be produced by a commercially acceptable process that minimizes flaws, such as the vacuum melt and degassing process. This provides adequate fracture toughness properties under reactor operating conditions. The acceptance criteria for flywheel design will be compatible with the safety philosophy of the Pressure Vessel Research Committee (PVRC) of the Welding Research Council (WRC) primary coolant pressure boundary criteria as appropriate considering the inherent design and functional requirement differences between the pressure boundary and the flywheel. 

For the combined EDS-batch SCWO, a variety of technical issues must be addressed the choice of materials of construction, the method used to introduce oxidant into the vessel, the durability of seals, the stability of SCWO reactions in a large-diameter vessel, the methods used to heat the vessel, the possibility of scaling and corrosion under batch SCWO conditions (salts are proposed to be captured in apan placed in the vessel, but this has not yet been demonstrated), the method used to fabricate the vessel (e.g., single forging vs. welded sections), the impact of repeated explosions followed by thermal and pressure cycles on the integrity of the EDS vessel and SCWO reactor (e.g., crack propagation), the most appropriate method of cooldown and depressurization following munition destruction, and the disposition of process residuals. 

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