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In order to maintain the integrity of the Reactor Containment Building (RCB) and to prevent leakage of radioactive materials during Severe Accidents (SAs), the RCB has been designed to have a sufficient volume so that the structural load is maintained below American Society of Mechanical Engineer (ASME) Section III Service Level C for a period of 24 hours following SAs. This also helps keep hydrogen concentration under 13% in case of a 75% oxidation of fuel clad-steam. Another design feature to prevent leakage has been the installation of a 1/4 inch steel liner plate on the inboard side of the RCB. In addition, the RCB has been constructed with pre-stressed concrete having a high compressive strength of 6,000 psi after 91 days of curing.
The reactor vessel cavity is designed to allow molten core materials spread out over the heat transferable area to measure not less than 0.02 ㎡/MW and is cooled to allow the materials to solidify on the cavity floor. Moreover, the convoluted vent path of the reactor vessel cavity prevents molten core debris from being released into the containment atmosphere.

Major Design Characteristics

  • Enlarged free volume of the RCB to maintain the structural load below code requirements and to keep the hydrogen concentration below the design limit
  • Lined with a 1/4 inch steel plate on the inboard side of the RCB to prevent the leakage of radioactive materials
  • Reinforced RCB with high compressive strength of 6,000 psi
  • Spacious reactor vessel cavity and convoluted vent path for the SAs mitigation