Reducing neutron fluence on the EPR TM reactor pressure vessel using a heavy reflector

The AREVA EPR TM nuclear power plant is an evolutionary nuclear energy facility reflecting advanced pressurized water reactor (PWR) technology and improvements from research and development (R and D) and lessons learned during construction and operations over the last 40 years. An improvement in PWR technology is found in the EPR TM reactor vessel heavy reflector. It is a large steel structure that replaces the thin baffle plates used in existing PWR reactor vessels. The reflector resides between the fuel and the core barrel and above the lower core-support plate. The heavy reflector improves the neutron economy in the active core and reduces the neutron fast flux on the reactor pressure vessel. The effectiveness of the heavy reflector to reduce the fast flux at the inside diameter of the RPV was determined utilizing the DORT and MCNP codes. The heavy reflector provides a factor of about 2.5 reduction in the neutron flux at the peak azimuthal location applying the AREVA NP INC. DORT-based RPV fluence methodology and by a factor of about three based on MCNP code calculations. (authors)