Neutron poison distribution in the central reflector to reduce the DLOFC temperature of a Th-LEU fueled OTTO PBMR DPP-400 core

Figures & data

Figure 1. Standard axial power and maximum DLOFC temperature profiles for a PBMR-400 core, fuelled with a 16 g/sphere LEU-Th in an OTTO fuelling scheme.

Figure 2. Modified axial power and DLOFC temperature profiles with ¹⁰B in the region 115–287 cm of the central reflector.

Figure 3. Reactor geometry used for VSOP simulation with the B-10 placement.

Figure 4. Modified power and maximum DLOFC temperature profiles with a ¹⁰B concentration of 6.75 × 10⁻⁶ atoms/(barn.cm) in the central reflector in the height-range of 172 and 345 cm below the top of the fuel core in order to reduce the maximum DLOFC temperature of the symmetric core.

Figure 5. A symmetric maximum DLOFC temperature peak, achieved by modifying the power profiles with a ¹⁰B concentration of 6.75 × 10⁻⁶ atoms/(barn.cm) in the suppression region of the central reflector and a ¹⁰B concentration of 0.544 × 10⁻⁶ atoms/(barn.cm) in a 57 cm region above the suppression zone, in order to further reduce the maximum DLOFC temperature of the symmetric core.

Figure 6. Axial power and maximum DLOFC fuel temperature profiles for producing a lower maximum DLOFC temperature, shown on a separate scale, for both the radially symmetric and asymmetric LEU-Th fuel cycles.

Figure 7. The asymmetric core with modified power and temperature profiles with a ¹⁰B concentration of 6.75 × 10⁻⁶ atoms/(barn.cm) in the suppression region of the central reflector and a ¹⁰B concentration of 0.544 × 10⁻⁶ atoms/(barn.cm) in a 57 cm region above the suppression, to further reduce the maximum DLOFC temperature of the asymmetric core.

Figure 8. Time profiles for maximum DLOFC temperatures with a ¹⁰B concentration of 6.75 × 10⁻⁶ atoms/(barn.cm) in the suppression region of the central reflector and a ¹⁰B concentration of 0.544 × 10⁻⁶ atoms/(barn.cm) in a 57 cm region above the suppression zone.