Fast Neutron Irradiation Influence Analysis in Thermal-Hydraulics Aspect of HTR-10 Reactor Using Modified PEBBLE Program

Abstract

Abstract Pebble Bed Reactor is a Gen-IV reactor that uses spherical fuel loaded into an active core. This reactor uses graphite that can be found on fuel and reflectors as a neutron moderator. The fast neutron can damage the atomic structure of fuel because the neutron with high energy can displace the graphite lattice. As its effect, the value of fuel thermal conductivity is influenced. PEBBLE is the program used for thermal-hydraulic calculation for pebble bed reactor type (PBR), and mPEBBLE was developed based on PEBBLE. The main difference between the two is that the mPEBBLE can take into account the fast neutron factor in the calculation. In this study, the thermal-hydraulics calculation for HTR-10 was performed using the mPEBBLE code. The result obtained is compared to the results from two different programs; THERMIX and WIMSTER. The comparison between the mPEBBLE and THERMIX has a temperature difference, which is relatively high at 63.3°C at the near-wall position. For the comparison between mPEBBLE and WISMTER, the noticeable difference happens in pebble center temperature, which is 65.3°C for the temperature difference.