Modeling of existing beam-port facility at PSU breazeale reactor by using MCNP5

The Radiation Science and Engineering Center facilities at the Pennsylvania State University (PSU) include the Penn State Breazeale Reactor, gamma irradiation facilities, and various radiation detection and measurement laboratories. Due to inherited design issues with the current arrangement of beam ports and reactor core-moderator assembly, the development of innovative experimental facilities utilizing neutron beams is extremely limited. Therefore, a new core-moderator location in PSBR pool and beam port geometry was needed to be developed. A study is underway with the support of DOE-INIE funds to examine the existing beam ports for neutron output and to investigate new moderator arid beam-port designs to produce more useful neutron beams. The overall system for this study consists of two major parts, the core model and beam port model. Core calculations are performed by using a three dimensional nodal diffusion code ADMARC-H. Beam port calculations are performed with the MCNP code. An interface program has been developed at PSU to link the diffusion code to the neutron transport code. The MCNP model consists of the D ₂O tank, graphite reflector block, and beam port tube with their surroundings. The results of the PSU package show good agreement with the experimental data.