Critical experiment on initial loading core of very high temperature reactor critical assembly (VHTRC)

A critical assembly VHTRC (Very High Temperature Reactor Critical Assembly) was constructed by modifying SHE (Semi-Homogeneous Experiment) in order to verify the nuclear design accuracy of the HTTR (High Temperature Engineering Test Reactor). The initial core named as VHTRC-1 core was made by loading fuel rods which contained fuel compacts of 4 W/0 enriched uranium coated particles. The following measurements were carried out in the VHTRC-1 core: (1) critical mass, (2) reactivity worths of mockup control rod and burnable poison rod, (3) neutron flux distribution and (4) kinetic parameter β_eff/Λ. Calculations were performed with the SRAC code system using the nuclear data based on the ENDF/B-IV. The agreement between experiment and calculation was fairly good for the most experimental items. The calculation, however, cannot predict accurately the value of the kinetic parameter. (author)