Recalculating the steady state conditions of the V-1000 zero-power facility at Kurchatov institute using Monte Carlo and nodal diffusion

Continuous-energy Monte Carlo reactor physics code Serpent 2 was used to model the steady state conditions measured in V-1000 zero-power critical facility at Kurchatov Institute, Moscow, in 1990-1992. The Serpent 2 results were compared to the steady state power measurements of the test facility with all control rods withdrawn from the core. Serpent 2 was used to generate group constants for reactor dynamics code HEXTRAN and a HEXTRAN calculation of the test facility was performed. The original measurements were carried out by inserting partial-length fuel rods into the core. The Serpent 2 calculation allowed direct calculation of the relative powers of these rods instead of relying on pin power reconstruction. The properties of the radial reflector and the gaps between the radial reflector and the fuel assemblies of the test facility were examined with additional detail. The relative power distribution of the zero-power steady state was found to be very sensitive to the properties of the radial reflector. Nodal diffusion calculations carried out previously by several different groups in 2003 found a significant power tilt in the core. This was reproduced in the Monte Carlo calculation. However, the reflector gaps produced another power tilt in addition to the previously known one.