MCU calculation of spacing grid influence on FA's axial power distribution
20th Symposium of AER on VVER Reactor Physics and Reactor Safety (2010, Hanasaari, Espoo, Finland)
Spectral and Core Calculations
Abstract
Presence of spacing grid in fuel assembly noticeably decreases local energy release
due to small local change of uranium-water ratio. Condition of total energy release
conservation leads to some increase in maximum of axial power distribution. With MCU
Monte Carlo code these increase/decrease were calculated for some VVER-440 and VVER1000 FA?s. Since geometry of spacing grid is very complicated, two different sensibly
simplified models were proposed. Both gave close results. Local minimums turn out to be
~5% lower than average and local maximums increase slightly more than 1%.