Consideration of influence of the gap size (between fuel assemblies) changes onto power field distribution in VVER‐1000 reactors with the help of PERMAK‐A code
26th Symposium of AER on VVER Reactor Physics and Reactor Safety (2016, Helsinki, Finland)
Core surveillance and monitoring continues
Abstract
CONSIDERATION OF INFLUENCE OF THE GAP SIZE (BETWEEN FUEL ASSEMBLIES) CHANGES ONTO POWER FIELD DISTRIBUTION IN VVER-1000 REACTORS WITH THE HELP OF PERMAK-A CODES. Aleshin, M. Kalugin, A. Pinegin, A. Ryzhov NRC “Kurchatov Institute”Moscow, RussiaABSTRACTThe gap sizes between FAs in VVER-1000 reactors can diverge from its design values due to influence of some factors. The changes in gaps between fuel assemblies lead to the changes in uranium-water ratio in some areas of fuel rods lattice. Hence, they lead to the changes in power of pins that located in peripheral rows of FA. In the paper it is presented methods and results of pin-by-pin power distribution numeric calculations using diffusion code PERMAK-A. The results of calculations using presented methods are well-corresponded with the results of precision calculations by Monte Carlo program complex MCU for the mini-core with seven FAs. Obtained results allow to carry out the series of pin-by-pin power distribution calculations with taking into account possible technological changes in gaps between FAs in the core with the help of PERMAK-A code. In the paper it is presented the results of test calculations for the core.The procedure of taking into account the changes in pin power due to changes gaps between FAs is included into STAT-TVS code. STAT-TVS code is intended for estimation (using Monte Carlo methods) the errors in power distribution, the minimum values of DNBR and maximal values of fuel temperatures in FA accounting technological and calculation errors. In the paper it is presented the results of statistical simulation neutron-physical and thermo- physical processes in FA. 26th Symposium of AER on VVER Reactor Physics and Reactor Safety 33 10 – 14 October 2016, Helsinki, Finland