Primary system hydraulic characteristics after modification of reactor coolant pumps` impeller wheels at Bohunice NPP executed in 2013
23rd Symposium of AER on VVER Reactor Physics and Reactor Safety (2013, Štrbské Pleso, Slovakia)
Core surveillance and monitoring
The paper follows the similar paper ?Primary system hydraulic characteristics after
modification of reactor coolant pumps` impeller wheels at Bohunice NPP? presented last year
in AER Symposium 2012 in Pr?honice [ 1 ].
The project ?Modification of reactor coolant pumps impeller wheels at EBO NPP? is
continuing also in 2013. During the outages in 2013 two impeller wheels were replaced at
both units. Nowadays Unit 4 is operated with all 6 new impeller wheels and Unit 3 with four
new impeller wheels. Modification of last two impeller wheels at Unit 3 will be performed
during the outage in 2014.
The paper presents the main results of non-standard primary system hydraulic
characteristics measurement executed in 2013. Comparison with expected values is presented
as well. Measurements showed that the increase of coolant flow through the reactor is in good
agreement with expected values. The increase of the coolant flow through the reactor was
proved not only by primary system hydraulic characteristics measurements, but also by
thermal balance measurements. Both measurements are based on different unit parameters.
The increase of coolant flow through the reactor in comparison with initial value in 2011 is at
Unit 4 circa 4,5 % (after modification of all 6 impeller wheels) and at Unit 3 circa 3,2 % (after
modification of 4 impeller wheels).