FINAL RESULTS OF THE PRIMARY SYSTEM HYDRAULIC CHARACTERISTICS AFTER MODIFICATION OF REACTOR COOLANT PUMPS IMPELLER WHEELS AT BOHUNICE NPP EXECUTED BETWEEN 2012-2014
24th Symposium of AER on VVER Reactor Physics and Reactor Safety (2014, Sochi, Russia)
Core surveillance and monitoring
FINAL RESULTS OF THE PRIMARY SYSTEM HYDRAULIC CHARACTERISTICS AFTER MODIFICATION OF REACTOR COOLANT PUMPS` IMPELLER WHEELS AT BOHUNICE NPP EXECUTED BETWEEN 2012-2014
Martin Závodský, Jozef Hermanský Division for Preparation of NPP Operation
VUJE Inc., Okruţná 5, 918 64 Trnava, Slovakia Martin.Zavodsky@vuje.sk, Jozef.Hermansky@vuje.sk
The paper follows the similar papers presented last two years at AER Symposiums in Průhonice (Czech Republic) and Štrbské Pleso (Slovakia).
The project “Modification of reactor coolant pumps impeller wheels at EBO NPP” has been successfully finished in summer 2014 after the outage at Bohunice NPP Unit 3. Nowadays both Bohunice Units are operated without any difficulty with modified impeller wheels. All new impeller wheels, produced by CKBM in St. Petersburg, have the same diameter 595 mm. Measurement after final modification showed that the increase of coolant flow through the reactor at Unit 3 is circa 5,5 %. The same measurement executed last year showed that the increase of coolant flow at Unit 4 is circa 4,5 %. These values are even higher than expected values and values required by operator (Slovenské Elektrárne).
The paper summarizes the results of the primary system hydraulic characteristics measurement executed between 2012 – 2014 after partial modification (2 and 4 out of 6 impeller wheels) and after complete modification (6 out of 6 impeller wheels). Comparison of measured values with expected values is presented as well. The results of the thermal balances measurements are mentioned as well. The values of coolant flow through the reactor calculated by two different methodologies are in a good agreement. The results of the measurements demonstrated that the characteristics of reactor core cooling are improved.