The verification of method for determining the weighted mean coolant temperature in the primary circuit hot legs of VVER-1000 reactor plants
The new method for determining the weighted mean coolant temperature in the primary circuit hot legs of WWER-1000 reactor plants has been developed by experts of JSC "Atomtechenergo". It was represented at previous 9th conference and also at 25th Symposium АER on WWER reactor physics and safety research. The new method developing was defined by necessity to decrease error in calculation of the weighted mean coolant temperature in hot legs due to the coolant temperature stratification. The executed experimental and calculating researches results have been considered in method developing.
Method verification has been fulfilled by comparison of calculations results received with using and without using methodology in various operational conditions of three WWER-1000 power units. These power units have differences in structure and placing of temperature detectors and also differed in fuel loading. For the aims of verification 39 operational conditions have been analysed. They were differed by capacity levels, positions of CR regulating group and e.t.c.
The received results of verification have confirmed that with use of new method the objective decreasing of error in determining the weighted mean coolant temperature in the primary circuit hot legs is reached. The amount of decreasing depends on the character of stratification which is various for different objects. The maximum decreasing of error among investigated objects during verification was 0,6 °С.
The executed verification shows that it is necessary to continue researches of coolant temperature stratification in hot legs and possibilities of new method. Besides, it is necessary to carry out additional researches of factors influencing on the feedwater flowrate measurement errors. The results of these researches also should provide increase the efficiency of method using.Full version (russian)