Estimation influence of boric acid drop entrainment to its accumulation in the VVER reactor in the case of accident

Abstract

Process of boric acid mass transfer during accidents accompanied with rupture of circulation pipelines in VVER reactors of new generation equipped with passive safety systems are examined. Results of calculation of variation of boric acid concentration in VVER-TOI reactor in case of accident development process are presented. Positive effects of boric acid droplet entrainment on the processes of acid accumulation and crystallization in the reactor core are demonstrated. The obtained results allow formulating the conclusion on the possibility of these processes in the reactor core which may lead to the disruption of heat removal from fuel pins. Review of available published reference data on physical properties of boric acid solutions (density, viscosity, thermal conductivity) is given. It is established that available information is of too general nature and fails to cover the whole range of parameters (acid temperature, pressure and concentration) typical for potential emergency situation on NPP equipped with VVER reactor. Necessity of experimental study of processes of droplet entrainment under parameters typical for VVER emergency operation conditions, as well as investigation of thermal physics properties of boric acid within wide range of acid concentration values is required.

Experimental Regulating Parameters of Bladder-Type Hydraulic Accumulator

“…Using hydraulic accumulators is useful due to the shortage of the number of pump switches, thus providing the increasing of its service life. Hydraulic accumulators are widely used in engineering: in water supply and other fluid pressure systems (Shi et al [1]; Zhuk et al [2]), in the power engineering (Morozov et al [3]), in hydro-drives (Bravo et al [4]; Kumar et al [5]; Puddu and Paderi, [6]; Wu et al [7]), etc. Parameters of transitional gas processes have a significant impact on the efficiency of the relevant engineering systems (Juhala et al [8]; Mamčic and Bogdevičius, [9]).…”

Experimental Integral Regulating Parameters of a Bladder-Type Hydraulic Accumulator

“…The use of hydraulic accumulators significantly decreases the frequency of pump switches, increasing its service period. Hydraulic accumulators are used in various fields of the engineering: in water supply and other pressure pipelines (Zhuk et al, 2016;Shi et al, 2019), hydro drive systems (Puddu & Paderi, 2013;Kumar et al, 2017;Bravo et al, 2018;Wu et al, 2019), energy engineering (Morozov et al, 2017), etc.…”

An experimental study into the solubility of boric acid in steam during boiling in conditions of atmospheric pressure

“…При аварии с разрывом главного циркуляционного трубопровода ВВЭР давление в системе реакторная установка защитная оболочка к началу работы ГЕ 3 составляет 0,2 МПа, температура среды в реакторе ~120 o C [7]. Максимальная концентра ция борной кислоты для данных параметров составляет ~385 г H 3 BO 3 /кг H 2 O. Согласно расчетам, проведенным в АО «ГНЦ РФ ФЭИ» [8], по достижении 24 х часов аварийного процесса концентрация борной кислоты в активной зоне составляет ~311 г/кг и не до стигает предела растворимости.…”