V.I. Skalozubov, O.A. Dorozh, D.S. Bundev, O.S. Suhomlinov, S.S. Prokofiev
Odesa National Polytechnic University, 1, Shevchenko ave, Odesa, 65044, Ukraine
DOI: doi.org/10.31717/2311-8253.24.3.3
Abstract
Accident management in small modular reactors (SMR) is carried out by natural circulation circuits of passive safety systems, which, taking into account the Fukushima accident, determines the grounds for the need to classify SMRs as nuclear power plants of a new safety generation (3+). However, for a reasoned adoption of such a decision, additional studies of the reliability of accident management by passive safety systems are necessary. Based on the analysis of the known results of the SMR safety analysis, it was established that for an objective assessment of the safety of the specified reactors with a natural circulation circuit of passive safety systems, it is necessary to take into account the possibility of the occurrence of inter-circuit thermal hydrodynamic instability (THI), which is accompanied by highamplitude fluctuations in the coolant level and pressure in the core of the SMR. A new method for determining the criteria and conditions for the occurrence of THI in the conditions of accidents with inter-circuit leaks in the SMR-160 small modular reactor has been developed, which is based on modeling the influence of fluctuation deviations of the determining hydrodynamic parameters on the conditions of the inter-circuit THI. Based on the results obtained, it was established that in general cases, under the condition of inter-circuit THI, additional actions of operational personnel are required to manage accidents in SMR-160. Taking into account possible unintentional erroneous actions of personnel, the safety level of SMR-160 modular reactors may be significantly lower than the design estimates. Thus, the need to qualify and implement modernized effective accident management strategies in the conditions of inter-circuit THI of passive safety systems of SMR-160 small modular reactors has been proven.
Keywords: safety, small modular reactors, accident management.
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