Parameter analysis of the cold-leg LBLOCA initiating event of the SCW-SMR reactor concept

BME is actively involved in the development and comprehensive assessment of the pre-conceptual design of a water-cooled small modular reactor operating at supercritical pressure (SCW-SMR). This innovative design incorporates seven heat-up stages and has been proposed in frame of the EU ECC-SMART project. The development and utilisation of an Apros system code model of the concept has enabled the execution of a series of analyses and the evaluation of its steady-state and transient behaviour and characteristics. This paper presents a detailed assessment of one of the most crucial initiating events, the 200% guillotine break of one of the cold-leg pipelines inside the containment. The primary objectives of these investigations were to examine the cooling and flooding conditions of the proposed complex reactor vessel flow path under such conditions, and to determine the minimum set of safety systems required. The key findings derived from the 27 cases investigated are summarised. • The Apros system code model of the SCW-SMR concept has been further improved. • A parameter analysis and optimisation of the safety systems have been performed. • The cold-leg LBLOCA event could be handled by passive safety systems. • High pressure injection is not required, but the hot-leg steam blowdown is crucial. • Effective in-vessel heat removal is also provided in lack of low-pressure injection.