29th Symposium on Fusion Technology (SOFT 2016)

P2.199 Parametric explorative study of DEMO galleries pressurization in case of ex-vessel LOCA

6 Sep 2016, 14:20

1h 40m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 199

Poster J. Power Plants Safety and Environment, Socio-Economics and Technology Transfer P2 Poster session

Speaker

Danilo Dongiovanni (FSN)

Description

Radioactive toxins confinement is a main safety function for nuclear power plants, hence the importance of confinement design parameters optimization. In this context, performing parametric assessments of thermodynamic variables thought to be relevant for confinement design can help at better framing the option design space. In the context of DEMO EUROfusion WP, FFMEA studies are going on for the selection of the most significant accident sequences to be analysed in a deterministic way. The FFMEA results are not available currently. In the meantime some sensitive analyses have been done focusing the attention on few expected relevant accidents as selected loss of coolant.   Moving from this perspective, present work focuses on two LOCA accidents relevant to Vacuum Vessel Primary Heat Transfer System water cooling loop and to Toroidal Field helium cooled coils. In particular the consequences of cooling inventory loss into gallery rooms surrounding the tokamak are explored. The importance of such accident investigation resides in the fact that these two LOCA accidents may impact galleries design parameters as they constitute a second confinement boundary for radioactive toxins. Building confinement is commonly required to be less performing with respect higher level barriers, so that this explorative analysis may support the definition of such performance requirements and also might suggest corrective actions to mitigate the accident. Based on publicly available ITER data, a first approximation scaling to DEMO is obtained and a set of sensitivity simulation analyses are performed on main variables (coolant inventories, enthalpy, rooms volume, etc.) in order to derive resulting galleries pressure and temperature conditions. A first feedback to the design of the systems considered is reported too. The deterministic analyses are simulated by mean of CONSEN5, a fast running thermohydraulics code, which relying on simplified input models, is suitable for such explorative analyses.