Ricerc@Sapienza

Being the Vacuum Vessel Pressure Suppression System (VVPSS) one of the most important passive safety systems to be foreseen in DEMO plant, design and integration challenges have to be faced to ensure that best performance within safety requirements are always achieved. In this framework, parametric safety analyses have been performed to support VVPSS design activities; in particular to determine the minimum flow area required by the suppression system pipework to limit the vacuum vessel pressure below the limit imposed as a requirement by design.

EU-DEMO is a European project, having the ambitious goal to be the first demonstrative
power plant based on nuclear fusion. The electrical power that is expected to be produced is in the
order of 700–800 MW, to be delivered via a connection to the European High Voltage electrical grid.
The initiation and control of fusion processes, besides the problems related to the nuclear physics,
need very complex electrical systems. Moreover, also the conversion of the output power is not

The Power Conversion System (PCS) is designed to remove heat from PHTSs and to ensure an efficient thermal power conversion to electricity. The Dual Coolant Lithium Lead (DCLL) breeding blanket concept is based on two coolant fluids flowing into two independent circuits: a helium circuit, cooling first wall, and a PbLi circuit, removing heat generated in the breeding zone (BZ).

In the frame of the EUROfusion roadmap for the development of the DEMO power plant, a research activity was carried out to develop a Lithium–Lead/water heat exchanger. The component should be capable to remove nuclear heat deposited in the liquid metal of the Dual Coolant Lithium Lead breeding blanket and feeding a steam turbine, ensuring an efficient thermal power conversion to electricity. One of the selected configurations is the steam generator bayonet tube.

Transient analyses in a water-cooled fusion DEMO (Demonstration Power Plant) reactor have been performed to support the WCLL (Water-Cooled Lithium Lead) breeding blanket design. In this framework, the Design Basis Accident (DBA) analysis of an in-box LOCA has been carried out. The WCLL breeding blanket concept relies on Lithium Lead (LiPb) as breeder, neutron multiplier and tritium carrier, which is cooled by water at 15.5 MPa with an inlet temperature of 295 °C and an outlet temperature of 328 °C.

In this early development phase of the DEMO design the uncertainty affecting many operational and design parameters can modify main outcomes of accident scenario aiming at studying the critical conditions for the vacuum vessel and the contiguous containment volumes. The aim of this paper is to perform a preliminary sensitivity analysis of an accident progression predicted by MELCOR code considering selected parameters as a figure of merit to predict possible code outcomes.

In-vessel Loss Of Coolant Accident (LOCA) is one of the Design Basis Accident to be considered to support the future DEMOnstration power plant safety assessment. The water-cooled lithium-lead (WCLL) Breeding Blanket (BB) concept relies on Lithium-Lead as breeder, neutron multiplier and tritium carrier. The breeding modules are cooled by two independent pressurized water systems: the fist-wall (FW) and the breeding zone (BZ) coolant systems. The postulated initiating event (PIE) considered for this safety analysis is a double-ended pipe rupture of the blanket module first wall channels.

The water-cooled lithium lead breeding blanket is one of the candidate systems considered for the implementation in the European Demonstration Power Plant (DEMO) nuclear fusion reactor. This concept employs lithium-lead liquid metal as tritium breeder and neutron multiplier, water pressurized at 15.5 MPa as coolant, and EUROFER as structural material. Current design is based on the Single Module Segment approach and follows the requirements of the DEMO-2015 baseline design.

The water-cooled lithium–lead breeding blanket is a candidate option for the European Demonstration Power Plant (DEMO) nuclear fusion reactor. This breeding blanket concept relies on the liquid lithium–lead as breeder–multiplier, pressurized water as coolant, and EUROFER as structural material. The current design is based on DEMO 2015 specifications and represents the follow-up of the design developed in 2015. The single-module-segment approach is employed. This is constituted by a basic geometry repeated along the poloidal direction.

The water-cooled lithium-lead breeding blanket is in the pre-conceptual design phase. It is a candidate option for European DEMO nuclear fusion reactor. This breeding blanket concept relies on the liquid lithium-lead as breeder-multiplier, pressurized water as coolant and EUROFER as structural material. Current design is based on DEMO 2017 specifications. Two separate water systems are in charge of cooling the first wall and the breeding zone: thermo-dynamic cycle is 295–328 °C at 15.5 MPa. The breeder enters and exits from the breeding zone at 330 °C.