Speaker
Xue Zhou Jin
(Institute of Neutron Physics and Reactor Technology (INR))
Description
HCPB (helium cooled pebble bed) blanket concept is one of the EU DEMO blanket concepts running for the final design selection. It is necessary to study the pressure behaviour in the blanket and the connected systems during the loss of coolant (LOCA) in a blanket module, as well as the temperature evolution in the coolant flow and the associated structures. The LOCA can be caused by rupture/leak of sealing weld or cooling channels inside the blanket box. Concerning cooling channel locations in the HCPB blanket design (version 2014), which are identified as the first wall (FW), the horizontal and vertical plates (HP, VP) of the stiffening grids (SG), and the cooling plate (CP) of the breeder unit (BU), three representative accidental sequences for the design basis accident (DBA) have been assessed: case I for a failure of one HP in the SG, case II for a failure of 10 channels in the FW, and case III for a failure of one CP in the BU. Case I and III are called in-box LOCA, while case II is in-vessel LOCA. In case I and II helium ingress into the vacuum vessel (VV) will enter into the expansion volume (EV) by exceeding the VV pressure limit. In case III helium ingresses into the purge gas system, this connects the EV for pressure relief. MELCOR 1.8.6 for fusion is used for the analysis of LOCAs. Two separate loops are modelled for the redundancy of the primary heat transport system (PHTS). The accident is initialised during the normal operation at the steady state. Pump is shut down in 3 s after the LOCA, while a fast plasma shutdown (FPSS) is activated in 4 s. The transient results are presented in this paper and the impact of the FW break size is discussed as well.
Co-author
Xue Zhou Jin
(Institute of Neutron Physics and Reactor Technology (INR), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany)
