This work presents the results of the implementation in the GEneral Tokamak THErmalhydraulic Model of available models for the generation and transport of any dispersed material in the PbLi eutectic mixture circulating in the Water-Cooled Lithium-Lead Breeding Blanket of the EU DEMO fusion reactor, with main focus on Activated Corrosion Products as solid suspension. A simple test case is used to show that the distribution of the concentration of activated corrosion products at any point of the PbLi loop, both in the water-cooled lithium-lead breeding blanket and in the related ITER Test Blanket System, can be determined by the model. The results obtained with this tool can be useful not only for radiological safety purposes, but also because activated corrosion products may affect the PbLi flow itself and the efficiency of the tritium removal system, with consequences on the achievable Tritium Breeding Ratio. A rigorous verification of the model is also performed.
INDEX TERMS Activated corrosion products, blanket, ITER, modelling, nuclear fusion
I. INTRODUCTIONThe design of the EU DEMO, performed by the EUROfusion Consortium [1], takes advantage of different computational tools, often aimed at modelling single physics and/or single systems. However, system-level tools used for plant integration studies require different pieces of physics and/or different subsystems to be modelled at the same time; this is one of the aims of the system-level GEneral Tokamak THErmal-hydraulic Model (GETTHEM), developed at Politecnico di Torino since 2015 [2], for the thermal-hydraulic modelling of the Breeding Blanket (BB) and related subsystems, e.g. the Primary Heat Transfer System (PHTS) and the Balance-of-Plant. The code was applied in the past for the thermal-hydraulic transient analysis of the Helium-Cooled Pebble Bed and Water-Cooled Lithium-Lead (WCLL) [3] BB designs in normal and off-normal scenarios [4,5]. In recent years, a model of the WCLL PbLi loop was introduced in GETTHEM, including MHD pressure drops [6], but a comprehensive model of the PbLi loop must include also additional models relevant to plant operation and safetye.g. for tritium production, transport, and extraction, as well as for the transport of other radioactive elements such as the Activated Corrosion Products (ACPs)since the different phenomena involved are interdependent with each other, hence a self-consistent model should be able to address them at the same time. The need for a self-consistent assessment of this phenomenon with a multiphysics approach is also highlighted by the recent efforts to couple the OSCAR tool for the assessment of the ACPs with other codes such as MCNP [7] or RAVEN [8], which are being pursued for the water cooling loops of the PHTS of tokamaks, but is still missing for liquid metal systems [9].
