Please cite this article in press as: L. Candido, et al., Tritium transport in HCLL and WCLL DEMO blankets, Fusion Eng. Des. (2016), http://dx.doi.org/10.1016/j.fusengdes.2016.03.017 ARTICLE IN PRESS G Model FUSION-8638; No. of Pages 7 Fusion Engineering and Design xxx (2016) xxx–xxx Contents lists available at ScienceDirect Fusion Engineering and Design jo ur nal home p age: www.elsevier.com/locate/fusengdes Tritium transport in HCLL and WCLL DEMO blankets Luigi Candido a , Marco Utili b , Iuri Nicolotti a , Massimo Zucchetti a,∗ a DENERG, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy b ENEA UTIS- C.R. Brasimone, Bacino del Brasimone, Camugnano, BO, Italy h i g h l i g h t s • Tritium inventories and tritium losses are the main output of the presented model for HCLL and WCLL. • A parametric study has been performed, to show the behavior of the two systems when certain parameters are changed, in order to minimize inventories and/or losses. • An improved design is needed, in order to reduce the radiological hazard related to tritium activity. According to test number 7, HCLL-BB could be able to have a tritium inventory of 33.05 g and losses of 19.55 Ci/d. • WCLL-BB shows a very low radiological risk, much lower than that suggested (inventory: 17.48 g, losses: 3.2 Ci/d). An ptimization study has been performed aiming to minimize the water flow rate for an upgraded design. • Both for HCLL and WCLL, the most critical parameters able to produce relevant variations in inventories and losses are the helium/water fraction, the CPS/WDS and the permeation reduction factors. a r t i c l e i n f o Article history: Received 10 September 2015 Received in revised form 1 March 2016 Accepted 1 March 2016 Available online xxx Keywords: Breeding blanket Tritium inventories DEMO HCLL WCLL Safety a b s t r a c t The Helium-Cooled Lithium Lead (HCLL) and Water-Cooled Lithium Lead (WCLL) Breeding Blankets are two of the four blanket designs proposed for DEMO reactor. The study of tritium transport inside the blankets is fundamental to assess their preliminary design and safety features. A mathematical model has been derived, in a new form making makes easier to determine the most critical components as far as tritium losses and tritium inventories are concerned, and to model the tritium performance of the whole system. Two cases have been studied, the former with tritium generation rate constant in time and the latter considering a typical pulsed operation for a time span of 100 h. Tritium inventories and tritium losses are the main output of the model. Tritium concentrations, inventories and losses are initially calculated and compared for the two blankets, in a reference case without permeation barriers or cold traps. A parametric study to show the behavior of the two systems when certain parameters are changed, in order to minimize inventories and/or losses, has been carried out. © 2016 Elsevier B.V. All rights reserved. 1. Introduction The Helium-Cooled Lithium Lead (HCLL) and Water-Cooled Lithium Lead (WCLL) Breeding Blankets are two of the four blanket designs proposed for DEMO reactor [1–6]. The activities referred to as TBM (Test Blanket Model) Program in ITER [6,7] foresee that six mock-ups of six whole DEMO-BB sys- tems will be tested in ITER; this means that the TBMs are connected with several ancillary systems, such as cooling systems, tritium extraction systems, coolant purification systems, and instrumenta- ∗ Corresponding author. E-mail address: massimo.zucchetti@polito.it (M. Zucchetti). tion and control systems. TBMs and associated systems are called Test Blanket Systems (TBSs). The HCLL Breeding Blanket configuration [3,4,6] is a specific DEMO version called HCLL-DEMO-2007, whose preliminary project was carried out in 2007 by CEA [8]. In 2012, the EFDA agency issued new specifications for DEMO: we will refer to this blan- ket configuration simply by HCLL-BB. The Water-Cooled Lithium Lead Breeding Blanket (WCLL-BB) [1,5,6], according to PPCS model A from which it derives, it is based on near-future technology requiring small extrapolation from present-day knowledge both on physical and technological aspect [5–8]. The study of tritium transport inside the blankets is fundamen- tal to assess their preliminary design and safety features. For this purpose, a mathematical model has been derived, in a new form. making easier to determine the most critical components as far as http://dx.doi.org/10.1016/j.fusengdes.2016.03.017 0920-3796/© 2016 Elsevier B.V. All rights reserved.