Fusion Engineering and Design 83 (2008) 1375–1379 Contents lists available at ScienceDirect Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes Experimental study of detritiation system catalyst poisoning Fabio Borgognoni a,∗ , Claudio Rizzello b,1 , Silvano Tosti a a ENEA, Dipartimento Fusione Tecnologie e Presidio Nucleare, C.R. ENEA Frascati, Via E. Fermi 45, Frascati, Roma I-00044, Italy b Tesi Sas, Via Bolzano 28, Roma, Italy article info Article history: Available online 11 September 2008 Keywords: VDS catalyst Catalyst poisoning Combustion tests abstract The catalyst of the ITER Vent Detritiation System (VDS) has to oxidise the tritiated gases: the resulting tritiated water is trapped in order to provide the tritium confinement function of the VDS. An experimental study has been carried out in order to determine the VDS catalyst ability to operate when exposed to the products of combustion released during a fire. In our tests the VDS catalytic recombiner has been tested in the presence of fumes generated by the combustion of selected materials (polyvinyl chloride, methyl methacrylate, vacuum pump oil and polyte- trafluoroethylene). These materials have been burnt in an oven at 200 ◦ C: the arising combustion fumes have been sent into a catalytic bed where a Pt 0.5% on alumina catalyst operated the conversion of the tritiated gases into tritiated water at 400 ◦ C with a spatial velocity of 6000 h -1 . The catalyst efficiency has been assessed by adding tritium as a tracer to the combustion fumes entering the catalytic recombiner and measuring the activity of the tritiated water collected after this reactor. The studied catalyst has been mainly affected by the fumes coming from the combustion of polyvinyl chloride: the measured catalyst efficiency has been 86.7%. Especially, in this case the presence of chlorides would have impaired the detritiation process by poisoning the catalyst. The combustion tests with methyl methacrylate and vacuum pump oil with polytetrafluoroethylene have shown slither reduced catalyst efficiencies of 91.1 and 93.5, respectively. © 2008 Elsevier B.V. All rights reserved. 1. Introduction In ITER, tritium is proposed to be handled under a multiple confinement system in a fusion reactor: each level of confinement will have its own detritiation system. The concept of the multiple confinement has been already adopted in several tritium facilities [1,2]. The Atmosphere Detritiation Systems play an important role in reducing the environmental releases as they remove and trap the tritium that may be escaped from process equipments in an operating area of the tritium plant. A fire accident could dam- age containment enclosure of the fuel cycle system and process components. Chlorinated and fluorinated plastics (polyvinyl chlo- ride, Teflon, etc.) under heating, burn or decompose and generate smokes, as well as some products of combustions, like hydrochloric and hydrofluoric acid, then can poison the catalyst and impair the detritiation system. ∗ Corresponding author. Tel.: +39 0694005560. E-mail address: fabio.borgognoni@frascati.enea.it (F. Borgognoni). 1 Tel.: +39 0697273277; fax: +39 0697273277. The process principles of the ITER Atmosphere Detritiation Sys- tems are based on catalytic oxidation of elemental tritium and tritiated hydrocarbon by using catalytic recombination (oxidation) followed by adsorption of the tritiated water vapor on molecular sieve beds. A concern on Atmosphere Detritiation Systems is related to the high temperatures and to the presence of combustion products in the fumes generated from a fire. Chlorinated or fluorinated plastics (polyvinyl chloride, Teflon, etc.) are not allowed in tritium building components; however, it is hard to exclude completely their pres- ence (non-metal joints and gaskets, plastic valve seats, glove boxes with transparent windows, electric equipment, etc.). Such plastics, under heating, burn or decompose by generating smokes, but also hydrochloric and hydrofluoric acid, that can poison the recombiner catalyst and impair the detritiation process. The tritium laboratory buildings of ITER will be important as a final confinement barrier of tritium to environment. It is especially important to confirm the tritium removal performance of the atmosphere detritiation system for the final confinement area. In the first approach, the detritiation system of ITER has been designed on the basis of results obtained under normal operation conditions (Tritium Process Laboratory, TPL, of JAERI [3,4] and Tri- tium System Test Assembly, TSTA, in the Los Alamos Laboratory 0920-3796/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.fusengdes.2008.07.021