New steam generation system for lead-cooled fast reactors, based on steam re-circulation through ejector Lorenzo Damiani ⇑ , Roberto Revetria DIME – Department of Mechanical Engineering, University of Genoa, via Montallegro 1, 16145 Genoa, Italy highlights  Innovative steam generation system for lead-cooled fast reactors secondary loop.  Water evaporation outside of vessel heated by recirculation steam in a surface exchanger.  Steam recirculation occurs through steam jet ejector feeding bayonet heat exchangers.  Improvement of safety, availability and efficiency with respect to Loeffler system (EBBSG). article info Article history: Received 7 May 2014 Received in revised form 15 September 2014 Accepted 4 October 2014 Keywords: Lead-cooled fast reactor Bayonet heat exchanger Steam generation system Steam jet ejector abstract The EBBSG (External Boiling Bayonet Steam Generator) system, proposed in previous publications, offers an alternative to the classical once-through high pressure steam generators. This system exploits the combination between the Loeffler external boiling scheme and the bayonet-tube steam generator and is expected to provide advantages in terms of safety while keeping good values of cycle performance and vessel size. The main disadvantages result in the increased size of the heat exchangers with respect to once-through steam boilers and in the need of steam blowers, as envisaged under the Loeffler scheme. In the present paper, a new and more efficient system is proposed, in which the steam circulation is assured by steam-jet ejectors instead of blowers. The innovative solution, named SJ-EBBSG (Steam-Jet External Boiling Bayonet Steam Generator), is expected to provide several advantages with respect to the original scheme. In particular, the advantages envisage an increased global efficiency (+0.49% with respect to EBBSG) due to the lower power consumption of the auxiliaries and smaller size of the bayonet heat exchangers (6.1% diameter, 7.3% length), other than increased safety and plant availability. Throughout the article, the two steam generation solutions are compared and the advantages demon- strated by calculations. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Within the Generation IV nuclear reactors projects [1–5], the interest in lead-cooled fast reactors design is increasing also in Italy [6–8]; presently, important Italian societies as Ansaldo Nucleare and ENEA are engaged in the development of the conceptual design of ALFRED (Advanced Lead-cooled Fast Reactor Demonstrator) demonstration facility. The most recent research in the field of lead fast reactors sec- ondary loops is presently focused on dynamic modeling for control and stability purpose [9–11], investigation on heat exchangers for decay heat removal purpose [12] and experimental investigations of natural circulation [13]. At present, new designs for the lead- cooled fast reactors secondary cycles are quite few in literature. An original design proposal for the ALFRED steam generators envisages the use of once-through bayonet-tube components [8,14,15] in which feed-water is transformed into superheated steam at 180 bar. The choice of bayonet-tube steam generators is motivated by the possibility of introducing an efficient pipe rup- ture detection system consisting in the outer pipe of the bayonets equipped with two steel layers separated by a gap where pressur- ized helium (contained in a dedicated plenum) can permeate; the gap is filled with microspheres of conductive material, such as alu- minum or industrial diamonds, in order to compensate for the gas low conductivity [16,17]. In case of failure, only one of the two metal layers composing the external pipe is expected to break, exposing the helium layer to the contact with either lead (in case of external layer rupture) or steam (in case of internal layer http://dx.doi.org/10.1016/j.apenergy.2014.10.014 0306-2619/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +39 0103532549; fax. +39 0103532566. E-mail addresses: Lorenzo.Damiani@unige.it (L. Damiani), Roberto.Revetria@u- nige.it (R. Revetria). Applied Energy 137 (2015) 292–300 Contents lists available at ScienceDirect Applied Energy journal homepage: www.elsevier.com/locate/apenergy