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Library material, and thus parchment, is frequently subjected to bio-deterioration processes caused by microorganisms. Fungi and bacteria cause alterations in the parchment inducing, in some cases, even the partial detachments of the surface layer and the loss of any text present on it. An important contribution to disinfection of the cultural heritage artefacts is given by the use of ionizing radiation. In this work, a preliminary study on the applicability of X-ray radiation as treatment for bio-deterioration removal is proposed. The results on the microbial growth after different irradiation treatments are shown in order to detect the dose protocol for the bio-degradation removal. Furthermore, the evaluation of the irradiation effects on the parchment microstructure is presented in order to define the applicability of the method on parchment artefacts.

The REX system is based on a linear electron accelerator and a removable head containing an electron to X-ray converter with its collimator. The machine and the irradiation chamber were manufactured and commissioned at ENEA Frascati Research Center. The activity of the Laboratory for Development of Particle Accelerators and Medical Applications is dedicated to the development of particle accelerators (electrons and protons) for medical, industrial and research applications, realized as sections of complex equipment or as stand-alone machine and offers related services to the scientific community. The REX facility is a versatile irradiation machine thought to be used for experimental campaigns in different research fields thanks to its customizable beam. Some of the cases we performed are related to irradiation of biological systems, development of in-beam monitoring devices, test of beam monitors, material radiation damage studies and cultural heritage. Experiments are carried out for specimen treatment with the two-radiation quality: electrons and X-rays. An overview of the laboratory and of the activities performed with the REX facility in its present status are given in this work and specific attention is devoted to the application on the cultural heritage for the preservation and conservation of artefacts.

In the framework of the COBRA project, elemental analyses of cultural heritage objects based on the particle induced X-ray emission (PIXE) are planned in a collaboration between the APAM laboratory of ENEA-Frascati and the LABEC laboratory of INFN in Florence. With this aim a 3–7 MeV pulsed proton beam, driven by the injector of the protontherapy accelerator under construction for the TOP-IMPLART project, will be used to demonstrate the feasibility of the technique with a small-footprint pulsed accelerator to Italian small and medium enterprises interested in the composition analysis of ancient artifacts. The experimental set-up for PIXE analysis on the TOP-IMPLART machine consists of a modified assembly of the vertical beam line usually dedicated to radiobiology experiments: the beam produced by the injector (RFQ + DTL, a PL7 ACCSYSHITACHI model) is bent to 90° by a magnet, is collimated by a 300 μm aperture inserted in the end nozzle and extracted into ambient pressure by an exit window consisting of a Upilex foil 7.5 μm thick. The beam is pulsed with a variable pulse duration of 20–100 μs and a repetition rate variable from 10 to 100 Hz. The X-ray detection system is based on a Ketek Silicon Drift Detector (SDD) with 7 mm2 active area and 450 μm thickness, with a thin Beryllium entrance window (8 μm). The results of the calibration of this new PIXE set-up using thick target standards and of the analysis of the preliminary measurements on pigments are presented.

The application of science and technology to the knowledge and protection of cultural heritage can help the experts in conservation of historical assets to develop new strategies.A multidisciplinary approach makes to tackle the issues of evaluation, restoration, use and enhancement in a more mature way. Physics and biology sciences applied to the care and diagnosis of cultural heritage is an innovative research field capable of giving unreleased answers to problems still open.As part of the activities undertaken in collaboration between the nuclear fusion technologies and safety department of the ENEA Frascati research center and the Mathematics, Physics and Natural Sciences Faculty of the University of Rome Tor Vergata, an innovative approach has been developed to the study and handling of library goods in general and parchment supports in particular.The aim of our work has been to demonstrate the applicability of bio-degradation removal treatments through ionizing radiation in a non-invasive and safe way and to the characterize the material from the microbiological and opto-thermal point of view.

Metal membranes mainly made of Pd alloys can be applied in membrane reformers for ultrapure hydrogen production from hydrocarbons and alcohols. Knowledge of the hydrogen mass transfer mechanisms through metals is very important to the purpose of properly designing and operating the membrane reactors. With the aim of understanding the deviations from the ideal behavior of the transport mechanisms predicted by the Sieverts' law, a permeation model which takes into account the surface effects has been applied to the permeability measurements that have been carried out on dense Pd-Ag permeator tubes from 473 to 623 K. The model has been validated by the results of permeation tests in a wide range of pressure (200-800 kPa) and membrane thickness (84-200 μm). The new model modifies the Sieverts' law by introducing the mass transfer resistances due to surface effects. The values of the surface resistance and permeability calculated by the model have been compared with the literature. Finally, the new hydrogen permeation expression has been applied in order to analyze the cost of a separation system which would consist of tubular Pd-based membranes. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

The APAM (Development of Particle Accelerators and Medical Applications) Laboratory of the ENEA Frascati Research Center is engaged in the preservation of cultural heritage as part of the COBRA (Sviluppo e diffusione di metodi, tecnologie e strumenti avanzati per la COnservazione dei Beni culturali, basati sull’applicazione di Radiazioni e di tecnologie Abilitanti) project addressed to the transfer of innovative technologies and methodologies from research to small and medium enterprises involved in the restorative measures. This work aims to demonstrate the effectiveness of ionizing radiation on the disinfection of biodegraded art objects. The conventional methods for the disinfestation of works of art, using chemicals toxic to humans and environment, might cause some damage to the treated material even on micrometric scale (i. e. either cellulose degradation). Ionizing radiations interact with the infesting biological material causing an irreversible DNA degradation. For this reason, they are certainly suitable for removal treatments of both macro organisms and bacterial colonies. A 4.8 MeV electron linear accelerator, normally dedicated to the characterization of dose detectors and radiographies, has been employed to produce Bremsstrahlung X-rays through a lead converter. The spectral fluence of the radiation source has been calculated using the Monte Carlo MCNPX code. The dosimetric characterization of the radiation field has been made using radiochromic films sensitive in the dose range of our interest (from 50 to 500 Gy) calibrated with a Markus ionization chamber. The irradiation of the artifact prototypes are made within a lead shielded room at a variable distance from the X-rays source. Samples subjected to irradiation consist of a soil bacterium, Agrobacterium rhizogenes , and an insect, Stegobium paniceum , that are found as wall paintings invasive coloniser and as a pest of books, wood works and paintings, respectively. Tests of irradiation have been performed on pest organisms as well as on woods mock-ups to evaluate potential damage to the material during the sterilization. The growing capacity of the treated bacterial cells re-cultured at the end of the treatment was evaluated on the bacterial sample and resulted to strongly inhibit cell growth during post-irradiation incubation, so that after incubation periods at 28 °C, no significant cell growth was observed. The induced levels of insect mortality and sterility vs absorbed dose and operative conditions have been also evaluated, demonstrating the induction of full sterility since the lower dose and 40% mortality by two days after the higher dose treatment. The experiments proved the ability to efficaciously treat objects of cultural heritage with X-rays in order to prevent the increase of the biodeterioration without damaging the materials: in fact, mechanical tests on both irradiated and not irradiated woods have demonstrated the absence of any induced degradation after the radiation exposition.

Irradiation is a common method used for sterilizing objects in several fields. In the entomology sector, insects are sterilized through irradiation and released in to the wild to sexually compete with the population at large reducing the chance for reproduction. This practice is the Sterile Insect Technique (SIT). Traditionally irradiation sources for SIT purpose are radioisotopes but many reasons compelled to getting efforts to develop other radiative technologies. Since gamma rays and electrons have similar sterilizing effects, the choice of source for SIT irradiation is based on considerations about penetration and environmental factors. Gamma irradiators are usually simpler to operate, and less expensive, than electron accelerators, at least within the range of power required for SIT applications. Currently, the increased difficulties to manage and ship radioisotopes is being successfully resolved by the introduction of novel X-ray irradiators that enable a safer use of irradiator machines and procedures for SIT applications. In the ENEA Frascati research center we developed irradiators for clinical radiotherapy consisting in a radiation converter from electrons to X-rays. Since X-rays penetrate deeper than the electrons from which they are generated, we used this technology in a configuration that delivers a uniform dose on large targets to irradiate insects for SIT aim. In this topic, we gained practical experience working with Aedes albopictus, a mosquito vector of various tropical diseases such as dengue and zika. Several dosimetric studies have been conducted to achieve male sterility without affecting male mating competitiveness in comparison with untreated males. Lower doses have been also tested on an Ae. albopictus strain modified with the bacterium Wolbachia, which also determines male sterility, to sterilize the females eventually escaping the sexing procedures preliminary to the releases of the males.

Nuclear waste management has to be taken into account for fusion machine in tritium experimentations. Soft housekeeping waste is produced during both operating and dismantling phases and is contaminated by tritium under reduced (HT) and oxidized (HTO) forms. At CEA Cadarache, a lab-scaled facility has been built for soft housekeeping detritiation. The tritiated gas exhausted from the process described above is foreseen to be treated by a tubular Pd–Ag membrane reactor, for gaseous tritium recovery. Since this membrane reactor uses hydrogen as swamping gas the compatibility toward explosive hazard has to be taken into account. Then, this work presents a double objective. A first study is presented in order to identify the best conditions for the declassification of soft housekeeping waste, without tritium recovery. Experiments carried out at 120 °C are not efficient enough and do not allow one to choose the most efficient carrier gas. Some other tests are being currently performed at higher temperatures (150 °C). Moreover, due to safety issues, the use of air has to be avoided during membrane reactor implementation phase. Preliminary results obtained with hydrogen hazard-free carrier gases are also presented.

An experimental campaign has been carried out in order to assess the performance of a two-step membrane process in terms of hydrogen production by methane auto-thermal reforming. A reformer operating at high temperature (700 °C) has been coupled with a module consisting of an array of 19 Pd–Ag membranes (length 250 mm, diameter 10 mm and wall thickness 0.150 mm) operating at 300–400 °C. The hydrogen produced in the reformer has been selectively separated through the membrane tubes. The capability of the whole system to produce pure hydrogen has been investigated by varying the operating parameters: reformer temperature 580–700 °C, reaction pressure 100–500 kPa, water/methane feed molar ratio from 1.5/1 to 4.5/1 and methane feed flow rate in the range 4.47 × 10 −4 –1.11 × 10 −3 mol s −1 . Auto-thermal conditions have been studied by adding air in order to provide oxygen/methane feed molar ratio of 0.1/1, 0.33/1, 0.5/1. A maximum pure hydrogen flow rate of 1.65 × 10 −3 mol s −1 has been collected in the membrane module shell with a reformer temperature of about 700 °C, membrane module temperature of 400 °C, reaction (lumen) pressure of 350 kPa, feed molar ratio methane/water/oxygen of 1/3/0.333 and methane feed flow rate of 1.11 × 10 −3 mol s −1 . Under these conditions the hydrogen yield measured has been 1.48.

The development of a Pd-based membrane reactor to be applied in processes for tritium removal from various gaseous streams of tokamak systems has been carried out. In particular, the membrane reactor has been designed for decontaminating soft housekeeping wastes of JET. This membrane reactor consists of Pd–Ag permeator tube fixed in a finger-like mode into a stainless steel shell. The feed stream (gases to be detritiated) is fed inside the membrane lumen where the isotopic exchange takes place on to a catalyst bed while pure hydrogen (protium) is sent in countercurrent mode in the shell side. The feed stream consists of 200 Ncm3 min−1 of helium with 10% of tritiated water (tritium content 1.11 × 108 Bq h−1). The membrane reactor design has been based on a simplified calculation model which takes into consideration the very low tritium content of the gas to be processed and the complete oxidation of the tritiated species in the feed stream. The model considers a tubular Pd–Ag membrane divided into finite elements where the mass balances are performed according to both the thermodynamic equilibrium reactions and permeation rates through the membrane of the hydrogen isotopes. The reactor model has permitted to verify that a Pd–Ag commercial tube of diameter 10 mm, length 500 mm and wall thickness 0.150 mm is capable to attain a decontamination factor larger than 10. A new mechanical design of the Pd membrane reactor has been also developed: especially, harmful mechanical stresses of the long permeator tube consequent to the hydrogenation and thermal cycling has been avoided. Furthermore, an innovative effective heating system of the membrane has been also applied.

An experimental test campaign has been carried out in order to investigate the performances in terms of pure hydrogen production of a multi-membrane module coupled with a methane reforming fixed bed reactor. The effect of operating parameters such as the temperature, the pressure, the water/methane feed flow rates and the feed molar ratio has been studied. The hydrogen produced into the traditional reformer has been recovered in the shell side of the membrane module by vacuum pumping. The membrane module consists of 19 Pd/Ag permeator tubes of wall thickness 150 μm, diameter 10 mm and length 250 mm: these dense permeators permitted to separate ultra-pure hydrogen. The experiments have been carried out with the reaction pressure of 100–490 kPa, the temperature of the reformer of 570–720 °C and the temperature of the Pd/Ag membranes module of 300–400 °C. A water/methane stream of molar ratio of 4/1 and 5/1 has been fed into the methane reformer at GSHV of 1547.6 and 1796.1 L(STP) kg−1 h−1. Hydrogen yield value of about 3 has been measured at reaction pressure of 350 kPa, temperature reformer of 720 °C and methane feed flow rate of 6.445 × 10−4 mol s−1.

The ethanol steam reforming reaction has been performed in a membrane reactor consisting of a Pd–Ag tube (wall thickness 150 μm) filled with a Ru-based catalyst. The experiments have permitted to characterize the Pd–Ag permeator in terms of both hydrogen permeability and yield of the steam reforming reaction at temperature of 400 and 450 °C in the pressure range 100–800 kPa. The permeation tests exhibited hydrogen permeability values in agreement with the literature and the complete hydrogen selectivity. In the reaction tests, water/ethanol mixtures of molar ratio 10/1 and flow rates of 5, 10 and 15 g h −1 have been fed in the lumen side of the membrane tube while the permeated hydrogen has been collected in the shell side by a nitrogen sweep stream. At 450 °C with a reaction pressure of about 400 kPa and a water/ethanol feed flow rate of 5 g h −1 , maximum values of hydrogen yield (5.5) and hydrogen recovery factor (close to 100) have been measured. The hydrogen yield reduces at lower temperatures and pressures as well as when larger water/ethanol flow rates are fed (10 and 15 g h −1 ). Finally, a simulation code based on a simplified reaction kinetics has been developed: the comparison with the results of the tests permitted to determine the parameters of such a kinetics. A model analysis of the membrane reformer aimed at verifying the influence of the main operating parameters has been carried out, too.

The PERMCAT membrane reactor is a coaxial combination of a Pd/Ag permeator membrane and a catalyst bed. This device has been proposed for processing fusion reactor plasma exhaust gas. A stream containing tritium (up to 1% of tritium in different chemical forms such as water, methane or molecular hydrogen) is decontaminated in the PERMCAT by counter-current isotopic swamping with protium. Different mechanical designs of the membrane reactor have been proposed to improve robustness and lifetime. The ENEA membrane reactor uses a permeator tube with a length of about 500 mm produced via cold-rolling and diffusion welding of Pd/Ag thin foils: two stainless steel pre-tensioned bellows have been applied to the Pd/Ag tube in order to avoid any significant compressive and bending stresses due to the permeator tube elongation consequent to the hydrogen uptake. An experimental test campaign has been performed using this reactor in order to assess the influence of different operating parameters and to evaluate the overall performance (decontamination factor). Tests have been carried out on two reactor prototypes: a defect-free membrane with complete (infinite) hydrogen selectivity and not perm-selective membrane. In this last case, the study has been aimed at verifying the behaviour of the PERMCAT devices under non-normal (accidental) conditions in the view of providing information for future safety analysis. The paper will present the specific mechanical design and the experimental results of tests based on isotopic exchange between H2O and D2.

The ITER Neutral Beam Test Facility (NBTF) will be located in the area of the RFX Consortium, (Council of National Researches – CNR), in Padua, Italy. The ITER NB accelerates negative deuterium ions with maximum energy of 1 MeV and maximum beam current of 40 A. The production of tritium from this facility, mainly due to the D–D nuclear reaction on the injector calorimeter, might be a concern from the radiological safety point of view. In the present paper, tritium release in atmosphere is evaluated. Analysis was performed using three different computer codes. Different release scenarios were taken into account, and doses to reference groups (population and workers) were calculated. Our results show that the dose limit of 1 mSv/year stated by Italian law for the population is not exceeded around the facility and away from it. Even considering the most conservative scenario, the dose rate per year to the reference group is about three order of magnitude lower than the dose limit.

In this work, it is described an experimental study regarding the performance of a Pd–Ag membrane reactor recently proposed and suitable for the production of ultra-pure hydrogen. A dense metallic permeator tube was assembled by an innovative annealing and diffusion welding technique from a commercial flat sheet membrane of Pd–Ag. A “finger-like” configuration of the self-supported membrane has been designed and used as a packed-bed membrane reactor (MR) for producing ultra-pure hydrogen via water–gas shift reaction (WGS). A CuO/ZnO/Al2O3 catalyst, from REB Research & Consulting, was used for packing the WGS membrane reactor. The performance of the reactor was evaluated in terms of CO conversion and H2 recovery in a wide range of conditions: temperature from 200 °C to 300 °C, feed pressure from 1.0 bar to 4.0 bar, vacuum and sweep-gas modes and with a simulated reformate feed (4.70% CO, 34.78% H2O, 28.70% H2, 10.16% CO2 balanced in N2). Also, the effect of the reactants feed composition was investigated and discussed. CO conversions remained in most conditions above the thermodynamic equilibrium based on feed conditions. In particular, it is worth mentioning that around 100% of CO conversion and almost complete H2 recovery was achieved when operating the MR at 300 °C with a GSHV = 1200 LN kgcat−1 h−1, Pfeed = 4 bar, Pperm = 3 bar and using 1000 mLN min−1 of sweep-gas.

The aim of this work is to investigate the performance and energy efficiency achieved by an integrated system based on two different ethanol fuel processor configurations: a Conventional Reactor (CR) and a Membrane Reactor (MR). The CR-based configuration system consists of an ethanol reformer followed by two water-gas shift reactors operating at high and low temperatures. The final hydrogen purification is carried out by a preferential oxidizer in order to reduce the CO concentration before feeding the polymer electrolyte membrane fuel cell (PEMFC). A multi-tubular MR process using thin Pd–Ag tubes has also been considered, where the water-gas shift reaction and the hydrogen separation take place simultaneously. The analysis showed that the MR process configuration possesses a simpler system design with a minor advantage in terms of energy efficiency (30%) compared with the conventional system (27%). Moreover, a detailed parametric analysis concerning the effects of water-to-ethanol molar ratio, reaction pressure, reformer and MR temperature, sweep-gas molar ratio and MR configuration on the achieved performance (hydrogen yield) and energy efficiency of the system has also been done. The importance of optimizing integrated systems is shown since the optimal operating conditions from a global efficiency analysis point of view are in general distinct when compared with those obtained when focusing on the reformer reactor or individual process units alone.

An experimental apparatus carrying out a membrane process for producing pure hydrogen via ethanol steam reforming has been tested in order to measure the hydrogen production by varying operative parameters such as temperature, pressure and membrane sweeping mode. The process consists of a traditional fixed bed reformer, which performs the ethanol steam reforming, and a multi-tube Pd–Ag membrane reactor, where both the water gas shift reaction and the separation of pure hydrogen take place. The water gas shift membrane reactor uses permeator tubes of wall thickness 50–60 μm, diameter 10 mm and length 250 mm. The experiments have been carried out with a reaction pressure in the range 100–250 kPa, while the reformer has been operated at a temperature of 690–890 °C with feed water/ethanol molar ratio of 10.5/1 and flow rates between 200 and 500 g h−1. The hydrogen has been recovered in the shell side of the membrane module by vacuum pumping or inert gas (nitrogen) sweeping at 350–400 °C. The highest hydrogen productions (about 3.5 NL min−1) have been attained by feeding 500 g h−1 of water/ethanol mixture and by recovering the hydrogen through vacuum pumping in the shell side of the membrane module at 400 °C.

The tritium confinement strategy adopted during the past years in the ITER hot cell building is compared to the safety requirements given by the standard ISO-17873 “Nuclear facilities – criteria for the design and operation of ventilation systems for nuclear installations other than nuclear reactors”. In fact, this is the reference safety guideline recommended by French licensing authorities. Several features of the considered design of the hot cell building are not in agreement with these guidelines. Main discrepancies concern the zoning of the hot cell complex, the flow rates of ventilation, and the possibility to recycle the room atmosphere and to detritiate the effluent air. These aspects are discussed together with some proposed modifications of the design.

The ethanol steam reforming reaction carried out in a Pd-based tubular membrane reactor has been modelled via a finite element code. The model considers the membrane tube divided into finite volume elements where the mass balances for both lumen and shell sides are carried out accordingly to the reaction and permeation kinetics. Especially, a simplified “power law” has been applied for the reaction kinetics: the comparison with experimental data obtained by using three different kinds of catalyst (Ru, Pt and Ni based) permitted defining the coefficients of the kinetics expression as well as to validate the model. Based on the Damkohler–Peclet analysis, the optimization of the membrane reformer has been also approached.

The Neutral Beam Test Facility (NBTF) to be realized in Padoa will test the Neutral Beam Injection (NBI), one of the Heating and Current Drive Systems foreseen for ITER. The NBI is based on the acceleration of hydrogen or deuterium negative ions up to 1 MeV. This work has been aimed at assessing the tritium release from the NBTF in order to provide data for the safety analysis. In particular, the diffusion of the tritium through the neutral beam target material (the CuCrZr alloy calorimeter panels) has been assessed by using literature data of the diffusion coefficient. The tritium generated inside the calorimeter panels moves into both the vacuum and water side: the tritium diffusion flux has been evaluated during the beam-on (200 °C) and the beam-off (20 °C) phases of the NBTF experiments consisting of an interim campaign and a final test. The penetration depth of the tritium through the 2 mm thick CuCrZr alloy material has been also evaluated by using a Monte-Carlo code. As main result, the assessed diffusion flux of tritium during both the beam-on and the beam-off phases are modest. In fact, at the end of the interim campaign (100 days), about the 96% of the all generated tritium (626.5 MBq) exits the calorimeter while the residual tritium inventory (25 MBq) leaves the copper alloy with a diffusion time of about 1 month. At the end of the final test (14 days) about the 99% of the total generated tritium (1.023 × 10 4 MBq) leaves the copper alloy and the remaining tritium inventory (152.2 MBq) is released by about 32 days. In both the interim campaign and the final test, more than the 99% of the total tritium is transferred into the vacuum side of the calorimeter panel while negligible tritium amounts enter the cooling water system thus showing a very low impact on the environment.

The water gas shift reaction has been studied in tubular Pd-based membranes: a thin walled dense tube and a composite Pd-ceramic tube have been considered. A computer code based on a finite element model has been developed for modelling the membrane reactor. The model accounts for the reaction kinetic, the hydrogen diffusion through the porous ceramic support and permeation through the PdAg membrane and for the partial pressure gradients of hydrogen generated at the permeate side of the membrane when a flow of purge gas is introduced. The code has been used to assess the influence of temperature, lumen pressure, presence of wall effects and sweep gas mode on the reaction conversion and hydrogen yield of the membrane reactors. At 200 kPa of lumen pressure and counter-current sweep mode, it was found that both reaction conversion and hydrogen yield increase with temperature: the dense and the composite membranes exhibit very close values of conversion (more than 99% at 400 °C) and hydrogen yield (96–97% at 400 °C). In co-current mode, the highest values of both reaction conversion and hydrogen yield have been assessed at 350 °C, while it was demonstrated that the beneficial effects of increasing the lumen pressure up to 400 kPa are maximum at 300 °C. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.

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 polytetrafluoroethylene). 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.

Palladium-silver thin wall tubes are produced by an innovative procedure based on the diffusion welding: these permeators are proposed for separating and producing high-pure hydrogen in both separators and membrane reactors. The reliability of these dense metallic permeators is strongly related to the design configuration of the membrane modules. In fact, as a consequence of hydrogenation and thermal cycles, the dense metallic tubes vary significantly in their length: in case of constraints between the membrane and the module, cyclic axial stresses are applied to the thin wall tube involving the rupture of the permeator. In our applications, a finger-like assembly of the permeator tube has been designed: it permits the free elongation and contraction of the palladium alloy tube avoiding any mechanical stress. In this work, different configurations of palladium membrane reactors used for separating ultra pure hydrogen are described and a study of a membrane process for producing ultra pure hydrogen from ethanol reforming is also presented. © 2008 International Association for Hydrogen Energy. 10.1016/j.ijhydene.2008.05.031

A membrane reactor has been studied for separating the hydrogen produced by the dissociation of hydroiodic acid in the thermochemical-sulfur iodine process. A dense metal membrane tube of wall thickness 0.250 mm has been considered in this analysis for hosting a fixed-bed catalyst: the selective separation of hydrogen from an azeotropic H2O–HI mixture has been studied in the temperature range of 700–800 K. The materials being considered for the construction of the membrane tube are niobium and tantalum; as a matter of fact, the most commonly used Pd–Ag membranes cannot withstand the corrosive environment generated by the hydroiodic acid. The Damkohler–Peclet analysis has been used for designing the membrane reactor, while a finite element method has simulated its behaviour: the effect of the temperature and pressure on the HI conversion and hydrogen yield has been evaluated.

The Pd–Ag membrane reformer has been packed with a Pt-based and Ni-based catalyst for carrying out the ethanol steam reforming. The experimental tests have been performed in the temperature range 400–450 °C: the effect of different operating parameters such as the sweep gas mode (co-current and counter-current), the spatial velocity and the water/ethanol feed molar ratio (8.4–13.0) on the hydrogen yields have been investigated. The results of these tests have been compared with the ones reported for the Pd–Ag membrane reformer using a Ru-based catalyst. With all the catalysts the best performances in terms of hydrogen yield have been attained at 450 °C and 200 kPa of lumen pressure with a water/ethanol feed molar ratio of 13. Especially, under these operating conditions both the Pt-based and Ni-based catalysts have exhibited hydrogen yield of about 50% against values higher than 80% reported for the Ru-based catalyst.

The ethanol steam reforming has been carried out in a membrane reactor consisting of a Ru-based catalyst bed packed into a thin wall Pd-Ag permeator tube produced via cold-rolling and diffusion welding of metal foils. The experimental tests have been performed in the temperature range 400–450 °C with the aim of studying the performances of the membrane reactor in terms of hydrogen yields. The main investigated operating parameters have concerned the water/ethanol feed molar ratio (8.4–13.0), the pressure inside the membrane (150–200 kPa), the sweep gas mode (co-current and counter-current) and the spatial velocity. In all the tests, ultra pure hydrogen has been separated through the Pd-Ag membrane: especially, operating at 450 °C and 200 kPa, a hydrogen yield higher than 80% has been produced thus demonstrating the membrane ability of promoting the reaction conversion (shift effect).

Pd-based dense membranes are used to separate hydrogen isotopes with infinite selectivity. Membrane modules have been studied for several detritiation processes in the fuel cycle of fusion reactors: plasma exhaust treatment, tritium extraction from the breeding blanket and detritiation of highly tritiated water. © 2015 IEEE.

The PERMCAT is a membrane reactor proposed for processing fusion reactor plasma exhaust gas: tritium removal is obtained by isotopic swamping operating in counter-current mode. In this work, a membrane reactor using a permeator tube of length about 500 mm produced via diffusion welding of Pd–Ag thin foils is described. An appropriate mechanical design of the membrane module has been developed in order to avoid any significant compressive and bending stresses on the very long and thin wall permeator tube: two expanded bellows have been applied to the Pd–Ag tube, so that it has been pre-tensioned before operating. The elongation of the metal permeator under hydrogenation has been theoretically estimated and experimentally verified for properly designing the membrane reactor.

Thin wall permeator tubes have been produced by diffusion welding of Pd-Ag foils. These dense metal membranes are proposed for separating and producing ultra-pure hydrogen as a result of their complete hydrogen selectivity. Furthermore, they present high hydrogen permeation fluxes as well as reduced costs on account of their reduced metal thickness. The reliability of these membrane tubes has been continuously tested during over 12 months of experimental campaign in presence of thermal and hydrogenation cycles. The permeability tests have been carried out measuring the hydrogen fluxes under controlled conditions of temperature and trans-membrane differential pressure. In particular, the behaviour of the membrane tube has been investigated in a wide range of temperatures (150-400 °C) and pressures (100-200 kPa) in order to simulate the use within permeators and membrane reactors where processes for producing hydrogen from hydrocarbons takes place. At temperature of 350-400 °C hydrogen permeability values around 1.0 × 10-8 mol m-1 s-1 Pa-0.5 have been measured and they are comparable with the literature data. A new mechanical design (finger-like configuration) of the membrane module has ensured the long life of the Pd-Ag permeator. The complete hydrogen selectivity of the membrane has been demonstrated by the tests. © 2006 Elsevier B.V. All rights reserved. 10.1016/j.memsci.2006.08.006

The Demonstration Power Plant (DEMO) will be a fusion reactor prototype designed to demonstrate the capability to produce electrical power in a commercially acceptable way. Two of the key elements of the engineering development of the DEMO reactor are the definitions of reliability and availability requirements (or targets). The availability target for a hypothesized Fuel Cycle has been analysed as a test case. The analysis has been done on the basis of the experience gained in operating existing tokamak fusion reactors and developing the ITER design. Plant Breakdown Structure (PBS) and Functional Breakdown Structure (FBS) related to the DEMO Fuel Cycle and correlations between PBS and FBS have been identified. At first, a set of availability targets has been allocated to the various systems on the basis of their operating, protection and safety functions. 75% and 85% of availability has been allocated to the operating functions of fuelling system and tritium plant respectively. 99% of availability has been allocated to the overall systems in executing their safety functions. The chances of the systems to achieve the allocated targets have then been investigated through a Failure Mode and Effect Analysis and Reliability Block Diagram analysis. The following results have been obtained:more » 1) the target of 75% for the operations of the fuelling system looks reasonable, while the target of 85% for the operations of the whole tritium plant should be reduced to 80%, even though all the tritium plant systems can individually reach quite high availability targets, over 90% - 95%; 2) all the DEMO Fuel Cycle systems can reach the target of 99% in accomplishing their safety functions. (authors)« less

Nuclear waste management has to be taken into account for fusion machine using tritium as fuel. Soft housekeeping waste (e.g. gloves, tissues, protective clothes, etc.) is produced during the whole life as well as during the dismantling of the reactor and is contaminated by tritium under reduced (HT) and oxidized (HTO) forms. In collaboration with ENEA, a lab-scaled facility has been built at CEA Cadarache for soft housekeeping waste detritiation and tritium valorization. The previously milled waste is placed in a reactor to be heated up to a temperature lower than the housekeeping melting point. A carrier gas is then injected in the detritiation reactor to remove tritium, thanks to the combined effects of temperature and carrier gas (type and feed flow). The tritiated gas exhausted from the detritiation reactor is then sent through a catalytic Pd-Ag membrane reactor (CMR) where tritium is recovered via isotopic exchange reaction and permeation phenomenon. Based on previous studies that have allowed defining the most efficient operating conditions for the detritiation process, this work presents the results obtained by the coupling of the detritiation facility with the CMR. Due to safety considerations, restrictions on the nature of the carrier gas were applied, rejecting air as the carrier gas even though air was the best candidate for the detritiation part of the process. The performance of the whole system was estimated by means of a parametric study on the influence of flow rates in the CMR and transmembrane pressure. © 2014 Elsevier B.V.

The relevant role of hydrogen in the new and clean energy systems motivates the interest in membrane technologies able to separate and purify such element. Dense Pd-based membranes are particularly attractive for the high values of hydrogen selectivity and good permeance provided. An established approach to model the mass transfer of hydrogen through dense metal membranes describes permeation flux as proportional to the difference of the square root of the hydrogen partial pressure in the feed and permeated side divided by the inverse of the membrane thickness. However, deviations from this law are reported in literature especially when large range of pressure and membrane thickness are considered.This work presents the results of an experimental activity carried out on three dense, defect-free, self-supported Pd-Ag membranes having a thickness of 84, 150 and 200μm, respectively. During testing, the measurements of the hydrogen flux permeated through the membranes were collected in the pressure and temperature ranges of 200-800. kPa and 473-623. K, respectively. The observed permeability pre-exponential factors and activation energies exhibited a dependence on the pressure and the membrane thickness, in agreement with the square root formula mentioned above.This dependence has been discussed by investigating the impact of two effects on the considered process: the relationship between the hydrogen diffusivity from the H/Pd ratio and the surface reactions. The analysis reported in this work shows that Sieverts' law does not account for these two effects. In fact, when applying Sieverts law at the experimental data, a specific pattern is observed in the activation energy (Ea) of the hydrogen permeability. This fact is in contrast with the definition of permeability which is an intrinsic property of the material. © 2013 Elsevier B.V.

Combined methane and ethanol steam reforming has been carried out in a conventional reformer filled with a Pt (0.5% wt.) catalyst bed. The reformer has been coupled with a multi-membrane module, where pure hydrogen has been recovered in the shell side by vacuum pumping. The experiments-that mainly aimed at measuring the hydrogen yield-have been carried out in the reaction (lumen) pressure range of 100-500 kPa, while the temperature of the reformer and the Pd/Ag membranes module has been of 760°C and 350°C, respectively. The water/ethanol/methane molar ratio has varied in the different experiments (10/1/0, 11/1/0.25, 14/1/1 and 26/1/4). Such water/ethanol mixtures have been investigated in order to simulate the treatment of dilute bioethanol with methane. The hydrogen yield decreases when the molar ratio methane/ethanol increases while-in presence of a high water excess (feed molar ratio water/ethanol/methane of 26/1/4)- A hydrogen yield up to 35% at 500 kPa can be achieved. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

The results of steam and oxidative reforming of methane carried out through a membrane system are being compared in this work. The capability of the experimental setup to produce ultra-pure hydrogen has been evaluated in terms of hydrogen yield under different operating conditions. The reforming reactions took place over a Pt on Al2O3 catalyst in a traditional high temperature reformer, while the hydrogen produced has been removed by selective permeation in a membrane module containing an array of 19 defect-free Pd-Ag tubes (length 250 mm, diameter 10 mm and wall thickness 0.150 mm). The reformer has been tested in the temperature range of about 570-720 C while the membrane module temperature has been maintained at 350 C and the reaction (lumen) pressure has been ranged between 100 and 500 kPa. Methane feed flow rates from about 0.4 × 10-3 to 1.1 × 10-3 mol s-1 have been fed into the reformer with methane/water molar ratios of 1/4 and methane/water/oxygen of 1/3/0.33 for the steam and the auto-thermal reforming, respectively. A maximum hydrogen yield value of 2.8 corresponding to a hydrogen flow rate of 1.20 × 10-3 mol s-1 has been measured during the methane steam reforming at pressure of 350 kPa, GHSV of 864 L(STP) kg-1 h-1 and reformer temperature of 700 C. © Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.