Lead Bismuth Eutectic Target Research Articles

Distribution of different no-carrier-added radionuclides in Pb and Bi fractions after separation of bulk components of lead bismuth eutectic

Large numbers of radionuclides are produced when 1.4 GeV proton beam hits lead bismuth eutectic (LBE) target. Separation of desired radionuclide from large amount of bulk components and other co-produced radionuclides is a challenging task. In this experiment, such a case has been simulated by irradiating a LBE target with low energy proton beam and spiked with nine radionuclides (56Co, 67 Ga, 90Nb, 149Gd, 157Dy, 172Lu, 182Re, 195mHg, 198Tl). The bulk Pb and bulk Bi were separated from irradiated LBE target matrix by different methods and the distribution pattern of these radionuclides were studied in the separated Pb and Bi fraction.

Separation of 206Po from alpha particle irradiated lead bismuth eutectic target

Lead bismuth eutectic (LBE) target was bombarded with 46 MeV α-particle. Possibility of separation of no-carrier-added (NCA) polonium radioisotopes from the bulk lead-bismuth eutectic target was explored. Differential precipitation showed presence of Po with bulk Bi, leaving behind bulk Pb in aqueous medium. NCA 206Po radioisotope was then separated from bulk Bi using trioctylamine (TOA) as the extractant. At best condition of 0.01 M TOA+0.1 M HCl, highest separation factor (>500) was achieved between NCA Po and bulk Bi.

Quantification of radioisotopes produced in 1.4 GeV proton irradiated lead–bismuth eutectic targets

Six cylindrical lead bismuth eutectic (LBE) targets having fixed diameter of 6 mm and varying lengths of 8–50 mm were irradiated with a 1.4 GeV proton beam at CERN-ISOLDE. Both short-lived ( $$5\hbox { h } {<}\hbox {T}_{1/2} {<}5\hbox { days}$$ ) and long-lived ( $$\hbox {T}_{1/2} {>}5\hbox { days}$$ ) radionuclides were identified by off-line $$\upgamma $$ -spectrometry and their activities at the end of bombardment (EOB) were determined. Total 80 $$\upgamma $$ -emitting radionuclides, ranging from $$^{7}\hbox {Be}$$ to $$^{209}\hbox {At}$$ , were identified in the 50 mm long LBE target. The yields of all the radioisotopes were compared with the Monte Carlo Code FLUKA. The spallation reaction was the dominant mode whereas fission induced reactions had no significant contribution. The high energy proton irradiated LBE target may act as a large source of several clinically important and other exotic radionuclides.

Spallation Target Design for Converting the Isfahan MNSR Reactor to an Accelerator Driven Subcritical System

There are many research reactors around the world that have been installed from many years ago and must be decommissioned sooner or later. Most of these reactors were fuelled with high enriched uranium and substantial amount of initial loaded fuel has not been exploited yet. The reactor conversion to an accelerator driven system (ADS) is one of the novel ideas for minor actinide utilization and reducing the spent fuel radio toxicity. The main objective of this study is dedicated to spallation target design in miniature neutron source reactor (MNSR) core conversion to an ADS one. The MNSR is a pool type research reactor, which was developed by China. After more than 25 years, the fuel burn-up could not be compensated more by adding shimming plates. The subcriticality in MNSR reactor was attained by entirely removing the top plate shims as well as control rod and installing the spallation target in interior space of guide thimble. Different state of the art targets such as tungsten, lead, bismuth, and LBE (lead-bismuth eutectic) have been investigated and target neutronic parameters including the spallation yield, neutron energy spectrum, deposited energy and the angular distribution of spallation neutrons were evaluated using MCNPX2.6 code. The results showed that the neutronic performance of tungsten is somewhat greater than its competitors. On the other hand the maximum power density in tungsten is about two times greater than lead and LBE targets.

Estimation of polonium radionuclides in proton irradiated lead-bismuth eutectic (LBE) targets by LSC-TDCR technique and gamma spectrometry

An accurate knowledge on the production of radiotoxic polonium from proton irradiated lead-bismuth eutectic (LBE) targets is essential for the use of LBE in accelerator driven systems or in next generation RIB facilities. In this paper, six LBE targets were irradiated at different proton energies from 8.95 to 21.95MeV. For the first time quantification of $ \alpha$ emitting 208, 210Po has been carried out in a proton irradiated lead-bismuth target, without radiochemical separation of Po radionuclides. The liquid scintillation counting along with triple to double coincidence ratio technique (LSC-TDCR) was used for the quantification of 208, 210Po . The $ \gamma$-emitting 207Po was quantified by $ \gamma$-ray spectrometry.

Separation of Pb and Bi from proton irradiated lead–bismuth eutectic target using different anion exchangers

Lead–bismuth eutectic (LBE) is the proposed material for use as converter targets in the ISOL facilities globally. In this paper, an LBE target was irradiated with 22 MeV proton beam for 7.6 h to produce 203,204,205,206Bi, 203Pb along with 207Po. Separation of bulk Pb and Bi has been carried out using Aliquat-336 (tricaprylmethylammonium chloride), TOA (trioctyl amine) and DOWEX-1 as extractants. Bi was selectively extracted to the organic/solid phase leaving Pb in aqueous medium. High separation factor between Pb and Bi was observed when 0.5 M TOA and 1 M HNO3 were used as organic and aqueous phase respectively.

Shielding analysis of Transmutation Experimental Facility

The Japan Atomic Energy Agency is planning to construct the Transmutation Experimental Facility (TEF) to promote research, development, and demonstration of elemental technologies for accelerator-driven systems (ADSs). At ADS Target Test Facility (TEF-T), 250-kW H– beams accelerated by the 400-MeV LINAC will be derived to a lead-bismuth eutectic target. Toward the construction of TEF, a shielding analysis is carried out for the whole structure of the TEF-T in detail. The analysis for the beam tunnel shows that backward neutrons produced from the LBE target have large a impact on the radiation dose in the TEF beam tunnel. This paper presents the analytical results for components such as target station, hot cell and beam tunnel, and the shielding structure of the whole TEF.

Separation of lead and bismuth from proton irradiated lead–bismuth eutectic (LBE) target by differential precipitation

A thin foil of lead–bismuth eutectic (LBE) has been bombarded with 18 MeV proton beam. Production of 203,204,205,206Bi along with 203Pb was observed. This paper reports the separation of bulk Pb and Bi from LBE target based on their differential precipitation properties. The irradiated foil in HNO3 medium was evaporated to dryness and after addition of deionised water, Bi precipitated out while Pb remained in supernatant with 86,000.

Separation of no-carrier-added astatine radionuclides from α-particle irradiated lead bismuth eutectic target: A classical method

Possibility of separation of no-carrier-added (NCA) astatine radionuclides from the bulk lead-bismuth-eutectic (LBE) target was explored in a simple way in the laboratory scale. A LBE target was irradiated by 40MeV α-particles delivered from a cyclotron facility, India. Quantitative analysis of the irradiated target indicated the production of 210,209At, 207Po radionuclides in the target matrix. The 210,209At radionuclides were separated by precipitation of bulk Pb, Bi and NCA radiotoxic Po radionuclides.

Implementation of an LBE spallation target in an accelerator-driven molten salt subcritical reactor

ABSTRACTAn accelerator-driven system (ADS) combined with a subcritical molten salt reactor (MSR) is a type of hybrid reactor originally designed to use Th/U (or U/Pu ) fuel cycles. In most accelerator-driven molten salt reactor (AD-MSR) concepts, the salt material is also used as a target for inducing spallation neutrons. Although a neutron source is an important component in the design of ADS, only a few studies have addressed the effects of the neutron spallation source in the AD-MSR. Incidentally, there is no quantitative study on how much the beam power can be reduced by installing a spallation target in a sodium chloride-based fast reactor. We studied the proton and the neutron source efficiencies of an AD-MSR with chloride fuels by considering an Lead Bismuth Eutectic (LBE) spallation target. This LBE target is found to increase the proton source efficiency significantly. The required beam power for an AD-MSR can be reduced by 33 % and 16 % for NaCl-Th/233U and NaCl-U/Pu fuels, respectively, relative to the AD-MSR without the LBE spallation target by keeping the same keff. The energy gain can be increased up to 1.5 times and 1.2 times for NaCl-Th/233U and NaCl-U/Pu fuels, respectively. Thus, incorporating a spallation target module in an AD-MSR can significantly reduce the burden on the accelerator.

Optimization of breeding properties of the spallation neutron source target for ADS

One of the main components of an ADS (accelerator-driven reactor systems) is the spallation target, generating neutrons for power plant. Neutrons are generated due in spallation reactions induced on heavy nuclei by accelerator beam of high-energy protons with subsequent multiplication of neutrons in the cascade process of interactions of secondary intermediate-energy particles with target nuclei, subcritical core and blanket.On average, from 20 (for Hg and Pb targets) to 50 (for U target) neutrons are produced per 1-GeV proton in spallation reactions in the target containing nuclei of heavy elements (for example, Hg, Ta, W, U,).Heavy elements such as lead, bismuth, mercury, tantalum, and tungsten are considered as suitable materials for the targets. Lead-bismuth eutectic targets are successfully developed.It is demonstrated in the present paper that there exist optimal size of the target material allowing obtaining for the given incident particle energy maximum number of “spallation” neutrons. Results of calculations of energy spectrum of neutrons generated in the proton interactions with heavy targets for the energy range of incident protons from 0.8 to 1.4GeV.Implemented analysis of variation of neutron generation rate for cylindrical target with 10cm diameter and length from 1 to 120cm at impinging proton energies from 0.8 to 1.4GeV allowed calculating optimal target dimensions consisting of heavy nuclei for the nuclear power installations under design.Optimization of dimensions of neutron generating targets consisting of natural natBi, natHg, natPb и natW isotopes was implemented.

Validation of PHITS Spallation Models from the Perspective of the Shielding Design of Transmutation Experimental Facility

The impact of different spallation models implemented in the particle transport code PHITS on the shielding design of Transmutation Experimental Facility is investigated. For 400-MeV proton incident on a lead-bismuth eutectic target, an effective dose rate at the end of a thick radiation shield (3-m-thick iron and 3-m-thick concrete) calculated by the Liege intranuclear cascade (INC) model version 4.6 (INCL4.6) coupled with the GEMcode (INCL4.6/GEM) yields about twice as high as the Bertini INC model (Bertini/GEM). A comparison with experimental data for 500-MeV proton incident on a thick lead target suggest that the prediction accuracy of INCL4.6/GEM would be better than that of Bertini/GEM. In contrast, it is found that the dose rates in beam ducts in front of targets calculated by the INCL4.6/GEMare lower than those by the Bertini/GEM. Since both models underestimate the experimental results for neutron-production doubledifferential cross sections at 180◦ for 140-MeV proton incident on carbon, iron, and gold targets, it is concluded that it is necessary to allow a margin for uncertainty caused by the spallation models, which is a factor of two, in estimating the dose rate induced by neutron streaming through a beam duct.

Preliminary physics study of the Lead–Bismuth Eutectic spallation target for China Initiative Accelerator-Driven System

The Lead–Bismuth Eutectic (LBE) spallation target has been considered as one of the two alternatives for the spallation target for China Initiative Accelerator-Driven System. This paper reports the preliminary study on physical feasibility of a U-type LBE target with window. The simulation results based on Monte Carlo transport code MCNPX indicate that the spallation neutron yield is about 2.5 per proton. The maximum spallation neutron flux is observed at about 3 cm below the lowest part of the window. When the LBE target is coupled with the reactor, the reactor neutrons from the fission reaction increased the neutron field significantly. The energy deposition of high-energy protons is the main heat source; the spallation neutrons and reactor neutrons contribute only a small fraction. The maximum energy deposition in the LBE is about 590 W/cm3 and that in the target window is about 319 W/cm3. To estimate the lifetime of the target window, we have calculated the radiation damages. The maximum displacement production rate in the target window is about 10 dpa/FPY. The hydrogen and helium production rates generated during normal operation were also evaluated. By analyzing the residual nucleus in the target during the steady operation, we estimated the accumulated quantities of the extreme radioactivity toxicant 210Po in the LBE target loop. The results would be helpful for the evaluation of the target behavior and will be beneficial to the optimization of the target design work of the experimental facilities.

Post-irradiation analysis of an ISOLDE lead-bismuth target: Stable and long-lived noble gas nuclides

We measured the isotopic concentrations of long-lived and stable He, Ne, Ar, Kr, and Xe isotopes in a sample from a lead-bismuth eutectic target irradiated with 1.0 and 1.4 GeV protons. Our data indicate for most noble gases nearly complete release with retention fractions in the range of percent or less. Higher retention fractions result from the decay of long-lived radioactive progenitors from groups 1, 2, or 7 of the periodic table. From the data we can calculate a retention fraction for 3H of 2–3%. For alkaline metals we find retention fractions of about 10%, 30%, and 50% for Na, Rb, and Cs, respectively. For the alkaline earth metal Ba we found complete retention. Finally, the measured Kr and Xe concentrations indicate that there was some release of the halogens Br and I during and/or after the irradiation.

Study of a conceptual accelerator driven system loaded with thorium dioxide mixed with transuranic dioxides in TRISO particles

Nuclear spent fuel management is one of the top major subjects in the utilization of nuclear energy. Hence, solutions to this problem have been increasingly researched in recent years. The basic aim of this work is to examine the fissile breeding and transuranic fuel transmutation potentials of a gas cooled accelerator-driven system. In line with this purpose, firstly, the conceptually designed system is optimized by using several target materials and fuel mixtures, from the point of neutronic. Secondly, three different material compositions, namely, pure lead bismuth eutectic (LBE), LBE+natural UO2, and LBE+15 % enrichment UO2, are considered as target material. The target zone is separated to two sub-zones but as one within the other. The outer sub-zone is pure LBE target, and the inner sub-zone is either UO2 or pure LBE target. The UO2 target sub-zone is cooled with helium gas. Finally, the thorium dioxide mixed with transuranic dioxides, discharged from PWR-MOX spent fuel, in pebbles composed of graphite and TRISO-coated spherical fuel particles, is used for breeding fissile fuel and transmuting transuranic fuels. Three different thorium-transuranic mixtures, (Th, Pu)O2, (Th, Cm)O2, (Th, Pu, MA)O2, are examined with various mixture fractions. The packing fractions of the fuel pebbles in the transmutation core and the tristructural-isotropic coated fuel particles in a pebble are assumed as 60 % and 29 %, respectively. The transmutation core is also cooled with a high-temperature helium coolant. In order to produce high-flux neutrons that penetrate through the transmutation core, the target is exposed to the continuous beams of 1 GeV protons. The computations have been carried out with the high-energy Monte Carlo code MCNPX using the LA150 library. The numerical outcomes show that the examined accelerator-driven system has rather high neutronic data in terms of the energy production and fissile fuel breeding.

Comparison on the production of radionuclides in 1.4 GeV proton irradiated LBE targets of different thickness

This is the first report on the inventory of radionuclides produced in 1.4 GeV proton induced reaction on Lead–Bismuth Eutectic (LBE) targets. LBE targets of 6 mm diameter and 1 to 8 mm lengths were irradiated with 1.4 GeV protons. The radionuclides ranging from 7Be (53.12 days) to 207Po (5.8 h) were identified in the samples with the help of time resolved γ-ray spectroscopy. However, there is no signature of formation of At radioisotopes, which can be produced by the interaction of secondary particles, typical for thick targets.

Measurement of Volatile Radionuclides Production and Release Yields followed by a Post-Irradiation Analysis of a Pb/Bi Filled Ta Target at ISOLDE

A crucial requirement in the development of liquid-metal spallation neutron target is knowledge of the composition and amount of volatile radionuclides that are released from the target during operation. It is also important to know the total amount produced, which could be released if there was an accident. One type is the lead-bismuth eutectic (LBE) target where different radionuclides can be produced following interaction with a high-energy proton beam, notably noble gases (Ar, Kr, Xe isotopes) and other relative volatile isotopes such as Hg and At. The results of an irradiation experiment performed at ISOLDE on a LBE target are compared with predictions from the MCNPX code using the latest developments on the Liège Intranuclear Cascade model (INCL4.6) and the CEM03 model. The calculations are able to reproduce the mass distribution of the radioisotopes produced, including the At production, where there is a significant contribution from secondary reactions. Subsequently, a post-irradiation examination of the irradiated target was performed. Investigations of both the tantalum target structure, in particular the beam window, and the lead-bismuth eutectic were performed using several experimental techniques. No sign of severe irradiation damage, previously observed in other ISOLDE targets, was found.

Preliminary optimization of proton energy and target for Lead-Bismuth Eutectic target of a demonstration ADS

Accelerator Driven subcritical System (ADS) is recognized as an efficient nuclear waste transmutation device. Recently Chinese Academy of Sciences has made a plan to research and develop ADS. As one of the main options, Lead-Bismuth Eutectic (LBE) is chosen to be both of target material and coolant in the target system. In the present work, the generated neutrons of the liquid lead-Bismuth spallation target were studied for an ADS demonstration facility of 1000 MW thermal power. We have investigated the variation of neutron yield, neutron leadage and spatial energy deposition in terms of the different incident proton energy, target height, buffer height and buffer thickness. The information of generated neutrons, including energy spectrum, neutron angle distribution and neutron spatial distribution of the most effective scheme was studied.

Conceptual design studies for the liquid metal target META:LIC

When the construction of ESS (European Spallation Source) in Sweden was initiated, the target station concept selection group decided to reevaluate a variety of target designs to respect new developments in their selection process. The META:LIC (MEgawatt TArget:Lead bIsmuth Cooled) target concept was developed following an extensive analysis of existing and new proposed designs and reached the level of proof of principle within only 2years. ESS selected META:LIC as comparative target option for licensing purposes during the design update phase of ESS. The present work describes the design motivation of META:LIC referring to properties and design features of other targets. Therefore, META:LIC design is an evolutionary target which incorporates the extensive experience of liquid metal targets.The modular LBE (Lead Bismuth Eutectic) target concept with focus on the target module is introduced. Both, a window target option for the start of operation and a windowless option with extended lifetime are foreseen. Thermohydraulic simulations show that adequate window cooling can be realized. The stability of the free surface in the windowless option has been shown. Robust target module instrumentation based on free surface levels and the MEGAPIE experience is proposed for target control. Since the META:LIC concept foresees a horizontal extraction for both moderators and target from the monolith a safety concept based on the SNS and JSNS experience is proposed.

Modeling astatine production in liquid lead-bismuth spallation targets

Astatine isotopes can be produced in liquid lead-bismuth eutectic targets through proton-induced double charge exchange reactions on bismuth or in secondary helium-induced interactions. Models implemented into the most common high-energy transport codes generally have difficulties to correctly estimate their production yields as was shown recently by the ISOLDE Collaboration, which measured release rates from a lead-bismuth target irradiated by 1.4 and 1 GeV protons. In this paper, we first study the capability of the new version of the Liège intranuclear cascade model, INCL4.6, coupled to the deexcitation code ABLA07 to predict the different elementary reactions involved in the production of such isotopes through a detailed comparison of the model with the available experimental data from the literature. Although a few remaining deficiencies are identified, very satisfactory results are found, thanks in particular to improvements brought recently on the treatment of low-energy helium-induced reactions. The implementation of the models into MCNPX allows identifying the respective contributions of the different possible reaction channels in the ISOLDE case. Finally, the full simulation of the ISOLDE experiment is performed, taking into account the likely rather long diffusion time from the target, and compared with the measured diffusion rates for the different astatine isotopes, at the two studied energies, 1.4 and 1 GeV. The shape of the isotopic distribution is perfectly reproduced as well as the absolute release rates, assuming in the calculation a diffusion time between 5 and 10hours. This work finally shows that our model, thanks to the attention paid to the emission of high-energy clusters and to low-energy cluster induced reactions, can be safely used within MCNPX to predict isotopes with a charge larger than that of the target by two units in spallation targets, and, probably, more generally to isotopes created in secondary reactions induced by composite particles.