System For Nuclear Waste Transmutation Research Articles

Calculation and analysis of cross-sections for p+184W reactions up to 200 MeV**Supported by National Basic Research Program of China, Technology Research of Accelerator Driven Sub-critical System for Nuclear Waste Transmutation (2007CB209903) and Strategic Priority Research Program of Chinese Academy of Sciences, Thorium Molten Salt Reactor Nuclear Energy System (XDA02010100)

A set of optimal proton optical potential parameters for p+ 184W reactions are obtained at incident proton energy up to 250 MeV. Based on these parameters, the reaction cross-sections, elastic scattering angular distributions, energy spectra and double differential cross sections of proton-induced reactions on 184W are calculated and analyzed by using theoretical models which integrate the optical model, distorted Born wave approximation theory, intra-nuclear cascade model, exciton model, Hauser-Feshbach theory and evaporation model. The calculated results are compared with existing experimental data and good agreement is achieved.

Conceptual study of fusion-driven system for nuclear waste transmutation

A conceptual study of a fusion-driven system for nuclear waste transmutation using a low aspect ratio (LAR) tokamak as a neutron source is performed. A configuration of the LAR tokamak neutron source optimised with respect to both transmutation rate and the tritium breeding ratio for aspect ratio A in the range of 1.5–2.0 is found. The transmutation characteristics of both transuranic actinides and minor actinides are investigated and compared. When the transuranic actinides are loaded in the blanket, the neutron multiplication factor decreases from its initial value, keff=0.95, but with the minor actinides loaded in the blanket, the neutron multiplication factor shows a peak value during burn-up. The peak value can be controlled by adjusting the blanket dimensions. To transmute the nuclear waste effectively, an equilibrium fuel cycle is developed for both transuranic actinide and minor actinide transmutation.

05/02819 Concept of a small-scale electron accelerator driven system for nuclear waste transmutation. Part 2. Investigation of burnup

A similarity model experiment was developed to investigate the liquid water transport in hydrophobic porous layers of polymer electrolyte membrane fuel cells (PEMFCs). The dimensionless numbers in the similarity model experiment were closely matched to those in operating PEMFCs. This allowed the visual inspection of invasion-percolation transport of a non-wetting fluid with active capillary fingering in multiple porous layers, similar to the liquid water transport in porous layers of PEMFCs. The experimental results showed that inserting an intermediate layer between a fine layer and a coarse layer suppresses the capillary fingering of the non-wetting fluid inside the coarse layer. Thus, it could be expected that the steady-state volume of the non-wetting fluid in the multiple porous layers decreases as the thickness of the intermediate layer increases. In fact, this trend was quantitatively verified by measuring the volume of the breakthrough droplets formed by the non-wetting fluid that emerged out of multiple porous layers. In addition, pore network simulations were also conducted to reproduce the observed non-wetting fluid transport in multi-layer porous media, and relatively good agreements between experimental and numerical results were obtained.

Fusion–fission hybrid system for nuclear waste transmutation (II): From the burn-up optimization to the tests of different data libraries

A possibility to use a fusion–fission molten salt (flibe) hybrid system to incinerate nuclear waste minor actinides (Np, Am, Cm) is considered. In this work an optimization procedure was developed in order to determine the fission-blanket composition corresponding to fast incineration rate of minor actinides. Performance parameters such as k src, burn-up, neutron fluxes and equilibrium conditions were obtained. Monteburns code system (MCNP+ORIGEN) was used for system modeling. Approximately 1.1 ton of minor actinides, originating from the spent nuclear fuel, could be incinerated annually with an output of 3 GWth fission power. Detailed burn-up calculations show that the equilibrium conditions of the fuel concentration in the flibe transmutation blanket could be achieved, if the originating tritium and fission products were removed at least in part and fresh actinides were added during the burn-up on line. The optimal transmutation blanket in equilibrium is dominated by minor actinides for which the cross sections may vary depending on the nuclear-data libraries used. Therefore, the system performance was tested comparing different sets of data libraries. A number of major differences among ENDF, JENDL and JEF data files were identified and quantified in terms of the averaged one-group cross sections. In this context, our study could be directly generalized for other transmutation systems with similar neutron-energy spectra.

Fusion–fission hybrid system for nuclear waste transmutation (I): Characterization of the system and burn-up calculations

Generally, a very intensive neutron source is needed for the efficient transmutation process of nuclear waste and minor actinides in particular. A plasma based fusion device is naturally a candidate neutron source. In this paper, we analyze a molten salt (flibe) blanket, driven by a plasma based fusion device, dedicated to burn actinides extracted from the LWR spent fuel. Performance parameters such as k scr, burn-up, fluxes and equilibrium conditions were calculated to assess the characteristics of a flibe based transmutation plant. It seems that nearly 1.1metric ton of spent fuel TRU could be burned annually with an output of 3 GW th fission power. Detailed burn-up calculations show that equilibrium conditions of the fuel concentration in the flibe transmutation blanket could be achieved, provided that fission products were removed at least in part and fresh spent fuel TRU was added during burn-up on-line.

Concept of a small-scale electron accelerator driven system for nuclear waste transmutation: Part 2. Investigation of burnup

In our earlier paper the target optimization of an electron–neutron (e–n) converter based molten salt ADS concept (MSENC) was presented. In this paper the burnup in this molten salt ADS is investigated. The system is continuously fueled with TRUs obtained from spent nuclear fuel by means of pyrochemical separation, while fission products are continuously filtered out. Effect of MSENC operation on transuranium consumption, mass reduction and radiotoxicity is considered. It seems that while the amount of plutonium is reduced significantly, the higher actinides will build up, which results that radiotoxicity of nuclear waste will not be reduced considerably.

04/02321 Concept of a small-scale accelerator driven system for nuclear waste transmutation, part 1. Target optimization: Brolly, Á. and Vértes, P. Annals of Nuclear Energy, 2004, 31, (6), 585–600

04/02321 Concept of a small-scale accelerator driven system for nuclear waste transmutation, part 1. Target optimization: Brolly, Á. and Vértes, P. Annals of Nuclear Energy, 2004, 31, (6), 585–600

Theoretical and experimental evaluation of the windowless interface for the TRASCO-ADS project

TRASCO-ADS is a national funded program in which INFN, ENEA, and Italian industries work on the design of an accelerator driven subcritical system for nuclear waste transmutation. TRASCO is the Italian acronym for Transmutation (TRAsmutazione) of Waste (SCOrie). One of the most critical aspects in the design of an Accelerator Driven System is related to the interface region, which is the part of the beamline located between the accelerator, operating under UHV conditions, and the pressurized reactor vessel, consisting of a contained plenum of Pb-Bi eutectic (LBE). A so-called window could separate these two environments, but thermomechanical considerations and radioprotection issues point out that this component could be critical. In the windowless interface, no window is located between the linac and the spallation target. Only a suitable pumping and trapping system, for the gases and the vapors outcoming from LBE, divides the UHV accelerator and the spallation target vacuum. Vacuum gas dynamics theoretical considerations and calculations are presented in this article. The need for a validation of the theoretical models gave the motivation for an experimental work, whose results are also discussed. Scale-up of the experimental setup to the full system needs accurate analyses for a proper dimensioning of the system in the interface region.

Concept of a small-scale accelerator driven system for nuclear waste transmutation, part 1. Target optimization

Recently, the transmutation of nuclear waste seems to be a solution of the most serious problem of nuclear energy. Since the past decade numerous conceptions of critical and sub-critical reactors dedicated to waste incineration were published. Mainly, because of safety problems, the proton accelerator driven sub-critical systems seem to be preferred. An alternative concept is based on electron–neutron (e–n) converter neutron source. In this paper after a short presentation of molten salt e–n converter (MSENC) transmuter concept, the target optimization for this device is given in details.

High intensity ECR ion source (H+, D+, H−) developments at CEA/Saclay

Source of light ions with high intensities The (SILHI) source has been producing proton beams since 1996. The first aim is to produce up to 100 mA cw beams at 95 keV for the injector of protons for high intensity demonstrator. This prototype is developed by a CEA/DSM–CNRS/IN2P3 collaboration for applications such as accelerator driven systems for nuclear waste transmutation, production of radioactive ion beams, or secondary particles. To measure installation reliability, continuous 5 day long runs have been performed. In October 1999, a 99.96% availability was achieved with a single short beam off and a 103 H uninterrupted beam. A new extraction system leads to lower beam losses and higher LEBT transparency. SILHI now produces a 95 keV–130 mA total beam with a proton fraction higher than 80%. Up to a 157 mA (247 mA/cm2) total cw beam has been extracted. The new EPICS control system, electromagnetic interference hardened devices and automatic control procedures now allow us to do longer runs. To analyze the reliability of these upgrades, a 4 week test was planned. In the framework of the International Fusion Material Irradiation Facility project CEA participation, 135 mA–95 kV deuteron pulsed beams were produced. Extraction simulations and recent SILHI results are also presented. In addition, a new test bench has been recently developed to analyze H− beam production.

TRIPS: The high intensity proton source for the TRASCO project

The TRASCO project (trasmutazione scorie) is a R&D program whose goal is the design of an accelerator driving system for nuclear waste transmutation. The high current continuous wave proton linear accelerator will drive a subcritical system to transmutate nuclear wastes, while producing energy. The proton source TRIPS is a high intensity microwave source, which should be highly reliable and that should provide a minimum proton current of 50 mA with a r−r′ root mean square normalized emittance lower than 0.2 π mm mrad. A program of cooperation has been entered into with CEA-Saclay, where the IPHI project is in progress and the proton source SILHI has been designed and built using goals close to those of TRIPS. The construction of TRIPS is underway and the first beam is scheduled for the first half of 2000. The main features of this source and the results of the optics calculations are presented.

Status and new developments of the high intensity electron cyclotron resonance source light ion continuous wave, and pulsed mode (invited)

The high intensity light ion source (SILHI) is the electron cyclotron resonance (ECR) source constructed and tested at CEA-Saclay. The first aim is to produce up to 100 mA cw proton beams at 95 keV for the proton injection high intensity (IPHI) beams [5 MeV radio frequency quadrupole (RFQ) and 10 MeV drift tube linac (DTL)]. This prototype is developed by a CEA–CNRS-IN2P3 collaboration for applications such as accelerator driven systems for nuclear waste transmutation, production of radioactive ion beams or secondary particles. SILHI is also used to study the production of deuteron and H− beams for the International Fusion Material Irradiation Facility and European spallation source projects, respectively. The present status of SILHI and the experiments planned for the near future in both cw and pulsed modes are presented in this article. 80 mA cw proton beams are now currently produced at 95 keV with a high availability (∼1 spark/day). The proton fraction is around 90% and the typical r–r′ rms normalized emittance after transport through a single solenoid low energy beam transport (LEBT) without beam losses is 0.3 πmm mrad. The best beam characteristics are obtained when an ECR zone is created at the frontier between the plasma chamber and the rf ridged transition. Extensive emittance measurements performed with different gas injection in the LEBT have shown a factor of three emittance reduction. Space charge compensation measurements in cw mode will be undertaken with a four-grid analyzer to understand this behavior. Time resolved space charge compensation measurements in pulsed mode are also discussed. The highest total beam current of 120 mA (240 mA/cm2) can be extracted with two ECR zones located at the plasma chamber extremities. Nevertheless a new electrode design must be done for this configuration to avoid excessive beam losses in the extraction system.