Radiotoxicity Characterization of HLW from Reprocessing of Uranium-Based and Thorium- Based Fuel- 11390 (original) (raw)
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2010
This paper reports the continued evaluation of the attractiveness of materials mixtures containing special nuclear materials (SNM) associated with various proposed nuclear fuel cycles. Specifically, this paper examines two closed fuel cycles. The first fuel cycle examined is a thorium fuel cycle in which a pressurized heavy water reactor (PHWR) is fueled with mixtures of plutonium/thorium and {sup 233}U/thorium. The used fuel is then reprocessed using the THOREX process and the actinides are recycled. The second fuel cycle examined consists of conventional light water reactors (LWR) whose fuel is reprocessed for actinides that are then fed to and recycled until consumed in fast-spectrum reactors: fast reactors and accelerator driven systems (ADS). As reprocessing of LWR fuel has already been examined, this paper will focus on the reprocessing of the scheme's fast-spectrum reactors' fuel. This study will indicate what is required to render these materials as having low utilit...
Recycling the Actinides, The Cornerstone of Any Sustainable Nuclear Fuel Cycles
Procedia Chemistry, 2012
The sustainability of the current nuclear fuel cycles is not completely achieved since they do not optimise the consumption of natural resource (only a very small part of uranium is burnt) and they do not ensure a complete and efficient recycling of the potential energetic material like the actinides. Promoting nuclear energy as a future energy source requires proposing new nuclear systems that could meet the criteria of sustainability in terms of durability, bearability and liveability. In particular, it requires shifting towards more efficient fuel cycles, in which natural resources are saved, nuclear waste are minimised, efficiently confined and safely disposed of, in which safety and proliferation-resistance are more than ever ensured. Such evolution will require (i) as a mandatory step, evolutionary recycling of the major actinides U and Pu up to their optimized use as energetic materials using fast neutron spectra, (ii) as an optional step, the implementation of the recycling of minor actinides which are the main contributors to the long term heat power and radiotoxicity of nuclear waste. Both options will require fast neutrons reactors to ensure an efficient consumption of actinides. In such a context, the back-end of the fuel cycle will be significantly modified: implementation of advanced treatment/recycling processes, minor-actinides recovery and transmutation, production of lighter final waste requiring lower repository space. In view of the 2012 French milestones in the framework of the 2006 Waste Management Act, this paper will depict the current state of development with regards with these perspectives and will enlighten the consequences for the subsequent nuclear waste management.
2011
Growing concerns regarding the disposal of spent nuclear fuel (SNF) may hamper the nuclear renaissance. The industry must therefore provide politically and socially acceptable solutions for the waste disposal problem. It is believed that reducing the intermediate and long‐term radiotoxicity of SNF will alleviate many of these concerns and lead to broader public acceptance of nuclear power. Westinghouse is proposing a partition and transmutation strategy to substantially reduce the radiotoxicity of the high level waste in a 300‐year time frame with a synergistic application of advanced reprocessing and reactor technologies. The high level waste is the focus of this study because it has the highest level of toxicity for the longest period of time and is the most mobile of the various forms of waste. A steady state material balance based methodology has been developed to support this objective which enables the evaluation of the impact of alternative design choices on the back‐end of...
Minimization of actinide waste by multi-recycling of thoriated fuels in the EPR reactor
Annals of Nuclear Energy, 2011
The multi-recycling of innovative uranium/thorium oxide fuels for use in the European Pressurized water Reactor (EPR) has been investigated. If increasing quantities of 238 U, the fertile isotope in standard UO 2 fuel, are replaced by 232 Th, then a greater yield of new fissile material (233 U) is produced during the cycle than would otherwise be the case. This leads to economies of natural uranium of around 45% if the uranium in the spent fuel is multi-recycled. In addition we show that minor actinide and plutonium waste inventories are reduced and hence waste radio-toxicities and decay heats are up to a factor of 20 lower after 10 3 years. Two innovative fuel types named S90 and S20, ThO 2 mixed with 90% and 20% enriched UO 2 respectively, are compared as an alternative to standard uranium oxide (UOX) and uranium/plutonium mixed oxide (MOX) fuels at the longest EPR fuel discharge burn-ups of 65 GWd/t. Fissile and waste inventories are examined, waste radio-toxicities and decay heats are extracted and safety feedback coefficients are calculated.
Use of Thorium for Transmutation of Plutonium and Minor Actinides in PWRs
The objective of this work was to assess the potential of thorium based fuel to minimise Pu and MA production in Pressurised Water Reactors (PWRs). The assessment was carried out by examining destruction rates and residual amounts of Pu and MA in the fuel used for transmutation. In particular, sensitivity of these two parameters to the fuel lattice Hydrogen to Heavy Metal (H/HM) ratio and to the fuel composition was systematically investigated. All burn-up calculations were performed using CASMO4 -the fuel assembly burn-up code. The results indicate that up to 1 000 kg of reactor grade Pu can potentially be burned in thorium based fuel assemblies per GW e Year. Up to 75% of initial Pu can be destroyed per path. Addition of MA to the fuel mixture degrades the burning efficiency. The theoretically achievable limit for total TRU destruction per path is 50%. Efficient MA and Pu destruction in thorium based fuel generally requires a higher degree of neutron moderation and, therefore, higher fuel lattice H/HM ratio than typically used in the current generation of PWRs. Reactivity coefficients evaluation demonstrated the feasibility of designing a Th-Pu-MA fuel with negative Doppler and moderator temperature coefficients.
Characteristics of Radionuclides on Thorium-Cycle Experimental Power Reactor Spent Fuel
Urania Jurnal Ilmiah Daur Bahan Bakar Nuklir, 2019
CHARACTERISTICS OF RADIONUCLIDES ON THORIUM-CYCLE EXPERIMENTAL POWER REACTOR SPENT FUEL. There are several options of nuclear fuel utilisation in the HTGR-based Experimental Power Reactor (Reaktor Daya Eksperimental/RDE). Although mainly RDE utilises low enriched uranium (LEU)-based fuel, which is the most viable option at the moment, it is possible for RDE to utilise other fuel, for example thorium-based and possibly even plutonium-based fuel. Different fuel yields different spent fuel characteristics, so it is necessary to identify the characteristics to understand and evaluate their handling and interim storage. This paper provides the study on the characteristics of thorium-fuelled RDE spent fuel, assuming typical operational cycle. ORIGEN2.1 code is employed to determine the spent fuel characteristics. The result showed that at the end of the calculation cycle, each thorium-based spent fuel pebble generates around 0,627 Watts of heat, 28 neutrons/s, 8.28x1012 photons/s and yiel...
Annals of Nuclear Energy, 2013
The present paper compares the reactor physics and transmutation performance of sodium-cooled Fast Reactors (FRs) for TRansUranic (TRU) burning with thorium (Th) or uranium (U) as fertile materials. The 1000 MWt Toshiba-Westinghouse Advanced Recycling Reactor (ARR) conceptual core has been used as benchmark for the comparison. Both burner and breakeven configurations sustained or started with a TRU supply, and assuming full actinide homogeneous recycle strategy, have been developed. State-ofthe-art core physics tools have been employed to establish fuel inventory and reactor physics performances for equilibrium and transition cycles. Results show that Th fosters large improvements in the reactivity coefficients associated with coolant expansion and voiding, which enhances safety margins and, for a burner design, can be traded for maximizing the TRU burning rate. A trade-off of Th compared to U is the significantly larger fuel inventory required to achieve a breakeven design, which entails additional blankets at the detriment of core compactness as well as fuel manufacturing and separation requirements. The gamma field generated by the progeny of U-232 in the U bred from Th challenges fuel handling and manufacturing, but in case of full recycle, the high contents of Am and Cm in the transmutation fuel impose remote fuel operations regardless of the presence of U-232.
Transmutation considerations of LWR and RBMK spent nuclear fuel by the fusion–fission hybrid system
Nuclear Engineering and Design, 2018
The performance of the fusion-fission hybrid system based on the molten salt (flibe) blanket, driven by a plasma based fusion device, was analyzed by comparing transmutation scenarios of actinides extracted from the LWR (Sweden) and RBMK (Lithuania) spent nuclear fuel in the scope of the EURATOM project BRILLIANT. The IAEA nuclear fuel cycle simulation system (NFCSS) has been applied for the estimation of the approximate amount of heavy metals of the spent nuclear fuel in Sweden reactors and the SCALE 6 code package has been used for the determination of the RBMK-1500 spent nuclear fuel composition. The total amount of trans-uranium elements has been estimated in both countries by 2015. Major parameters of the hybrid system performance (e.g., k scr , k eff , Φ n (E), equilibrium conditions, etc.) have been investigated for LWR and RBMK trans-uranium transmutation cases. Detailed burn-up calculations with continuous feeding to replenish the incinerated trans-uranium material and partial treatment of fission products were done using the Monteburns (MCNP + ORIGEN) code system. About 1.1 tons of spent fuel trans-uranium elements could be burned annually with an output of the 3 GW th fission power, but the equilibrium stage is reached differently depending on the initial trans-uranium composition. The radiotoxicity of the remaining LWR and RBMK transmuted waste after the hybrid system operation time has been estimated.
Nuclear waste impact reduction using multiple fuel recycling strategies
2007
The paper deals with the use of a symbiotic cycle in order to minimize the LWR waste radiotoxicity, improving, on the same line, previous work . The obtained results could be considered rather positive. We will show what is possible to do in this field using new original symbiotic cycles, remarkably improving the previous results. To reach this goal, we investigated innovative fuel cycles by using the gas cooled reactors (both thermal and fast). Their very favourable neutronic economy, supported by an appropriated spectrum, allows to transmute/fission actinides, in particular transuranic ones. In this frame, we developed a strategy based on an original symbiotic fuel cycle. We assume to begin using, as normal, enriched uranium in LWRs. The second step deals with burning all the actinides recovered from LWRs spent fuel in HTRs. One of the major innovative results after this irradiation consists in the strong reduction of the neptunium which represents one of the greatest concerns in long term disposal. The last one consists in adding, as fuel in GCFRs, depleted uranium together with all the residual actinides of HTR spent fuel. As final result we obtain a reduction of the Level Of Mine Balancing Time (LOMBT) from 250000[11] (LWR once through) to about 200 years (proposed symbiotic cycle). This research has to be considered in progress and needs of further confirmation mainly by technological point of view.