Design Studies of a Low Sodium Void Reactivity Core Able to Accommodate Degraded TRU Fuel

K, Kawashima; Sugino, Kazuteru; Ohki, Shigeo; Ōkubo, Tsutomu

doi:10.13182/nt13-38

Cited by 5 publications

(5 citation statements)

References 4 publications

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“…Additionally, this approach leads to potential "safety" issues for reactor operations, as high minor actinides fractions in the fuel have a negative impact on coolant void worth and Doppler feedback and thus lower the "safety" margins of the core [9] [10] compared to MA-free fuel. These can be prevented by either decreasing the power density in the core [11], which decreases the efficiency of the core, or by modifying the core layout [12].…”

Section: Optimization Of Minor Actinides Bearing Radial Blankets For mentioning

confidence: 99%

Optimization of Minor Actinide–Bearing Radial Blankets for Heterogeneous Transmutation in Fast Reactors

Kooyman

Buiron²,

Rimpault

2017

Nuclear Science and Engineering

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Introduction:Minor actinides transmutation is a potential solution which is currently investigated for long-term management of nuclear waste. In the case of a closed plutonium fuel cycle, minor actinides are the main responsible for long-term radiotoxicity and short-term decay heat of the nuclear waste package. In the transmutation process, neptunium, americium and eventually curium, which are the three main minor actinides produced in nuclear reactors, are submitted to a neutron flux in order to turn them into shorter-lived fission products by fission or successive captures followed by fissions. This way, radiotoxicity levels can be lowered up to a factor 200 in the best case [1] and a reduction of a factor 3 of the final repository footprint can be achieved [2].Various options have been proposed so far for minor actinides transmutation, including thermal reactors [3], ADS [4] and fast reactors [5]. We will focus here on the fast reactor option as targeted by French R&D programs. Two approaches have been discussed for transmutation in fast reactors, namely the homogeneous one and the heterogeneous one. A complete comparison of these two options can be found in [6] and a small breakdown of the most salient points for each case is done below.

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Section: Optimization Of Minor Actinides Bearing Radial Blankets For mentioning

confidence: 99%

Optimization of Minor Actinide–Bearing Radial Blankets for Heterogeneous Transmutation in Fast Reactors

Kooyman

Buiron²,

Rimpault

2017

Nuclear Science and Engineering

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“…In FR, fission reaction increases when coolant is voided and spectrum becomes harder because of the threshold fission cross section of 238 U in the fast region from 10 5 MeV to 10 6 MeV (Fukaya, et al 2009). Then, it should be designed with pancake type core (Fukaya, et al 2009) and/or sodium plenum concept (Kawashima, et al 2013) to increase neutron leakage for axial direction when the coolant is voided. With these design approach, the void reactivity coefficient can be improved, but breeding ability is depleted as well at the same time.…”

Section: Safety Feature Of Self-regulation For Htgrmentioning

confidence: 99%

Sustainable and safe energy supply with seawater uranium fueled HTGR and its economy

Fukaya

Goto

2017

Annals of Nuclear Energy

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Sustainable and safe energy supply with High Temperature Gas-cooled Reactor (HTGR) fueled by uranium from seawater have been investigated and discussed. From the view point of safety feature of self-regulation with thermal reactor of HTGR, the uranium resources should be inexhaustible. The seawater uranium is expected to be alternative resources to conventional resources because it exists so much in seawater as a solute. It is said that 4.5 billion tons of uranium is dissolved in the seawater, which corresponds to a consumption of approximately 72 thousand years. Moreover, a thousand times of the amount of 4.5 trillion tU of uranium, which corresponds to the consumption of 72 million years, also is included in the rock on the surface of the sea floor, and that is also recoverable as seawater uranium because uranium in seawater is in an equilibrium state with that. In other words, the uranium from seawater is almost inexhaustible natural resource. However, the recovery cost with current technology is still expensive compared with that of conventional uranium. Then, we assessed the effect of increase in uranium purchase cost on the entire electricity generation cost. In this study, the economy of electricity generation of cost of a commercial HTGR was evaluated with conventional uranium and seawater uranium. Compared with ordinary LWR using conventional uranium, HTGR can generate electricity cheaply because of small volume of simple direct gas turbine system compared with water and steam systems of LWR, rationalization by modularizing, and high thermal efficiency, even if fueled by seawater uranium.

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“…Most of the work related to transmutation has been carried out seeking for an efficient transmutation system, that is to say a reactor design which exhibits high minor actinides consumption rate with "acceptable" safety parameters. The common approach to this problem was to start from an existing core and modify it to accommodate the loading of a given fraction of minor actinides, as it is proposed for instance in [9], where the core geometry is modified to decrease the sodium void worth, permitting a subsequent addition of minor actinides in the reactor.…”

Section: Scope Of the Studymentioning

confidence: 99%

Sensitivity analysis of minor actinides transmutation to physical and technological parameters

Kooyman

Buiron

2015

EPJ Nuclear Sci. Technol.

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Minor actinides transmutation is one of the three main axis defined by the 2006 French law for management of nuclear waste, along with long-term storage and use of a deep geological repository. Transmutation options for critical systems can be divided in two different approaches: (a) homogeneous transmutation, in which minor actinides are mixed with the fuel. This exhibits the drawback of "polluting" the entire fuel cycle with minor actinides and also has an important impact on core reactivity coefficients such as Doppler Effect or sodium void worth for fast reactors when the minor actinides fraction increases above 3 to 5% depending on the core; (b) heterogeneous transmutation, in which minor actinides are inserted into transmutation targets which can be located in the center or in the periphery of the core. This presents the advantage of decoupling the management of the minor actinides from the conventional fuel and not impacting the core reactivity coefficients. In both cases, the design and analyses of potential transmutation systems have been carried out in the frame of Gen IV fast reactor using a "perturbation" approach in which nominal power reactor parameters are modified to accommodate the loading of minor actinides. However, when designing such a transmutation strategy, parameters from all steps of the fuel cycle must be taken into account, such as spent fuel heat load, gamma or neutron sources or fabrication feasibility. Considering a multi-recycling strategy of minor actinides, an analysis of relevant estimators necessary to fully analyze a transmutation strategy has been performed in this work and a sensitivity analysis of these estimators to a broad choice of reactors and fuel cycle parameters has been carried out. No threshold or percolation effects were observed. Saturation of transmutation rate with regards to several parameters has been observed, namely the minor actinides volume fraction and the irradiation time. Estimators of interest that have been derived from this approach include the maximum neutron source and decay heat load acceptable at reprocessing and fabrication steps, which influence among other things the total minor actinides inventory, the overall complexity of the cycle and the size of the geological repository. Based on this analysis, a new methodology to assess transmutation strategies is proposed.

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Design Studies of a Low Sodium Void Reactivity Core Able to Accommodate Degraded TRU Fuel

Cited by 5 publications

References 4 publications

Optimization of Minor Actinide–Bearing Radial Blankets for Heterogeneous Transmutation in Fast Reactors

Optimization of Minor Actinide–Bearing Radial Blankets for Heterogeneous Transmutation in Fast Reactors

Sustainable and safe energy supply with seawater uranium fueled HTGR and its economy

Sensitivity analysis of minor actinides transmutation to physical and technological parameters

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