CEMSO (Catalyst Enhanced Molten Salt Oxidation) for Complete and Continuous Pyrochemical Reprocessing of Spent Nuclear Fuel: An Overview of a Viable New Technology for Next Generation Nuclear Reactors

AbstractDuring the past 70 years, more than 2000 metric tonnes of Pu, and substantial quantities of the ‘minor’ actinides such as Np, Am and Cm, have been generated in nuclear reactors. Some of these transuranium elements can be a source of energy in fission reactions (e.g. 239Pu), a source of fissile material for nuclear weapons (e.g. 239Pu and 2Np), and of environmental concern because of their long half-lives and radiotoxicity (e.g. 239Pu and 237Np). There are two basic strategies for the disposition of these transuranium elements: (1) to ‘burn’ or fission the actinides using nuclear reactors or accelerators; (2) to dispose of the actinides directly as spent nuclear fuel or to ‘sequester’ the actinides in chemically durable, radiation-resistant materials that are also suitable for geological disposal. For the latter strategy, there has been substantial interest in the use of actinide-bearing minerals, especially isometric pyrochlore, A2B2Oi (A = rare earths; B = Ti, Zr, Sn, Hf), for the immobilization of actinides, particularly plutonium, both as inert matrix fuels and nuclear waste forms. Systematic studies of rare-earth pyrochlores have led to the discovery that certain compositions (B = Zr, Hf) are stable to very high doses of α-decay event damage. Recent developments in the understanding of the properties of actinide-bearing solids have opened up new possibilities for the design of advanced nuclear materials that can be used as fuels and waste forms. As an example, the amount of radiation damage that accumulates over time can be controlled by the selection of an appropriate composition for the pyrochlore and a consideration of the thermal environment of disposal. In the case of deep borehole disposal (3—5 km), the natural geothermal gradient may provide enough heat to reduce the amount of accumulated radiation damage by thermal annealing.

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Release of 108Ag from Irradiated PWR Control Rod Absorbers under Deep Repository Conditions

MRS Proceedings ◽

10.1557/opl.2015.372 ◽

2015 ◽

Vol 1744 ◽

pp. 217-222

Author(s):

O. Roth ◽

M. Granfors ◽

A. Puranen ◽

K. Spahiu

Keyword(s):

Nuclear Fuel ◽

Source Term ◽

Spent Nuclear Fuel ◽

Nuclear Reactors ◽

Reactor Irradiation ◽

Spent Fuel ◽

Control Rod ◽

Potential Source ◽

Absorber Material ◽

Control Rods

ABSTRACTIn a future Swedish deep repository for spent nuclear fuel, irradiated control rods from PWR nuclear reactors are planned to be stored together with the spent fuel. The control rod absorber consists of an 80% Ag, 5% Cd, 15% In alloy with a steel cladding. Upon in-reactor irradiation 108Ag is produced by neutron capture. Release of 108Ag has been identified as a potential source term for release of radioactive substances from the deep repository.Under reducing deep repository conditions, the Ag corrosion rate is however expected to be low which would imply that the release rate of 108Ag should be low under these conditions. The aim of this study is to investigate the dissolution of PWR control rod absorber material under conditions relevant to a future deep repository for spent nuclear fuel. The experiments include tests using irradiated control rod absorber material from Ringhals 2, Sweden. Furthermore, un-irradiated control rod absorber alloy has been tested for comparison. The experiments indicate that the release of Ag from the alloy when exposed to water is strongly dependent on the redox conditions. Under aerated conditions Ag is released at a significant rate whereas no release could be measured after 133 days during leaching under H2.

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On a Long Term Strategy for the Success of Nuclear Power

10.20944/preprints201704.0050.v1 ◽

2017 ◽

Author(s):

Bruno Merk ◽

Dzianis Litskevich ◽

Karl R. Whittle ◽

Mark Bankhead ◽

Richard Taylor ◽

...

Keyword(s):

Nuclear Fuel ◽

Nuclear Power ◽

Nuclear Reactor ◽

Spent Nuclear Fuel ◽

Nuclear Reactors ◽

Theoretical Perspective ◽

Strategic Development ◽

Safety And Reliability ◽

Water Reactors

The current generation of nuclear reactors are evolutionary in design, mostly based on the technology originally designed to power submarines, and dominated by Light Water Reactors. The aims of the GenIV consortium are driven by sustainability, safety and reliability, economics, and proliferation resistance. The aims are extended here to encompass the ultimate and universal vision for strategic development of energy production, the ‘perpetuum mobile’ – at least as close as possible. We propose to rethink nuclear reactor design with the mission to develop a system which uses no fresh resources and produces no fresh waste during operation as well as generates power safe and reliably in economic way. The results of the innovative simulations presented here demonstrate that, from a theoretical perspective, it is feasible to fulfil the mission through the reuse of spent nuclear fuel from currently operating reactors as the fuel for a new reactor. The produced waste is less burdensome than current spent nuclear fuel which is used as feed to the system. However, safety, reliability and operational economics will need to be demonstrated to create the basis for the long term success of nuclear reactors as a major carbon free, sustainable, and applied highly reliable energy source.

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MODERATOR TO FUEL RATIO AND URANIUM FRACTION ANALYSIS OF SQUARE LATTICE MOLTEN SALT TRANSATOMIC POWER

JURNAL TEKNOLOGI REAKTOR NUKLIR TRI DASA MEGA ◽

10.17146/tdm.2017.19.1.2995 ◽

2017 ◽

Vol 19 (1) ◽

pp. 1

Author(s):

Dion Bagus Nugraha B ◽

Andang Widi Harto ◽

Sihana Sihana

Keyword(s):

Molten Salt ◽

Nuclear Fuel ◽

Mole Fraction ◽

Spent Nuclear Fuel ◽

Light Water Reactor ◽

Zirconium Hydride ◽

Molten Salt Reactor ◽

Inherent Safety ◽

Light Water ◽

Optimum Variation

Molten Salt Reactor Transatomic Power (MSR TAP) is a further development of the nuclear reactor Generation IV Reactor Molten Salt Reactor (MSR). MSR TAP generates clean electric power. It has a passive safety, resistance to proliferation, and low cost. MSR TAP can consume the rest of the nuclear fuel/spent nuclear fuel (SNF) of a commercial Light Water Reactor (LWR) fuel or use the main fuel, a salt solution UF4 - LiF - BeF2. MSR TAP uses Zirconium Hydride material for the moderator. This research has a purpose to determine the optimal size of uranium mole fraction on fuel and moderator radius from core design in order to produce optimum enrichment with the value 1 < keff <1.0065 using MCNP5 program. On the other hand, this research also aims to look for the optimum enrichment, which have inherent safety characteristics with αVoid < 0. Variations were made including the changes in the geometry of the moderator radius with a variation of 0.5 cm, 1 cm, 1.5 cm, 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, and 4.5 cm; and the changes in the fuel uranium molar UF4 - LiF - BeF2 with molar variation of 15%, 20%, 25% and 30%. The geometry of Transatomic Power (MSR TAP) of companies Transatomic Power Corporation was used. The results show that the optimum variation is the salt solution UF4 - LiF - BeF2 with 25 % uranium mole fraction, 2.6 % enrichment and moderator radius of 1.5 cm. The optimum variation gives the keff value of 1.00124 ± 0.00078. The optimum value of reactivity void coefficient is -0.0684. It indicates an inherently safe design.Keywords : Molten Salt Reactor Transatomic Power, MCNP5, Uranium Fuel Mole Fraction, Optimum Variation, Moderator, Inherent Safety. ANALISIS FRAKSI URANIUM DAN RASIO MODERATOR – BAHAN BAKAR PADA SQUARE LATTICED MOLTEN SALT TRANSATOMIC POWER. Molten Salt Reactor Transatomic Power (MSR TAP) merupakan reaktor nuklir pengembangan lebih lanjut dari Reaktor Generasi IV Molten Salt Reactor (MSR). Reaktor MSR TAP ini menghasilkan daya listrik yang bersih, memiliki keselamatan pasif, mempunyai resistensi terhadap proliferasi, dan memiliki biaya yang rendah. Reaktor ini dapat mengkonsumsi bahan bakar nuklir sisa/spent nuclear fuel (SNF) dari penggunaan bahan bakar Light Water Reactor (LWR) yang komersial atau menggunakan bahan bakar utama yaitu larutan garam UF4 – LiF – BeF2. Moderator yang digunakan pada MSR TAP ini adalah moderator berbahan Zirconium Hydride. Penelitian ini bertujuan untuk menentukan ukuran perbandingan nilai fraski mol uranium dan jari-jari moderator yang optimal dari dari desain teras Reaktor MSR TAP agar dihasilkan pengayaan yang optimum dengan nilai 1 < keff < 1,0065 menggunakan program MCNP5. Selain itu penelitian ini juga bertujuan mecari pengayaan optimum yang mempunyai sifat keselamatan melekat dengan . Variasi yang dilakukan meliputi perubahan geometri jari-jari moderator dengan variasi 0,5 cm, 1 cm, 1,5 cm, 2 cm, 2,5 cm, 3 cm, 3,5 cm, 4 cm, dan 4,5 cm; dan perubahan molar uranium pada bahan bakar UF4 – LiF – BeF2 dengan variasi persen molar 15%, 20%, 25%, dan 30%. Geometri reaktor yang digunakan dalam silmulasi adalah MSR TAP dari perusahaan Transatomic Power Corporation. Hasil penelitian menunjukkan variasi optimum perbandingan moderator bahan dan fraksi mol bahan bakar larutan garam UF4 – LiF – BeF2 pada fraksi mol uranium bahan bakar pada variasi molar uranium 25% dengan pengayaan 2,6% dan jari-jari moderator 1,5 cm, dengan nilai keff 1,00124±0,00078. Koefisien reaktivitas void yang didapatkan dari variasi optimum tersebut adalah -0,0684 yang menandakan bahwa desain ini telah memenuhi syarat keselamatan melekat.Kata kunci: Molten Salt Reactor Transatomic Power, MCNP5, Fraksi mol uranium, Variasi optimum, Moderator, Keselamatan melekat.

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