atw - International Journal for Nuclear Power | 03.2024

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36 Research and Innovation Conclusions Utilising a nuclear reactor as the primary energy source for hydrogen production in a co-generation setup offers significant prospects for enhancing energy efficiency and simultaneously reducing carbon emissions from energy generation and industrial operations. The co-location of considerable amounts of flammable substances introduces new hazards and could increase overall risk levels. Demonstrating the safe operation of hydrogen production technologies in a co-generation arrangement with a nuclear licensed site is a vital step to enable successful deployment of nuclear enabled hydrogen. Generation of hydrogen from a nuclear energy source is not in itself novel or likely to introduce a disproportionate level of risk to the nuclear site, so long as the hazards are managed in line with the current expectations for safety. Considerations for storage of any required chemical stocks and keeping the nuclear licensed site informed of changes to the surrounding facilities in an intelligent way will be important to support robust safety and security management of the reactor and its safeguard buildings. Authors Howard Chapman National Nuclear Laboratory Limited 5 th Floor, Chadwick House, Birchwood Park, Warrington, WA3 6AE, UK Howard.Chapman@uknnl.com Howard Chapman is a Principal Safety Consultant and has worked in the nuclear industry for over thirty-five years, with vast experience in the production and management of radiological and high hazard chemotoxic safety cases at several sites throughout the UK and internationally. His career spans across all aspects of the nuclear project lifecycle and has considerable experience in producing many safety cases for fuel enrichment, production, and reprocessing facilities. More recently Howard has been working on Advanced Modular Reactors and on co-generation safety. Stephen Lawton National Nuclear Laboratory Limited Building A709, Springfields, Salwick, Preston, Lancashire, PR4 0XJ, UK stephen.lawton@uknnl.com Stephen Lawton is a Radiological and Chemotoxic Safety Consultant primarily covering the civil nuclear fuel cycle as well as for research and development projects and new reactor designs. He routinely undertakes radiological and chemotoxic dispersion modelling for a range of projects as part of Nuclear Safety Cases and COMAH Safety Reports. References [1] HM Government, Net Zero Strategy: Build Back Greener, October 2021 (ISBN 978-1-5286-2938-6) [2] HM Government, The Ten Point Plan for a Green Industrial Revolution, November 2020 [3] HM Government, Industrial Decarbonisation Strategy, March 2021 (ISBN 978-1-5286-2449-7) [4] Department for Transport, Decarbonising Transport, 2021 [5] A Pragmatic Approach to Chemotoxic Safety in the Nuclear Industry Chapman, Howard, Thomas, Marc, & Lawton, Stephen (2019). VGB PowerTech, 99(8), 83-87. Joseph Hargreaves Abbott Risk Consulting Limited 3000 Aviator Way, Manchester, M22 5TG, UK joseph.hargreaves@uknnl.com Joe is a chartered engineer and physicist. He has worked in the nuclear industry for more than 18 years supporting Safety Case and radiological safety assessment/fault studies. In this time, he has gained experience working in Nuclear New Build, electricity generation, decommissioning, research and defence sectors. Joe has worked at a wide range of technical/engineering offices, nuclear power stations, research reactors and other nuclear licensed sites. He has spent time at operational Advanced Gas Reactors, Pressurised Water Reactors and Magnox power stations at various stages of operation, interim life extensions and to support ultimately their decommissioning. Notably, he worked on a long-term international assignment for more than 4 years providing direct nuclear safety engineering support to EDF-SA as part of the Generic Design Assessment and classification engineering sequence for the UK EPR. Joe is currently supporting an internal NNL project on nuclear enabled hydrogen providing ongoing safety advice and supporting the advanced modular reactor programme. Ausgabe 3 › Mai
Fuel 37 Progress in ceramic technologies for SSiC encapsulation of nuclear fuel › Juergen Knorr, Albert Kerber This article describes the progress in ceramic technologies for SSiC encapsulation ( pressure-less sintered silicon carbide) of nuclear fuel elements, preferably of pebbles for so-called pebble bed reactors. It is understood that the described principles and technologies can be adapted to other fuel element geometries and reactor concepts. The fuel design of pebbles for High and Very High Temperature reactors has been unchanged since the development of this reactor type in the early sixties of the last century. Despite the inherent safety claimed for (V)HTR reactors some non negligeable deficiencies have been identified such as flammability of graphite, dust generation, temperature limitation and lack of fuel element traceability. The need of TRISO fuel particles is considered as a further disadvantage because of batch-wise manufacturing in a fluidized bed reactor with low outcome and high costs. For said reasons, the authors have started to improve the fuel pebbles gradually since the beginning of the new millennium. The overall guideline was to eliminate the shortcomings of a naked graphite sphere by transforming the micro-solution of the very thin SiC shell in the case of TRISO fuel to the macro-solution of a robust outer SiC shell offering various advantages. The suitability of silicon carbide as encapsulation material is beyond dispute due to its outstanding properties. Various new manufacturing technologies for components have emerged in the last two decades enabling a variety of innovative solutions described in four distinct steps. The development started with two SiC half shells surrounding the graphite pebble, followed by a hollow SiC sphere, a compact sphere without seam and finally the most innovative technology of dual extrusion 3D-printing which opens new design opportunities. The two latter named solutions do not require TRISO particles as fuel. The single stages of development, their advantages and disadvantages are described. Calculations of neutron economy and criticality will be published elsewhere. 1 Introduction Pebble bed reactors are considered worldwide as a promising GenIV concept to solve the energy problem in the future, at least as part of bridge technologies. This reactor concept is applicable to Small Modular Reactors (SMR) as well as for hydrogen production on large scale with (V)HTR. But the fuel design has not changed since the invention of this reactor type even though severe deficiencies became obvious [1] during the operation of two experimental reactors in Germany (AVR and THTR). The concerns relate mainly to safety aspects as well to the fact that the very high temperatures necessary for hydrogen production could not be safely realized. Even in the very beginning of the AVR-reactor in Jülich, Germany, the inventor Prof. R. Schulten, intended to encapsulate the graphite pebbles in a SiC shell [2] , but the technology of manufacturing SiC components by pressure-less sintering was not available at that time. The investigations of material properties during the development of TRISO fuel particles revealed that silicon carbide represents an effective diffusion barrier for the fission products leading to a 30 µm thick coating by a CVD process. Demkowicz et al. have published a highly detailed report on the history of TRISO fuel [3] . Such a coating is not mechanically robust, and it does not protect the graphite pebble from being abraded or inflamed/oxidized in case of air or water ingress. Both, the advantages and deficiencies of the SiC coating of the TRISO particles led to the insight that a robust encapsulation of the fuel element as a whole would be the better solution. Considerable progress during the past two decades has been made in ceramic technologies, especially in shape forming of components. It became feasible to produce half shells and hollow spheres by injection moulding using a thermoplastic feedstock followed by de- bonding and sintering. The latest step in shape forming development is 3D-printing [4], [5] , which has been applied to manufacture spheres with open cooling channels and closed fuel chambers. Printers with dual extrusion heads allow to print simul taneously two dissimilar materials; in the given case one is the enclosing SiC wall material and the other is the uranium oxide fuel dispersed in a SiC matrix. It is impossible to produce such geometries by other existing techniques. Vol. 69 (2024)
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Page 3 and 4: Editorial 3 Zu teuer und zu langsam
Page 5 and 6: Did you know? 5 Did you know? Zukun
Page 7 and 8: Feature: Environment and Safety 7 V
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Page 25 and 26: Interview 25 Endlagerung in der Sch
Page 27 and 28: Energy Policy, Economy and Law 27 Z
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Page 31 and 32: Research and Innovation 31 Nuclear
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Page 41 and 42: Die Digitalisierung Ihrer Gebäudef
Page 43 and 44: Spotlight on Nuclear Law 43 Verzög
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Page 51 and 52: Environment and Safety 51 Fazit Zus
Page 53 and 54: At a Glance 53 Kontakt Timo Knoll G
Page 55 and 56: Vor 66 Jahren 55 Vol. 69 (2024)
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Page 63 and 64: KTG-Fachinfo 63 rund 5,6 Milliarden
Page 65 and 66: KTG-Fachinfo 65 Investitionen, Stru
Page 67 and 68: KTG-Fachinfo 67 aktuellen Diskussio
Page 69 and 70: Kerntechnik 2024 69 Programmvorscha
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Page 73 and 74: Kerntechnik 2024 73 Poster Session
Page 75 and 76: Kerntechnik 2024 75 Unsere Partner
Page 77 and 78: KTG Inside 77 Mitgliederversammlung
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atw - International Journal for Nuclear Power | 03.2024

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