Tag Archives: nuclear energy

Reliable predictions of non-Newtonian flows of sludge

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Regular readers of this blog will be aware that I have been working for many years on validation processes for computational models of structures employed in a wide range of sectors, including aerospace engineering [see ‘The blind leading the blind’ on May 27th, 2020] and nuclear energy [see ‘Million to one’ on November 21st, 2018].  Validation is determining the extent to which predictions from a model are representative of behaviour in the real-world [see ‘Model validation’ on September 18th, 2012].  More recently, I have been working on model credibility, which is the willingness of people, besides the modeller, to use the predictions from models in decision-making [see, for example, ‘Credible predictions for regulatory decision-making’ on December 9th, 2020].  I have started to consider the complex world of predictive modelling of fluid flow and I am hoping to start a collaboration with a new colleague on the flow of sludges.  Sludges are more common than you might think but we are interested in modelling the flow of waste, both wastewater (sewage) and nuclear wastes.  We have a PhD studentship available sponsored jointly by the GREEN CDT and the National Nuclear Laboratory.  The project is interdisciplinary in two dimensions because it will combine experiments and simulations as well as uniting ideas from solid mechanics and fluid mechanics.  The integration of concepts and technologies across these boundaries brings a level of adventure to the project which will be countered by building on well-established research in solid mechanics on quantitative comparisons of measurements and predictions and by employing current numerical and experimental work on wastewater sludges.  If you are interested or know someone who might want to join our research then you can find out more here.

Image: Sewage sludge disposal in Germany: Andrea Roskosch / UBA

Structural damage assessment using infrared detectors in fusion environments

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Schematic representation of plasma flux in a fusion reactorAbout six months ago, I described the success of my research group in detecting the early stages of the development of damage in structural components using small, cheap devices based on infrared measurements [see ‘Seeing small changes is a big achievement‘ on October 26th, 2022] after it had been reported in the Proceedings of the Royal Society.  The research was motivated by the needs of the aerospace industry and largely supported via the European Union’s Horizon 2020 research and innovation programme.  We are planning to extend the research to allow our technology to be used for diagnostics in future fusion power plants.  Plasma facing components in these powerplants will experience significant structural and functional degradation in service due to the extreme condition in the reactor.  Our aim is to develop systems based on our infrared monitoring technology that can identify and track material degradation without the need for plant shutdown thereby enabling unplanned maintenance to be undertaken at the earliest sign of component failure.  We are collaborating with the UKAEA and are looking to recruit a PhD student to work on the project supported by the GREEN CDT and Eurofusion.  If you are interested or know someone who might be interested then please follow this link for more information.

Reference:

Amjad, K., Lambert, C.A., Middleton, C.A., Greene, R.J., Patterson, E.A., 2022, A thermal emissions-based real-time monitoring system for in situ detection of cracks, Proc. R. Soc. A., 478: 20210796.

Admiral’s comments on fission hold for fusion 70 years later

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Last month the US Energy Secretary, Jennifer Granholm announced a successful experiment at the Lawrence Livermore National Laboratory in which 192 lasers were used to pump 2.05 mega Joules of energy into a capsule heating its contents to 100 million degrees Centigrade causing fusion of hydrogen nuclei and the release of 3.15 mega Joules of energy.  An apparent gain of 1.1 mega Joules until you take account of the 300 mega Joules consumed by the 192 lasers.  The reaction in the media to this fusion energy experiment and the difficulties associated with building a practical fusion power plant, such as the Spherical Tokamak Energy Production (STEP) project in the UK (see ‘Celebrating engineering success‘ on November 11th, 2022) reminded me of a well-known memorandum penned by Admiral Rickover in 1953.  Rickover was first tasked, as a Captain, to look at atomic power in May 1946 not long after first human-made self-sustaining nuclear chain reaction was initiated in Chicago Pile #1 during an experiment led by Enrico Fermi in 1942.  He went on to become Admiral Rickover who directed the US Navy’s nuclear propulsion programme and the Nautilus, the first nuclear-powered submarine was launched in 1954.  With thanks to a regular reader of this blog who sent me a copy of the memo and apologies to Admiral Rickover, here is his memorandum edited to apply to fusion energy:

Important decisions about the future of fusion energy must frequently be made by people who do not necessarily have an intimate knowledge of the technical aspects of fusion.  These people are, nonetheless, interested in what a fusion power plant will do, how much it will cost, how long it will take to build and how long and how well it will operate.  When they attempt to learn these things, they become aware the confusion existing in the field of fusion energy.  There appears to be unresolved conflict on almost every issue that arises.

I believe that the confusion stems from a failure to distinguish between the academic and the practical.  These apparent conflicts can usually be explained only when the various aspects of the issue are resolved into their academic and practical components. To aid in this resolution, it is possible to define in a general way those characteristics which distinguish one from the other.

An academic fusion reactor almost always has the following basic characteristics: (1) It is simple. (2) It is small.  (3) It is cheap. (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose . (7) The reactor is in the study phase.  It is not being built now.  On the other hand, a practical fusion reactor can be distinguished by the following characteristics: (1) It is being built now.  (2) It is behind schedule. (3) It is requiring an immense amount of development on apparently trivial items. (4) It is very expensive. (5) It takes a long time to build because of the engineering development problems. (6) It is large. (7) It is complicated.

The tools of the academic-reactor designer are a piece of paper and a pencil with an eraser. If a mistake is made, it can always be erased and changed.  If a mistake is made, it can always be erased and changed.  If the practical-reactor designer errs, they wear the mistake around their neck; it cannot be erased.  Everyone can see it. 

The academic-reactor designer is a dilettante.  They have not had to assume any real responsibility in connection with their projects.  They are free to luxuriate in elegant ideas, the practical shortcomings of which can be relegated to the category of ‘mere technical details’.  The practical-reactor designer must live with these same technical details.  Although recalcitrant and awkward, they must be solved and cannot be put off until tomorrow.  Their solutions require people, time and money.

Unfortunately for those who must make far-reaching decisions without the benefit of an intimate knowledge of fusion technology and unfortunately for the interested public, it is much easier to get the academic side of an issue than the practical side. For the large part those involved with academic fusion reactors have more inclination and time to present their ideas in reports and orally to those who will listen.  Since they are innocently unaware of the real and hidden difficulties of their plans, they speak with great facility and confidence.  Those involved with practical fusion reactors, humbled by their experiences, speak less and worry more.

Yet it is incumbent on those in high places to make wise decisions, and it is reasonable and important that the public be correctly informed.  It is consequently incumbent on all of us to state the facts as forth-rightly as possible.  Although it is probably impossible to have fusion technology ideas labelled as ‘practical’ or ‘academic’ by the authors, it is worthwhile both authors and the audience to bear in mind this distinction and to be guided thereby.

Image: The target chamber of LLNL’s National Ignition Facility, where 192 laser beams delivered more than 2 million joules of ultraviolet energy to a tiny fuel pellet to create fusion ignition on Dec. 5, 2022 from https://www.llnl.gov/news/national-ignition-facility-achieves-fusion-ignition

Horsepower driving ambition

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A photograph of 'Physical Energy' in Kensington Gardens - a sculpture of a man on a horseWalking across Kensington Gardens in London last week, on my way to attend a conference on Carbon, I came across the sculpture in the picture.  It is ‘Physical Energy’ by George Frederick Watts (1817 – 1904), which really confused me because I automatically started thinking about the sort of energy that is associated with horsepower.  Horsepower is a unit of power (energy per unit time) developed by James Watt (1736 – 1819) to evaluate the output of his steam engines.  The plaque below the sculpture calls it a ‘sculptural masterpiece; a universal embodiment of the dynamic force of ambition’ and states that the artist described it as a ‘symbol of that restless physical impulse to seek the still unachieved in the domain of physical things.’  So, while the connections seemed obvious to me, it would appear that Watts was not inspired by Watt.

The conference was interesting too.  There were delegates from all over the world presenting research on a wide range of topics from new designs of batteries to using carbon as an sorbent for toxins, carbon-based composites and self-assembly of metal-organic meso-crystals.  Two students that I have supervised were presenting their research on establishing credibility for models of the graphite core in nuclear power plants and on algorithms for identifying the surface morphology in samples of graphite.