Predicting release rates of hydrogen from stainless steel

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Decorative photograph showing electrolysis cellThe influence of hydrogen on the structural integrity of nuclear power plant, where water molecules in the coolant circuit can be split by electrolysis or radiolysis to produce hydrogen, has been a concern to engineers for decades.  However, plans for a hydrogen economy and commercial fusion reactors, in which plasma-facing structural components will likely be exposed to hydrogen, has accelerated interest in understanding the complex interactions of hydrogen with metals, especially in the presence of irradiation.  A key step in advancing our understanding of these interactions is the measurement and prediction of the uptake and release of hydrogen by key structural materials.  We have recently published a study in Scientific Reports in which we developed a method for predicting the amount hydrogen in a steel under test conditions.  We used a sample of stainless steel as an electrode (cathode) in an electrolysis cell that split water molecules producing hydrogen atoms that were attracted to the steel. After loading the steel with hydrogen in the cell, we measured the rate of release of the hydrogen from the steel over two minutes by monitoring the drop in current in the cell, using a technique called potentiostatic discharge.  We used our measurements to calibrate a model of hydrogen release rate, based on Fick’s second law of diffusion, which relates the rate of hydrogen motion (diffusion) to the surface area perpendicular to the motion and the concentration gradient in the direction of motion.  Finally, we used our calibrated model to predict the release rate of hydrogen over 24 hours and checked our predictions using a second measurement based on the hydrogen released when the steel was melted.  So, now we have a method of predicting the amount of hydrogen in a steel remaining in a sample many hours after exposure during electrolysis without destroying the test sample.  This will allow us to perform better defined tests on the influence of hydrogen on the performance of stainless steel in the extreme environments of fission and fusion reactors.

Source:

Weihrauch M, Patel M, Patterson EA. Measurements and predictions of diffusible hydrogen escape and absorption in cathodically charged 316LN austenitic stainless steel. Scientific Reports. 13(1):10545, 2023.

Image:

Figure 2a from Weihrauch et al , 2023 showing electrolysis cell setup for potentiostatic discharge experiments.

Clouds, bees and artificial friends

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Decorative image of a bee on a flowerAnthropomorphism featured in several of the books that I read during my recent digital detox [see ‘Entropy and junkies‘ on August 2nd, 2023].  I really liked the opening section of ‘When I Sing, Mountains Dance‘ by Irene Sola which is narrated from the perspective of clouds that arrive over a landscape with painfully full ‘black bellies, burdened with cold, dark water, lightening bolts, thunderclaps.’  Her poetic prose, beautifully translated from the Catalan by Mara Faye Lethem, is wonderfully evocative and explores the complex relationship between people and the land they inhabit.  I was less impressed with a fig tree as a narrator in Elif Shafak’s novel ‘The Island of Missing Trees‘.  There was too much emphasis on facts about trees and their relationship to the fauna and flora around them which are well-described in recent non-fiction books [see, for example, ‘Tree are amongst the slowest moving being with which we share our world‘ on October 16th, 2019 and ‘The rest of the planat has been waiting patiently for us to figure it out‘ on September 21st, 2022].  However, I did enjoy the bee’s eye perspective on being trapped in a room when someone closed the window through which the bee had flown to find out what was happening inside.  At the moment, I am reading ‘Klara and the Sun‘ by Kazou Ishiguro, which is told from the perspective of Klara, an Artificial Friend or AF, and is in a similar vein to ‘Frankisstein‘ by Jeanette Winterson and ‘Machines like Me‘ by Ian McEwan [see ‘Where is AI on the hype curve?‘ on August 12th, 2020].

 

Is it time to change priorities on climate change?

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It seems unlikely that global warming will be limited to only 1.5 degrees Centigrade above pre-industrial levels in the light of recent trends in temperature data [see ‘It was hot in June and its getting hotter’ on July 12th, 2023 ]. It is probable global warming will lead to average surface temperatures on the planet rising by 4 or 5 degrees, perhaps within a matter of decades.  A global average temperature rise of only 2 degrees would make the Earth as warm as it was 3 million years ago when sea levels were 25 to 35 m (80 to 130 ft) high (Blockstein & Wiegman, 2010).  While it is still important to aim for zero carbon emissions in order to limit global warming and avoid global temperatures reaching a tipping point, it seems improbable that politicians worldwide will be able to agree and implement effective actions to achieve the goal in part because of the massive, vested interests in industrialised economies based on fossil fuels [see ‘Are we all free-riders?’ On April 6th, 2016].  Hence, we need to start planning for potentially existential changes in the climate and environment that will force us to adapt the way we live and work.  In addition to rises in sea levels, a world that is 4 degrees hotter is likely to have an equatorial belt with high humidity causing heat stress across tropical regions that make them uninhabitable for most of the year. To the north and south of this equatorial belt will be mid-latitude belts of inhospitable deserts extending as far north as a line through Liverpool, Manchester, Hamburg, the straits north of Sapporo in Japan, Prince Rupert in British Columbia and Waskaganish on the Hudson Bay.  The habitable zones for humans are likely to be north of this line and in the south in Antarctica, Patagonia, Tasmania and the south island of New Zealand.  Agriculture will probably be viable in these polar regions but will compete with a very dense population [see ‘Belts of habitability in a 4° world’ in Nomad Century by Gaia Vince].  In other words, there will likely be mass migrations that will force a re-organisation of society and a restructuring of our economies.  Some estimates suggest that there could be as many as 1.2 billion environmental migrants by 2050 (Bellizzi et al, 2023).  We need to start adapting now, the world around us is already adapting [see ‘Collaboration and competition’ on June 8th, 2022].

Napping, releasing the soul and brain maintenance

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Decorative photograph of painting: The Punishment of Lust.I read recently about the renovation of a small Parisian flat into a single office for the writer, Simon Kuper (How I made my perfect office).  The furniture included a sofa by the window for his post-lunch 15-minute nap (20 minutes on a bad day).  There was a brief period when I regularly had a nap in my office in the middle of day.  Now, I regularly nap at the weekend in the afternoon, or a weekday in the early evening after dinner.  Research has found short daytime naps improve cognitive performance (Lovato & Lin, 2010) and may help to preserve brain health by slowing the rate at which the brain shrinks with age (Paz et al, 2023).  So, short naps are probably good for you, though longer naps have been associated with reductions in cognition, the ability to think and form memories (Li et al, 2016) as well as increased blood pressure (Vizmanos et al, 2023).  In his outstanding novel, ‘The Salt of the Earth‘, Jozef Wittlin describes sleep as releasing or giving freedom to the soul.  Perhaps it is the wandering of the soul that we sometime recall as dreams.  On a more sinister note, sleep is described as practice for death by Ernesto Sabato in his novel, ‘On Heroes and Tombs‘, when presumably our soul is released forever to drift to Nirvana as in Giovanni Segantini’s painting ‘The punishment of lust’ in which the souls of neglectful mothers are shown floating towards the mountains representing Nirvana, a Buddhist heaven.  In the light of the inevitability of death, I quite like the idea that we can practice for it; however, I prefer to think of naps preserving my aging brain and improving my cognition.

Image: photograph of ‘The punishment of lust’ by Giovanni Segantini in the Walker Gallery, Liverpool.