October 14, 2017

Despacito/Desparate Cheeto.

A senior person in my wife's office is a Trumper; and she was out yesterday, and the group left behind, including one American native of Puerto Rico, had a celebration of "Less than Sympathy for the Devil.".

As an old guy decidedly on the Nerdist side, I'm certainly unaware of what's the hottest and most notable Pop Music.

But I understand this song, allegedly slightly oversexed (I don't speak Spanish) from the devastated American island of Puerto Rico hated by the racist in chief is a big hit:

<iframe width="854" height="480" src="

" frameborder="0" allowfullscreen></iframe>

My wife showed me this video yesterday, so that I could understand the humor of "Desperate Cheeto."

<iframe width="854" height="480" src="" frameborder="0" allowfullscreen></iframe>

Enjoy

October 12, 2017

Two Interesting Papers On the Utilization of Low Grade Heat.

It is an incontrovertible law of thermodynamics - the famous second law - that the system that can sustain the highest temperatures will be the most efficient.

In the dangerous natural gas industry, which is the fastest growing energy business in the world - if one is intelligent enough and educated enough to understand that the peak power of a so called "renewable energy" facility is nowhere near its average continuous power (intelligence and education which seem increasingly rare) - the most efficient systems are combined cycle system, which can demonstrate efficiency of close to 60%. In a combined cycle gas plant the gas is burned and expands against a turbine, its temperature actually exceeding the melting point of the turbine blades, were they not coated with thermal barrier coatings. The exhaust leaving the turbine is still hot enough to boil water even under pressure, and as such is used to power a standard Rankine steam cycle.

I discussed this state of affairs in a relatively recent post in this space (An interesting thesis on the utility of MAX phases in the manufacture of turbine blades.

Despite its use in high efficiency systems, and despite having the so called "renewable energy" industry function as a smokescreen for its use, natural gas is not sustainable. It's continued use is a crime against all future generations, humans who are babies today, and humans who will be babies 500 years from now, assuming that there will be humans in 500 years.

The only sustainable form of energy is nuclear energy, whether we admit it to ourselves or prefer going along stupidly claiming otherwise, and nuclear energy, and only nuclear energy is capable of continuously providing combustion free high temperatures.

The problem of course is that the laws of thermodynamics require that the heat must go somewhere, and usually that "somewhere" is most often a body of water. (This is true not only for nuclear plants, but is also true of gas plants and coal plants. This is the subject of considerable public ignorance which assumes, incorrectly, that only nuclear plants have cooling towers.) Where thermal electric plants operate away from ocean water, they are generally net water consumers. This point is made in the first of the two papers I will briefly discuss in this post: A Combined Heat- and Power-Driven Membrane Capacitive Deionization System (Hatzel, Hatzel and Zhang, Environ. Sci. Technol. Lett., Article ASAP Published online October 2, 2017)

The paper is open sourced, anyone can read it.

The introduction says it all:

Managing energy consumption during water treatment processes and water use during energy generation is a critical component of the water–energy nexus.(1) Thermoelectric power plants account for 38% of fresh water withdrawals in the United States, and a majority of this water is used for on-site cooling (?80%) and power generation (?10%).(2, 3) Technologically, dry cooling could aid in minimizing the demand for water during cooling, and low-energy water treatment technologies could reduce the amount of energy spent on boiler water treatment. Furthermore, improvements made in treating boiler water have a direct impact on improving plant thermal efficiencies, as high total dissolved solids (TDS) result in a low rate of heat transfer due to corrosion and fouling.(4) Boiler water treatment will become increasingly important because high-efficiency supercritical based power plants require more stringent water quality.(4)

Treating water to pure and ultrapure levels can be energy intensive and traditionally requires treatment strategies that combine softening with multiple passes through a reverse osmosis (RO) system. Most energy generation and industrial sites that require pure water also have access to an abundance of waste heat, which could act as an ideal free energy source for water treatment.(5) Therefore, developing synergistic approaches to use this “waste energy” source has become desirable. Currently, indirect and direct means for converting low-grade waste heat into deionized water do exist. Indirect approaches include those that convert heat to power through technologies such as thermoelectric devices and then use that power to operate a water treatment system.(6) While possible, undesirable energy conversion losses, larger system footprints, and cost typically limit their practical implementation.

Here is what the authors claim:

Here, we aim to detail a process for harvesting thermal energy within an electrochemically driven deionization system termed membrane capacitive deionization (MCDI). MCDI offers several advantages for effective brackish water treatment (low specific energy consumption), yet is purely driven by electrical energy.(14) We experimentally investigate the potential for harvesting thermal energy through exploiting the electrostatic and membrane potentials dependence on temperature. We also highlight the role heat plays in limiting losses that arise when moving MCDI toward high-water recovery operating conditions.

The details are in the paper, which is, again, open sourced.

Here's a nice cartoon that suggests what is going on:



This desalination system consumes electricity, but does so more efficiently than, for example, reverse osmosis, and it utilizes low grade heat in such a way as to eliminate its disposal to water.

Some comments on desalination. I'm not entirely sanguine about desalination, owing to a concern about changes to ocean currents deriving from saline gradients. This is probably not quite as serious as changing planetary weather patterns as the wind industry proposes to do - I've seen several very silly references in the the literature to using wind turbines to stop hurricanes, one proposed by the anti-nuke idiot Mark Z. Jacobsen at Stanford, which suggests (were it true, undoubtedly its not) that wind turbines can stop the, um, wind. This said, changing salt gradients in the ocean is certainly problematic. (Happily the wind industry is too expensive and useless to actually produce significant energy, so weather patterns are safe for the time being.)

However, desalination may be a risk that future generations may have to assume, since we have left them with nothing other than trillion ton quantities of dangerous fossil fuel waste.

I note that the concentration of carbon dioxide on a volumetric scale is much higher in seawater than in air, which suggests that if one were trying to remove dangerous fossil fuel waste from the atmosphere, the processing of seawater would be a key to accomplishing that task - if it can be achieved. I've written about that in this space elsewhere.

Another paper I've seen on waste heat, written by Mexican scientists (both of whom are far more intelligent than that orange excuse for a human being in the White House) proposes to add a third layer to a combined cycle system by using a working fluid that boils at temperatures much lower than that of water, 100C.

Here is the paper, which is regrettably not open sourced but must be obtained in a good science library: Thermo-Economic Multiobjective Optimization of a LOW Temperature Organic Rankine Cycle for Energy Recovery (Ruben Omar Bernal-Lara† and Antonio Flores-Tlacuahuac Ind. Eng. Chem. Res., 2017, 56 (40), pp 11477–11495)

Here is the introduction:

The high energy demand in the world in the last years has become a focus of attention for researchers due to the constant quest of alternative processes to produce power in a economic way and low environmental impact. The recovery of energy from waste heat streams is an example of an alternative energy process seeking to meet energy demand and taking care of sustainability issues.1,2 In fact, waste heat sources are commonly found in solar and geothermal sources, as well as in industrial process streams. Thermodynamic cycles have been widely studied to use waste heat sources and produce power.3?5 Most of those cycles use water as working fluid for low-temperature energy recovery. The most common thermodynamic cycle is the water Rankine cycle. However, the thermodynamic efficiency of the Rankine cycle is low at temperatures below 370 °C.6 To improve the performance of the Rankine cycle for lowtemperature energy recovery, the Organic Rankine Cycle (ORC), featuring organic compounds as working fluids, has been proposed. 1 Organic compounds are good candidates as working fluids because of their low boiling point, low medium vapor pressure, and high vaporization enthalpy at low temperature ranges.

Unfortunately several of the working fluids in these systems are in fact, HFC's (and even one banned CFC), all of which are potent greenhouse gases in their own right; a safer and more sustainable option would be to use flammable working fluids, and several are examined, including cyclopropane, n-butane, isobutane and n-pentane.

This is a math heavy paper - clearly over the head of an American President with tiny hands and an even tinier brain - but the point is well taken. No matter how one goes about this matter however, all these systems require a low temperature heat sink. It's not clear that, since we have elected to do absolutely nothing about climate change except to post ever more absurd fantasies about the so called "renewable energy" nirvana which did not come, is not here and will never come, there will be appropriate low temperature heat sinks in the future, almost certainly not in Mexico.

Here is a nice graphic that touches on the cost of these systems:



Here is the Pareto curve and a schematic cartoon of the system:



I have been thinking and reading about approaches to waste heat utilization for some time - these are just two examples - and note that there are many other useful things that might be done with it, but those are subjects for another day.

Have a nice day tomorrow.

October 9, 2017

Zeolites for the Rapid and Selective Uptake of Cesium.

If you were born after the late 1940's or early 1950's you have always been "contaminated" with the radionuclide cesium-137.

This isotope was released in large quantities during the era of open air nuclear weapons testing, and a clearly detectable amount of it usually leaks out after underground nuclear weapons testing. The isotope is so ubiquitous that it is often utilized as a tracer to understand soil erosion.

I explored this issue of nuclear testing and its relationship to modern soil testing elsewhere: Every Cloud Has A Silver Lining, Even Mushroom Clouds: Cs-137 and Watching the Soil Die.

Of course, this isotope was also released by the nuclear screw up at Chernobyl as well as the failure of the Fukushima reactors in a natural disaster.

As it happens, the amount of radioactivity cesium-137 leaching into the oceans from the Fukushima event are trivial when compared with the natural radioactivity of the ocean, which is largely connected with the huge amounts of naturally occurring (and impossible to avoid) potassium-40 and the polonium-210 which is a product of the decay series. This point was clearly made in the famous "Fukushima Tuna" paper, which was immediately and grotesquely misinterpreted by journalists around the world, causing a fair amount of hysterical gas and coal burning to power computers for people who can't read a scientific paper (or anything else) very well leading them to freak out and announce we're all going to die because of Fukushima.

We didn't.

Here is a link to the famous Fukushima Tuna paper: Pacific bluefin tuna transport Fukushima-derived radionuclides from Japan to California


Here is the text comparing the Fukushima radioactivity with the natural radioactivity that has always been in the ocean and always will be in the ocean, no matter how much we do - and we're doing a lot of it with dangerous fossil fuels - to destroy the ocean:

Inferences about the safety of consuming radioactivity-contaminated seafood can be complicated due to complexities in translating food concentration to actual dose to humans (12), but it is important to put the anthropogenic radioactivity levels in the context of naturally occurring radioactivity. Total radiocesium concentrations of post-Fukushima PBFT were approximately thirty times less than concentrations of naturally occurring 40K in post-Fukushima PBFT and YFT and pre-Fukushima PBFT (Table 1). Furthermore, before the Fukushima release the dose to human consumers of fish from 137Cs was estimated to be 0.5% of that from the ?-emitting 210Po (derived from the decay of 238U, naturally occurring, ubiquitous and relatively nonvarying in the oceans and its biota (13); not measured here) in those same fish (12). Thus, even though 2011 PBFT showed a 10-fold increase in radiocesium concentrations, 134Cs and 137Cs would still likely provide low doses of radioactivity relative to naturally occurring radionuclides, particularly 210Po and 40K.

Here is another paper in the same journal by the same authors (with a few added to boot) complaining about the stupidity, fear, and ignorance with which their original paper, which was about the migration of Tuna and not about risk to human health, was handled by the media and the general public:

Evaluation of radiation doses and associated risk from the Fukushima nuclear accident to marine biota and human consumers of seafood (Madigan et al, PNAS, 110, 26, 10670-10675.)

Recent reports describing the presence of radionuclides released from the damaged Fukushima Daiichi nuclear power plant in Pacific biota (1, 2) have aroused worldwide attention and concern. For example, the discovery of 134Cs and 137Cs in Pacific bluefin tuna (Thunnus orientalis; PBFT) that migrated from Japan to California waters (2) was covered by >1,100 newspapers worldwide and numerous internet, television, and radio outlets. Such widespread coverage reflects the public’s concern and general fear of radiation. Concerns are particularly acute if the artificial radionuclides are in human food items such as seafood. Although statements were released by government authorities, and indeed by the authors of these papers, indicating that radionuclide concentrations were well below all national safety food limits, the media and public failed to respond in measure. The mismatch between actual risk and the public’s perception of risk may be in part because these studies reported radionuclide activity concentrations in tissues of marine biota but did not report dose estimates and predicted health risks for the biota or for human consumers of contaminated seafood. We have therefore calculated the radiation doses absorbed by diverse marine biota in which radioactivity was quantified (1, 2) and humans that potentially consume contaminated PBFT

Never underestimate the power of stupidity.

The ocean contains about 530 billion curies of potassium-40, which corresponds to about 2 times 10 to the 22nd power nuclear decays per second, or since, there are 31,556,736 seconds in a sidereal year, 6.2 times 10 to 29th power per year. The specific activity of cesium is 3.12 times 10 to the 12th power bequerels per gram, meaning that to match the natural radioactivity associated with radiopotassium in the ocean, we would need to deliberately and directly dump 6100 tons of cesium-137 directly into the ocean. However, this is more radiocesium, by orders of magnitude, than has ever been produced by all the world's nuclear reactors operating - and all the nuclear weapons detonations - for more than half a century.

In high concentrations, in any case, Cs-137 can and does represent a real risk, not quite the same risk as dangerous fossil fuel waste which kills half of the seven million people who die each year from air pollution, the other half being killed by the combustion products of "renewable" biomass.

Further, it turns out that as a strong gamma radiation emitter, cesium-137 should be regarded as an extremely valuable material for mineralizing the vast amounts of halocarbons that have been dumped into the environment, where they represent a huge risk. These are the fluorocarbons like PFOS, chlorocarbons like the famous CFC's, the extremely toxic PCBs, certain insecticides like DDT, and the awful business about brominated flame retardants like the PBDE's and their related compounds.

Thus it is a pretty bad idea to throw this stuff away, either in the idiotic notion of waste dumps, or by either deliberate or unintentional release. Thus we need to recover this stuff in order to utilize it.

Thus it is with interest I came across this paper for highly selective removal of cesium from dilute solutions:

Highly Selective and Rapid Uptake of Radionuclide Cesium Based on Robust Zeolitic Chalcogenide via Stepwise Ion-Exchange Strategy (Feng et al Chem. Mater. 2016, 28, 8774?8780)

From the introduction:

As an efficient and low-carbon power generation method, nuclear power plays a critical role in meeting the increasing energy needs. However, nuclear wastes and reactor accidents could result in the leak of radionuclides into environments, which is a key reason limiting more widespread use of nuclear energy.1,2 Among various radioactive nuclides, 137Cs+ is the most hazardous due to its high fission yield (6.09%), long halflife (?30 years), and high solubility.3?5 When accidentally released to the sea or ground, it must be decontaminated immediately for public safety. The 137Cs+ ions also need to be recycled effectively from nuclear waste solutions in the reprocessing plants. Therefore, for 137Cs+ cleanup, high selectivity for Cs+ in the presence of relatively high concentration of competing cations (Na+, K+, Ca2+, Mg2+), fast kinetics, and commercial availability are desired in largescale application.6

The authors then describe some problems systems similar to the one they synthesize here were, and claim to address them:

For ion-exchange applications, maximizing the concentration of exchangeable cations is of critical importance for the process efficiency. The concentration of cations in traditional oxidebased zeolites is determined by the framework Al3+/Si4+ molar ratio which has a maximum value of 1 due to the Löwenstein’s rule (as in NaAlSiO4). Surprisingly, the Löwenstein’s rule is not obeyed in zeolite-type metal chalcogenides so that M3+/M4+ ratio can be significantly great than 1.31 This motivates us to initiate investigating the ion-exchange applications of such materials, because we expect that the large negative charge of framework and the associated high concentration of exchangeable cations will lead to a record-high cation exchange capacity. In addition, unlike low-dimensional materials, these zeolite-type chalocgenides have 3-D multidimensional, and mutually intersecting channels that could greatly facilitate ion diffusion and ion exchange kinetics. At the early stage of this study, we encountered a major obstacle to unlock the aforementioned intrinsic advantages of zeolite-type chalcogenides. Specifically, the as-synthesized materials typically contain bulky protonated amines in the channels and their ion exchange process is quite sluggish. 29,32?34

Herein we designed a two-step ion-exchange strategy to address this issue (Scheme 1). In this work, we selected a highly stable and porous amine-directed zeolitic chalcogenide framework, namely UCR-20 (zeolite type code: RWY).34,35 We demonstrated that the protonated amines located in its channels can be exchanged completely into “hard” alkali ions through the stepwise ion-exchange strategy. Interestingly, the K+-exchanged RWY (K@RWY) can rapidly capture Cs+ with high selectivity. This material also shows an excellent ability for Cs+ capture from real water samples including potable water and even seawater.

Here's a cute cartoon of their approach:



Here's some graphic data:



The caption:

Figure 2. (a) Equilibrium curve for cesium uptake fitted by Langmuir model with Ci = 1?500 ppm (RT, V:m = 1000 mL/g). (b) Distribution coefficient and removal efficiency for cesium uptake under different initial concentrations. (c) Adsorption kinetics of K@ RWY and Pristine RWY for Cs+ uptake with initial concentration around 50 ppm at room temperature (V:m = 1000 mL/g). (d) pH dependent cesium uptake. The initial concentrations were set to 10 ppm.

Their conclusion:

In conclusion, we designed and successfully realized a stepwise ion-exchange strategy based on zeolitic chalcogenide (RWY) to replace the organic amines in the channels with “hard” K+. The K@RWY could rapidly capture Cs+ with excellent selectivity, high capacity, good resistance against acid and alkali, and excellent resistance to ?- and ? irradiation. High selectivity of Cs+ uptake against Na+, K+, Ca2+, and Mg2+ has been confirmed by further competitive ion exchange experiments. It should also be noted that K@RWY could capture Cs+ efficiently in real water samples including seawater with trace levels. The results indicated that K@RWY is a very promising ion exchanger for the removal of radioactive 137Cs+. Because amine-directed chalcogenide frameworks are a large family of compounds with various compositions and topologies, this strategy reported here could greatly extend the applications of this family of materials to nuclear waste remediation and toxic metal sequestration.

Nice work I think.

Enjoy the coming workweek.

October 8, 2017

Conjugated Polymeric Photosensitizers for Photodynamic Cancer Therapy.

I stumbled upon a very cool paper this afternoon on cancer therapy.

It's here: Two-Dimensional Fully Conjugated Polymeric Photosensitizers for Advanced Photodynamic Therapy (Dai et alChem. Mater., 2016, 28 (23), pp 8651–8658)

Many people are aware that radiation can both cause and cure cancer - sometimes do both - and the mechanism by which this takes place often involves highly energetic species, often free radicals. Of course, "radiation" is a broad term; it applies not just high energy radiation, but also to light, radio waves, microwaves and radiant heat (infrared). The most efficient forms of energy for providing free radicals are high energy, UV radiation (as in the generation of sunburns and melanoma), x-rays, and gamma rays. However, under certain circumstances lower energy radiation can generate reactive species. That's what this paper refers to doing.

Photodynamic therapy is a therapy that generates reactive oxygen species (high energy species) that can react locally with cancer cells and kill them. However since human tissue is opaque, the idea is to use light waves that can penetrate tissue without depositing energy. As people who have used microwaves and understand something about how they work, know, radio and infrared radiation can do this.

From the introductory text:

Photodynamic therapy (PDT) has attracted tremendous attention as an emerging clinical modality for treatment of neoplastic and nonmalignant lesions, including cancers of the head and neck, brain, lung, pancreas, intraperitoneal cavity, breast, prostate, and skin, to name a few.(1-3) PDT generally involves photoexcitation of a photosensitizer, which transfers energy to surrounding O2 to generate reactive oxygen species (ROS), especially singlet oxygen (1O2),(4) to impart a selective irreversible cytotoxic process to malignant cells with respect to noncancerous tissues. PDT with an optical precision could show a minimal toxicity to normal tissues, negligible systemic (organ) or long-term effect, and excellent cosmetic appeal. However, the near-infrared (NIR) light is often required to effectively penetrate biological tissues, such as skin and blood, with minimal normal tissue damage.(2, 4) This is because visible light below 700 nm cannot penetrate deep into tissues with a high level of endogenous scatters and/or absorbers, such as oxy-/deoxy-hemoglobin, lipids, and water, in skin and blood.(5) Therefore, it is important to develop efficient photosensitizers with strong absorption in the desired therapeutic window (particularly, 700–1000 nm) for advanced PDT.

Porphyrin, a conjugated macrocycle with intense optical absorption, plays important roles in our life (e.g., in heme to act as a cofactor of the protein hemoglobin) and has been widely used as a photosensitizing reagent for PDT.(2) Due to the short conjugation length intrinsically associated with individual porphyrin macrocycles of a limited size, however, most of the clinically approved porphyrin-based photosensitizers show optical absorption well below 700 nm with insignificant absorption within the tissue transparency window (e.g., 700–900 nm)2. As a typical example, porfimer sodium (Photofrins), one of the widely used clinical PDT agents, with oligomeric porphyrin units being linked by nonconjugated ester and ether linkages to gain solubility, shows diminished absorption above 630 nm.(6) Therefore, it is highly desirable to develop new photosensitizers of a long conjugation length with alternating C–C single and C═C double bonds, and hence efficient absorption within the tissue transparency window (e.g., 700–900 nm).

Here's a picture of the molecules they make:



The reactive molecule they generate with these species is "singlet oxygen"

Mechanism study on singlet oxygen generation

To study the mechanism of singlet oxygen generation from photoirradiation of COP-P-SO3H, we performed the first-principles calculations with B3LYP hybrid density functional theory with the Gaussian program(15) based on the cluster model derived from the above experimental characterization data. Our calculations revealed that O2 molecules prefer to adsorb via the Yeager model(12, 27) (Figures S8–17 and Table S2) in COP-P-SO3H and that the optimized O2 adsorption site is on the top of the H-free pyrrolic N in the porphyrin ring (Figure S13). Furthermore, our molecular orbital calculations indicated that the HOMO is almost entirely localized in the porphyrin ring, being dominantly associated with the ?-bonding orbital from the pyrrolic N (No. 22 and No. 24 in Figure S18) and the ?-bonding orbital from the pyrrolic and methine bridge carbons in the porphyrin ring, while the LUMO is mainly associated with the ?-antibonding orbital from oxygen molecules and the ?-antibonding orbital from the pyrrolic ring and the methine bridge carbon in the porphyrin (Figure 7A). Clearly, therefore, the charge density distribution calculations indicate that the electron was dominantly transferred from pyrrolic N (No. 24 in Figure S18) to an oxygen molecule when it approached the porphyrin ring (Figure S19).

The conclusion:

In summary, we have, for the first time, developed a well water-dispersive, fully conjugated two-dimensional covalent organic polymer (i.e., COP-P-SO3H) via a facile and scalable, but very efficient and cost-effective, Yamamoto Ullmann cross-coupling of multiple porphyrin macrocycles through conjugated linkages followed by sulfonation. The resultant COP-P-SO3H of a good dispersiveness and low band gap exhibited strong optical absorption up to 1100 nm and acted as an efficient photosensitizer for advanced photodynamic therapy with a 20% higher singlet oxygen quantum yield than that of the clinically used protoporphyrin IX (PPIX), but a negligible cyto-/genotoxicity without light exposure. Compared to those isolated porphyrin macrocycles (e.g., PPIX, TBBPP), COP-P-SO3H, with fully conjugated multiple porphyrin macrocycles, could effectively generate singlet oxygen species during the PDT process to efficiently kill the breast tumor cells (MDA-MD-231 cells) through successive DNA damage, as revealed by the combined experimental and theoretical approach used in this study. This is the first time for 2D covalent organic polymers (COPs) to be used as efficient photosensitizers of practical significance for advanced PDT. This work clearly opens up exciting new applications for COPs as well as new avenues for the development of other novel 2D COPs for advanced cancer therapy and beyond.

The nice graphic overview:



Cool I think.

Enjoy your Sunday evening.

October 7, 2017

Frustrated Inner-City Students Running Out Of Ideas To Motivate Teachers

October 6, 2017

The Effect of Closing TVA Nuclear Plants on Infant Health.

I hadn't noticed, but Nature started a new Journal called Nature Energy. The parent journal is, of course, one of the world's most important scientific journals, and Google Scholar in fact rates it (in terms of h index) as the most prestigious journal.

No matter.

Having discovered the journal, and being interested in issues in Energy as they apply to climate change - which is getting worse, not better - I decided to leaf through some issues of this new journal.

I was pleased to find a paper on what I personally regard as the only acceptable form of centralized energy, nuclear energy.

The paper is here: Impacts of nuclear plant shutdown on coal-fired power generation and infant health in the Tennessee Valley in the 1980s (NATURE ENERGY 2, 17051 (2017))

Some excerpts from the text:

Nuclear accidents usually give rise to public backlash against nuclear energy. Three major accidents the 1979 Three Mile Island partial nuclear meltdown in the US, the 1986 Chernobyl disaster in the Soviet Union, and the 2011 Fukushima accident in Japan have led to the discontinuation of nuclear programs in several countries. After the Fukushima disaster, for instance, German support for nuclear energy dropped by about 20 per cent1, and Germany permanently shut down eight of its seventeen reactors, pledging to complete the phase-out by 2022. In the US, Fukushima added pressure to the power industry. Facing cheap natural gas, stalled carbon emissions legislation, and growing safety concerns, they eventually announced the closure of six large nuclear power plants2. Although the media has discussed the public health consequences of potential exposure to radioactivity associated with nuclear accidents extensively, emissions and health costs prevented by nuclear power generation have been overlooked.

"...stalled carbon emission legislation..."

"...cheap natural gas..."

In reference to the latter, I would ask, "cheap for whom?" The people who are using it while we all wait for the make believe solar and wind miracle that has not come, is not come and will never come, or for all future generations who will live with the consequences of the absolute and total failure of so called "renewable energy" to actually work?

More from the paper's text:

The Three Mile Island Unit 2 reactor partially melted down on 28 March 1979, near Middletown, Pennsylvania. Being the worst accident in US commercial nuclear power plant history, the accident crystallized anti-nuclear safety concerns among activists and the general public. Following the public backlash, the Nuclear Regulatory Commission (NRC) intensified inspections in nuclear facilities, leading to new regulations and the shutdown of several nuclear plants around the nation in the 1980s, including Browns Ferry and Sequoyah in the TVA area in 1985. At Browns Ferry, NRC inspectors identified 652 violations bet ween 1981 and 1984, and the agency imposed $413,000 (1986 USD) in fines9_11. In July 1984, the NRC issued an order requiring TVA to implement its Regulatory Performance Improvement Program (RPIP) and provide periodic reports. In February 1985, reactor vessel water level instrumentation problems happened in Unit 3, leading TVA to cease operations in March 19 at all three Browns Ferry units to undertake programmatic improvements. By September 1985, the NRC found the RPIP to be ineffective and required another plan from TVA. The shutdown of Browns Ferry would last for many years, as shown by the timeline in Fig. 1.

The timeline shows that the Sequoyah Nuclear Plant shut in August of 1985 and restarted in November of 1988, the Browns Ferry Reactors shut in 1985 with Browns Ferry 2 restarting in 1991, Browns Ferry 3 restarting in 1995, and Browns Ferry 1 restarting in 2007.

Wow! This reads like an account written by that anti-nuke asshole Ed Lyman over at the Union of Concerned "Scientists."

Bad huh? 652 violations, this while the plant was operating! It's a wonder everyone in the Tennessee Valley wasn't killed, just like everyone in Japan was killed by Fukushima and everyone in Harrisburg PA died from Three Mile Island.

The author continues:

In this study, I exploit the shutdown of nuclear facilities in the TVA after the Three Mile Island accident in 1979 to estimate its direct impact on coal-fired power generation, particle pollution as measured by total suspended particulate (TSP), and infant health as captured by birth weight, a health indicator that has high predictive power for later-life outcomes. In fact, low birth weight infants experience severe health and developmental diffculties that can impose large costs on society14. It has a negative e ect on IQ, height and earnings15, and an inverse relationship with adult mortality particularly cardiovascular mortality16.Using econometricmethods with plant-level monthly electricity generation data, county-level TSP concentration, and birth-level data, I find three key results.

Three key results:

First, the shutdown of nuclear facilities in the TVA in the 1980s led to a shift in electricity generation towards coal-fired power plants. The substitution between nuclear and coal seems to be one to one, that is, each megawatt-hour not produced by nuclear power plants because of the shutdown appears to have been generated by coal-powered plants. Second, air pollution increased substantially in counties where coal-fired plants were producing large shares of the electricity originally generated by the nuclear facilities. The additional coal burning triggered by the nuclear shutdown led to an increase in TSP concentration by around 10 _gm?3, which is equivalent to reversing the gains observed after two years of the implementation of the Clean Air Act Amendments of 1970 17. Third, and last, infant health may have deteriorated in places experiencing higher levels of air pollution induced by the nuclear shutdown. In fact, average birth weight in the most affected areas decreased considerably. The decline was approximately 134 g, or 5.4 per cent, which is large even when we rescale it by the change in TSP concentration.

Thank goodness the Tennessee Valley had people like Ed Lyman to protect its citizens from healthy full weight babies who would grow up to be intelligent, tall, human beings with a low incidence of heart disease and a normal life span.

The paper speaks for itself, but it is worth noting that the author kind of shrugs and says, more or less, "Well, we could always replace nuclear plants with natural gas."

Seven million people die each year from air pollution according to a paper I often reference from Lancet, which is by the way #4 on the Google Scholar list of the world's most prestigious scientific journals.

A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010 (Lancet 2012, 380, 2224–60: For air pollution mortality figures see Table 3, page 2238 and the text on page 2240.)

These papers speak for themselves, or should speak for themselves were it not for the fact that we on the left are only a little less willing to lie to ourselves than our opponents on the left.

Oh, and maybe you've been hearing that coal is dead because solar and wind energy are so wonderful. This too is a lie, a lie on a Trumpian scale.

If you don't think so, I consider it my duty to direct you to the EIA web page containing a graph of all electric power sources in the United States.

EIA ELECTRICITY DATA BROWSER

The graph is interactive, you can highlight the line associated with any form of energy by moving your cursor over the caption at the bottom for each form of energy.

After 50 years of cheering by people who hate nuclear energy because they are incompetent to understand a damned thing about it - but who are perfectly fine with dangerous natural gas because in their useless imaginations they regard it as "transitional" - the solar and wind industry combined can't even produce a fraction of the energy provided by nuclear energy using reactors mostly built 30 years ago by a generation of engineers this country can no longer match. To separate the (light blue) solar line from the x-axis, you may need a magnifying glass, and wind and hydroelectric are about tied for second closest to zero.

The fastest growing form of electrical energy generation in the United States, for anyone who can read a graph, is natural gas. The solar, wind, and hydroelectric industries are trivial in comparison to dangerous natural gas, and are in fact still trivial compared to coal.

The brown line is coal and it is more or less tied with dangerous natural gas for the #1 spot for fuels for electricity, after having been the chief supply of American electricity from the dawn of the 21st century up until 2015, when the surge in dangerous natural gas use - a crime against all future generations - began to surge.

By the way, there are no "Fossil Fuel Free" groups, few "Fossil Free" activists here at DU, except maybe me, even though we have had lots of "nuclear free" activists at DU, and of course a "nuclear free" group, not that I know all that much about them anymore after years of expressing my low opinion of their education and knowledge, since I've been liberally utilizing the wonderful "ignore" button here to address the worst and least educated of these people.

And if we care about the future, no, we can't always replace nuclear with natural gas. To do so, given the climate impact of this fuel, not to mention the permanent, irreversible damage to the subsurface structures through which much of water flows, is, again, a crime against all future generations, a crime more odious than low birth rates, short life spans, and impaired intellects. It is a crime that all future generations will not even have the resources to address, as we have selfishly determined to leave them with nothing.

It is difficult to think. It takes work. But, if you care about the future, and I personally regard this as an ethical imperative, it is your responsibility to do it.

Tomorrow's Friday. Enjoy it.

October 5, 2017

On the Solubility of Carbon Dioxide in Ionic Liquids.

A few years back, it was my privilege to attend this lecture, given at Princeton University, by Dr. Joan Brennecke of Notre Dame University on carbon dioxide capture using phase change ionic liquids:

"Ionic Liquids" are salts, generally where at least either the cation or the anion or both are organic molecules (although a few inorganic eutectic salts nearly qualify) that are liquids either near or at room temperature.

In my writing around the internet, I have never evinced a fondness for carbon capture of the dangerous fossil fuel waste carbon dioxide since I believe dangerous fossil fuels need to be phased out quickly.

However, to the extent that carbon dioxide can be removed from the atmosphere by biological materials, perhaps under reformation conditions at high temperatures provided by clean energy - by clean energy I mean nuclear energy - I believe this may offer an opportunity for future generations to reverse, to whatever extent possible, the great screwing over our generation gave them while claiming that, for one example of a worthless rationalization, that dangerous natural gas burning is only "transitional" while we all wait for the wonderful solar and wind utopia that did not come, is not here, and will never come.

To the extent that carbon capture is utilized to make carbon products, for instance carbides, nanotubes, graphene, and even polymers, this is value added sequestration.

And that is why I made sure I could leave work early and attend this lecture.

After the lecture, which was quite interesting, I collected some of Dr. Brennecke's papers and just got around to reading a few tonight.

Dr. Brennecke is the editor of the Journal of Chemical Engineering Data, where she's imposed some rather rigorous standards, much to the betterment of the world in general.

Here's one of the papers I collected:

On the High-Pressure Solubilities of Carbon Dioxide in Several Ionic Liquids (Joan Brennecke et al J. Chem. Eng. Data 2013, 58, 2642?2653)

Some excerpts from the text, beginning with the introductory paragraphs:

Ionic liquids (ILs) are arguably among the most interesting and important solvents to be developed in recent years. They are highly versatile due to their remarkably low vapor pressures, generally high thermal and chemical stability, nonflammability, and the ability to tune the chemical and physical properties by the incorporation of various functional groups into the anions and cations. As a result, they are effective media for reactions,1 have been considered as solvents for CO2 separation,2?8 can be used as absorbents in absorption refrigeration systems,9,10 serve in reactive catalysis,11?13 and have been evaluated for a wide variety of other separation processes.14?18 CO2 solubilities in the ILs are important for a number of these applications.

In addition, supercritical or near-critical CO2 has been studied by several authors as a way to recover valuable products from IL mixtures. For instance, CO2 can be used to separate the product from an IL + catalyst reaction mixture, leaving the IL and the catalyst ready for reuse.15,17 Scurto et al.19 demonstrated that CO2 could be used to separate ILs from aqueous solutions. Subcritical and supercritical CO2 has also been used successfully to induce separations of IL and organic compounds.16,17,19,20 It is well-known that high-pressure CO2 can affect the solvent strength of mixtures, especially when the solvent swells significantly with the addition of CO2. Thus, this is another situation where high pressure IL + CO2 phase behavior is important.

Note that some of the applications are actually carbon dioxide utilization schemes, where the (supercritical) carbon dioxide acts as a cosolvent.

An interesting and fun paragraph from the editor (and author in) this journal dedicated to accuracy and precision:

The Span?Wagner58 equation of state was used to calculate the density of the CO2 and determine the amount of CO2 transferred from the delivery system to the cell side. Knowing the volume of the lines on the cell side and the headspace of the cell, it is possible to determine the solubility of CO2 in the IL by difference, once again using the Span?Wagner equation of state for the vapor phase. Assuming that the vapor is pure CO2 is a very good assumption for the liquids investigated here since the ILs have very low volatility. Using a cathetometer to determine the height changes of the liquid level, one can also get the molar volume of the liquid mixture. The combined expanded uncertainty of the molar volume is calculated from the standard uncertainty of the cell volume which is determined from the height measurement with the cathetometer, the IL mass (± 0.0002 g), and the moles of CO2 dissolved in the liquid. This last uncertainty is determined from propagation of the uncertainties of the temperatures, Ruska pump volume, and volumes of the cell and lines.

The Span-Wagner equation is a wonderfully Rube Goldbergish equation that works to give highly reliable state variables for carbon dioxide. I had a little riff on this equation earlier in this space:

Paper on the Equation of State for High Efficiency Supercritical Carbon Dioxide Driven Turbines. (I wrote it before the subscript and superscript codes became unavailable at DU)

She finds that fluoroalkyl containing anions are the best at dissolving CO2.

The solubility behavior is [OTf]? < [Tf2N]? < [eFAP]?. Increasing the fluorination of the anion increases the solubility dramatically, as reported by Muldoon et al.39 We attribute this to both stronger interactions of the CO2 with the electronegative fluorine atoms and the higher free volume of anions with fluoroalkyl chains.

(This is unfortunate, because fluoroalkonic acids (notably PFOS) are a huge environmental problem to which we are too busy to pay attention. The only sink for these types of persistent pollutants, which are now present pretty much in every living thing on the planet, is radiation, which suggests yet another application for so called "nuclear waste" not that people who spend their lives uselessly on cartoonish anti-nuke websites are bright enough or informed enough to allow such use.)

The solubility of carbon dioxide in the alkyl phosphonium salts discussed in the paper are higher than those using imidazolium cations.

However the mixed organic/inorganic ionic liquid emim HSO4 shows very high solubility.

I thought this interesting.

Have a nice day tomorrow.

October 3, 2017

Thermochemical Conversion of Water and Carbon Dioxide into Synthesis Gas.

A great deal has been written in the energy field about the solid state structural class known as perovskites.

Here is the Wikipedia picture (not bad) of the perovskite structure:



Much of this interest has been directed at the quixotic enterprise of making the so called "renewable" solar industry actually work - it hasn't, it isn't and it won't - research has involved perovskite type structure consisting of lead, a halogen, usually iodine or bromine and an element like cesium.

For example: Imaging the Anomalous Charge Distribution Inside CsPbBr3 Perovskite Quantum Dots Sensitized Solar Cells (Panagrahi et al ACS Nano, ASAP accessed 10/02/17)

Perovskites of this type show high light to electricity efficiency, but like most all solar cells, they suffer from the usual draw backs, low energy to mass ratios which means that their material environmental impact will be enormous. Of course the fact that these cells contain the highly toxic element lead will have no bearing on people declaring them "green," any more that the equally stupid idea of "distributing" for "distributed energy" cadmium in cadmium telluride solar cells prevented these future toxic nightmares from being declared "green." Were they ever to make it to 10 exajoules (out of 570 exajoules used by humanity as a whole) per year - they won't - they would rival dangerous fossil fuels as environmental disasters, simply because of the volume and mass of toxic waste that would be required to be processed.

When I read about perovskite solar cells - and one really has no choice given the cockamamie energy funding pop culture has promoted - I usually want to throw up.

History will not forgive this generation, nor should it.

In more than half a century of nuclear operations in the United States, by contrast to the much more toxic and far less sustainable, successful or safe solar industry, only 75,000 MT of used nuclear fuel - a valuable resource - has accumulated, almost all of it easily contained at the site where it was generated. By contrast any wasteful scheme intended to make the solar industry work - it won't - would require the processing of tens of thousands of toxic materials per day, worse, distributed, where, much of it will be abandoned, making lots of little Flint Michigans (or their cadmium equivalents) all of the world.

Solar waste will never be as easily confined as fission products and actinides are.

My own interest in perovskites goes back a little longer than this recent solar fad. I've been interested in them as oxygen conducting membranes.

Way back in 2011, I spent a few weeks compiling all kinds of literature about perovskite oxygen conducting membranes, and actually built a spreadsheet listing the references I'd reviewed, the elements in the periodic table that they used, and the oxygen flux at reported temperatures...blah...blah...blah.

My interest was motivated by consideration of thermochemical water splitting cycles, of which a great many are known. I was investigating several that would theoretically make a 1:1 stoichiometric mixture of oxygen and carbon dioxide, and I was thinking about separations. (There are much better approaches, by the way, than such separations, but that's another issue.)

Thus my interest was piqued when I came across a paper in the current issue, released today (10/2/17), of the Journal ACS Sustainable Chemistry and Engineering

It's this one:

Oxygen Transport Membrane for Thermochemical Conversion of Water and Carbon Dioxide into Synthesis Gas (Jiang et al ACS Sustainable Chem. Eng. 2017, 5, 8657?8662)

With synthesis gas, one can pretty much make any large scale organic chemical obtained from petroleum, including those utilized in polymers. To the extent these chemicals are obtained from carbon dioxide and water, they represent value added sequestration of carbon dioxide. If the carbon dioxide is removed chemically (or physically) from the atmosphere, or is obtained by the controlled combustion of biomass, this sequestered carbon in theory at least could reverse climate change. (Realistically that is not going to happen. We're going to burn fossil fuels until we simply can't do so any more, all the time prattling on about the grand renewable future that never arrived, is not arriving and will not arrive. I'm speaking "in theory" and not "in practice." )

From the introductory text:

In the past few decades, transforming H2O and CO2 into high energy chemicals by artificial photosynthesis with the aid of solar power is getting more and more attractive, because of its important role in mitigation of energy shortage and global warming.1,2 Synthesis gas, a mixture of CO and H2, is a precursor to liquid hydrocarbon fuels. Synthesis gas can be obtained from splitting of CO2 and H2O using photocatalytic processes,3?7 high-temperature steam/CO2 coelectrolysis,8?11 or solar thermochemical loop processes.12,13 In the photocatalytic process, oxidic materials can decompose H2O and/or CO2 into H2 and/or CO. However, photocatalysis is impeded by its inherently limited energy conversion efficiency associated with band gap excitation.14 By contrast, thermochemical processes operating at elevated temperature can use the solar spectrum for thermal energy and possess fast chemical reaction kinetics. Previous research has demonstrated that the direct thermolysis of H2O and CO2 requires ultrahigh temperatures (>2500 K). To avoid the recombination and the formation of an explosive mixture, the generated gas products have to be separated at such high temperatures.15 To tackle the two issues of (i) ultrahigh temperature and (ii) gas separation at these temperatures, multistep thermochemical cycles - especially two step thermochemical loop cycles using metal oxide redox reactions - have been put forward and widely studied in the past several decades.

I'm not entirely sanguine about this description of thermochemical cycles, first because many are known thermochemical that do not require temperatures >2500K, (including the most famous thermochemical cycle, the sulfur iodine cycle) and secondly, I find the perfunctory and obligatory reference to solar thermal plants absurd. All of the thermal solar plants ever built on this planet after decades of cheering have been huge commercial and environmental disasters, the most egregious case being the Ivanpah plant in California, which has been more successful on shooting down precooked (or overcooked or even vaporized) birds in flight than in providing meaningful energy. If solar thermal plants were workable, decades of cheering for them would have made them practical and significant. They are neither.

Nevertheless, the paper is interesting; not all "solar thermal" thermochemical cycles are useless simply because it is straight forward to convert them to cleaner energy, that being nuclear energy.

The perovskite oxygen containing membranes are "cobalt free" although they do contain small amounts of praseodymium and cerium, generally the most available (along with neodymium) of the lanthanide elements to which I recently referred in this space while trashing the useless wind industry. Cerium in this case serves at the multivalent element necessary to conduct oxygen gas, along with iron. Their are two perovskites in this paper, utilized as a mixture, a cerium strontium iron version, and a praseodymium strontium iron version.

In order for this system to function efficiently, to remove oxygen from the splitting of carbon dioxide and water, the oxygen must be consumed. In some incarnations of similar systems, this is done by reacting the oxygen with the dangerous fossil fuel methane obtained from dangerous natural gas. And that's what they do here. (There are, of course, better things to do with oxygen, but we'll leave that aside for now.)

In this work, methane was used not only as a sweep gas to consume the permeated oxygen by the POM reaction, but also to produce additional synthesis gas with a H2/CO ratio of 2. Figure S5 presents the influence of temperature on the CH4 conversion, CO selectivity, and yield on the permeate/sweep side. It is shown that both CH4 conversion and CO yield increased with rising temperature. At 930 °C, a CH4 conversion of 62% and a CO selectivity of 99% were achieved, and synthesis gas at a rate of 3.9 mL min?1 cm?2 was obtained.

In any case, the thermochemical cycle can proceed in its entirety at less than 1000 degrees centigrade, and its certainly interesting, if less than entirely practical.

From the conclusion:

In conclusion, for the first time the effective generation of synthesis gas with H2/CO ratio of 2 by the simultaneous decomposition of water and carbon dioxide at the relatively low temperature of <1000 °C was experimentally demonstrated in an oxygen transport membrane reactor. Benefiting from the in situ fast removal of the generated oxygen by the membrane, the effective splitting of CO2 and H2O was achieved at lower temperatures, compared to the usual thermochemical decomposition. A synthesis gas flow rate of 1.3 mL min?1cm?2 on the feed side was obtained at 930 °C at a H2O/CO2 feed ratio of 5. To have a stable and sufficient driving force for oxygen permeation through the membrane, the oxygen partial pressure on the sweep side was effectively reduced using reactive methane as sweep gas. Simultaneously, synthesis gas at a rate of 3.9 mL min?1cm?2 was obtained on the methane side.


In consideration of the disadvantages of the conventional two-step thermochemical route on the requirement of ultrahigh-temperature and discontinuous oxygen transport, the combination of solar energy, catalytic thermolysis, and oxygen transport membrane reactor proposed in this work offers a new perspective and an alternative route to convert water and CO2 into synthesis gas.

Full details can be obtained by accessing the paper in a good science library or with a subscription.

I wish you a pleasant day tomorrow.

October 1, 2017

Some Reactor Physics for the Production of Anti-Proliferation Plutonium.

All of humanity's puny efforts to address climate change have failed. I keep a spreadsheet of data from the Mauna Loa Carbon Dioxide Observatory which compares the weekly measurement with the same measurement the year before. This week, the level of carbon dioxide was 2.07 ppm higher than it was a year ago, which compared with most of the data over the last 5 years, is relatively mild, but over the broader scale, highly disturbing. In the 20th century, the average of all such data (collected beginning in 1958) was 1.54 ppm per year. In the 21st century this same figure is 2.12 ppm. Of the 30 highest such data points, 19 occurred in the last 5 years, 21 in the last 10 years, and 23 in the 21st century. The highest ever such recorded piece of data was recorded on July 31, 2016, 5.04 ppm over the value for the same week in in 2015.

We are now approaching the late September/Early October annual minimum for atmospheric concentrations of the dangerous fossil fuel waste carbon dioxide in the planetary atmosphere. It will be well above 400 ppm, 22 ppm or 23 ppm more than it was just ten years ago. No one now living will ever see carbon dioxide concentrations below 400 ppm in their lifetimes.

The popular response to addressing climate change consists these days almost entirely of hyping so called "renewable energy." Since so called "renewable energy" has not worked, is not working, and will not work, this approach is extremely dangerous to humanity, and indeed, all living things, particularly when one considers the trillions of dollars squandered on it in just the last ten years. Combined, all the solar and wind energy produced by all the expensive and useless facilities ever built in half a century of wild cheering cannot produce as much energy in a year as is produced by the annual increase in the use of the dangerous fossil fuel natural gas, said use being secured by the popular imagination about so called "renewable energy." ("Renewable" is, by the way is a fraudulent term, since wind and solar plants depend on access to either exotic or extremely dangerous materials.)

In more than 3 decades of study, I have convinced myself that the only option that might work to mitigate climate change, even to arrest it (although that's very unlikely), is nuclear energy.

Of course, nuclear energy suffers from a negative public perception owing to selective attention paid to its risks - and like all energy systems nuclear energy has risks - to the exclusion of the risks of all other forms of energy. For example, half of the 7 million air pollution deaths that take place each year result from dangerous fossil fuel waste, the other half from dangerous "renewable" dangerous biomass waste, and yet very little concern is expressed about this point compared to so called "nuclear waste," which I will argue below is not even "waste" at all.

Another fun comparison is the risk of nuclear war. Since the early 20th century, the vastly overwhelming number of people killed by weapons of mass destruction have been killed by fossil fuel weapons. The number of people killed by petroleum based weapons of mass destruction dwarfs the number of people killed by nuclear weapons of mass destruction; and yet no one calls for shutting petroleum refineries because crude oil can be and is diverted to make Napalm and jet fuel.

We cannot un-invent nuclear weapons, nor can we ever make them impossible, since the supply of uranium on this planet is inexhaustible. I showed this by appeal to the scientific literature elsewhere on the internet:

Is Uranium Exhaustible?

I offered my views on the implications of this fact in yet another place on the internet: On Plutonium, Nuclear War, and Nuclear Peace

We now have accumulated sufficient used nuclear fuel, which is incorrectly called by people who can't think clearly "nuclear waste" to do some of the remarkable things that scientists in the 1950's and 1960's envisioned for radioactive materials; this back when most of the world's nuclear reactors were designed not to generate energy, but to make weapons grade plutonium. Back then there simply wasn't enough, say, cesium-137, to destroy organohalides contaminating water supplies worldwide. Regrettably fear and ignorance of all things radioactive has prevented application of this superior approach to addressing such serious environmental issues.

Used nuclear fuel also contains considerable amounts of the elements neptunium and americium, which, I argued in one of the links above, are excellent tools for making plutonium - the key to any effort to serious effort to address climate change - that is simply unusable in nuclear weapons.

These ideas certainly don't originate with me; I merely report them. (I refer to them, as short hand, to the "Kessler solution" since Kessler is one of the nuclear scientists who has worked to advance this idea, although he is surely not the only one.)

Despite catcalls from the peanut gallery of folks who know nothing at all about nuclear energy but hate it anyway, highly educated and hightly trained nuclear engineers around the world have been working on these ideas, one hopes with a growing sense of urgency, since nuclear weapons are now being controlled by petulant brats who grew up isolated from the real world, the puerile so called "President of the United States" and the disgusting little twerp who rules North Korea.

In my files this morning, as I stumbled through some collected literature that I have had not yet reviewed, I came across this paper:

Long-life fast breeder reactor with highly protected Pu breeding by introducing axial inner blanket and minor actinides (Hamase et al Annals of Nuclear Energy 44 (2012) 87–102)

From the introductory text of the paper (with some artifacts of its translation from Japanese), we can grasp the basic idea:

In the wake of an interest in nuclear electricity production due to exhaustion of fossil fuels and issue of global warming, today the requirement of uranium (U) is increasing in the world. On the other hand, the prospect of U supply in the world has been reported to be about 100 years (OECD/NEA-IAEA, 2008) and the exhaustion of U resources is concerned with the expansion of nuclear power use. To meet the energy demand, a FBR has been focused on as a Pu producer. However, in the conventional FBR, generated Pu in axial/radial outer blankets consists of more than 93% of 239Pu. This kind of Pu is categorized as a ‘‘weapon-grade Pu’’ (Pellaud, 2002) and is concerned for nuclear proliferation. Recently, the concept of Protected Plutonium Production (P3) to increase the proliferation resistance of Pu by transmutation of MA has been proposed by Saito (2002, 2004, 2005). In this concept, MA can be utilized as an origin of 238Pu since dominant nuclides of MA such as 237Np and 241Am are mainly well transmuted to that isotope. The features of 238Pu, high decay heat (567 W/kg) and high spontaneous fission neutron rate (2660 n/g/s) (Matsunobu et al., 1991) are well known to hinder the assembling Pu in a nuclear explosive device (NED) and reduce the nominal explosive yield. Furthermore, it has been reported that 240Pu and 242Pu also play an important role for denaturing of Pu (Sagara et al., 2005), since 240Pu and 242Pu transmuted from MA has relatively large BCM and high spontaneous fission neutron rate (1030 n/g/s and 1720 n/g/s) (Matsunobu et al., 1991). Also, based on the P3 proposal, Meiliza et al. (2008) has reported that the proliferation resistance of Pu produced in axial/radial blankets of conventional FBR was increased by doping a small amount of MA into axial/radial outer blankets. MA is, therefore, effective to mitigate the nuclear proliferation concern.

"BCM" is "bare critical mass."

The paper contains a great deal of technical information about the reactor design and properties, and various cases are shown.

Depending on the type of fuel used, (oxide or metal) the reactor can be designed to operate for as long as 6000 full power days, roughly 16 years. Plutonium that is undergoing fission is hardly available for making nuclear weapons, and in any case, the usefulness of any plutonium in the reactor for use in nuclear weapons is greatly reduced by the presence of denaturing isotopes, in particular the heat generating isotope 238Pu (the same isotope that powered the Cassini mission).

Basically these types of reactors are essentially fueled by depleted uranium. One can show that the uranium already mined, along with the waste thorium generated by the failed and useless wind and electric car industry, can easily fuel all of humanity's energy needs for several centuries to come without any mining of any energy related material of any type, no petroleum, no coal, no natural gas, and indeed, no lanthanides, cadmium, etc, etc for useless wind and solar junk.

From the paper's conclusion:

The feasibility study on simultaneous approaches to the extension of core life-time and the high protected Pu breeding by introducing the axial inner blanket and doping MAs in a large-scale sodium-cooling FBR has been performed for mix-oxide MOX and metallic fuel. Firstly, as the extension of core life-time, the analytical results showed that if MA was doped into the axial inner blanket, the main fission reaction zones were shifted from the active core to the axial inner blanket, and the core life-time was extended remaining reactivity swing small because 238Pu transmuted from MA was the fissionable nuclide in the fast neutron region. The maximum available EFPDs in MOX-fueled FBR with introducing the axial inner blanket and MA was extended from 1700 to 2900 compared with the conventional MOX-fueled FBR. The maximum available EFPDs in the case of metallic-fueled FBR with introducing the axial inner blanket and MA was extended to 5900.

Secondly, as the proliferation resistance of Pu, it has been reported that Pu produced in axial/radial outer blankets of conventional FBR was increased by doping a small amount of MA into them, and ATTR, an evaluation function of proliferation resistance of Pu based on isotopic material barriers such as DH and SN, has been suggested to categorize produced Pu. In the present paper, conventional ATTR was modified by taking into account BCM as ATTRmod, which was applied to evaluate the proliferation resistance of Pu generated in the axial inner blanket and axial/radial outer blankets. It was found that if 40 wt.% and 28.5 wt.% of MA were doped into the axial inner blanket in MOX and metallic fuel, respectively, the proliferation resistance of Pu generated in the axial inner blanket was significantly increased to satisfy the criteria of ‘‘practically unusable for an explosive device’’ proposed by Pellaud and ‘‘technically unfeasible for a high-technology HNEDs’’ proposed by Kessler and Kimura. Assumed that Pu generated in the axial inner blanket and also axial/radial outer blankets were collected and reprocessed together, the proliferation resistance of Pu generated in all blankets was also increased. Furthermore, in order to increase the proliferation resistance of Pu generated in axial/radial outer blankets, only 4 wt.% of MA was required in MOX and metallic fuel. For not purpose of extension of core life-time, only 5 wt.% of MA doping into the axial inner blanket was needed to increase the proliferation resistance of Pu in MOX and metallic fuel.

I am not necessarily, by the way, endorsing this particular reactor; it's sodium cooled, and I personally don't like sodium coolants. But the basic ideas of plutonium management are very important, since plutonium is the last best hope of Earth.

Have a nice Sunday afternoon.

October 1, 2017

Working with one of the most refractory and hardest materials known Tantalum Hafnium Pentacarbide.

Generally, most people are aware that spacecraft and supersonic aircraft require refractory (high melting) materials to avoid being burned up by air friction.

Since the end of the "space race" and the "cold war" there has been less interest in refractory materials than there might have been some years back, something I know from having attended a bunch of presentations of materials science departments while my son was selecting a school.

Be that as it may, whether it is generally known or not, is that future generations, owing to our inattention, fixation on dumb ideas that don't work, and general irresponsibility, will require refractory materials to reverse whatever can be reversed from our willingness to screw them over by dumping trillion ton quantities of dangerous fossil fuel waste (at a rate of over 30 billion tons per year) while we all wait, insipidly, like Godot, for the grand solar and wind Nirvana that never comes (and never will come.)

I could discuss that for hours, but rather than do so, I'd rather simply focus on a paper I collected some time ago on a rather remarkable material that fits the bill, Ta4HfC5, tetratantalum hafnium pentacarbide.

The paper I'll discuss is this one: Reduced-temperature processing and consolidation of ultra-refractory Ta4HfC5 (Int. Journal of Refractory Metals and Hard Materials 41 (2013) 293–299)

The introduction gives a nice description of the remarkable properties of this material:

Carbides, nitrides, and borides are of interest for many applications because of their high melting temperatures, high elastic moduli, and high hardness. Among all refractory compounds, 4TaC-HfC ranks among the highest, with an estimated melting temperature of 3942 °C and hardness of approximately 20 GPa at 100 g-f [1–3]. TaC is the most metallic of the IV and V transition metal monocarbides. It has the NaCl-type structure (B1, space group Fm3?m) and an exceptionally high melting point of 3880 °C [4–7]. TaC's relatively good oxidation resistance and resistance to chemical attack have been attributed to strong covalent-metallic bonding [8]. Other relevant properties of TaC include high strength, high hardness (11 to 26 GPa), wear resistance, fracture toughness (KIC ? 12.7 MPa-m1/2), low electrical resistivity (42.1 ??-cm at 25 °C), and high elastic modulus (up to 550 GPa). TaC is also reported to exhibit a ductile-to-brittle transition in the temperature range 1750–2000 °C that allows it to be shaped above the DBTT, and it also exhibits ductility of 33% at 2160 °C [9–12]. Similarly, HfC also crystallizes in the NaCl-type structure (B1, space group Fm3?m, close packed), and exhibits a high melting point (3890 °C, the highest among the binary metallic compounds) [13–15]. HfC also has good chemical stability, high oxidation resistance, high hardness (up to 33 GPa [16]), high electrical and thermal conductivity, and a high Young's modulus (up to 434 GPa) [17–24]. HfC has found applications in coatings for ultrahigh-temperature environments due to its high hardness, excellent wear resistance, good resistance to corrosion, and low thermal conductivity. HfC is also found in high-temperature shielding, field emitter tips, and arrays (HfC has the lowest work function of all transition metal carbides). In addition, HfC can be used as a reinforcing phase in tool steels [25–27].

However, if you reflect on it for even a moment, you realize the difficulty of working with such a material. It cannot be worked easily, and as it's melting point is higher than almost any container in which it can be processed, it certainly can't be cast. It's melting point is even higher than remarkable materials like uranium nitride, thorium nitride and thorium carbide. (Thorium oxide, which is mildly radioactive, has been widely used for ceramic refractory crucibles for handling molten metals.)

Such materials can only be handled by sintering, which involves heating them to roughly two thirds of their melting temperature (pretty extreme in any case) and applying extreme pressure, conditions under which the elements can diffuse to a smaller to larger extent.

In this case, the authors milled hafnium carbide and tantalum carbide powders for a long period of time (18 hours) and placed them in a graphite press under a pressure roughly 1000 times atmospheric pressure, and heated them at 1500 C (much lower than the melting point) and got pretty decent tetratantalum hafnium tetracarbide. (Machining this stuff is yet another problem, not addressed here.)

This material is not ready for prime time, nor will it ever be.

Tantalum is mostly utilized in cell phones, where it is a constituent of the supercapacitors on which those devices depend. The mining of tantalum is a great human tragedy, the "coltan" issue. (Tantalum is always found in ores that also contain niobium which was formerly known as columbium, hence the name "coltan" for the ore.) Tantalum is one of the "conflict" elements, and mining it is simply a horror.

This disturbing documentary, "Blood Coltan" is available on line:



Hafnium is a side product of the nuclear industry. It is always found in ores of its cogener zirconium, which is widely used in nuclear reactors. Typically the amount of hafnium in zirconium ores is on the order of 1-3% However, since hafnium has a very large neutron capture cross section (and is sometimes used in control rods, particularly in small reactors like those on nuclear powered ships) it must be removed from zirconium before the zirconium can be used in nuclear reactors.

It is possible however, to obtain pure hafnium free zirconium from used nuclear fuel, where it is a major fission product. The chemical separation of hafnium and zirconium is nontrivial, as is the chemical separation of niobium and tantalum, owing to the "lanthanide contraction." It is possible to obtain monoisotopic zirconium, zirconium-90, (which is lighter than "natural zirconium) from the decay of the fission product Sr-90, itself a useful heat source. Thus at some point it may be cheaper to utilize fission product zirconium instead of natural zirconium, at least it would be so in a sensible world run by intelligent and responsible people, a nuclear powered world.

But we don't live in such a world. (One may hope that future generations will be smarter than ours.)

This said, this information might be useful under many imaginable exotic conditions, and I found it interesting.

Have a nice Sunday.