farmerben
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Posts posted by farmerben
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1 hour ago, RCgothic said:
I have professional expertise in this area.
Fuel storage must comply with the "double contingency principle", which means that two or more unlikely independent things need to go wrong simultaneously before you end up with criticality incident.
One defence is spacing, but big pools are expensive so fuel is stored close enough together that absent any other mitigations it would go critical, so in most cases this doesn't count.
Another defense could be neutron absorbers in the racks themselves, but if there's a problem with the absorbers, that's only one contingency, so we add another - soluble boron in the pool water.
Soluble boron is gains its effect from its concentration. If it gets diluted, it loses its effect. What could cause it to get diluted? Flooding. What causes flooding? Big Tsunamis, for one.
So for me as a nuclear professional I'd say Fukushima's designers got this one right. The pools didn't get diluted by the enormous tsunami and the critically contingency was preserved.
I'm not talking about a criticality incident I'm talking about residual decay heat setting the zirconium on fire. If an earthquake or an explosion prevented the pool from holding water at all, that could be a (non-critical) worst case scenario.
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The designers of the Fukishima plant did something potentially even dumber than putting backup generators in the basement. The spent fuel pool was located above ground on a second story. Fortunately, they were able to keep the spent fuel covered with water. However, if the pool had cracked it would be impossible to keep the fuel covered with water. In that case the zirconium could catch fire and release atmospheric contamination.
In hindsight its obvious to put the pools in the basement and the generators above ground. What else could be done to eliminate this vulnerability? Also does anyone know how long the spent fuel is hot enough to pose a fire risk?
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As a child I had a really nice picture book about the solar system. The planets and moons were always more interesting to me than dinosaurs. In fifth grade my teacher called my parents and said "We finally found something he is interested in, rockets!" When I was 11 I got to attend Space Camp in Huntsville. I've been back to Huntsville and JSC a couple of times since. Just getting to stand next to the Saturn V is worth the price of admission.
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One function you could fulfill with this is to increase snowfall on Antarctica. Ice loss has little to do with greenhouse warming at night in the winter, and much to do with how little precipitation falls on the continent.
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Steam in a pipe moves pretty fast, it might flow to the tropopause in a couple of minutes. If we go above that, we can reach altitudes where water vapor does not exist, and our exhaust will become snowflakes. Making steam at low altitudes in semi-saturated air probably increases the greenhouse effect more than albedo. I think high altitude release does more to albedo.
Desalinization on shore could be done in other ways. This idea could work out at sea.
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1 hour ago, HvP said:
If you're worried about not having enough water from rainfall then where are you getting all this water to make the steam?
the sea
20 minutes ago, mikegarrison said:What does that have to do with it being adiabatic?
If you don't add heat during the rise, then it's adiabatic. If you want to counter the fact that it's going to cool as it rises, you have to add more heat during the rising.
New steam supplies pressure from the bottom adding energy continuously.
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43 minutes ago, mikegarrison said:
Gas adiabatically rising in the air cools. Your steam would condense.
I agree that condensation is the limiting factor, but it doesn't have to be adiabatic. We can superheat and pressurize the steam at the source.
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Suppose it was our goal to create artificial clouds to influence local rainfall and climate. Conventional smokestacks and cooling towers often have vapor trails that dissipate well below cloud level. If we inject steam at much higher altitude it will create more clouds.
A giant nylon windsock would serve as a tube to convey the steam thousands of meters. A toroidal hydrogen balloon at the top could help lift it. Steam is a buoyant gas anyway so the horizontal vector is unstable. It would bounce around like the vertical windsock signs seen at car dealerships, etc. Such a device mounted to a powerful boiler could elevate steam above the clouds, even discharging steam in layers where the temperature is freezing and the humidity is zero.
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Is this the same company that tried to develop an aerospike and only defrauded investors?
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7 hours ago, Pixophir said:
Unfortunately, there's nothing to 'like' in a sense of a good, well thought through solution that would have a clear, positive effect on climate change with known side effects. Many of them, like aerosols to reflect sunlight, have known bad side effects (ocean acidification for instance). A lot of work is going on in the area.
One would have to show for each proposal what its projected positive effects are, and what the negative side effects could be. Youtube videos are not helpful there.
This is very true.
Flooding a desert with saltwater to create a stagnant (=bad) water body, assuming it could be done with the help of gravity alone and without blowing more ghg into atmosphere, creates a salt pan unsuitable for land use. It's net effect through raising albedo (clouds) is very low. Saltwater will filtrate into ground water with negative effects on the environment, and human habitability in an already fresh water deprived area. Idk what's known about known aquifers in that area, if they are connected or confined, .... Salt can also be distributed through aeolian transport, negatively affecting land use in the vicinity. Afaik there is no ephemeral highly saline water body that somehow supports stable vegetation (see bitter lake). Iow, they are pretty much dead apart from extremophiles.
In the case a Qattara there are no valuable freshwater aquifers in the area, there just a few small natural gas wells. Even a hypersaline sea might be more valuable than what is there now. It would be possible to flush brine back into the Mediterranean sea to keep the salinity constant.
The greatest effect on climate by far is evaporation and increased water vapor in the atmosphere. Climate models all suck at modelling water vapor and clouds.
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Most people are talking about what they don't like. What about what you do like?
We are probably changing the climate through land use alone, not even counting CO2.
This is my current favorite project.
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What are you favorite geoengineering options?
1. Flood the Qattara Depression to create a new sea the size of Lake Erie in the Sahara Desert.
2. Create artificial sea ice. Multiple options including (A) use artic rivers to produce picrete (B) off shore wind driven heat pumps. A vertical axis wind turbine on a bouy could pump heat from the ocean to the atmosphere throughout the year. (C) desalinate seawater and use some kind of snow machines to pile freshwater on Antarctica.
3. Add aerosols to the atmosphere, introduce impunities into airplane contrails to increase reflectivity.
4. Add minerals and feed to the remote oceans to increase biomass in oceanic deserts. Track ocean biomass with sonar and increase it wherever deficient.
5. Electrolyze steel underwater which creates calcium carbonate coatings around the steel, thus directly sequestering the carbon and creating artificial structures under the sea.
6. Pay farmers who can prove tonnage of soil carbon absorbed. There are multiple known solutions and good reason to do it anyway. A graphite layer .5mm, like a mechanical pencil lead, spread across all the land on earth would absorb all the manmade CO2. The top 2 feet of topsoil can usually hold that much increase in the form of underground biomass.
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The moon-mars transit only requires about 5000 m/s of dV. That is about half of Earth to LEO. A single stage chemical rocket can make the transit. A mass driver (electromagnetic track) on the Moon could easily handle half the dV requirement.
Zubrin argues it is a two year mission with a free return trajectory in case of abort. Extra propulsion should be used to increase payload, rather than cut travel time.
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If by most practical and likely we mean the most common and not the best. For launches off the moon or Mars an electromagnetic launch ramp makes good sense. The Earth's atmosphere mitigates the advantages here. Launching from the top of Olympus Mons with 30,000 m/s initial velocity is totally doable.
Weaker, though cooler and simpler rockets can make the Mars-Moon voyage. Ethanol and hydrogen peroxide only gives 225 sec of ISP, but it's pretty cool in other respects. And very simple and cheap assuming the next few centuries bring us revolutionary improvement in bio-ethanol production.
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I've wondered about de-orbiting an airship. The whole problem is with overheating. I don't think we know conclusively if it would work.
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On 5/10/2022 at 2:55 PM, JoeSchmuckatelli said:
I've been delving into a variety of historical and political topics and analysis recently - which I won't post about here - but an interesting thread emerged in a couple of them, that I think works with the theme of and people who populate this forum: The concept of 'cycles' or game-changing technological inventions that effectively brings on a new age of development and prosperity (although and albeit via massive disruptions and disenfranchisement of the prior beneficiaries).
The examples given (largely focused on the US/West) are:
- Factories
- the Railroad
- Electricity
- the Automobile, and finally,
- the Microchip.
Each new technology had a massive impact - a transformative impact - on not only the economy, but also society and how humans use our time and interact with the world.
One part of this thesis is that we are (with Social Media & the ubiquity of the Microchip in pretty much everything) at the end of the current era / cycle.
If true - we are ripe for the next big 'game changing technology'.
Prognostication isn't my strong suit* but maybe some of you have ideas?
What's your guess about the next game changer?
*(or I'd have picked a different long-shot in the Derby!)
The innovations have been fast and furious for several centuries. We are seeing the age of the individual amatuer inventor diminish as time goes on, with larger institutions driving more expensive research.
Funny how the prosperity is a "cycle", while the development is a hockey stick. Railroads are still working perfectly. But the era of inflating money to lend to railroads has long past.
The US and perhaps the whole world is addicted to economic bubbles. This is perhaps a feature of how our money is created. In the absence of the next great tech, the money flows into redistribution bubbles, like real estate, fine art, crypto-currency, etc which do not really uplift the rest of humanity.
Hopefully space colonization is more of a one way street than a cycle. But there must be an initial period when the Earth is making massive investments in the hope of future returns. This means lots of jobs financed by debt, synonymously a cyclical boom of prosperity for most people. Ultimately the jobs and the debt will cease and we are left with increased asset value, the other half of the economic cycle.
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On 6/27/2022 at 5:36 PM, JoeSchmuckatelli said:
That's one of the things I'm pondering - because in the context of the question I originally asked the technology cannot replace people, but instead,
- The concept of 'cycles' or game-changing technological inventions that effectively brings on a new age of development and prosperity (although and albeit via massive disruptions and disenfranchisement of the prior beneficiaries)
Note that disenfranchisement of the prior beneficiaries is analogous to the number of farriers and blacksmiths and wainwrights prior to the automobile becoming common. Their specialty may have become anachronistic - but they could still work. (And it was far from a flick of the switch transition)
Fundamentally people must still be able to work for there to be an economy in the first place.
This is one of the things contributing to my current belief. Especially, trucking.
The covid crisis laid bare the flaws and risks inherent in our logistics systems. One of the most important things within the US is trucking... And yet we have a trucking shortage. Or rather a driver shortage and an inflexible system w/r/t where drivers are needed and where they can afford to live. Someone will solve the problem and one solution is legislation that says 'only authorized autonomous vehicles are allowed on the interstates'. Musk has even said that if the only vehicles on the road are automated and in the same system... Accidents are unlikely.
The US has a precident for 'making this work' and it is the advent of rail. Legislation that absolves any corporation involved with transportation from liability (simple negligence) can make this happen in a decade, especially if it's profitable
There is no driver shortage. I can't find the stats right now but over half the qualified CDL-A holders are not driving. The lifestyle commitment for an over the road truck driver is so extreme that very few people choose to do it continuously for decades. The pay is decent compared to a normal job, until you factor in all the lifestyle sacrifices. So really we have a pay shortage, which could also be ameliorated by making the job better.
Everything difficult happens within the first or the last five miles of a trip. The interstate is a cake walk. We may see a period when a truck driver is required on board but allowed to sleep while on the interstate. Also a period where autonomous vehicles are purchased to do one routine over and over, while the flexible part of the industry still requires humans.
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Thunderfoot performs some fascinating experiments with Sodium Potassium alloy. He considers using it in contrails to fight global warming.
https://www.youtube.com/watch?v=bW5lqA_U7Tg
Not explored by him is the possibility of using this for space exploration. It has several unique advantages. It is a conductive reflective solid under nominal conditions. But easily converts to a conductive liquid with low vapor pressure. Meaning it could flow in space with minimal evaporation without containment tubes.
It is possible also to make refillable solid rocket motors with NaK alloy.
It can make mirrors. And the smoky exhuast, NaO2 and KO2, are highly reflective compared to other types of exhaust.
It would be excellent hull shielding for both radiation and micrometeors. There is better potential for self repair of NaK surfaces since it flows easily.
I believe that NaK + 4H2O => NaO2 + KO2 + 8H
So using pure water as an oxidizer releases lots of hydrogen, which is very good for ISP, through I don't know what the exact ISP would be.
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Sodium potassium alloy could be used as a hypergolic liquid fuel. I have no idea what the ISP is, probably nobody has made a rocket with it before.
Hydrogen and nitrogen are precious on the moon. Almost any regolith mining operation is likely to have sodium and potassium byproducts.
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2 hours ago, Terwin said:
Due to expansion, this would allow multiple objects that are at 'absolute rest' even though they are traveling at close to C relative to each other if they are far enough apart.
Agreed.
It's not easy to pin down an exact standard of absolute rest. The relativistic distortions only show up when moving close to the speed of light.
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12 minutes ago, Terwin said:
You propose a definition of absolute rest to be going at a speed that is the average of your observable universe?
Wouldn't that mean (possibly rapid) acceleration every time something left your observable universe?
I think I would have difficulty agreeing that a state is 'absolute rest' if I can be pulled out of that state due solely to a very distant object moving beyond my detection range.
If the universe appeared blue in one direction and red in other directions, then we would know we not at rest. We might be in an inertial reference frame which we could claim to be rest, and the universe moving in a peculiar asymmetric way. If we see symmetry then we are in some sense at rest relative to some absolute standard.
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It may be possible to define absolute rest and absolute motion. If the amount of redshifted and blueshifted objects in every direction are equal you are essentially at rest. If you began moving closer to the speed of light the appearance of the entire universe would change.
That the speed of light is constant in every direction is neither an observation nor a hypothesis. It is an axiom we can stipulate in order to create a definition of simultaneity.
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If we bore directly through the center of the planet, we don't need maglev. Gravity will accelerate us and slow us down. It takes about 43 minutes to transit the diameter of the Earth with it's gravity. If we take some off center chord line it takes the same amount of time, assuming no friction.
On an internally dead body like the Moon or Mars tunneling through the center is a viable possibility, travel times vary depending on the planet.
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On 5/14/2022 at 12:16 PM, kerbiloid said:
The experiment was mentioned above, Echo-1&2.
so what happened when they entered the atmosphere?
Spent nuclear fuel safety
in Science & Spaceflight
Posted
The fuel rods must be kept submerged in cooling water for some period of time before they can go into dry storage. I'm not sure what the period is (possibly 18 months). The spent fuel could meltdown which might not be catastrophic or the zirconium cladding could catch fire and belch radioactive smoke into the atmosphere which is catastrophic. This seems to be the weakest link in nuclear safety as currently designed.