Concorde didn't cruise at Mach 2 in afterburner -- imagine how much fuel it would use pouring JP-4 into the engine exhausts for two hours. Concorde flew supersonic at 20km altitude by means of large powerful engines which burned a lot of fuel but in a conventional manner. It did use afterburners on takeoff and initial climb out because the engines and the intake nacelles were optimised for supersonic cruise flight and at takeoff the fuel load, as much as 50% of its total on-wheels weight made the entire airframe quite heavy.
My rather dated 900MHz mobile phone (a Nokia 7110 on Tesco branded O2) in my bedroom in an Edinburgh tenement (ObUS: brownstone) typically shows zero or one bar of signal strength and sometimes drops out completely. There are three or four 50cm-thick sandstone walls between me and the nearest cell towers which cover a busy trunk road outside my door and a mainline railway station about a hundred metres away. I think higher frequency services carrying data etc. would be even less capable of penetrating the building.
The US DoD uses Pu238 "batteries" in stealthy spacecraft, spysats without large solar panels that would otherwise be easily tracked using ground-based telescopes and radars. Another use for such power sources is seabed listening stations used to monitor submarine and surface-ship movements in "areas of interest".
Pu-238 is made in specialised isotope-producing reactors. It's not extracted by reprocessing regular spent nuclear fuel from power-station reactors as it would be impossible to separate the Pu-238 out from the large quantities of other Pu isotopes bred from U-238 during regular operation. Those isotope-production reactors have been getting shut down in the US, Canada and elsewhere over the past couple of decades due to age, more restrictive licencing regulations and occasionally by celebrity-powered publicity campaigns. The ex-Soviet isotope reactor fleet is about the only regular source of such material operational today hence the national-security aspect -- the Russians are not that keen to make it easier for the DoD to spy on them by supplying them with lots of Pu-238.
Last report I saw said that Japan's carbon emissions are up 17% over last year and that includes a period when many of their nuclear reactors were still running. TEPCO has announced a 9% increase in domestic electricity prices starting in September this year, to cover the cost of the coal and oil imports needed to generate electricity that was previously produced by the nuclear stations.
Two Japanese reactors at Ohi restarted recently, generating about 2.4GW baseload, that is day and night. Another reactor in Shikoku might restart before winter but the rest are still shut down and will be until the panic is over.
My "one true power" goal would be 150% nuclear with the extra power being used to produce liquid fuels from atmospheric CO2 for mobile and transport needs.
You don't remember correctly. Three of the four damaged reactors were running normally, the fourth (no. 4) was shut down for a scheduled inspection and refuelling operation -- power-generating reactors in Japan get inspected every 13 months and the operators usually refuel them at this point. The oldest reactor, no. 1 was coming to the end of its 40-year operating licence. It would have been relicenced after a thorough inspection if nothing substantially wrong was found although given its age it might have been tagged for decommissioning anyway. The other 3 damaged reactors still had a few years to go before they would need relicencing, and the undamaged reactors, no.s 5 and 6 were built around 1980 and they still have nearly a decade before their operating licences run out.
Panasonic have good build quality even in their business range and their Toughbooks are especially well-built. Not stylish though. Expect to pay for that quality though, 50-100% more than an Apple of similar hardware spec, but when was the last time you saw a laptop advertised as being resistant to disinfectant?
HP had a deskstand that would take some of their small-form-factor PCs like the dc7900 and an HP LCD and make an all-in-one PC with the SFF case mounted behind the display. I don't think it was available ready-built.
There are a thousand ways to build a heavy-lift launcher, including using the STS ET and RS-25s or RS-68s plus strap-on boosters etc. There are problems with most of them engineering-wise, economic and political.
The ET is not structural, it can't transfer a large thrust load vertically from a motor ring at its base to a second stage or payload package on top of it. The tankage sections of staging rockets like the Saturn V are built with vertical stringers to deal with that load. A redesigned ET will be heavier and take time and money to produce; it's probably best to toss it and design a Saturn-V-like cryogenic first stage like the Delta 4 with its RS-68 motor(s) if you want to go fully cryogenic, something that has its own expensive ground-handling problems.
The real problem is time and money; the longer a NASA project takes to get to the point where it is ready to fly the more likely its funding will be cut or shaved by politicians out to make a point about extravagance or "waste" (as long as the funding cuts don't impact jobs and bennies in their neck of the woods, of course...). Attempts to keep a zombie program running by extending deadlines as its budgets are cut year after year usually just extends the agony. Developing an improved F1A engine will take several years, and even restarting the manufacturing operation to build replica vintage F1s will take some time which would make the program more vulnerable. The RS-68(A) and the RD-171 motors are available now and only cost money to make and fly.
If I was blue-skying a heavy-lifter I'd be tempted by the Delta 4 Heavy design which uses three substantially similar first stages side-by-side. It's not trivial engineering to cope with the extra thrust in the central stage but adding more booster "cores" in a 4 plus 1 or even 6 plus 1 arrangement would be easier in terms of design and flexibility, and these cores are already in production. I think this is the way SpaceX is approaching their own clean-sheet heavy-lifter project although they have proposed a rather Heath Robinsonish process for transferring fuel and oxidiser between cores in flight rather than throttling back the central core or only firing its motor in flight as a pseudo-second stage after the booster cores have been running for some time.
"Fuel is cheap, fuel tanks are cheap, engines are expensive."
Mass is expensive in a rocket design and fuel/oxidiser is mass. The Saturn V burned over 10% of its first stage fuel and oxidiser load, about 220 tonnes just clearing the tower after ignition. With less efficient engines and a greater fuel load it might never have got off the pad.
Fully-cryogenic engines are more efficient than LOX/RP-1 but they come with a bunch of drawbacks, the major one of which at takeoff is a lack of mass fraction, the amount of mass in the exhaust stream. This requires much larger engine bells and turbopumps for the same amount of thrust since liquid hydrogen is the least dense liquid known. This also means much larger tankage is needed (see the Giant Flying Turd the Shuttle was attached to) even if the fuel mass is less and tankage is mass too.
The beauty of LOX/LH2 as a fuel is in its performance at altitude and near-vacuum where the reduced backpressure means a very high exhaust velocity; the vacuum Isp figure for the RS-25 Shuttle engine is 450-odd, compared to the F-1's sea-level Isp of 263. It's why the Saturn V's second and third stages were fully-cryogenic. Rocket scientists (who are, as their name suggests, smart people) have designed around this limitation by building pseudo-SSTO LOX/LH2 launchers like the Shuttle, Ariane etc. by afitting strap-on boosters to add some extra oomph at takeoff and to get the stack to a high enough altitude that the lessened weight due to fuel burn and the loss of the boosters will take the rest of the stack to orbit.
The F1-A doesn't exist other than as a concept, and to be blunt it probably never will exist. If it ever flies it will cost billions to develop and take maybe a decade from funding to flight. The RD-171 and RD-180 are being built and flown today and the development costs are already buried in the production line. An SLS based on those motors only requires the vehicle structure to be designed and built; by the time the first prototype rolls off the production line well-tested engines will be waiting for it to fit and fly.
The problem with that approach is that the stack has to carry more fuel at takeoff which requires more engine power to lift the stack since it's heavier which requires more fuel to provide that power which requires bigger tanks... OTOH more efficient engines mean more payload delivered to orbit for the same amount of fuel and vehicle structure.
There are modern well-tested engines which have better performance than the venerable F-1 motor -- the RD-171 engine in the Zenit launcher has four chambers fed by a single set of pumps, delivering more thrust than the F-1 ever did and with greater efficiency. A cut-down 2-chamber version, the RD-180 propels the modern Atlas launcher.
The F-1 is actually quite crude by today's standards. It's not throttleable so the acceleration curve for a Saturn-V launch started off slow and picked up to about 4-Gs as the first stage's fuel ran out which beat up the crew somewhat. The Shuttle in comparison never exceeded 3-G. The F-1 has a low chamber pressure (70 bar) and reduced Isp (263 seconds) compared to modern LOX/RP-1 engines like the throttleable RD-180 (266 bar and 311 seconds) as used on the Atlas launcher.
The US government built special-purpose reactors at Hanford and elsewhere to make nearly all the weapons-grade plutonium-239 they needed during the 40s and 50s, well before the first commercial reactors were built. Commercial nuclear power stations are badly suited to creating material for nuclear weapons; long fuelling cycles mean any Pu being bred in the fuel pellets gets badly contaminated by Pu-240 due to neutron capture. There were a couple of power station reactor designs which were dual-use allowing in-situ refuelling but they were not American -- the British Magnox and the infamous Soviet RMBK-4 of Chernobyl fame. Even they were not used much for producing weapons-grade material since pretty much everyone who has ever built Pu weapons has used dedicated reactors to do so. Some other commercial reactors can be converted to make weapons-grade Pu-239, like the CANDU but in normal operation they're proliferation-proof.
The reason uranium won over thorium, and continues to be the main choice for power station reactors is that it's simple to design and build uranium reactors. Thorium is not fertile and only borderline fissile so making it fission requires, as others have mentioned, a sparkplug of medium-enriched uranium to kick off the process. If it is stopped for any reason then more enriched uranium, or even plutonium is needed to get it started again. It's also difficult to "swing" the output of a thorium reactor to load-follow whereas modern uranium reactors can reduce their output significantly without problems to meet lessened demand.
The LFTR is a logistical horror requiring continuous chemical processing of highly-radioactive boiling-hot material for the reactor to operate and to prevent proliferation of bomb-grade material, and it was not within the technology or the knowledge of 1950s nuclear science to get this sort of system to work in any timescale short of decades. The pressure-vessel uranium reactor with coolant and moderator was piss-easy to design, build and operate by comparison.
Areva is building a pair of reactors in China (the Taishan EPR 1400s), and it's not an American company. They're on time (about 4 years) and on budget (about $4 billion per unit) according to reports. How much corner-cutting is involved I don't know.
The 30-pin docking connector and its dock "mate" in iPhones, iTouches etc. are standard off-the-shelf components, not built specifically for Apple in the first place. My old PDA (a Fujitsu Pocket Loox) has the same connector pair in its body and dock.
The pinout for the Loox is radically different to the Apple pinout and any attempt to plug my PDA into an Apple dock would be useless or at worst I would end up destroying something. I tracked down a pinout diagram so I could hack a spare Ebay cable to provide USB host signalling for my PDA; the Loox doesn't use all 30 pins either.
There is a 400-tonne spacecraft in orbit around the Earth right now. It carries a crew of between 6 and 12 people in a shirt-sleeve environment and it was put together, is kept supplied and intermittently boosted in orbit by a range of vehicles which each have a payload capability of less than 20 tonnes.
If the Chinese are serious about building the Long March 9 superlifter as a "one-shot mission" stack they are further back down the technology history books than I thought they were, given they've already got a small space station module in orbit and have demonstrated docking a manned capsule with it, the product of two separate launches by smaller boosters. If they wanted to put together a "boots and banners" Moon mission they've got the demonstrated launch capability to cope with an Apollo-style program -- launch a lander/ascent stage and park it in LEO, launch a similarly-sized service module and dock it with the lander and then after everything checks out launch the command module with crew to rendezvous with the rest of the in-orbit resources. Even better, send the lander/ascent stage to the Moon first to have it in place in orbit waiting for the crew when they arrive.
As for Dinorwic it was built in the 1970s and used the most efficient turbine/pump generator sets available at the time. I don't know if there is new magic technology that gets rid of frictional losses in pipes, cavitation, energy recovery in electric motors (which are usually about 90% efficient in themselves) and/or other tricks that can tweak pumped storage efficiencies up towards the level of supercapacitors. I suspect not.
From the Wikipedia article about the Dinorwic pumped-storage utility -- "The plant runs on average at 74-75% efficiency - i.e. it uses 33% more electricity (when pumping the water up to the Machlyn Mawr) than it actually produces."
That's about as good as it gets, really. There are frictional losses involved in moving large quantities of water uphill to the top reservoir, heat transfers from pumping and losses in the motor/generator sets etc. that can't be recovered when the water is released back down through the turbines at the bottom again. You might get 90% energy recovery out of flywheels spinning in vacuum on magnetic bearings or possibly out of the best chemical batteries or supercapacitors but pumping stuff up hills or into pressure vessels is going to be lossy. The big win for such systems is that they are mostly large-scale civil engineering, holes in the ground and they're cheap per cubic metre whereas batteries and flywheels are expensive per GWhr of storage -- Dinrowic can hold up to 8 GWhr of potential generating capacity, about the same as the Cruachan pumped-storage reservoir in the Highlands I mentioned.
"In the UK, we have three pumped storage facilities of about 50MW each (or thereabouts)."
The Dinorwig pumped storage system in Wales has 1800MW of generating capacity which it can deliver for at least 30 minutes full load; I believe its total storage capacity is about a GWhr or so. Cruachan in the Highlands is the other major pumped-storage plant in the UK, capable of supplying 440MW on 30 seconds notice but it can sustain that level for over 20 hours. It is always kept at a minimum 12-hour level as a "black start" facility in case a major grid disruption takes down other big generating stations.
Modern pumped-storage systems run about 65-70% efficient, that is a GWHr of energy stored will return about 650MWhr. Compressed air systems are going to be a lot lossier in both energy injection and energy recovery, and 350 million bucks is a lot of money to generate just 300MW of power from storage -- Dinorwic cost about a billion dollars US back in the 70s. The news article also didn't say how many hours at that rated output the salt dome system can hold but given the energy density of air probably not more than a few hours.
Most of the corporates and large institutional organisations I've done IT support for have USB ports and CD drives locked down. Techs can use USB sticks to install drivers etc. on specific machines but they're specialised devices, hardware encrypted and password-protected and the only type of external data device the OS installed on the user machines will accept -- sticking a commodity USB stick into a network-connected PC will do nothing except generate a log entry and flag up an alarm if the security policy requires it. Talking to the user about their unsanitary habits was carried out by someone higher grade than me, thankfully.
Two reactors, the no. 3 and 4 units at Ohi on the coast north of Nagoya are being prepped for restart at the moment and they should be online by mid-July delivering about 2.25GW into the Kansai grid. All the other reactors currently shut down by inspection and refuelling requirements are either undergoing or awaiting confirmation of the results of their paper "stress test" exercise and the go-ahead from local and national authorities before they can do the same.
I figure once the Ohi reactors are running and nothing bad happens then the rest will gradually be brought back on-line as opposition dissipates.
CANDU and other heavy-water power reactors have to be tweaked during the fuelling cycle to produce sufficiently pure Pu-239 without adding lots of Pu-240 which makes it useless as bomb material. The British Magnox and Soviet-era RBMK-4s were designed from the ground up so they could be run with very short fuelling cycles to reduce the Pu-240 levels in the fuel rods while their stated purpose was power generation. I think the US used Magnox-bred plutonium in one of their mid-50s test shots to see if power-station-derived Pu could be weaponised but it was moot since the Hanford reactors were churning out as much weapons-grade Pu as they could expect to need.
Fast-spectrum reactors expose U-238 metal targets to neutrons in a short pass through the core to breed almost-pure Pu-239, essential for "small-ball" cores that can be launched on missiles. Both India and Pakistan have such reactors for this purpose -- they're not too difficult to build and operate assuming they can get MEU to fuel them. Pakistan at least also had a weapons-grade HEU production facility.
Signatories to the NPT have to accept international inspectors on site at operating reactors to prevent fuelling cycle modification and possible diversion of materials for covert weapons development. India and Pakistan, like North Korea and Israel can do what they like as they are not NPT signatories.
India has no large deposits of uranium ore so it has gone for rather clumsy uranium-plutonium-thorium power reactor designs. It is not a signatory to the Non-Proliferation Treaty so it shouldn't be getting any international help with their nuclear programme, things like uranium imports, technology transfers etc. but the US decided a couple of years back to ignore the NPT and start helping them out in that regard with a pinky swear that the Indians won't transfer the tech or materials to their weapons programme, really honest to Shiva.
Any country with a workable weapons plutonium breeding operation uses purpose-built reactors, not uranium power reactors to make their bomb material. There were a couple of clumsy dual-purpose designs early on in the history of power reactors (Magnox and the Russian RBMK-4) which allowed time-limited exposure of U-238 to neutron flux to produce marginally-pure Pu-239 but nobody builds or uses them today and few nuclear weapons were made from material produced by those reactors.
The other thing is that after having bred enough plutonium for an arsenal of weapons there's no real point making more so the idea that countries build tested and proven uranium reactor designs rather than thorium-uranium burners or complex and unproven flow-thorium reactors because of their wish for weapons-grade plutonium is kinda silly. The US for example has over 70 tonnes of weapons-grade Pu in stock, the result of stockpile reductions and better weapons design requiring smaller amounts of fissionable material. Britain has over a hundred tonnes in stock, I believe, and the old Soviet states have been selling their own surplus Pu-239 weapons pits to the West to be burned up in power reactors as Mixed-Oxide (MOX) fuel.
The LFTR designs can be easily tweaked to produce U-233 (indeed the precursors have to be actively removed from the "exhaust" to prevent it forming). U-233 works well enough as a bomb core as the US found out when it fired off a couple of test samples in the Fifties and a continuous-process system such as LFTR makes it much easier to remove U-233 during regular operations to create a stockpile of weapons-grade material.
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Concorde didn't cruise at Mach 2 in afterburner -- imagine how much fuel it would use pouring JP-4 into the engine exhausts for two hours. Concorde flew supersonic at 20km altitude by means of large powerful engines which burned a lot of fuel but in a conventional manner. It did use afterburners on takeoff and initial climb out because the engines and the intake nacelles were optimised for supersonic cruise flight and at takeoff the fuel load, as much as 50% of its total on-wheels weight made the entire airframe quite heavy.
My rather dated 900MHz mobile phone (a Nokia 7110 on Tesco branded O2) in my bedroom in an Edinburgh tenement (ObUS: brownstone) typically shows zero or one bar of signal strength and sometimes drops out completely. There are three or four 50cm-thick sandstone walls between me and the nearest cell towers which cover a busy trunk road outside my door and a mainline railway station about a hundred metres away. I think higher frequency services carrying data etc. would be even less capable of penetrating the building.
The US DoD uses Pu238 "batteries" in stealthy spacecraft, spysats without large solar panels that would otherwise be easily tracked using ground-based telescopes and radars. Another use for such power sources is seabed listening stations used to monitor submarine and surface-ship movements in "areas of interest".
Pu-238 is made in specialised isotope-producing reactors. It's not extracted by reprocessing regular spent nuclear fuel from power-station reactors as it would be impossible to separate the Pu-238 out from the large quantities of other Pu isotopes bred from U-238 during regular operation. Those isotope-production reactors have been getting shut down in the US, Canada and elsewhere over the past couple of decades due to age, more restrictive licencing regulations and occasionally by celebrity-powered publicity campaigns. The ex-Soviet isotope reactor fleet is about the only regular source of such material operational today hence the national-security aspect -- the Russians are not that keen to make it easier for the DoD to spy on them by supplying them with lots of Pu-238.
Last report I saw said that Japan's carbon emissions are up 17% over last year and that includes a period when many of their nuclear reactors were still running. TEPCO has announced a 9% increase in domestic electricity prices starting in September this year, to cover the cost of the coal and oil imports needed to generate electricity that was previously produced by the nuclear stations.
Two Japanese reactors at Ohi restarted recently, generating about 2.4GW baseload, that is day and night. Another reactor in Shikoku might restart before winter but the rest are still shut down and will be until the panic is over.
My "one true power" goal would be 150% nuclear with the extra power being used to produce liquid fuels from atmospheric CO2 for mobile and transport needs.
You don't remember correctly. Three of the four damaged reactors were running normally, the fourth (no. 4) was shut down for a scheduled inspection and refuelling operation -- power-generating reactors in Japan get inspected every 13 months and the operators usually refuel them at this point. The oldest reactor, no. 1 was coming to the end of its 40-year operating licence. It would have been relicenced after a thorough inspection if nothing substantially wrong was found although given its age it might have been tagged for decommissioning anyway. The other 3 damaged reactors still had a few years to go before they would need relicencing, and the undamaged reactors, no.s 5 and 6 were built around 1980 and they still have nearly a decade before their operating licences run out.
Panasonic have good build quality even in their business range and their Toughbooks are especially well-built. Not stylish though. Expect to pay for that quality though, 50-100% more than an Apple of similar hardware spec, but when was the last time you saw a laptop advertised as being resistant to disinfectant?
HP had a deskstand that would take some of their small-form-factor PCs like the dc7900 and an HP LCD and make an all-in-one PC with the SFF case mounted behind the display. I don't think it was available ready-built.
There are a thousand ways to build a heavy-lift launcher, including using the STS ET and RS-25s or RS-68s plus strap-on boosters etc. There are problems with most of them engineering-wise, economic and political.
The ET is not structural, it can't transfer a large thrust load vertically from a motor ring at its base to a second stage or payload package on top of it. The tankage sections of staging rockets like the Saturn V are built with vertical stringers to deal with that load. A redesigned ET will be heavier and take time and money to produce; it's probably best to toss it and design a Saturn-V-like cryogenic first stage like the Delta 4 with its RS-68 motor(s) if you want to go fully cryogenic, something that has its own expensive ground-handling problems.
The real problem is time and money; the longer a NASA project takes to get to the point where it is ready to fly the more likely its funding will be cut or shaved by politicians out to make a point about extravagance or "waste" (as long as the funding cuts don't impact jobs and bennies in their neck of the woods, of course...). Attempts to keep a zombie program running by extending deadlines as its budgets are cut year after year usually just extends the agony. Developing an improved F1A engine will take several years, and even restarting the manufacturing operation to build replica vintage F1s will take some time which would make the program more vulnerable. The RS-68(A) and the RD-171 motors are available now and only cost money to make and fly.
If I was blue-skying a heavy-lifter I'd be tempted by the Delta 4 Heavy design which uses three substantially similar first stages side-by-side. It's not trivial engineering to cope with the extra thrust in the central stage but adding more booster "cores" in a 4 plus 1 or even 6 plus 1 arrangement would be easier in terms of design and flexibility, and these cores are already in production. I think this is the way SpaceX is approaching their own clean-sheet heavy-lifter project although they have proposed a rather Heath Robinsonish process for transferring fuel and oxidiser between cores in flight rather than throttling back the central core or only firing its motor in flight as a pseudo-second stage after the booster cores have been running for some time.
"Fuel is cheap, fuel tanks are cheap, engines are expensive."
Mass is expensive in a rocket design and fuel/oxidiser is mass. The Saturn V burned over 10% of its first stage fuel and oxidiser load, about 220 tonnes just clearing the tower after ignition. With less efficient engines and a greater fuel load it might never have got off the pad.
Fully-cryogenic engines are more efficient than LOX/RP-1 but they come with a bunch of drawbacks, the major one of which at takeoff is a lack of mass fraction, the amount of mass in the exhaust stream. This requires much larger engine bells and turbopumps for the same amount of thrust since liquid hydrogen is the least dense liquid known. This also means much larger tankage is needed (see the Giant Flying Turd the Shuttle was attached to) even if the fuel mass is less and tankage is mass too.
The beauty of LOX/LH2 as a fuel is in its performance at altitude and near-vacuum where the reduced backpressure means a very high exhaust velocity; the vacuum Isp figure for the RS-25 Shuttle engine is 450-odd, compared to the F-1's sea-level Isp of 263. It's why the Saturn V's second and third stages were fully-cryogenic. Rocket scientists (who are, as their name suggests, smart people) have designed around this limitation by building pseudo-SSTO LOX/LH2 launchers like the Shuttle, Ariane etc. by afitting strap-on boosters to add some extra oomph at takeoff and to get the stack to a high enough altitude that the lessened weight due to fuel burn and the loss of the boosters will take the rest of the stack to orbit.
The F1-A doesn't exist other than as a concept, and to be blunt it probably never will exist. If it ever flies it will cost billions to develop and take maybe a decade from funding to flight. The RD-171 and RD-180 are being built and flown today and the development costs are already buried in the production line. An SLS based on those motors only requires the vehicle structure to be designed and built; by the time the first prototype rolls off the production line well-tested engines will be waiting for it to fit and fly.
The problem with that approach is that the stack has to carry more fuel at takeoff which requires more engine power to lift the stack since it's heavier which requires more fuel to provide that power which requires bigger tanks... OTOH more efficient engines mean more payload delivered to orbit for the same amount of fuel and vehicle structure.
There are modern well-tested engines which have better performance than the venerable F-1 motor -- the RD-171 engine in the Zenit launcher has four chambers fed by a single set of pumps, delivering more thrust than the F-1 ever did and with greater efficiency. A cut-down 2-chamber version, the RD-180 propels the modern Atlas launcher.
The F-1 is actually quite crude by today's standards. It's not throttleable so the acceleration curve for a Saturn-V launch started off slow and picked up to about 4-Gs as the first stage's fuel ran out which beat up the crew somewhat. The Shuttle in comparison never exceeded 3-G. The F-1 has a low chamber pressure (70 bar) and reduced Isp (263 seconds) compared to modern LOX/RP-1 engines like the throttleable RD-180 (266 bar and 311 seconds) as used on the Atlas launcher.
When the iPad first came out I had to explain, repeatedly and at length, to some photographers that no, they couldn't run PhotoShop on it.
The US government built special-purpose reactors at Hanford and elsewhere to make nearly all the weapons-grade plutonium-239 they needed during the 40s and 50s, well before the first commercial reactors were built. Commercial nuclear power stations are badly suited to creating material for nuclear weapons; long fuelling cycles mean any Pu being bred in the fuel pellets gets badly contaminated by Pu-240 due to neutron capture. There were a couple of power station reactor designs which were dual-use allowing in-situ refuelling but they were not American -- the British Magnox and the infamous Soviet RMBK-4 of Chernobyl fame. Even they were not used much for producing weapons-grade material since pretty much everyone who has ever built Pu weapons has used dedicated reactors to do so. Some other commercial reactors can be converted to make weapons-grade Pu-239, like the CANDU but in normal operation they're proliferation-proof.
The reason uranium won over thorium, and continues to be the main choice for power station reactors is that it's simple to design and build uranium reactors. Thorium is not fertile and only borderline fissile so making it fission requires, as others have mentioned, a sparkplug of medium-enriched uranium to kick off the process. If it is stopped for any reason then more enriched uranium, or even plutonium is needed to get it started again. It's also difficult to "swing" the output of a thorium reactor to load-follow whereas modern uranium reactors can reduce their output significantly without problems to meet lessened demand.
The LFTR is a logistical horror requiring continuous chemical processing of highly-radioactive boiling-hot material for the reactor to operate and to prevent proliferation of bomb-grade material, and it was not within the technology or the knowledge of 1950s nuclear science to get this sort of system to work in any timescale short of decades. The pressure-vessel uranium reactor with coolant and moderator was piss-easy to design, build and operate by comparison.
Areva is building a pair of reactors in China (the Taishan EPR 1400s), and it's not an American company. They're on time (about 4 years) and on budget (about $4 billion per unit) according to reports. How much corner-cutting is involved I don't know.
The 30-pin docking connector and its dock "mate" in iPhones, iTouches etc. are standard off-the-shelf components, not built specifically for Apple in the first place. My old PDA (a Fujitsu Pocket Loox) has the same connector pair in its body and dock.
The pinout for the Loox is radically different to the Apple pinout and any attempt to plug my PDA into an Apple dock would be useless or at worst I would end up destroying something. I tracked down a pinout diagram so I could hack a spare Ebay cable to provide USB host signalling for my PDA; the Loox doesn't use all 30 pins either.
There is a 400-tonne spacecraft in orbit around the Earth right now. It carries a crew of between 6 and 12 people in a shirt-sleeve environment and it was put together, is kept supplied and intermittently boosted in orbit by a range of vehicles which each have a payload capability of less than 20 tonnes.
If the Chinese are serious about building the Long March 9 superlifter as a "one-shot mission" stack they are further back down the technology history books than I thought they were, given they've already got a small space station module in orbit and have demonstrated docking a manned capsule with it, the product of two separate launches by smaller boosters. If they wanted to put together a "boots and banners" Moon mission they've got the demonstrated launch capability to cope with an Apollo-style program -- launch a lander/ascent stage and park it in LEO, launch a similarly-sized service module and dock it with the lander and then after everything checks out launch the command module with crew to rendezvous with the rest of the in-orbit resources. Even better, send the lander/ascent stage to the Moon first to have it in place in orbit waiting for the crew when they arrive.
Please, post those results.
As for Dinorwic it was built in the 1970s and used the most efficient turbine/pump generator sets available at the time. I don't know if there is new magic technology that gets rid of frictional losses in pipes, cavitation, energy recovery in electric motors (which are usually about 90% efficient in themselves) and/or other tricks that can tweak pumped storage efficiencies up towards the level of supercapacitors. I suspect not.
From the Wikipedia article about the Dinorwic pumped-storage utility -- "The plant runs on average at 74-75% efficiency - i.e. it uses 33% more electricity (when pumping the water up to the Machlyn Mawr) than it actually produces."
That's about as good as it gets, really. There are frictional losses involved in moving large quantities of water uphill to the top reservoir, heat transfers from pumping and losses in the motor/generator sets etc. that can't be recovered when the water is released back down through the turbines at the bottom again. You might get 90% energy recovery out of flywheels spinning in vacuum on magnetic bearings or possibly out of the best chemical batteries or supercapacitors but pumping stuff up hills or into pressure vessels is going to be lossy. The big win for such systems is that they are mostly large-scale civil engineering, holes in the ground and they're cheap per cubic metre whereas batteries and flywheels are expensive per GWhr of storage -- Dinrowic can hold up to 8 GWhr of potential generating capacity, about the same as the Cruachan pumped-storage reservoir in the Highlands I mentioned.
"In the UK, we have three pumped storage facilities of about 50MW each (or thereabouts)."
The Dinorwig pumped storage system in Wales has 1800MW of generating capacity which it can deliver for at least 30 minutes full load; I believe its total storage capacity is about a GWhr or so. Cruachan in the Highlands is the other major pumped-storage plant in the UK, capable of supplying 440MW on 30 seconds notice but it can sustain that level for over 20 hours. It is always kept at a minimum 12-hour level as a "black start" facility in case a major grid disruption takes down other big generating stations.
Modern pumped-storage systems run about 65-70% efficient, that is a GWHr of energy stored will return about 650MWhr. Compressed air systems are going to be a lot lossier in both energy injection and energy recovery, and 350 million bucks is a lot of money to generate just 300MW of power from storage -- Dinorwic cost about a billion dollars US back in the 70s. The news article also didn't say how many hours at that rated output the salt dome system can hold but given the energy density of air probably not more than a few hours.
Most of the corporates and large institutional organisations I've done IT support for have USB ports and CD drives locked down. Techs can use USB sticks to install drivers etc. on specific machines but they're specialised devices, hardware encrypted and password-protected and the only type of external data device the OS installed on the user machines will accept -- sticking a commodity USB stick into a network-connected PC will do nothing except generate a log entry and flag up an alarm if the security policy requires it. Talking to the user about their unsanitary habits was carried out by someone higher grade than me, thankfully.
Haud yer wheesht. It almost didn't rain at all yesterday. What more do you want? Temperatures above 60 Fahrenheit too?
Two reactors, the no. 3 and 4 units at Ohi on the coast north of Nagoya are being prepped for restart at the moment and they should be online by mid-July delivering about 2.25GW into the Kansai grid. All the other reactors currently shut down by inspection and refuelling requirements are either undergoing or awaiting confirmation of the results of their paper "stress test" exercise and the go-ahead from local and national authorities before they can do the same.
I figure once the Ohi reactors are running and nothing bad happens then the rest will gradually be brought back on-line as opposition dissipates.
CANDU and other heavy-water power reactors have to be tweaked during the fuelling cycle to produce sufficiently pure Pu-239 without adding lots of Pu-240 which makes it useless as bomb material. The British Magnox and Soviet-era RBMK-4s were designed from the ground up so they could be run with very short fuelling cycles to reduce the Pu-240 levels in the fuel rods while their stated purpose was power generation. I think the US used Magnox-bred plutonium in one of their mid-50s test shots to see if power-station-derived Pu could be weaponised but it was moot since the Hanford reactors were churning out as much weapons-grade Pu as they could expect to need.
Fast-spectrum reactors expose U-238 metal targets to neutrons in a short pass through the core to breed almost-pure Pu-239, essential for "small-ball" cores that can be launched on missiles. Both India and Pakistan have such reactors for this purpose -- they're not too difficult to build and operate assuming they can get MEU to fuel them. Pakistan at least also had a weapons-grade HEU production facility.
Signatories to the NPT have to accept international inspectors on site at operating reactors to prevent fuelling cycle modification and possible diversion of materials for covert weapons development. India and Pakistan, like North Korea and Israel can do what they like as they are not NPT signatories.
India has no large deposits of uranium ore so it has gone for rather clumsy uranium-plutonium-thorium power reactor designs. It is not a signatory to the Non-Proliferation Treaty so it shouldn't be getting any international help with their nuclear programme, things like uranium imports, technology transfers etc. but the US decided a couple of years back to ignore the NPT and start helping them out in that regard with a pinky swear that the Indians won't transfer the tech or materials to their weapons programme, really honest to Shiva.
Any country with a workable weapons plutonium breeding operation uses purpose-built reactors, not uranium power reactors to make their bomb material. There were a couple of clumsy dual-purpose designs early on in the history of power reactors (Magnox and the Russian RBMK-4) which allowed time-limited exposure of U-238 to neutron flux to produce marginally-pure Pu-239 but nobody builds or uses them today and few nuclear weapons were made from material produced by those reactors.
The other thing is that after having bred enough plutonium for an arsenal of weapons there's no real point making more so the idea that countries build tested and proven uranium reactor designs rather than thorium-uranium burners or complex and unproven flow-thorium reactors because of their wish for weapons-grade plutonium is kinda silly. The US for example has over 70 tonnes of weapons-grade Pu in stock, the result of stockpile reductions and better weapons design requiring smaller amounts of fissionable material. Britain has over a hundred tonnes in stock, I believe, and the old Soviet states have been selling their own surplus Pu-239 weapons pits to the West to be burned up in power reactors as Mixed-Oxide (MOX) fuel.
The LFTR designs can be easily tweaked to produce U-233 (indeed the precursors have to be actively removed from the "exhaust" to prevent it forming). U-233 works well enough as a bomb core as the US found out when it fired off a couple of test samples in the Fifties and a continuous-process system such as LFTR makes it much easier to remove U-233 during regular operations to create a stockpile of weapons-grade material.