Neighbourhood-scale generating systems are great until the central generator has to be taken off-line to be fixed or refurbished or whatever at which point the people being supplied need a solid grid connection to other generators to keep the lights on. That somewhat obviates the cost benefits of local power generation to start with.
Small nuclear plants supplying a local need are being closed down in the US and elsewhere because of economics and the cost of licencing, inspection etc. The operators of Vermont Yankee, an old 600MW single-reactor station announced it was going to close next year because it was not cost-effective to keep it running. It had a licence to keep operating for several more years but the low cost of gas and the high cost of regulation made the decision for them. A similar 550MW reactor at Kewaunee in Wisconsin shut down earlier this year for similar reasons.
A single 100MW LFTR plant for a city will still have to pay for inspections and monitoring like a dual-1400MW pressurised-water reactor operator does, maybe not as much but still a substantial overhead per kWh generated. It would cost the builders hundreds of millions of dollars to get the licence to build and operate the reactor in the first place, and good luck getting an exemption through Congress for these "safe" but totally unproven reactors with no history of operations, no generational knowledge of engineering etc.
The Oak Ridge uranium-fuelled molten-salt reactor never generated any electricity, the 7MW of heat it produced at full power for short periods was dumped directly to the atmosphere through a fan-assisted radiator. Assuming it had been coupled up to heat exchangers and a turbine generating system it could have produced maybe 3MW of electricity, no more. A modern EPR1400 PWR will produce about 4700MW of heat energy and deliver about 1500MW of electricity to the grid 24/7 when operating with an expected uptime of about 90% annually and an expected lifespan of at least 60 years with the possibility of continuing safe reliable operations for a century.
Read what I wrote more carefully -- the reactor built in the 60s was a molten salt reactor, IT DID NOT USE THORIUM. It used U-233 exclusively as a fuel, derived from military or research reactors at a guess. Lots of folks have conflated the molten-salt fuel transport system demonstrated in the 1960s with the Powerpoint presentations of purely theroetical LFTRs which have never been built or operated; as far as I know no-one has even made a benchtop demonstration of the operating principles. It is meant to breed thorium (Th-232) into fissile U-233 and then fission that in the same reactor to produce energy. This is a lot more complicated than what was achieved fifty years ago in a tiny (by modern commercial standards) laboratory model reactor.
I'm not sure what the LFTR boosters are about, really -- they may be cultist true believers aiming for the Promised Land but mostly they're chasing something that has fits no commercial niche today or for the next fifty years or so, while uranium is cheap and abundant (and that's without lots more recycling of spent fuel) and while there is an atom of carbon left under the surface of the earth that can be extracted and burnt to provide energy for free.
The Indians are closest to using thorium in any scale as a fuel source in heavy-water PWRs. They're basically regular-geometry fuel rod assemblies with a lot of thorium as well as kickstarter 20%-enriched U-235 and some Pu, probably a mix of -239 and -240 derived from spent fuel. The theory is they spend neutrons to breed the thorium up into U-233 which then fissions and generates energy and releases enough fast neutrons to breed more U-233 as well as slower moderated thermal neutrons to fission it. This is complicated and messy compared to one-step thermal moderated neutron fission of low-enriched uranium in regular fuel pellets and even MOX. They think they can make it work but they're spending a lot of effort and money in the process. The reason is political; they've got very limited native sources of uranium and they're not signatories to the Non Proliferation Treaty (NPT) which means theoretically they can't buy it from regular sources since nobody's supposed to help out non-NPT nations with nuclear equipment, materials etc. They do have a lot of thorium though hence their efforts to use it no matter how much it costs per kWh.
As for the fuel-rod thing I've got really no idea what you're on about. Most nations with more than one or two reactors make their own fuel assemblies, indeed many of them enrich their own fuel. It's not a razorblade handle situation, fuel costs including assembly manufacture are a trivial part of operating a nuclear reactor -- about 0.75 cents US per kWh according to the IAEA. The real stumbling-block is the five billion bucks plus per reactor up-front cost before the first truckload of concrete hits the rebar. That funding has to be in place even before the licencing and contruction application paperwork gets started, a process that can cost $500 million in itself and take more than two years before approval.
Nuclear weapons cores made from Pu-239 don't really degrade in storage and the material can always be reformed into new warheads as demands require but only in expensive facilities. The equipment around the cores does degrade -- for example the chemical explosive lenses arranged around the cores are precision devices and close proximity to a large amount of radiation will degrade them over time as will simple ageing and they do need to be swapped out as necessary. It's part of the expensive business of owning deployable nuclear weapons.
Britain has something like 70 tonnes of weapons-grade Pu-239 surplus to requirements from the time we had nearly a thousand warheads (we now have less than 200) and the US and Russians have a lot more than that in storage. It's just sitting there in several expensive storage facilities "somewhere". There's a much bigger cost penalty to converting material like that into usable weapons, not including the missiles, submarines and aircraft required to deliver them, the personnel to operate them, the training, security, release protocols etc. so most of those decommissioned warheads from the 60s and 70s have been dismantled beyond the point where they could be quickly put back into service. The US maintains a second-string reserve of warheads, mothballed at great expense beyond its incredibly expensive front-line fleet ready for use sitting on top of Minuteman-IIIs in South Dakota or riding in Ohio boomers somewhere in the Pacific. Notice the use of that word, "expensive". You tend to see it turn up a lot in discussions about nuclear weapons and materials. Keeping a secret stash of nukes and/or Pu-239 costs a lot of money, it can't simply be parked in a shed on an army base somewhere with a padlock on the door.
The Russians have sold the US a lot of highly-enriched U-235, some of it from weapons cores which has been downblended into nuclear fuel for power reactors, the "Megatonnes to Megawatts" project. The Russians surplus Pu-239 stockpile is more of a challenge but they are looking at using it in their BN-series fast reactors as well as MOX fuel for PWRs and the like. The US still hasn't licenced any MOX operations in its own commercial reactor fleet although there's a good deal of operational experience with it elsewhere in the world. This is the obvious way to use up surplus weapons-grade Pu-239 but the security of moving such materials around to downblend it is problematic -- commercial MOX with pure Pu-239 is a very great security risk.
U-233 -- no, the US does not have hundreds of tonnes of the stuff. It has two tonnes, no more. There are no real thorium reactors planned, granted Construction and Operating Licences (COLs) or pouring concrete now or in the forseeable future (unlike the US where there are four new-generation PWRs under construction and several more COLs have been issued). Assuming a series of financial, regulatory and licencing miracles occurs the earliest a molten-salt thorium reactor would be starting up anywhere would be fifteen to twenty years from now, and even that's optimistic as long as gas is cheap, coal is cheaper and yellowcake is $35/lb at the minehead. Storing that bomb-grade U-233 is expensive (oh look, there's that word again!) and it's not necessary to use U-233 to start up a thorium breeder, this can be done using U-235 and Pu-239 as the Indians plan to in their heavy-water PWRs in a thorium/MOX fuel cycle.
President Nixon was the one who started the nuclear arms reduction talks as I remember, so why did the White House want or need more bomb-grade plutonium by the late 1960s? A quick check on Wikipeida suggests US stockpiles peaked about 1965 or thereabouts at a bit over 30,000 warheads of all types. By the early 70s it was down to 20,000.
The purpose-built reactors at Hanford and elsewhere had already produced as much bomb-grade material as the US ever needed, building dual-purpose commerical reactors was pointless. The UK did go down this road with the flexible-fuel-cycle Magnox designs but again by the time they came into operation the UK already had as much Pu-239 as it needed for its own stockpile of warheads.
The Soviet-era BN series fast reactors have an iffy safety record with classical sodium leaks and fires -- the rumour mill was that the BN-600 had two turbine halls, one would burn down when the sodium leaked out of the heat exchangers and caught fire but it was easy to get the leak fixed and they could use the other turbine hall until the next leak and fire while they rebuilt the first turbine hall.
IFRs are basically breeder reactors and they have generally proved to be uneconomic in the world energy markets even if the technical problems many of them have suffered from in the past could be overcome. Generating electricity at 20, 30 or 50 cents US per kWh with IFRs or LFTRs is pointless when gas is cheap, coal is cheaper and no-one cares enough about CO2, acid rain, particulates, mercury and all the other ills of burning billions of tonnes of carbon-based fossil fuel each year in a planetary atmosphere.
No, there was no molten-salt thorium reactor in the mid-60s. There was a small (7MW thermal maximum output, never generated any electricity) molten-salt reactor fuelled with U-233, a testbed that ran only for a few weeks total over its lifespan and at maximum output for a very small part of that time. Other people have worked on breeding thorium into U-233 for use as a nuclear fuel but no-one's done it in a molten-salt reactor.
It depends on the operation being carried out. Reactor 4 at Fukushima Daiichi was famously empty of fuel rods with the entire core load stored in the adjacent Spent Fuel Pool of Doom Doom Doomity DOOM! (sorry, channeling Arne Gunderson there for a moment) but the Japanese nuclear authority requires a complete inspection of each reactor structure every 13 months and it was usual to empty the entire reactor core of fuel to allow this to be done during a refuelling operation, but as you say some of the less-spent fuel rods would be returned to the core before restart. Inspection of the inside of the vessel and the core structures is, I understand, carried out with cameras and remote probes underwater while it remains flooded as the core and inner lining are noticeably radioactive.
The outside of the pressure vessel (RPV) is also checked at this time with engineers entering the void between the vessel and the inner containment structure to do so. Once fission had stopped there was some residual radioactivity there (less because of the screening effects of 20cm of steel) but not enough to trip personal exposure limits for the inspectors, as long as they didn't make a picnic of it.
Without a moderator there is no criticality to worry about. Molten-salt reactors operate by moving a salt stream carrying fissile fuel through a moderator core where neutrons are slowed down, fission occurs and heat is generated. The fuel then leaves the core, fission stops and it enters a heat exchanger which produces steam or hot gas to drive a turbine and thus generate electricity. The LFTR designs add a breeding stage to the basic fuel transport system, converting Th-232 into U-233 which fissions in the moderator core. Thorium by itself is useless as a nuclear fuel. The often-touted experimental salt reactor run in the 1960s never actually used thorium, it was fuelled with U-233. As far as I know nobody's ever run a thorium-to-uranium breeder using molten salt. Thorium can be bred into fissile U-233 in other conventional reactors, commonly heavy-water PWRs and the like but it might also work in regular PWRs. There's no real demand for it today though since uranium is plentiful and incredibly cheap.
Almost all current reactors have fixed solid fuel elements and flow coolant (water, steam, gas, sodium, lead/bismith alloy etc.) around them to extract the heat of fission. Sometimes the coolant is also the moderator (PWRs and BWRs), sometimes a separate moderator is used, like graphite in the British AGRs and the ex-Soviet RMBK-4s. I think most of the many LFTR designs being promoted rely on graphite cores for moderation. If there's no moderating material in the LFTR fuel stream then dumping it into tanks has no bearing on whether the salt/fuel mixture can go critical or not. It will have a large payload of fission products and the dump tanks will have a lot of decay heat to cope with and the fuel salt will be intensely radioactive for a long time, long after it has cooled down enough to solidify; centuries or millenia perhaps, depending on the radiochemistry and amounts involved. It might be necessary to make the tanks removable using remote-handling equipment but that simply moves the problem, it doesn't deal with the dumped salt itself.
Actually the core of a regular PWR or BWR and even CANDU, Magnox, AGR or even the dreaded RBMK-4 graphite moderated reactor designs don't get very radioactive thanks mostly to careful choices of the steel alloys and other materials used in their construction (no cobalt, for example). The vessels can be removed from the containment after shutdown during decommissioning within a year or two with minimal shielding or after forty or fifty years of Safstor on site they're no more radioactive than, say, granite and can be treated as low-level waste. It is common for the inside and outside of a BWR/PWR reactor vessel and its core structures to be manually inspected during refuelling outages, for example.
The really intense radioactivity in a conventional reactor is contained in the spent fuel rods which, if undamaged, can be easily handled, transported and after a few years dry-casked for storage or shipped to a reprocessing plant to be recycled. It's done all the time in hundreds of reactors around the world during refuelling operations and has been for decades.
The LFTR concept involves moving intensely hot radioactive fuel in a salt stream through a carbon moderator for decades with no capability to repair or even properly inspect this part of the reactor as the piping will be mindbogglingly highly radioactive even if the fuel stream is removed to permit inspection.
Germany's burning coal and gas like there was no tomorrow. Its per-capita carbon emissions curve is on the rise again as it starts to shut down its non-CO2-emitting nuclear reactors while supertaxing the ones still operating to help pay for the construction of new coal-fired and gas-fired power stations from its climate change fund -- they can't put consumer electricity prices up any more to pay for these new fossil plants as they're already the highest in Europe, double that of 80% nuclear France next door which has half the carbon footprint of its solartopian neighbour.
Meanwhile states like Ontario are moving away totally from fossil-fuel for electricity generation, having embraced nuclear generation along with hydro and closing down their main fossil-fuel plants. Germany will still be burning tens of millions of tonnes of brown coal and lignite a year in 2050 by the best hopes of the supporters of renewable generation, not to mention Russian gas if there's any left.
On one hand there are about 400 "conventional" nuclear reactors generating power around the world, nearly all boiling-water or pressurised-water reactors with a few other types like the heavy-water CANDUs, the British gas-cooled AGRs and the infamous ex-Soviet RMBK-4s. They all use water or gas to cool solid-fuel elements fixed in place in a core structure. They have a typical uptime of 90% between refuelling outages and repair/inspection cycles and mostly sit there generating away and keeping the lights on.
On the other hand there are a few experimental power reactors in existence that use liquid metal cooling because they run much hotter thermally (700 deg C and higher) and with very high neutron economies (incredibly high fluxes in a small volume, thermal moderated neutrons for fission and also fast-spectrum neutrons for breeding and waste destruction). Most of the worked examples are hangar queens, breaking down repeatedly due to the thermal stresses and neutron flux damage to core structures, leaking coolant and catching fire and generally being unreliable. Because of this a lot of them have been shut down permanently as uneconomic to operate. A few are still running despite fires and leaks and the Russians are maintaining some interest in further developing their BN series of sodium-cooled fast reactors, possibly with investment from the Chinese.
In addition there are a host of new reactor designs which are basically paper exercises, grad student presentations and the like, dragging a wing around the academic world and hoping for a bite from one of the Big Guys who will drop a few billion bucks on bending metal and pouring concrete for their Precious. Probably not going to happen -- the only concrete pours going on right now are for more PWRs and BWRs which have a proven track record of producing electricity and making money for their operators.
Then what? The reactor operators can't just leave this mindbogglingly-radioactive boiling-hot slurry in those tanks, they have to clean it up. How do they intend to do so? It will be a requirement of the licencing of such a reactor design that they have plans and procedures ready if it ever does and equipment on standby just in case. "...and then a miracle occurs." is not going to pass scrutiny anywhere in the modern world's nuclear regulatory environment.
BTW the dump tanks don't need to be of sub-critical volume -- in fact they can't be. The molten salt stream carrying the fissionable materials only goes critical when it passes through the carbon moderator in the reactor core. Outside that core no fission can occur unless something goes really badly wrong and moderating material gets mixed into the molten salt stream (say if the graphite moderator core gets badly damaged) at which point you really don't want to be within a thousand miles downwind of this "safe" reactor -- one of the commonly posited cost-saving points of molten salt reactors is that like the Soviet RMBK-4s they don't need an expensive containment structure because they're "safe". Honest.
The molten-salt reactor could have produced weapons-grade plutonium (just add U-238 and continuously extract Pu-239 from the molten salt flow) but by the time it was up and running the US had as much plutonium as it wanted or needed for its thousands of in-service nuclear warheads, created in purpose-built breeder reactors running in Hanford and elsewhere in the 50s and early 60s.
As for "just drain(ing) the liquid nuclear fuel from the reactor" then what? How do you clean it up afterwards? You can't just leave it there. Mop and buckets, or a big sponge?
Going back to the original article there are some fun things folks have been doing recently with experimental reactors but the usual result has been expensive messes that are difficult to clean up afterwards. Commercial breeder reactors, for example, most of which have been shut down as either uneconomic or easily broken (or both). Gas-cooled pebble-bed designs; the Germans are still waiting for the radioactivity in their one to decay sufficiently so they can finally defuel it, including all the bits of fuel pebbles that fractured and jammed the mechanisms. It's been 25 years now and counting. Gas-cooled graphite-moderated son-of-Magnox designs like the British AGRs have high thermal efficiency but fuel is cheap and they were expensive to build and operate so the extra efficiency didn't help them proliferate in the world markets. We'll pass quickly over the RMBK-4 graphite moderator designs... CANDUs are doing quite well in some markets but they're expensive for the amount of generating capacity they provide and heavy water reactors present all sorts of proliferation risks. The Russians are doing some interesting things with compact fast-spectrum reactors which have very high burnup rates, effectively closed-cycle breeders with a possible sideline in isotopic waste destruction but they are very very experimental -- liquid sodium coolant, say no more.
Actually no. The oldest reactor at Fukushima Daiichi, no. 1 was about 40 years old but still operating problem-free and it was likely to get a ten-year licence extension after inspection. The average working life of 1970s-era reactors looks to be about 50 years or more; in a few cases economics and the dash for gas are getting some smaller facilities like Vermont Yankee (a 600MWe single-reactor plant) shut down. Reactors 2, 3 and 4 at Fukushima Daiichi were more modern designs and had at least ten years life left in them before the tsunami hit. Reactors 5 and 6 were built in the 1980s and were totally undamaged but they will be decommissioned as the site is considered inoperable in toto.
As for new modernised reactors designs Japan has three new reactors under construction at various stages of completion and its newest complete reactor came on-line a few years ago (2005, I think). The delay in building new reactors is due to the fact the older models are still operating safely and that reduces the demand for new ones. Gas is cheap at the moment as is coal and that also cripples the case for new nuclear builds because of the very large upfront costs of licencing and building any new reactors (which are expected to have a service life of 60 years).
International laws about dumping all sorts of waste materials at sea stop the Japanese from dumping the contaminated waste water there. They're making efforts to stop contaminated ground water escaping the site into the ocean, with variable results hence all the large storage tanks full of water being built on the site. In fact much of this water is actually safe to swim in or even drink by radiation standards adopted from the World Health Organisation and similar groups but it has enough measurable contamination to make it against the law to simply pour it down a drain into the sea.
Two reactors at Ohi were restarted back in 2012. Japanese nuclear regulations require a shutdown and inspection of all reactors every thirteen months, usually done as part of a refuelling operation. The Ohi reactors have been shut down again after operating for thirteen months but are not restarting after inspection and refuelling for various reasons, mainly bureaucratic and local-political.
They are filtering the waste water and using ion exchange systems, zeolite cartridges and the like to remove the radioactive materials in solution. That's how they're "treating" contaminated water (irradiation isn't the problem).
The water itself isn't radioactive, it's just hydrogen and oxygen. There may be some tritiated water in there but very very little, same with radioactive isotopes of oxygen. The contamination they are dealing with is radioactive particles in some cases, in others chemical substances in solution like cesium and strontium. Until the levels for all the contaminants are below international standards then the water can't be released into the sea.
The Germans had most of their military forces in the East because that's where most of the actual fighting was taking place especially after the withdrawal from North Africa. Stalin wanted the Allies to invade Western Europe to take some pressure off his forces and the Normandy landings in June 1944 did so, but not to any great extent. By the end of 1944 the majority of German military forces in were still concentrated on fighting the Russians in a desperate and ultimately futile attempt to keep them from Berlin and German soil. The efforts by the Germans to stop the liberation of France and the Low Countries was negligible in comparison. It just seems important to us in the West because it was Our Boys doing the fighting there but none of the western Allies ever faced a single meatgrinder fight like, say, Citadel/Kursk (Soviet casualties of over a million men, 8000 tanks lost or damaged, and it was considered a Soviet win!) and Kursk was only one of several such bloodbaths. The famous Battle of the Bulge in contrast cost the western Allies about 100,000 casualties, peanuts in comparison to Citadel/Kursk.
Whole lot of wrong there but "American chest-beating" after the war fed into the history books which took a very parochial view of the entire affair -- for example the Germans took 90% of their casualties in the East, the Allied landings at Normandy and liberation of Western Europe were a sideshow as far as they were concerned. So it is with the Japanese theatre of the war and latterly the use of nukes there. BTW the Nagasaki plutonium implosion bomb design was the one actually tested at Trinity, it was the Hiroshima uranium bomb that was considered simple enough it didn't need a test shot.
The nukes were a new wonder-weapon in a war filled with wonder-weapons, they were ready for use and they were used, that's all. The Allies already had city-killers, they were thousand-bomber raids causing firestorms that killed more people in a night in places like Tokyo than the Hiroshima bomb ever did. Sure the nukes were super-effective at the hypocentre, melting concrete and glass with the heat flash but the effects died away with distance whereas mattress-bombing with ten thousand tonnes of conventional explosives and 4lb incendiaries destroyed a much wider area. Here's an interesting thought -- bomber losses over Japan were tiny compared to the German campaign and in September the Boeing plant in Seattle built 300 B-29s and that's after the Japanese surrendered. It took them months to stop the production lines. All those bombers would have been available to continue conventional attacks on Japan even without the nukes.
As for scaring the Soviets, they had been fucked over by experts and in the end it was the hammer-and-sickle that flew over what was left of the Reichstag, not the swastika over Red Square. Nukes didn't scare them; if you want to play that game try getting a map of the Soviet Union at the end of 1945 and draw a few dozen two-mile-diameter circles, the effective damage area of a 20 kilotonne nuke on it and then look at what's left. That's assuming the US could actually make that number of nukes and deliver them to target -- Moscow was out of range from western Europe using B-29s and the greater-range B-36 was still getting debugged by the time 1946 rolled around.
It took the Soviets months to position over a million troops around Manchuria, moving them from the Western front after V-E Day along the Trans-Siberian railroad along with tens of thousands of artillery pieces, tanks etc. Marshal Vasilevsky who planned and organised the operation is regarded by some as the greatest general in history for just this achievement. The attack took place exactly 90 days after Germany surrendered as Stalin had promised at Potsdam, the timing was in no way related to the US using its first nuclear bombs.
The Japanese and Manchurian troops the Russians faced had never actually been in combat, they were quite well supplied with equipment from local factories and fuel was abundant and they were well dug-in having had months to prepare for an attack they knew was coming. Unfortunately for them they were up against the soldiers who had taken Berlin, the toughest bastards in uniform that walked the earth at that time.
As for MacArthur neither he nor the Japanese forces positioned there could stop the Russians taking the Kuril and Sakhalin islands, the only opposed landing of foreign troops on Japanese soil apart from Okinawa. They also grabbed off a large chunk of Korea into the bargain and many historians claim that only running out of supplies stopped them taking the rest of the peninsula.
The last US bombing raid on Japan was carried out on the 14th or 15th of August, several days after the second nuclear bombing since up till then there had been no official notice of surrender by the Japanese government. There had been a reduction in operations for a day or two after the Nagasaki attack but no complete cessation.
Europe isn't focussed on space. It sees a space industry and a space presence as a valuable asset to civil life in Europe and elsewhere. The US sees it mostly as another place to put military hardware.
As for "maintaining focus" we've seen other powers lose, for example, intrinsic manned space capability and having to go cap-in-hand to the Old Enemy to get their people into orbit. No names no pack-drill, but as you point out retrenchment could happen to ESA too.
The US space launch business has never been healthier thanks to the US DoD and intelligence organisations. More spy satellites, more global dominance infrastructure, not so much commercial launches which are going more and more to the cheaper European and the Russian specialists who only launch military gear sometimes.
The only time NATO has fought under the treaty's Article 5, the "attack on one is an attack on all" umbrella was when the mighty US was laid low by a bunch of Saudis armed with boxcutters. If the US wants to get out from under the NATO umbrella, on you go but watch out for those scary Muslims with their oh-so-nasty knives! Papercut!
Jamming GPS is actually quite difficult at least at a distance. The signals are low-power but very directional and if someone ignores satellites at low sky angles especially in the direction of hostile forces then singals from the other satellites in the constellation should be uncorrupted.
Local jamming of GPS is easier to carry out. If there is only a few km or so between the receivers and the jammers then they can be swamped or subverted, fed corrupt data to make them inaccurate. General jamming isn't going to work unless aircraft fly over the area to be jammed and that puts them at risk of being shot down in a conflict. They also need to stay on station for extended periods and as yet drones can't carry the amount of equipment and generating capacity to do a good job in such circumstances.
NASA has never built rockets, it's bought them from Boeing and a whole host of other US companies over the years. The new "private" launch startup companies are Seven Dwarfs who will rely to a large part on US government money via NASA and other organisations like US DoD to offset their costs and pad the bottom line.
Slashdot Mirror
Neighbourhood-scale generating systems are great until the central generator has to be taken off-line to be fixed or refurbished or whatever at which point the people being supplied need a solid grid connection to other generators to keep the lights on. That somewhat obviates the cost benefits of local power generation to start with.
Small nuclear plants supplying a local need are being closed down in the US and elsewhere because of economics and the cost of licencing, inspection etc. The operators of Vermont Yankee, an old 600MW single-reactor station announced it was going to close next year because it was not cost-effective to keep it running. It had a licence to keep operating for several more years but the low cost of gas and the high cost of regulation made the decision for them. A similar 550MW reactor at Kewaunee in Wisconsin shut down earlier this year for similar reasons.
A single 100MW LFTR plant for a city will still have to pay for inspections and monitoring like a dual-1400MW pressurised-water reactor operator does, maybe not as much but still a substantial overhead per kWh generated. It would cost the builders hundreds of millions of dollars to get the licence to build and operate the reactor in the first place, and good luck getting an exemption through Congress for these "safe" but totally unproven reactors with no history of operations, no generational knowledge of engineering etc.
The Oak Ridge uranium-fuelled molten-salt reactor never generated any electricity, the 7MW of heat it produced at full power for short periods was dumped directly to the atmosphere through a fan-assisted radiator. Assuming it had been coupled up to heat exchangers and a turbine generating system it could have produced maybe 3MW of electricity, no more. A modern EPR1400 PWR will produce about 4700MW of heat energy and deliver about 1500MW of electricity to the grid 24/7 when operating with an expected uptime of about 90% annually and an expected lifespan of at least 60 years with the possibility of continuing safe reliable operations for a century.
Read what I wrote more carefully -- the reactor built in the 60s was a molten salt reactor, IT DID NOT USE THORIUM. It used U-233 exclusively as a fuel, derived from military or research reactors at a guess. Lots of folks have conflated the molten-salt fuel transport system demonstrated in the 1960s with the Powerpoint presentations of purely theroetical LFTRs which have never been built or operated; as far as I know no-one has even made a benchtop demonstration of the operating principles. It is meant to breed thorium (Th-232) into fissile U-233 and then fission that in the same reactor to produce energy. This is a lot more complicated than what was achieved fifty years ago in a tiny (by modern commercial standards) laboratory model reactor.
I'm not sure what the LFTR boosters are about, really -- they may be cultist true believers aiming for the Promised Land but mostly they're chasing something that has fits no commercial niche today or for the next fifty years or so, while uranium is cheap and abundant (and that's without lots more recycling of spent fuel) and while there is an atom of carbon left under the surface of the earth that can be extracted and burnt to provide energy for free.
The Indians are closest to using thorium in any scale as a fuel source in heavy-water PWRs. They're basically regular-geometry fuel rod assemblies with a lot of thorium as well as kickstarter 20%-enriched U-235 and some Pu, probably a mix of -239 and -240 derived from spent fuel. The theory is they spend neutrons to breed the thorium up into U-233 which then fissions and generates energy and releases enough fast neutrons to breed more U-233 as well as slower moderated thermal neutrons to fission it. This is complicated and messy compared to one-step thermal moderated neutron fission of low-enriched uranium in regular fuel pellets and even MOX. They think they can make it work but they're spending a lot of effort and money in the process. The reason is political; they've got very limited native sources of uranium and they're not signatories to the Non Proliferation Treaty (NPT) which means theoretically they can't buy it from regular sources since nobody's supposed to help out non-NPT nations with nuclear equipment, materials etc. They do have a lot of thorium though hence their efforts to use it no matter how much it costs per kWh.
As for the fuel-rod thing I've got really no idea what you're on about. Most nations with more than one or two reactors make their own fuel assemblies, indeed many of them enrich their own fuel. It's not a razorblade handle situation, fuel costs including assembly manufacture are a trivial part of operating a nuclear reactor -- about 0.75 cents US per kWh according to the IAEA. The real stumbling-block is the five billion bucks plus per reactor up-front cost before the first truckload of concrete hits the rebar. That funding has to be in place even before the licencing and contruction application paperwork gets started, a process that can cost $500 million in itself and take more than two years before approval.
Nuclear weapons cores made from Pu-239 don't really degrade in storage and the material can always be reformed into new warheads as demands require but only in expensive facilities. The equipment around the cores does degrade -- for example the chemical explosive lenses arranged around the cores are precision devices and close proximity to a large amount of radiation will degrade them over time as will simple ageing and they do need to be swapped out as necessary. It's part of the expensive business of owning deployable nuclear weapons.
Britain has something like 70 tonnes of weapons-grade Pu-239 surplus to requirements from the time we had nearly a thousand warheads (we now have less than 200) and the US and Russians have a lot more than that in storage. It's just sitting there in several expensive storage facilities "somewhere". There's a much bigger cost penalty to converting material like that into usable weapons, not including the missiles, submarines and aircraft required to deliver them, the personnel to operate them, the training, security, release protocols etc. so most of those decommissioned warheads from the 60s and 70s have been dismantled beyond the point where they could be quickly put back into service. The US maintains a second-string reserve of warheads, mothballed at great expense beyond its incredibly expensive front-line fleet ready for use sitting on top of Minuteman-IIIs in South Dakota or riding in Ohio boomers somewhere in the Pacific. Notice the use of that word, "expensive". You tend to see it turn up a lot in discussions about nuclear weapons and materials. Keeping a secret stash of nukes and/or Pu-239 costs a lot of money, it can't simply be parked in a shed on an army base somewhere with a padlock on the door.
The Russians have sold the US a lot of highly-enriched U-235, some of it from weapons cores which has been downblended into nuclear fuel for power reactors, the "Megatonnes to Megawatts" project. The Russians surplus Pu-239 stockpile is more of a challenge but they are looking at using it in their BN-series fast reactors as well as MOX fuel for PWRs and the like. The US still hasn't licenced any MOX operations in its own commercial reactor fleet although there's a good deal of operational experience with it elsewhere in the world. This is the obvious way to use up surplus weapons-grade Pu-239 but the security of moving such materials around to downblend it is problematic -- commercial MOX with pure Pu-239 is a very great security risk.
U-233 -- no, the US does not have hundreds of tonnes of the stuff. It has two tonnes, no more. There are no real thorium reactors planned, granted Construction and Operating Licences (COLs) or pouring concrete now or in the forseeable future (unlike the US where there are four new-generation PWRs under construction and several more COLs have been issued). Assuming a series of financial, regulatory and licencing miracles occurs the earliest a molten-salt thorium reactor would be starting up anywhere would be fifteen to twenty years from now, and even that's optimistic as long as gas is cheap, coal is cheaper and yellowcake is $35/lb at the minehead. Storing that bomb-grade U-233 is expensive (oh look, there's that word again!) and it's not necessary to use U-233 to start up a thorium breeder, this can be done using U-235 and Pu-239 as the Indians plan to in their heavy-water PWRs in a thorium/MOX fuel cycle.
President Nixon was the one who started the nuclear arms reduction talks as I remember, so why did the White House want or need more bomb-grade plutonium by the late 1960s? A quick check on Wikipeida suggests US stockpiles peaked about 1965 or thereabouts at a bit over 30,000 warheads of all types. By the early 70s it was down to 20,000.
The purpose-built reactors at Hanford and elsewhere had already produced as much bomb-grade material as the US ever needed, building dual-purpose commerical reactors was pointless. The UK did go down this road with the flexible-fuel-cycle Magnox designs but again by the time they came into operation the UK already had as much Pu-239 as it needed for its own stockpile of warheads.
The Soviet-era BN series fast reactors have an iffy safety record with classical sodium leaks and fires -- the rumour mill was that the BN-600 had two turbine halls, one would burn down when the sodium leaked out of the heat exchangers and caught fire but it was easy to get the leak fixed and they could use the other turbine hall until the next leak and fire while they rebuilt the first turbine hall.
IFRs are basically breeder reactors and they have generally proved to be uneconomic in the world energy markets even if the technical problems many of them have suffered from in the past could be overcome. Generating electricity at 20, 30 or 50 cents US per kWh with IFRs or LFTRs is pointless when gas is cheap, coal is cheaper and no-one cares enough about CO2, acid rain, particulates, mercury and all the other ills of burning billions of tonnes of carbon-based fossil fuel each year in a planetary atmosphere.
No, there was no molten-salt thorium reactor in the mid-60s. There was a small (7MW thermal maximum output, never generated any electricity) molten-salt reactor fuelled with U-233, a testbed that ran only for a few weeks total over its lifespan and at maximum output for a very small part of that time. Other people have worked on breeding thorium into U-233 for use as a nuclear fuel but no-one's done it in a molten-salt reactor.
It depends on the operation being carried out. Reactor 4 at Fukushima Daiichi was famously empty of fuel rods with the entire core load stored in the adjacent Spent Fuel Pool of Doom Doom Doomity DOOM! (sorry, channeling Arne Gunderson there for a moment) but the Japanese nuclear authority requires a complete inspection of each reactor structure every 13 months and it was usual to empty the entire reactor core of fuel to allow this to be done during a refuelling operation, but as you say some of the less-spent fuel rods would be returned to the core before restart. Inspection of the inside of the vessel and the core structures is, I understand, carried out with cameras and remote probes underwater while it remains flooded as the core and inner lining are noticeably radioactive.
The outside of the pressure vessel (RPV) is also checked at this time with engineers entering the void between the vessel and the inner containment structure to do so. Once fission had stopped there was some residual radioactivity there (less because of the screening effects of 20cm of steel) but not enough to trip personal exposure limits for the inspectors, as long as they didn't make a picnic of it.
Without a moderator there is no criticality to worry about. Molten-salt reactors operate by moving a salt stream carrying fissile fuel through a moderator core where neutrons are slowed down, fission occurs and heat is generated. The fuel then leaves the core, fission stops and it enters a heat exchanger which produces steam or hot gas to drive a turbine and thus generate electricity. The LFTR designs add a breeding stage to the basic fuel transport system, converting Th-232 into U-233 which fissions in the moderator core. Thorium by itself is useless as a nuclear fuel. The often-touted experimental salt reactor run in the 1960s never actually used thorium, it was fuelled with U-233. As far as I know nobody's ever run a thorium-to-uranium breeder using molten salt. Thorium can be bred into fissile U-233 in other conventional reactors, commonly heavy-water PWRs and the like but it might also work in regular PWRs. There's no real demand for it today though since uranium is plentiful and incredibly cheap.
Almost all current reactors have fixed solid fuel elements and flow coolant (water, steam, gas, sodium, lead/bismith alloy etc.) around them to extract the heat of fission. Sometimes the coolant is also the moderator (PWRs and BWRs), sometimes a separate moderator is used, like graphite in the British AGRs and the ex-Soviet RMBK-4s. I think most of the many LFTR designs being promoted rely on graphite cores for moderation. If there's no moderating material in the LFTR fuel stream then dumping it into tanks has no bearing on whether the salt/fuel mixture can go critical or not. It will have a large payload of fission products and the dump tanks will have a lot of decay heat to cope with and the fuel salt will be intensely radioactive for a long time, long after it has cooled down enough to solidify; centuries or millenia perhaps, depending on the radiochemistry and amounts involved. It might be necessary to make the tanks removable using remote-handling equipment but that simply moves the problem, it doesn't deal with the dumped salt itself.
Actually the core of a regular PWR or BWR and even CANDU, Magnox, AGR or even the dreaded RBMK-4 graphite moderated reactor designs don't get very radioactive thanks mostly to careful choices of the steel alloys and other materials used in their construction (no cobalt, for example). The vessels can be removed from the containment after shutdown during decommissioning within a year or two with minimal shielding or after forty or fifty years of Safstor on site they're no more radioactive than, say, granite and can be treated as low-level waste. It is common for the inside and outside of a BWR/PWR reactor vessel and its core structures to be manually inspected during refuelling outages, for example.
The really intense radioactivity in a conventional reactor is contained in the spent fuel rods which, if undamaged, can be easily handled, transported and after a few years dry-casked for storage or shipped to a reprocessing plant to be recycled. It's done all the time in hundreds of reactors around the world during refuelling operations and has been for decades.
The LFTR concept involves moving intensely hot radioactive fuel in a salt stream through a carbon moderator for decades with no capability to repair or even properly inspect this part of the reactor as the piping will be mindbogglingly highly radioactive even if the fuel stream is removed to permit inspection.
Germany's burning coal and gas like there was no tomorrow. Its per-capita carbon emissions curve is on the rise again as it starts to shut down its non-CO2-emitting nuclear reactors while supertaxing the ones still operating to help pay for the construction of new coal-fired and gas-fired power stations from its climate change fund -- they can't put consumer electricity prices up any more to pay for these new fossil plants as they're already the highest in Europe, double that of 80% nuclear France next door which has half the carbon footprint of its solartopian neighbour.
Meanwhile states like Ontario are moving away totally from fossil-fuel for electricity generation, having embraced nuclear generation along with hydro and closing down their main fossil-fuel plants. Germany will still be burning tens of millions of tonnes of brown coal and lignite a year in 2050 by the best hopes of the supporters of renewable generation, not to mention Russian gas if there's any left.
On one hand there are about 400 "conventional" nuclear reactors generating power around the world, nearly all boiling-water or pressurised-water reactors with a few other types like the heavy-water CANDUs, the British gas-cooled AGRs and the infamous ex-Soviet RMBK-4s. They all use water or gas to cool solid-fuel elements fixed in place in a core structure. They have a typical uptime of 90% between refuelling outages and repair/inspection cycles and mostly sit there generating away and keeping the lights on.
On the other hand there are a few experimental power reactors in existence that use liquid metal cooling because they run much hotter thermally (700 deg C and higher) and with very high neutron economies (incredibly high fluxes in a small volume, thermal moderated neutrons for fission and also fast-spectrum neutrons for breeding and waste destruction). Most of the worked examples are hangar queens, breaking down repeatedly due to the thermal stresses and neutron flux damage to core structures, leaking coolant and catching fire and generally being unreliable. Because of this a lot of them have been shut down permanently as uneconomic to operate. A few are still running despite fires and leaks and the Russians are maintaining some interest in further developing their BN series of sodium-cooled fast reactors, possibly with investment from the Chinese.
In addition there are a host of new reactor designs which are basically paper exercises, grad student presentations and the like, dragging a wing around the academic world and hoping for a bite from one of the Big Guys who will drop a few billion bucks on bending metal and pouring concrete for their Precious. Probably not going to happen -- the only concrete pours going on right now are for more PWRs and BWRs which have a proven track record of producing electricity and making money for their operators.
Then what? The reactor operators can't just leave this mindbogglingly-radioactive boiling-hot slurry in those tanks, they have to clean it up. How do they intend to do so? It will be a requirement of the licencing of such a reactor design that they have plans and procedures ready if it ever does and equipment on standby just in case. "...and then a miracle occurs." is not going to pass scrutiny anywhere in the modern world's nuclear regulatory environment.
BTW the dump tanks don't need to be of sub-critical volume -- in fact they can't be. The molten salt stream carrying the fissionable materials only goes critical when it passes through the carbon moderator in the reactor core. Outside that core no fission can occur unless something goes really badly wrong and moderating material gets mixed into the molten salt stream (say if the graphite moderator core gets badly damaged) at which point you really don't want to be within a thousand miles downwind of this "safe" reactor -- one of the commonly posited cost-saving points of molten salt reactors is that like the Soviet RMBK-4s they don't need an expensive containment structure because they're "safe". Honest.
The molten-salt reactor could have produced weapons-grade plutonium (just add U-238 and continuously extract Pu-239 from the molten salt flow) but by the time it was up and running the US had as much plutonium as it wanted or needed for its thousands of in-service nuclear warheads, created in purpose-built breeder reactors running in Hanford and elsewhere in the 50s and early 60s.
As for "just drain(ing) the liquid nuclear fuel from the reactor" then what? How do you clean it up afterwards? You can't just leave it there. Mop and buckets, or a big sponge?
Going back to the original article there are some fun things folks have been doing recently with experimental reactors but the usual result has been expensive messes that are difficult to clean up afterwards. Commercial breeder reactors, for example, most of which have been shut down as either uneconomic or easily broken (or both). Gas-cooled pebble-bed designs; the Germans are still waiting for the radioactivity in their one to decay sufficiently so they can finally defuel it, including all the bits of fuel pebbles that fractured and jammed the mechanisms. It's been 25 years now and counting. Gas-cooled graphite-moderated son-of-Magnox designs like the British AGRs have high thermal efficiency but fuel is cheap and they were expensive to build and operate so the extra efficiency didn't help them proliferate in the world markets. We'll pass quickly over the RMBK-4 graphite moderator designs... CANDUs are doing quite well in some markets but they're expensive for the amount of generating capacity they provide and heavy water reactors present all sorts of proliferation risks. The Russians are doing some interesting things with compact fast-spectrum reactors which have very high burnup rates, effectively closed-cycle breeders with a possible sideline in isotopic waste destruction but they are very very experimental -- liquid sodium coolant, say no more.
Actually no. The oldest reactor at Fukushima Daiichi, no. 1 was about 40 years old but still operating problem-free and it was likely to get a ten-year licence extension after inspection. The average working life of 1970s-era reactors looks to be about 50 years or more; in a few cases economics and the dash for gas are getting some smaller facilities like Vermont Yankee (a 600MWe single-reactor plant) shut down. Reactors 2, 3 and 4 at Fukushima Daiichi were more modern designs and had at least ten years life left in them before the tsunami hit. Reactors 5 and 6 were built in the 1980s and were totally undamaged but they will be decommissioned as the site is considered inoperable in toto.
As for new modernised reactors designs Japan has three new reactors under construction at various stages of completion and its newest complete reactor came on-line a few years ago (2005, I think). The delay in building new reactors is due to the fact the older models are still operating safely and that reduces the demand for new ones. Gas is cheap at the moment as is coal and that also cripples the case for new nuclear builds because of the very large upfront costs of licencing and building any new reactors (which are expected to have a service life of 60 years).
International laws about dumping all sorts of waste materials at sea stop the Japanese from dumping the contaminated waste water there. They're making efforts to stop contaminated ground water escaping the site into the ocean, with variable results hence all the large storage tanks full of water being built on the site. In fact much of this water is actually safe to swim in or even drink by radiation standards adopted from the World Health Organisation and similar groups but it has enough measurable contamination to make it against the law to simply pour it down a drain into the sea.
Two reactors at Ohi were restarted back in 2012. Japanese nuclear regulations require a shutdown and inspection of all reactors every thirteen months, usually done as part of a refuelling operation. The Ohi reactors have been shut down again after operating for thirteen months but are not restarting after inspection and refuelling for various reasons, mainly bureaucratic and local-political.
They are filtering the waste water and using ion exchange systems, zeolite cartridges and the like to remove the radioactive materials in solution. That's how they're "treating" contaminated water (irradiation isn't the problem).
The water itself isn't radioactive, it's just hydrogen and oxygen. There may be some tritiated water in there but very very little, same with radioactive isotopes of oxygen. The contamination they are dealing with is radioactive particles in some cases, in others chemical substances in solution like cesium and strontium. Until the levels for all the contaminants are below international standards then the water can't be released into the sea.
The Germans had most of their military forces in the East because that's where most of the actual fighting was taking place especially after the withdrawal from North Africa. Stalin wanted the Allies to invade Western Europe to take some pressure off his forces and the Normandy landings in June 1944 did so, but not to any great extent. By the end of 1944 the majority of German military forces in were still concentrated on fighting the Russians in a desperate and ultimately futile attempt to keep them from Berlin and German soil. The efforts by the Germans to stop the liberation of France and the Low Countries was negligible in comparison. It just seems important to us in the West because it was Our Boys doing the fighting there but none of the western Allies ever faced a single meatgrinder fight like, say, Citadel/Kursk (Soviet casualties of over a million men, 8000 tanks lost or damaged, and it was considered a Soviet win!) and Kursk was only one of several such bloodbaths. The famous Battle of the Bulge in contrast cost the western Allies about 100,000 casualties, peanuts in comparison to Citadel/Kursk.
Whole lot of wrong there but "American chest-beating" after the war fed into the history books which took a very parochial view of the entire affair -- for example the Germans took 90% of their casualties in the East, the Allied landings at Normandy and liberation of Western Europe were a sideshow as far as they were concerned. So it is with the Japanese theatre of the war and latterly the use of nukes there. BTW the Nagasaki plutonium implosion bomb design was the one actually tested at Trinity, it was the Hiroshima uranium bomb that was considered simple enough it didn't need a test shot.
The nukes were a new wonder-weapon in a war filled with wonder-weapons, they were ready for use and they were used, that's all. The Allies already had city-killers, they were thousand-bomber raids causing firestorms that killed more people in a night in places like Tokyo than the Hiroshima bomb ever did. Sure the nukes were super-effective at the hypocentre, melting concrete and glass with the heat flash but the effects died away with distance whereas mattress-bombing with ten thousand tonnes of conventional explosives and 4lb incendiaries destroyed a much wider area. Here's an interesting thought -- bomber losses over Japan were tiny compared to the German campaign and in September the Boeing plant in Seattle built 300 B-29s and that's after the Japanese surrendered. It took them months to stop the production lines. All those bombers would have been available to continue conventional attacks on Japan even without the nukes.
As for scaring the Soviets, they had been fucked over by experts and in the end it was the hammer-and-sickle that flew over what was left of the Reichstag, not the swastika over Red Square. Nukes didn't scare them; if you want to play that game try getting a map of the Soviet Union at the end of 1945 and draw a few dozen two-mile-diameter circles, the effective damage area of a 20 kilotonne nuke on it and then look at what's left. That's assuming the US could actually make that number of nukes and deliver them to target -- Moscow was out of range from western Europe using B-29s and the greater-range B-36 was still getting debugged by the time 1946 rolled around.
It took the Soviets months to position over a million troops around Manchuria, moving them from the Western front after V-E Day along the Trans-Siberian railroad along with tens of thousands of artillery pieces, tanks etc. Marshal Vasilevsky who planned and organised the operation is regarded by some as the greatest general in history for just this achievement. The attack took place exactly 90 days after Germany surrendered as Stalin had promised at Potsdam, the timing was in no way related to the US using its first nuclear bombs.
The Japanese and Manchurian troops the Russians faced had never actually been in combat, they were quite well supplied with equipment from local factories and fuel was abundant and they were well dug-in having had months to prepare for an attack they knew was coming. Unfortunately for them they were up against the soldiers who had taken Berlin, the toughest bastards in uniform that walked the earth at that time.
As for MacArthur neither he nor the Japanese forces positioned there could stop the Russians taking the Kuril and Sakhalin islands, the only opposed landing of foreign troops on Japanese soil apart from Okinawa. They also grabbed off a large chunk of Korea into the bargain and many historians claim that only running out of supplies stopped them taking the rest of the peninsula.
The last US bombing raid on Japan was carried out on the 14th or 15th of August, several days after the second nuclear bombing since up till then there had been no official notice of surrender by the Japanese government. There had been a reduction in operations for a day or two after the Nagasaki attack but no complete cessation.
Europe isn't focussed on space. It sees a space industry and a space presence as a valuable asset to civil life in Europe and elsewhere. The US sees it mostly as another place to put military hardware.
As for "maintaining focus" we've seen other powers lose, for example, intrinsic manned space capability and having to go cap-in-hand to the Old Enemy to get their people into orbit. No names no pack-drill, but as you point out retrenchment could happen to ESA too.
The US space launch business has never been healthier thanks to the US DoD and intelligence organisations. More spy satellites, more global dominance infrastructure, not so much commercial launches which are going more and more to the cheaper European and the Russian specialists who only launch military gear sometimes.
The only time NATO has fought under the treaty's Article 5, the "attack on one is an attack on all" umbrella was when the mighty US was laid low by a bunch of Saudis armed with boxcutters. If the US wants to get out from under the NATO umbrella, on you go but watch out for those scary Muslims with their oh-so-nasty knives! Papercut!
Jamming GPS is actually quite difficult at least at a distance. The signals are low-power but very directional and if someone ignores satellites at low sky angles especially in the direction of hostile forces then singals from the other satellites in the constellation should be uncorrupted.
Local jamming of GPS is easier to carry out. If there is only a few km or so between the receivers and the jammers then they can be swamped or subverted, fed corrupt data to make them inaccurate. General jamming isn't going to work unless aircraft fly over the area to be jammed and that puts them at risk of being shot down in a conflict. They also need to stay on station for extended periods and as yet drones can't carry the amount of equipment and generating capacity to do a good job in such circumstances.
NASA has never built rockets, it's bought them from Boeing and a whole host of other US companies over the years. The new "private" launch startup companies are Seven Dwarfs who will rely to a large part on US government money via NASA and other organisations like US DoD to offset their costs and pad the bottom line.