I always felt that the AGR was a much better idea than the PWR, because in the event of accident convection would keep the core cool.
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Theoretically a very good design, but almost all were delivered late with skyrocketing costs. Wasn't Dungeness B something like 11 years late? The first few then suffered engineering problems that reduced their availability during their first years - although to be fair in recent years they have done sterling work.
A 2nd generation AGR was considered when it came to looking at a 3rd generation reactor programme for the UK, it came way behind a Westinghouse PWR - so we ended up with Sizewell B.
so let me ask you this - what is the most environmentally safe way to use Nuclear Fission? Costs aside, and you have to get a decent usable energy surplus. Just out of interest..
There are a group of technologies called safe reactors - where safe is a relative term of course.
The most well-known of them is an American design called the Pebble Bed Modular Reactor in which uranium is encapsulated within graphite pellets (pebbles). These fill the reactor vessel and chain react - the graphite acting as a moderator. Helium is pumped over the pebbles as coolant and that drives a steam generator. Spent pebbles are removed from the bottom of the reactor, new pebbles added at the top. It's a lovely design, the fuel is encapsulated - so no fission products escape, the coolant is chemically neutral and does not get contaminated AND the reactor can be made much smaller than conventional units.
Another is the PIUS reactor which sits in a deep pool of borated water. The reactor vessel is open at the bottom, in normal operating, pure water circulates around the reactor core and drives a heat exchanger. As the reaction increases, borated water is drawn into the bottom of the reactor. Boron has the effect of absorbing neutrons - the reaction slows, the reactor generates less power, the borated water leaves the reactor vessel - it is self-moderating.
But those are still experimental. In the 1990s, the UK was looking for a family of next-generation reactors to replace our Magnox stations. They looked at all designs, experimental and in operation and concluded the Pressurised Water Reactor is hard to beat - it has had almost 50 years of operation around the World and has been subject to almost continuous improvement.
The worst-case scenario, that of Three Mile Island - where the operators inadvertantly sabotaged the reactor's safety system was an economic disaster - but the environment was not harmed. Westinghouse now has an improved PWR which has been sold to Korea.
The biggest weakness of the PWR is a loss of coolant - a leak in the system which sends hot water and steam into the containment facility. As TMI showed, this is a serious problem - although not necessarily catastrophic.
So if you don't like the thought of enriched uranium being diverted to bomb production, or you don't want to put all your isotopic eggs in one pressure vessel - I have to give the award to the Canadians. Their CANDU reactor has three levels of containment. First of all, fuel elements are jacketed with tubes containing high pressure heavy water coolant, around that is the moderator - a tank of low pressure heavy water, which is contained within a pressure vessel.
In a CANDU reactor, if the fuel ruptures, it only contaminates the coolant - and does not threaten the environment. If a jacket ruptures, pressurised coolant spills into the moderator and not the containment vessel. The reactor can be brought to a halt easily without any risk of damage to the entire core.
It might be cheaper to just get more Uranium, but isn't that the mentality that got us here in the first place? Don't worry about efficiently using what you've go, it's cheaper to just drill for more oil.... The fact is, something needs to be done. We would be very wise to partition our nuclear waste (separate out Cs-137, St-90, and Tc-99, and a few others) so that we can separate the short lived isotopes from the long lived ones.
If only it was that simple, but the solvents used to extract the various isotopes become contaminated, as does all of the equipment, containers, and facilities used to handle the separation. Most of the waste generated in Britain has been from the reprocessing operation. Had we kept fuel in its rods, we wouldn't have half the mess we have today. (Okay, to be fair, the Magnox elements have to be reprocessed, but the fuel from AGRs and our PWR does not).
I'd argue that separating out plutonium is a risky proposition - particularly in the current world climate. Sellafield is sitting on upwards of 40 tonnes of pure plutonium and must be one of the most tempting targets on Earth. Keeping plutonium inside spent fuel means that anyone diverting spent pins at least faces a difficult and hazardous procedure to extract plutonium.
Since Britain, which has reprocessed more spent fuel than every other country on the planet, and which has the most modern plant has shown it can't be done cleanly - why rush to do it? The uranium and plutonium in spent fuel isn't going anywhere - and leaving it reduces the risk from some of the nastier fission products. Uranium is abundant so there is no economic need to reprocess. If fission is still important when reserves run low - which won't be any time soon - there is about as much uranium in the Earth's Crust as tin, and plenty in the oceans - then we can revisit reprocessing. If it isn't a long term energy supply, then we have saved ourselves an environmental risk.
And whilst Sellafield certainly could be improved, a modicum of British pride stirs itself - we aren't the worst. Experience is that it isn't just the British that can't do it. The COGEMA facility at La Hague also discharges waste into the environment - so the French can't do it cleanly either. Hanford in Washington State is worse than both - so much so that the Americans have called in the British for help and the former Soviet Union - well type in Chelyabinsk to Google...
It would have been even better if the reactors had been designed so as to make prompt criticality unatainable. Prevention is better than the cure.
Yep, it was just that problem which stopped the British developing their own graphite moderated, water-cooled reactor in the 1960s - they even told the Soviets of their concern.
The Soviet Union was aware of the problem and had committed to PWRs, however, it had never managed to perfect the technology of creating the very large pressure vessels required in a power plant PWR. The VVR was still very new technology at the time, but energy demand in the Soviet Union and the Eastern Bloc required new nuclear capacity.
So Chernobyl had 'stretched' RBMKs - believe it or not, they were considerably more safe than their predecessors!
If Britain went for an serious nuclear strategy, like France, it would be more than viable.
For most of the 1980s and 90s Electricite de France was the most indebted organisation in the World. It's books are only now turning around because it is generating power for export.
But I agree, Britain does need to seriously consider a new generation of PWRs - and soon. But 'Trust me - I'm Tony' ain't gonna do anything unpopular before next year's election. Okay, anything else that is unpopular - except for Iraq, oh and ID cards, and then there is...
Hmmm compared to that lot, announcing a dozen new PWRs could almost be seen as good news.
The books were opened up with British Nuclear Fuels a few years ago, and the sheer costs involved have shown that nuclear plants in other parts of the world must have been susbsidised far more than would have been suspected. People can try to blame environmentalists for the lack of new nuclear plants, but Thatcher was certainly no enviromentalist.
Agree in part, but the UK had a particularly bad record of nuclear economics because of its attachment to reprocessing - which was included in the price of power generation, and more seriously, the very stupid decision in the late 1960s to adopt the Advanced Gas Reactor over the Pressurised Water Reactor. The AGRs were delivered late, proved to be staggeringly unreliable in their first decade of operation and have never lived up to their specifications.
Funny that, how the fossil fuel people are allowed to pump all their dirty crap (carbon dioxide) out into the atmosphere.
The UK has a climate change levy on fossil fuel power generation, and Kyoto provides for carbon trading by which large carbon emitters have to pay to pollute.
I don't know very much about three mile island, but as I recall, the Soviet reactor designs were all quite unreliable. At the time, I guess what the Soviet Government really cared about was the electricity plutonium that the reactor produced.
The RMBK reactor was designed to generate power and plutonium. It was unusual in that it allowed on-line refuelling. Bomb-grade plutonium is almost pure Pu239 which is made by U238 capturing a neutron. If Pu239 is left in the core for longer, it can capture another neutron or two to make Pu240 or Pu241 which dramatically affect reliability of the weapon.
The RMBK used a robot crane to extract fuel elements after a short period of time, consequently the lid of the reactor was pieced by hundreds of fuel channels through which fuel was added and removed. This is unlike the Pressurised Water Reactor in which the lid is sealed for months at a time.
When the reactor failed, the fuel channels proved a fatal weakness, so the lid was blown off and allowed radiation into the environment. The RMBK design was fairly elderly at this time and no more were planned by the Soviet Union. However, Chernobyl was a new reactor with relatively good safety equipment and excellent reliability. It was just misused.
It would have been better had Chernobyl had a true containment facility like PWRs, but none of the RMBKs were so fitted.
The Soviet Union was in the process of changing over to its own PWRs - called VVRs which did have proper containment. There had been a number of technical issues with their development.
The UK looked at a Chernobylesque design in the 1960s, but concluded that it presented an unacceptable risk in the event of a minor problem.
And finally, Three Mile Island turned out to be an economic disaster for the operators, but its environmental impact was essentially zero. The PWR is a good reactor design, it showed its relience at TMI, and it has been improved since.
You forget, you Americans (by that, I do of course mean the Government, and not the quite palatable denizens) use hardly any of the energy available in that Uranium. 98% of the mass put in comes out as waste. Look at Sellafield in the UK, only 2% comes out as waste, as a hell of a lot of reprocessing goes on, I in fact believe that they are the most efficient in the world! If everyone reprocessed their waste a lot, then Yucca mountain would not be necessary to store all the waste, you could in fact use a place at least 20 times smaller, and somewhere a little safer too I might add!
The economics of reprocessing don't make sense. Sellafield could not exist without the British government imposing a levy on all energy sales AND bailing BNFL out on a regular basis.
Furthermore, reprocessing produces enormous amounts of high-level liquid waste which must be treated and stored as well as biblical quantities of low-level waste. Even if you don't have to fill up Yucca Mountain, you still need huge nuclear dumps. Reprocessing *increases* the volume of nuclear waste compared to spent fuel elements.
It is significant that Britain has yet to find a long-term solution for the reprocessing waste generated at Sellafield - which is much more dangerous than spent fuel. We are now told that we might have one in 50 years, in the meantime, the high-level waste is being kept liquid, above ground in 30 year-old tanks. I'm glad I don't live in Cumbria.
All the time, Sellafield has been pouring actinides down the pipe into the Irish Sea - which are now detectable across large areas of the Irish, Scottish and Norwegian coasts.
Sellafield's last big hope was Mixed Oxide Fuel, so far its only customer, the Japanese, have refused to accept MOX after it was found that BNFL was faking safety data. The MOX plant at Sellafield is still not working reliably, MOX is far more expensive than new fuel *and* there are concerns that MOX may shorten the lifespan of Pressurised Water Reactors.
Sellafield is a bad joke and should be closed down.
Its sole reason for existance after the development of the British Bomb was to provide plutonium for Britain's Fast Breeder Reactor programme. Well that was abandoned long ago, FBRs are an engineering boondoggle and have never worked reliably. So we sit on 40 tonnes of plutonium with no end use.
Uranium is cheaper now than in 1970, there is no sign of reserves running out, so there is no need to worry about supplies in the foreseeable future.
Using fuel once then putting it into dry store above ground is better economically and environmentally than reprocessing.
Let's say it's 1985, and the Soviet tanks start pouring through the Fulda Gap in East Germany. What does NATO do? Why, stops them, of course. Through the application of no fewer than 108 nuclear-armed Pershing II intermediate-range missiles.
The Soviet Union made it quite clear that were NATO to use nuclear weapons on the battlefield it would retaliate with a strategic nuclear launch against the West. 'Limited' nuclear war was a fantasy held by the super-hawks, fortunately they never got a chance to play out that game.
More to the point, he's literally the only person in the UK who thinks ID cards are a good thing and yet still they're being pushed through.
No, there is also the other one - what's he called? - oh you know - popular in America, warmonger - bit posh - Blair! yes, that's the one. Unsurprisingly both of them admit to being technologically illiterate.
Even the house of commons thinks he's crazy, and everyone else has been wondering for years why Blunkett still has a job.
Which is why Blunkett has suddenly switched to the ID cards will solve international terrorism argument. It's nonsense, but which MP will be brave enough to stand up and say it? If they do, the whole House of Commons will be told to remember 9/11* and that they should be ashamed of themselves, after all it's what the dead would want us to do.
This morning he was on Radio 4 saying that we had to be first to adopt Blunkettcards because everyone was doing it and we might be able to sell the technology abroad.
Perhaps the most disgraceful thing (well apart from railroading civil liberties into the bin next to Belmarsh prison) is that when this all goes horribly wrong, mortifyingly over budget and is a national outrage, Blunkett will not have to pay a penny or face any criminal charges. If he was a local councillor he would be liable to a surcharge for even the smallest problem - when we are talking about a project which is guesstimated to be between 1.3 and 3.1 billion, the taxpayer picks up the can.
Best wishes,
Mike.
* Pet peeve. What is it with this country? We can't even keep our dates correctly - it is NOT 9/11 - it is September 11th!
Paranoid? Maybe. Look back to what happened Germany in the 1930s and we should be very, very concerned about how this kind of "information" could be abused.
A very good comparison. The Nazis used IBM punchcards to identify 'undesirable' sections of the populations. Perhaps one of the first data mining operations.
And it needn't even be a malign organisation that performs the data collection. Loathe him or despise him, David Blunkett isn't a fascist dictator - but what guarantee do we have that we won't have one in the future? All of that data which people hand over will be sitting there ready for misuse.
Have you read 'IBM and the Holocaust', (Edwin Black, ISBN: 0316857718), which discusses just this point? The Netherlands automated all of its census system using IBM punchcards before the war. All done in the best interests of the people, to improve social provision and so on.
As soon as the Nazis came to power in 1940, all they needed to do was run the punchcards again - this time with a slightly different question.
And out popped all the names of the Jews. In short, 75% of Dutch Jews were murdered by the Nazis thanks to an extensive automated ID system. In France, which had similar levels of integration, but no automation, 'only' 25% were killed.
To be honest, i'd be for ID cards in a way - we do have a bit of a problem with illegal immigrants in this country lately, who are totally abusing the system - the current trend is buying cheap cars, and then they just drive around the city in them with no tax insurance or anything.
Errrr...
If they're illegal they wouldn't have Blunkettcards anyway, so you still couldn't identify them. The ID card link is spurious.
Sadly this sort of transparent argument is driving the government, simultaneously these little pieces of plastic will solve crime, end international terrorism, make voting secure, give us better Internet security, save the NHS and probably give us minty-fresh breath.
Ane one more thing. Your human, you'll learn to adapt with nature like the rest of life. Nature will ensure that for better or for worse.
I'm sure Nature will adapt in time - but we're seeing problems in Europe where climate change is outstripping the rate of vegetation to adapt. As the climate get warmer - fast, native vegetation can't move north fast enough to survive. And what's at the top has a hell of a problem - what will polar bears or walruses do when there is no ice?
The Nature that does come through global warming might be an impoverished form of what we have today.
As for us, our method of survival appears to involve turning up the air con when its hot, and cranking up the heating when it is cold, rather than build decently insulated buildings. If it's a desert, keep the lawns green by pumping in the water from somewhere else rather than grow something more appropriate.
I'm not sure that is sustainable in the long term, and there is no law of Nature that says we're actually needed.
Well ain't I cheery? It's the first nice day of Spring and I'm thinking about mass extinctions.
Those huge herds of unatural cattle... Man, it is a good thing we killed all the buffaloes...
Modern agriculture supports far larger populations of animals than were ever possible in Nature because we feed livestock on grain rather than them having to forage.
You know what - it's really not popular, but I don't agree with the doomsday global warming scenarios either. There's a couple of reasons:
1. There's been a measured increase in Solar activity and radiation, which is *where* we get our heat from, obviously. Once the Sun gets over it's current temper tantrum, temperatures will get more moderate.
Already factored into the climate models. The Earth should by now be dipping back towards a glacial episode. Warming since the mid 20th Century appears to be man made.
Additionally, the rate of climate change is almost entirely unprecedented. Whilst global temperatures are not high on the geological timescale they are rising at an extraordinary rate which appears to lack a natural cause.
2. If Dinosaurs ruled a tropical paradise 65 million years ago, wouldn't the current trend of Global Warming just be the Earth returning to a Tropical state?
In short - no. During the Mesozoic both poles were covered by ocean, water could move freely through the oceans, heat was effectively distributed round the globe. Overall temperatures were higher. Since then, Antarctica has slipped over the South Pole and the North Pole is now almost entirely enclosed by land. Oceanic circulation is much more dynamic with cold water forming at the poles and descending to the floor of the oceans - which are only just about freezing point. The warming of these cold waters in the tropics is what holds the temperature way below Mesozoic levels.
3. Isn't is just a little bit arrogant on the part of humanity to assume that we really affect the environment that much?
Not really, we seem to have done a wonderful job devastating the ecologies of places such as Iceland (once had forests), the seasonally dry areas around the deserts which were once productive grasslands and are now deserts, the salinisation of the Middle East and Pakistan thanks to faulty irrigation, we've buggered the Aral Sea beyond recognition, we're busy knackering the Mekong River with badly-thought through hydropower projects, the Colorado only occasionally reaches the sea, god only knows what we've done by carrying rats and cats around the World to places where they were previously unknown. And so on. So actually, no, it would be amazing if we WEREN'T screwing up the atmosphere.
What about bovine methane?
Methane was estimated to produce about 20% of global warming in the 1990s. Its sources are many - melting permafrost, natural gas leaks, swamps are some of the natural ones. However we contribute to it by things such as rice paddies and those huge herds of cattle which just aren't natural.
What about a single volcanic eruption spewing more CFC's then we've ever thought about using?
Errr volcanoes don't spew CFCs. They release carbon dioxide which is a global warming agent, but they also pour out ash, sulphuric acid and hydrogen chloride which serve to depress temperatures.
Make sure you sit next to the first class car! You just might get free access. "Warsitting", perhaps?
If you know when you want to travel and you have at least seven days before travelling, buy a First Class Apex ticket for the journey - first class comfort, free refreshments, now - free WiFi - AND it's cheaper than a standard ticket.
There's a genuinely stunning quantity of oil under the Gulf of Mexico... it's just too difficult and expensive to drill for it with current technology, so it doens't really count as "oil reserves.
The USGS who traditionally take a high figure for reserves estimate to a 95% confidence rating that there are no more than 112.6 billion barrels in the US - including reserves located in offshore areas and those that will become available through higher prices and improved extraction techniques. Proven reserves are only 30.4 billion barrels, so the USGS is extrapolating heavily and depending on better estimates of existing fields - not the development of new fields.
Reserves simply can't go much higher because all of the oil provinces in the US have been thoroughly explored and drilling deeper takes you through the oil formation window and into a zone where natural gas is created.
Saudi Arabia's proven reserves are 261.8 billion barrels, with an estimated 40 billion more down there somewhere. However, you cut the cake, there is at least 2.5 times as much oil under Saudi Arabia as under the US.
The reserves/production value are also telling, the US has a R/P value of 10.8 - that is less than eleven years before existing reserves run dry at current production rates; Mexico surprisingly goes dry in 10.1 years, Saudi Arabia? 86 years!
The reason for China's increased oil demands is their growing economic success. They were, until recently, a fantastically poor country for the amount of resources they had. Now, thanks in large part to free-market reforms (and the absorbtion of Hong Kong, one of the most libertarian capitalist cities in the world), they are becoming bigger consumers.
A major part of this prosperity depends on trade with the West.
At the moment - China's internal market is growing explosively as are neighbouring countries such as India and Russia.
Also, it's silly to suggest that Middle East oil will ever be "practically all that is left." If anything, that's the oil which will run out first. South and Central America are practically floating on the stuff.
You reckon? Okay here goes...
According to no less an authority than BP, North America (including Mexico) contains 4.8% of global oil reserves, Central and South America a further 9.4%, giving the entire Americas a grand total of 14.2%.
Saudi Arabia alone contains - wait for it - 25% of the World's oil. The Middle Eastern region sits on nearly 2/3 of reserves.
Since their draw-down rate is lower the fields will continue to flow long after the US runs dry. US oil production peaked in 1970 and has been in almost continuous decline since then. Much of the Middle East has yet to peak.
Best wishes,
Mike.
Re:Talking about insanely short-sighted...
on
Weapons in Space
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· Score: 3, Informative
That wasn't just our belief. Germany was indeed well on its way, and we succeeded in being 'first' mainly due to a large number of clandestine operations by the Allies/SOE.
Actually no, Germany had abandoned a nuclear weapon before then when physicists made an incorrect series of measurements to determine the possibility of fast-fission in enriched uranium. They still believed that slow fission in a reactor would have been possible and continued work on a heavy water reactor.
Since at the time they had no idea of the existence of plutonium, it is safe to say that the German bomb project was very, very dead.
They continued to explore the possibility of a radiological bomb right up to the end of the War, but never developed a potent enough irradiation source.
An excellent book on this is The Making of the Atomic Bomb by Richard Rhodes.
Best wishes,
Mike.
Re:The bad side of course...
on
Weapons in Space
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· Score: 4, Informative
China posesses no interest in weapons war with other country. Except for Tibet state and persistent Taiwan problem.
But it does have one thing that is driving China's expansion - an insatiable thirst for oil and gas. China has just become a net importer of fossil fuels, most of which is being met from the Persian Gulf and Central Asia - both places where America has said it has strategic interests.
Chinese energy consumption will DOUBLE in the next five years, a large share of which will have to be met by imports, oil imports are growing by 30%+ per year and are now over 100 million tonnes per annum - a figure that was only expected to be reached in 2010.
And let's not forget, with its bumper surpluses, China can afford to buy all the oil it needs.
The Chinese State Petroleum company is now one of the largest operators in the Caspian region and of the huge gas reserves in Kazakhstan and is looking to sign exclusive details so that energy flows east not west.
China has plenty to fear about American control of the region, so it is looking to arm itself to compete with American global reach. Not in the next five years, but the next thirty when Middle Eastern oil is practically all that is left. A global military power needs access to space, and the Chinese will not allow the Americans to deprive them of it.
In the E=mc^2 sense, that is true. But that has absolutely no bearing on the amount of Plutonium you'll have left after a fission event.
Uh no, as the chain reaction starts, the other atoms in the core gain an enormous amount of thermal kinetic energy and the core attempts to vapourise. If it disperses, neutrons are far less likely to hit a nucleus and produce further fission events. If this process is allowed to continue fissile material is physically removed from the path of the neutrons - so some fissile material would never undergo fission.
The outward expansion of the core is unstoppable, it always disassembles the core before the reaction can run to completion - a matter of microseconds. The objective must be to stop the outward expansion of the core for as long as possible by producing an inward pressure of equal or greater force. So modern weapons use a heavy metal tamper around the core to provide a lot of inertia against expansion, and a huge amount of implosion pressure to counteract the outward movement of the core material for as long as possible.
I did some checking, Little Boy was 1.3% efficient, Fat Man was 16% efficient. Apparently normal fission cores are limited to around 25% efficiency, larger ones might be up to 50% efficient. Some of the later US tests that used so-called levitated cores got efficiencies up to 35% - which is pretty damn impressive - in a horribly scary sort of way.
The worry isn't so much about the fissionable nature of plutonium as that very fine particles of plutonium can lodge in the lungs where they irradiate surrounding tissues with high energy alpha particles.
Unlike a chemical explosion, a nuclear explosion is rarely more than 10% efficient. Most of the fissionable material is not consumed in the nuclear reaction, instead it is vaporised into the environment. The vast majority of fissionable material ever used for explosions has been put into the atmosphere where it has gradually settled back to Earth.
I'd agree with you if we knew this was an isolated incident. It may very well be, I don't know, like most slashdotters I didn't read the article.
It's happened more than you might think. There are problems with those satellites that use nuclear reactors and those that use radioisotope thermal generators (RTGs). From memory...
As for those returning to Earth...
Transit 5-BN-3 (1964), returned to Earth in 1965, Its RTG split open spilling 17 000 curies of plutonium 238 into the environment (all nuclear testing to that point had released only 9 000 curies of plutonium 238). It forced a redesign of all subsequent US RTGs
Kosmos 954 (1977), impacted in Canada after failing to fire its booster to reach a disposal orbit. The reactor vessel failed spilling fuel and fission products across some 124 000 km2. Subsequent Soviet satellites were programmed to separate their reactor cores from the containment vessel so that the two would burn up at a higher altitude. Which was lucky because...
Kosmos 1402 (1985), failed to achieve disposal orbit. The core was ejected and the entire satellite burned up over the South Atlantic.
There have been a number of launch failures.
Nimbus B1 (1968), rocket destroyed during ascent - its RTG was recovered and used in a later mission;
Kosmos 305 (1969), radiation was detected when the craft re-entered the Earth's atmosphere after failing to reach the correct altitude. No details of what it was carrying.
Unnamed Kosmos launch (1973), radiation from a reactor was detected when the craft disintegrated over Japan.
The coolant spills have been seen from some of the later Kosmos reactors which have ejected their cores, so it appears to be a shortcoming in the design of the eject mechanism. The first signs of leakage came from Kosmos 1900 in 1997 - this is also a Kosmos which has failed to send its reactor into a high-level disposal orbit. Having said that, some 14 Kosmos RORSATs did successfully eject their cores between the first flight of the design in 1980 and the suspension of the programme in 1988.
NASA and the Air Force have tracked a number of satellites that have begun to disintegrate after many years in orbit. The cause of this failure is completely unknown, but amongst the ones that are known to have failed are the US SNAPSHOT satellite - the first to be flown with a nuclear reactor in 1965 that began disintegrating in the late 1970s, and Nimbus VI, launched in 1975 which appears to have completely broken up.
Kosmos 1461 appears to have exploded in orbit for no readily apparent reason. Kosmos 1900 is also stuck in a lower orbit that intended and will fall back to Earth before the nominal 600 year period.
Finally, there was the RTG from Apollo 13 which should have powered its Lunar experimental station, but remained on the Lunar Module which acted as a lifeboat for the failed mission. The LM disintegrated in the atmosphere, the RTG appears to have survived and crashed into the West Pacific. No radiation was detected.
Slashdot Mirror
IIRC it would have run at higher temperatures and pressures, but it never amounted to more than a paper exercise.
Best wishes,
Mike.
Theoretically a very good design, but almost all were delivered late with skyrocketing costs. Wasn't Dungeness B something like 11 years late? The first few then suffered engineering problems that reduced their availability during their first years - although to be fair in recent years they have done sterling work.
A 2nd generation AGR was considered when it came to looking at a 3rd generation reactor programme for the UK, it came way behind a Westinghouse PWR - so we ended up with Sizewell B.
Best wishes,
Mike.
Oh dear - and on Slashdot???
so let me ask you this - what is the most environmentally safe way to use Nuclear Fission? Costs aside, and you have to get a decent usable energy surplus. Just out of interest..
There are a group of technologies called safe reactors - where safe is a relative term of course.
The most well-known of them is an American design called the Pebble Bed Modular Reactor in which uranium is encapsulated within graphite pellets (pebbles). These fill the reactor vessel and chain react - the graphite acting as a moderator. Helium is pumped over the pebbles as coolant and that drives a steam generator. Spent pebbles are removed from the bottom of the reactor, new pebbles added at the top. It's a lovely design, the fuel is encapsulated - so no fission products escape, the coolant is chemically neutral and does not get contaminated AND the reactor can be made much smaller than conventional units.
Another is the PIUS reactor which sits in a deep pool of borated water. The reactor vessel is open at the bottom, in normal operating, pure water circulates around the reactor core and drives a heat exchanger. As the reaction increases, borated water is drawn into the bottom of the reactor. Boron has the effect of absorbing neutrons - the reaction slows, the reactor generates less power, the borated water leaves the reactor vessel - it is self-moderating.
But those are still experimental. In the 1990s, the UK was looking for a family of next-generation reactors to replace our Magnox stations. They looked at all designs, experimental and in operation and concluded the Pressurised Water Reactor is hard to beat - it has had almost 50 years of operation around the World and has been subject to almost continuous improvement.
The worst-case scenario, that of Three Mile Island - where the operators inadvertantly sabotaged the reactor's safety system was an economic disaster - but the environment was not harmed. Westinghouse now has an improved PWR which has been sold to Korea.
The biggest weakness of the PWR is a loss of coolant - a leak in the system which sends hot water and steam into the containment facility. As TMI showed, this is a serious problem - although not necessarily catastrophic.
So if you don't like the thought of enriched uranium being diverted to bomb production, or you don't want to put all your isotopic eggs in one pressure vessel - I have to give the award to the Canadians. Their CANDU reactor has three levels of containment. First of all, fuel elements are jacketed with tubes containing high pressure heavy water coolant, around that is the moderator - a tank of low pressure heavy water, which is contained within a pressure vessel.
In a CANDU reactor, if the fuel ruptures, it only contaminates the coolant - and does not threaten the environment. If a jacket ruptures, pressurised coolant spills into the moderator and not the containment vessel. The reactor can be brought to a halt easily without any risk of damage to the entire core.
And best of all - they are available right now.
Best wishes,
Mike.
If only it was that simple, but the solvents used to extract the various isotopes become contaminated, as does all of the equipment, containers, and facilities used to handle the separation. Most of the waste generated in Britain has been from the reprocessing operation. Had we kept fuel in its rods, we wouldn't have half the mess we have today. (Okay, to be fair, the Magnox elements have to be reprocessed, but the fuel from AGRs and our PWR does not).
I'd argue that separating out plutonium is a risky proposition - particularly in the current world climate. Sellafield is sitting on upwards of 40 tonnes of pure plutonium and must be one of the most tempting targets on Earth. Keeping plutonium inside spent fuel means that anyone diverting spent pins at least faces a difficult and hazardous procedure to extract plutonium.
Since Britain, which has reprocessed more spent fuel than every other country on the planet, and which has the most modern plant has shown it can't be done cleanly - why rush to do it? The uranium and plutonium in spent fuel isn't going anywhere - and leaving it reduces the risk from some of the nastier fission products. Uranium is abundant so there is no economic need to reprocess. If fission is still important when reserves run low - which won't be any time soon - there is about as much uranium in the Earth's Crust as tin, and plenty in the oceans - then we can revisit reprocessing. If it isn't a long term energy supply, then we have saved ourselves an environmental risk.
And whilst Sellafield certainly could be improved, a modicum of British pride stirs itself - we aren't the worst. Experience is that it isn't just the British that can't do it. The COGEMA facility at La Hague also discharges waste into the environment - so the French can't do it cleanly either. Hanford in Washington State is worse than both - so much so that the Americans have called in the British for help and the former Soviet Union - well type in Chelyabinsk to Google...
Best wishes,
Mike.
Yep, it was just that problem which stopped the British developing their own graphite moderated, water-cooled reactor in the 1960s - they even told the Soviets of their concern.
The Soviet Union was aware of the problem and had committed to PWRs, however, it had never managed to perfect the technology of creating the very large pressure vessels required in a power plant PWR. The VVR was still very new technology at the time, but energy demand in the Soviet Union and the Eastern Bloc required new nuclear capacity.
So Chernobyl had 'stretched' RBMKs - believe it or not, they were considerably more safe than their predecessors!
Best wishes,
Mike.
For most of the 1980s and 90s Electricite de France was the most indebted organisation in the World. It's books are only now turning around because it is generating power for export.
But I agree, Britain does need to seriously consider a new generation of PWRs - and soon. But 'Trust me - I'm Tony' ain't gonna do anything unpopular before next year's election. Okay, anything else that is unpopular - except for Iraq, oh and ID cards, and then there is...
Hmmm compared to that lot, announcing a dozen new PWRs could almost be seen as good news.
Best wishes,
Mike.
Agree in part, but the UK had a particularly bad record of nuclear economics because of its attachment to reprocessing - which was included in the price of power generation, and more seriously, the very stupid decision in the late 1960s to adopt the Advanced Gas Reactor over the Pressurised Water Reactor. The AGRs were delivered late, proved to be staggeringly unreliable in their first decade of operation and have never lived up to their specifications.
Best wishes,
Mike.
The UK has a climate change levy on fossil fuel power generation, and Kyoto provides for carbon trading by which large carbon emitters have to pay to pollute.
Best wishes,
Mike.
The RMBK reactor was designed to generate power and plutonium. It was unusual in that it allowed on-line refuelling. Bomb-grade plutonium is almost pure Pu239 which is made by U238 capturing a neutron. If Pu239 is left in the core for longer, it can capture another neutron or two to make Pu240 or Pu241 which dramatically affect reliability of the weapon.
The RMBK used a robot crane to extract fuel elements after a short period of time, consequently the lid of the reactor was pieced by hundreds of fuel channels through which fuel was added and removed. This is unlike the Pressurised Water Reactor in which the lid is sealed for months at a time.
When the reactor failed, the fuel channels proved a fatal weakness, so the lid was blown off and allowed radiation into the environment. The RMBK design was fairly elderly at this time and no more were planned by the Soviet Union. However, Chernobyl was a new reactor with relatively good safety equipment and excellent reliability. It was just misused.
It would have been better had Chernobyl had a true containment facility like PWRs, but none of the RMBKs were so fitted.
The Soviet Union was in the process of changing over to its own PWRs - called VVRs which did have proper containment. There had been a number of technical issues with their development.
The UK looked at a Chernobylesque design in the 1960s, but concluded that it presented an unacceptable risk in the event of a minor problem.
And finally, Three Mile Island turned out to be an economic disaster for the operators, but its environmental impact was essentially zero. The PWR is a good reactor design, it showed its relience at TMI, and it has been improved since.
Best wishes,
Mike.
The economics of reprocessing don't make sense. Sellafield could not exist without the British government imposing a levy on all energy sales AND bailing BNFL out on a regular basis.
Furthermore, reprocessing produces enormous amounts of high-level liquid waste which must be treated and stored as well as biblical quantities of low-level waste. Even if you don't have to fill up Yucca Mountain, you still need huge nuclear dumps. Reprocessing *increases* the volume of nuclear waste compared to spent fuel elements.
It is significant that Britain has yet to find a long-term solution for the reprocessing waste generated at Sellafield - which is much more dangerous than spent fuel. We are now told that we might have one in 50 years, in the meantime, the high-level waste is being kept liquid, above ground in 30 year-old tanks. I'm glad I don't live in Cumbria.
All the time, Sellafield has been pouring actinides down the pipe into the Irish Sea - which are now detectable across large areas of the Irish, Scottish and Norwegian coasts.
Sellafield's last big hope was Mixed Oxide Fuel, so far its only customer, the Japanese, have refused to accept MOX after it was found that BNFL was faking safety data. The MOX plant at Sellafield is still not working reliably, MOX is far more expensive than new fuel *and* there are concerns that MOX may shorten the lifespan of Pressurised Water Reactors.
Sellafield is a bad joke and should be closed down.
Its sole reason for existance after the development of the British Bomb was to provide plutonium for Britain's Fast Breeder Reactor programme. Well that was abandoned long ago, FBRs are an engineering boondoggle and have never worked reliably. So we sit on 40 tonnes of plutonium with no end use.
Uranium is cheaper now than in 1970, there is no sign of reserves running out, so there is no need to worry about supplies in the foreseeable future.
Using fuel once then putting it into dry store above ground is better economically and environmentally than reprocessing.
Best wishes,
Mike.
The Soviet Union made it quite clear that were NATO to use nuclear weapons on the battlefield it would retaliate with a strategic nuclear launch against the West. 'Limited' nuclear war was a fantasy held by the super-hawks, fortunately they never got a chance to play out that game.
Best wishes,
Mike.
No, there is also the other one - what's he called? - oh you know - popular in America, warmonger - bit posh - Blair! yes, that's the one. Unsurprisingly both of them admit to being technologically illiterate.
Even the house of commons thinks he's crazy, and everyone else has been wondering for years why Blunkett still has a job.
Which is why Blunkett has suddenly switched to the ID cards will solve international terrorism argument. It's nonsense, but which MP will be brave enough to stand up and say it? If they do, the whole House of Commons will be told to remember 9/11* and that they should be ashamed of themselves, after all it's what the dead would want us to do.
This morning he was on Radio 4 saying that we had to be first to adopt Blunkettcards because everyone was doing it and we might be able to sell the technology abroad.
Perhaps the most disgraceful thing (well apart from railroading civil liberties into the bin next to Belmarsh prison) is that when this all goes horribly wrong, mortifyingly over budget and is a national outrage, Blunkett will not have to pay a penny or face any criminal charges. If he was a local councillor he would be liable to a surcharge for even the smallest problem - when we are talking about a project which is guesstimated to be between 1.3 and 3.1 billion, the taxpayer picks up the can.
Best wishes,
Mike.
* Pet peeve. What is it with this country? We can't even keep our dates correctly - it is NOT 9/11 - it is September 11th!
A very good comparison. The Nazis used IBM punchcards to identify 'undesirable' sections of the populations. Perhaps one of the first data mining operations.
And it needn't even be a malign organisation that performs the data collection. Loathe him or despise him, David Blunkett isn't a fascist dictator - but what guarantee do we have that we won't have one in the future? All of that data which people hand over will be sitting there ready for misuse.
Have you read 'IBM and the Holocaust', (Edwin Black, ISBN: 0316857718), which discusses just this point? The Netherlands automated all of its census system using IBM punchcards before the war. All done in the best interests of the people, to improve social provision and so on.
As soon as the Nazis came to power in 1940, all they needed to do was run the punchcards again - this time with a slightly different question.
And out popped all the names of the Jews. In short, 75% of Dutch Jews were murdered by the Nazis thanks to an extensive automated ID system. In France, which had similar levels of integration, but no automation, 'only' 25% were killed.
It's a terrifying, but brilliant read.
Best wishes,
Mike.
Errrr...
If they're illegal they wouldn't have Blunkettcards anyway, so you still couldn't identify them. The ID card link is spurious.
Sadly this sort of transparent argument is driving the government, simultaneously these little pieces of plastic will solve crime, end international terrorism, make voting secure, give us better Internet security, save the NHS and probably give us minty-fresh breath.
Best wishes,
Mike.
I'm sure Nature will adapt in time - but we're seeing problems in Europe where climate change is outstripping the rate of vegetation to adapt. As the climate get warmer - fast, native vegetation can't move north fast enough to survive. And what's at the top has a hell of a problem - what will polar bears or walruses do when there is no ice?
The Nature that does come through global warming might be an impoverished form of what we have today.
As for us, our method of survival appears to involve turning up the air con when its hot, and cranking up the heating when it is cold, rather than build decently insulated buildings. If it's a desert, keep the lawns green by pumping in the water from somewhere else rather than grow something more appropriate.
I'm not sure that is sustainable in the long term, and there is no law of Nature that says we're actually needed.
Well ain't I cheery? It's the first nice day of Spring and I'm thinking about mass extinctions.
Best wishes,
Mike.
Modern agriculture supports far larger populations of animals than were ever possible in Nature because we feed livestock on grain rather than them having to forage.
Best wishes,
Mike.
Already factored into the climate models. The Earth should by now be dipping back towards a glacial episode. Warming since the mid 20th Century appears to be man made.
Additionally, the rate of climate change is almost entirely unprecedented. Whilst global temperatures are not high on the geological timescale they are rising at an extraordinary rate which appears to lack a natural cause.
2. If Dinosaurs ruled a tropical paradise 65 million years ago, wouldn't the current trend of Global Warming just be the Earth returning to a Tropical state?
In short - no. During the Mesozoic both poles were covered by ocean, water could move freely through the oceans, heat was effectively distributed round the globe. Overall temperatures were higher. Since then, Antarctica has slipped over the South Pole and the North Pole is now almost entirely enclosed by land. Oceanic circulation is much more dynamic with cold water forming at the poles and descending to the floor of the oceans - which are only just about freezing point. The warming of these cold waters in the tropics is what holds the temperature way below Mesozoic levels.
3. Isn't is just a little bit arrogant on the part of humanity to assume that we really affect the environment that much?
Not really, we seem to have done a wonderful job devastating the ecologies of places such as Iceland (once had forests), the seasonally dry areas around the deserts which were once productive grasslands and are now deserts, the salinisation of the Middle East and Pakistan thanks to faulty irrigation, we've buggered the Aral Sea beyond recognition, we're busy knackering the Mekong River with badly-thought through hydropower projects, the Colorado only occasionally reaches the sea, god only knows what we've done by carrying rats and cats around the World to places where they were previously unknown. And so on. So actually, no, it would be amazing if we WEREN'T screwing up the atmosphere.
What about bovine methane?
Methane was estimated to produce about 20% of global warming in the 1990s. Its sources are many - melting permafrost, natural gas leaks, swamps are some of the natural ones. However we contribute to it by things such as rice paddies and those huge herds of cattle which just aren't natural.
What about a single volcanic eruption spewing more CFC's then we've ever thought about using?
Errr volcanoes don't spew CFCs. They release carbon dioxide which is a global warming agent, but they also pour out ash, sulphuric acid and hydrogen chloride which serve to depress temperatures.
Best wishes,
Mike.
If you know when you want to travel and you have at least seven days before travelling, buy a First Class Apex ticket for the journey - first class comfort, free refreshments, now - free WiFi - AND it's cheaper than a standard ticket.
Best wishes,
Mike.
The USGS who traditionally take a high figure for reserves estimate to a 95% confidence rating that there are no more than 112.6 billion barrels in the US - including reserves located in offshore areas and those that will become available through higher prices and improved extraction techniques. Proven reserves are only 30.4 billion barrels, so the USGS is extrapolating heavily and depending on better estimates of existing fields - not the development of new fields.
Reserves simply can't go much higher because all of the oil provinces in the US have been thoroughly explored and drilling deeper takes you through the oil formation window and into a zone where natural gas is created.
Saudi Arabia's proven reserves are 261.8 billion barrels, with an estimated 40 billion more down there somewhere. However, you cut the cake, there is at least 2.5 times as much oil under Saudi Arabia as under the US.
The reserves/production value are also telling, the US has a R/P value of 10.8 - that is less than eleven years before existing reserves run dry at current production rates; Mexico surprisingly goes dry in 10.1 years, Saudi Arabia? 86 years!
Best wishes,
Mike.
A major part of this prosperity depends on trade with the West.
At the moment - China's internal market is growing explosively as are neighbouring countries such as India and Russia.
Also, it's silly to suggest that Middle East oil will ever be "practically all that is left." If anything, that's the oil which will run out first. South and Central America are practically floating on the stuff.
You reckon? Okay here goes...
According to no less an authority than BP, North America (including Mexico) contains 4.8% of global oil reserves, Central and South America a further 9.4%, giving the entire Americas a grand total of 14.2%.
Saudi Arabia alone contains - wait for it - 25% of the World's oil. The Middle Eastern region sits on nearly 2/3 of reserves.
Since their draw-down rate is lower the fields will continue to flow long after the US runs dry. US oil production peaked in 1970 and has been in almost continuous decline since then. Much of the Middle East has yet to peak.
Best wishes,
Mike.
Actually no, Germany had abandoned a nuclear weapon before then when physicists made an incorrect series of measurements to determine the possibility of fast-fission in enriched uranium. They still believed that slow fission in a reactor would have been possible and continued work on a heavy water reactor.
Since at the time they had no idea of the existence of plutonium, it is safe to say that the German bomb project was very, very dead.
They continued to explore the possibility of a radiological bomb right up to the end of the War, but never developed a potent enough irradiation source.
An excellent book on this is The Making of the Atomic Bomb by Richard Rhodes.
Best wishes,
Mike.
But it does have one thing that is driving China's expansion - an insatiable thirst for oil and gas. China has just become a net importer of fossil fuels, most of which is being met from the Persian Gulf and Central Asia - both places where America has said it has strategic interests.
Chinese energy consumption will DOUBLE in the next five years, a large share of which will have to be met by imports, oil imports are growing by 30%+ per year and are now over 100 million tonnes per annum - a figure that was only expected to be reached in 2010.
And let's not forget, with its bumper surpluses, China can afford to buy all the oil it needs.
The Chinese State Petroleum company is now one of the largest operators in the Caspian region and of the huge gas reserves in Kazakhstan and is looking to sign exclusive details so that energy flows east not west.
China has plenty to fear about American control of the region, so it is looking to arm itself to compete with American global reach. Not in the next five years, but the next thirty when Middle Eastern oil is practically all that is left. A global military power needs access to space, and the Chinese will not allow the Americans to deprive them of it.
Best wishes,
Mike.
Uh no, as the chain reaction starts, the other atoms in the core gain an enormous amount of thermal kinetic energy and the core attempts to vapourise. If it disperses, neutrons are far less likely to hit a nucleus and produce further fission events. If this process is allowed to continue fissile material is physically removed from the path of the neutrons - so some fissile material would never undergo fission.
The outward expansion of the core is unstoppable, it always disassembles the core before the reaction can run to completion - a matter of microseconds. The objective must be to stop the outward expansion of the core for as long as possible by producing an inward pressure of equal or greater force. So modern weapons use a heavy metal tamper around the core to provide a lot of inertia against expansion, and a huge amount of implosion pressure to counteract the outward movement of the core material for as long as possible.
I did some checking, Little Boy was 1.3% efficient, Fat Man was 16% efficient. Apparently normal fission cores are limited to around 25% efficiency, larger ones might be up to 50% efficient. Some of the later US tests that used so-called levitated cores got efficiencies up to 35% - which is pretty damn impressive - in a horribly scary sort of way.
Best wishes,
Mike.
Unlike a chemical explosion, a nuclear explosion is rarely more than 10% efficient. Most of the fissionable material is not consumed in the nuclear reaction, instead it is vaporised into the environment. The vast majority of fissionable material ever used for explosions has been put into the atmosphere where it has gradually settled back to Earth.
Best wishes,
Mike.
It's happened more than you might think. There are problems with those satellites that use nuclear reactors and those that use radioisotope thermal generators (RTGs). From memory...
As for those returning to Earth...
There have been a number of launch failures.
The coolant spills have been seen from some of the later Kosmos reactors which have ejected their cores, so it appears to be a shortcoming in the design of the eject mechanism. The first signs of leakage came from Kosmos 1900 in 1997 - this is also a Kosmos which has failed to send its reactor into a high-level disposal orbit. Having said that, some 14 Kosmos RORSATs did successfully eject their cores between the first flight of the design in 1980 and the suspension of the programme in 1988.
NASA and the Air Force have tracked a number of satellites that have begun to disintegrate after many years in orbit. The cause of this failure is completely unknown, but amongst the ones that are known to have failed are the US SNAPSHOT satellite - the first to be flown with a nuclear reactor in 1965 that began disintegrating in the late 1970s, and Nimbus VI, launched in 1975 which appears to have completely broken up.
Kosmos 1461 appears to have exploded in orbit for no readily apparent reason. Kosmos 1900 is also stuck in a lower orbit that intended and will fall back to Earth before the nominal 600 year period.
Finally, there was the RTG from Apollo 13 which should have powered its Lunar experimental station, but remained on the Lunar Module which acted as a lifeboat for the failed mission. The LM disintegrated in the atmosphere, the RTG appears to have survived and crashed into the West Pacific. No radiation was detected.
Best wishes,
Mike.