Before an anti-nuclear lot scream “no reactors!” view what this spectrum of technology offers (in plain English and in order of: worst designs,
1. CO2 Cooled, Graphite Moderated Reactor:
Fuelled on few percent of Uranium 235 (U235 –is only 0.7202% of all uranium) this reactor works
because (somewhat counter intuitively) the chances of neutron radiation splitting another uranium atom is increased, whenever slowed down by something
called a Moderator.
-usually graphite. CO2 gas isn’t very good at cooling but (by not absorbing much of the neutron radiation itself -compared with water) this type of
reactor, produces far more plutonium, than almost any other reactor. That happens because (by adding a neutron to the relatively stable & naturally
abundant Depletive Uranium (U238) Plutonium (Pu239) is then created (the most toxic element of them all, and incidentally -or not, totally manmade).
One problem with using graphite is (it’s originally flat) carbon chain structure, becomes deformed by neutron bombardment, and this results in
Potential Energy becoming trapped in it (rather like if you squeeze a spring or even crush a can). This energy (actually Called Wigner Energy
) is prone to spontaneously releasing itself, and whenever it does, huge spikes in
temperature are caused. To cope with this, the reactor core must be (regularly) rapidly heated, and then cooled. The “cooling” is done by
inserting Control Rods (which simply absorb some of the reactions, neutron radiation). Because neutrons are absorbed, heat production is reduced,
whilst the rectors physical cooling (with circulating gas or water) remains just the same (vital if you need a constant amount of heat production like
all electricity generating stations do).
As you can see from the above link, the Wigner Effect (when not properly understood) caused a serious nuclear accident, but the effects existence,
means all graphite reactor, need constant monitoring. Graphite is often used because it’s relatively cheap, and very high temperature resistant.
Gas cooled reactors aren’t all bad (but without getting ahead of myself) this one sucks! Thankfully it’s now (widely) considered, obsolete.
2. Light water reactor:
This is the type most commonly used (and therefore shown most often on TV) but in my view is still appallingly bad.
It’s exactly the same as the above, except (distilled) tap water is used as the coolant.
3. The Heavy Water Reactor:
This works exactly the same way as the light water reactor, except no graphite is needed. This is because heavy
water (unlike ordinary water) slows down neutron radiation, to the right speed, all by itself. Heavy Water weighs more than ordinary water, because it
has Heavy Hydrogen, and this is heavy because it contains 1 proton and 1 neutron (whilst ordinary hydrogen is only one neutron). Heavy water exists
naturally in all water (at 0.25%) and is not radioactive. However because it is a real pain to extract, it means Heavy Water reactors cost far more
than Light Water Reactors.
Types of Boiling…
4. Boiling Water Reactors:
For the above 3 reactors you can boil water under just enough pressure to drive the turbines.
5. Pressurised Reactors:
Or (slightly more risky, but far more economically) you can boil water under pretty much whatever level of pressure
you like. The main advantage is that the higher the pressure, the higher the temperature water is before it can boil (water only boils at 100
centigrade at normal pressures, but will boil in a vacuum, or boil at temperatures (normally) hot enough to melt lead from certain volcanic vents,
coming from the ocean floor). The reason why this is a good thing (for an investor) is because you can lower the pressure the water is under (once it
comes out of the reactor at its higher than normal temperature) you can therefore make far more steam from it, and subsequently electricity, from
exactly the same volume of water.
However it’s obviously less safe, because (the fact it’s under higher pressure) means it’s more likely to leak –burst potentially, and that
would be very bad news because you’ve then got a Core designed to be cooled by water, but which boils water (under normal pressure) almost instantly
into steam. It therefore follows that the cheapest (but most safety insane) of all the reactors mentioned above, is a: Light Water, Graphite
Moderated, Pressurised Water, Reactor.
6. The Pebble Bed Reactor
with either uranium, or with plutonium added too,
this reactor is so called because unlike all the above reactors it doesn’t have Fuel Rods (i.e. pipes containing metal fuel pellets, which contain
the fuel). Rather it has spherical balls (that look rather like pebbles) made from a specially designed mixture of fuel and graphite. These balls are
simply placed on top of each other, in a metal container that looks like a dustbin without a proper bottom. Simply placing (enough) of these pebbles
in close proximity to one another is enough to start the nuclear reaction. No control rods are needed because the reaction controls itself (whenever
the pebbles get very hot, the frequency at which neutron radiation leaves their fuel atoms, changes enough, to make it less likely to split another
This means you can take an axe to its cooling system, or even put monkeys in its control room for 10,000 years, and never
get meltdown! This is
called Passive Safety
(i.e. a reactor whose safety components don’t need humans or moving parts –both of which could obviously fail).
It is cooled with helium gas, which has two advantages: The first is that Helium loses half its radioactivity every 0.8 seconds (at most). The second
is that if it leaks it only heads in one direction (which is ultimately about 80 miles above our heads). Only hydrogen would be more economical, but
nobody has been stupid enough to use that yet, as obviously (hot) hydrogen explodes whenever in contact with oxygen.
The main disadvantage:
Is that it creates stacks (as in literally heaps) of nuclear waste, and for that reason is not my favourite reactor.
That said the type of nuclear waste created can be at least 97% be recycled into new nuclear fuel, using something called Nuclear Reprocessing.
Here’s a British 1997 TV advert for it: uk.adforum.com...
This massive waste production is caused by something called Nuclear Transmutation which is when elements (which weren’t in the reactor originally
–like plutonium) are created by the neutron radiation adding or taking away neutrons from literally anything inside the reactor. Transmutation
causes the creation of at least some of every element in the Periodic Table. This isn’t a safety issue, as the high temperature of any reactor
causes them to react (and therefore chemically stabilise themselves) near instantly. But they do absorb neutron radiation, and this can slow –or
even stop, the carefully arranged nuclear activity in any core. But all the other reactors (so far mentioned) are largely immune to it. This is
because every time Transmutation creates more rubbish, a few more control rods are removed (and therefore the reaction can continue for 5 years, until
the 3% of waste that’s built up in the rods finally has to be removed). But the pebble bed reactor doesn’t have this option, so it’s fuel needs
to be replaced almost constantly.
7. Fast Neutron (Breeder) Reactors…
These work by having nuclear fuel at such high concentrations that you don’t need a moderator to slow down their neutron radiation (so much
radiation is being produced, from the high fuel concentration, that some radiation is naturally at the right speed anyway). They can be powered by
either Uranium of nuclear waste (like Plutonium) and are famous for being to create more Plutonium than they consume (through converting the
relatively atomically stable, yet almost worthless depleted uranium U238 into P23).
They are cooled down using metals, for different reasons…
8. Liquid Sodium:
This (has been) the favourite coolant because it looks great on paper. The downside is that liquid sodium spontaneously
bursts into flames, whenever in contact with either water or air! Stupid idea, but not stupid enough to stop a number being built (then against all
calculations they had leaks, and have basically given up ever since).
This is what the reactors on British Nuclear Submarines do: Boil mercury, use the vapour to power a turbine, then condense the
mercury (on pipes filled with water). This water in the pipes boils, and so powers yet another turbine (i.e. the process is efficient). Mercury is
obviously incredibly chemically toxic, but (despite the crew being at sea, in a confined space, for often months at a time) it obviously doesn’t
leak enough to harm the same people, our government (in an emergency) intends to fight a nuclear war.
10. Lead cooled reactor:
This works brilliantly because the lead absorbs a lot of the unwanted neutron radiation, which would otherwise damages
the reactor through transmutation. The hot lead (in pipes) directly boils the water. Lead is obviously also chemically toxic, but nowhere near as bad
as mercury and because it’s not actually being boiled the chances of any escaping is remote too. Unlike liquid sodium the stuff is not corrosive.
The reason why the idiots ever considered using molten sodium is because it conducts heats 4 times as well –and is therefore more economical (at
least on paper!)
12. The Integral Reactor
This another kind of Fast Neutron Reactor but deserves its own
category, as is frankly a work of pure genius! However there are two possible versions: The molten Sodium cooled one = bad, and the molten lead cooled
one = very good. The reason why it’s different is because if all the other Fast Neutron Reactors do (somehow) go into meltdown there is very little
you can do stop them. Sure: You could obviously insert Control Rods, or inject Neutron Poisons (elements that absorb radiation particularly well) into
the core, but this requires equipment (operated by human-monkeys to work –be used on time!). The Integral Reactor is different (in that like the
Pebble Bed Reactor) it uses Passive Safety
, but unlike the Pebble Bed Reactor does so without any of the additional nuclear waste. The way this
works, is that the cladding (immediately around the reactor) reflects neutrons back onto the reactor core in order for the reactor to remain critical
(i.e. work). But the cladding has a combination of carefully position holes and slits, which (if the reactor overheats) expand in size (like all metal
does whenever heated) to the point they align more, as well as letting more neutron radiation out by virtue of their bigger size (this radiation
reactors containment wall –creating almost no heat). Without so many neutrons being reflected back onto the core, the reactor no longer contains a
Critical Mass, and subsequently the reaction rapidly grinds to a halt (since more neutrons are being emitted into space, than used to keep the
reaction going). In addition you can still insert Control Rods, and Neutron Poisons (to prevent the reactor getting to this stage in first place
–but if you didn’t, it will look after itself).
The Integral Reactor was so good that it offered to solve all our energy needs, whilst disarming nuclear critics. I think that’s why it’s funding
was (in the US at least) cancelled i.e. because if nuclear too cheap it will end the need for coal, gas, and oil, and this has the potential to
seriously anger vested (evil) interests.
So far we’ve looked at all the main types of reactor in order (of what I believe to be) worst first.
They all have two things in common: They consume Uranium 235 which is rare, and the production of which results in depletive uranium. I dislike DU
intensely because it’s being used in (so-called) conventional weapons, although (realistically) we could shut down all nuclear reactors tomorrow,
and still have enough U238 for (literally) a hundred Iraq wars, and the same applies to plutonium for nuclear weapons (more than enough exists within
the West to wipe the world out as many times, as our leaders could consider!).
Or they use plutonium, and can create far more than they destroy (a double edged sword). Only (proper) exception being the proposed…
13. GE Hitachi, PRISM reactor
GE Hitachi Nuclear Energy has proposed to the U.K. government to build an advanced nuclear reactor that
would consume the country’s stockpile of surplus plutonium.
Plutonium, from being regarded as a waste
product, is starting to be regarded by the government as a resource. King said it would be needed to fuel new power stations, because stocks of
uranium are being rapidly depleted, and only a fraction of the mined supplies are suitable for use in generating power.
Whilst this all makes precious little difference to countries that already have nuclear weapons –or could make them easily, it means it’s unwise
to export the technology to backward places like Africa –the Middle East generally. This is a problem, because their massive population (begin) to
truly catch up with the West they’re going to want things –like the family of 30’s first (ever) TV.
Which brings us to my favourite reactor…
14. The Thorium Reactor: en.wikipedia.org...
This reactor has been unlucky. It’s never done bad to deserve
it’s bad luck –all it ever promised was to solve all man’s, carbon free, energy needs (just like the Integral Reactor) but in a way that would
make nuclear weapon production (almost) impossible. Thorium is almost as abundant as lead, and there’s thought to be enough US reserves (alone) to
meet all America’s energy needs for 1000 years. In addition Passive Safety can employed, and it’s much less likely to go into meltdown anyway.
Too good to be true? No. Too good to allowed to happen (yet) certainly.
Short Intro: Thorium Energy Benefits 4.15 minutes
Motherboard TV: The Thorium Dream (add first)
The best is 21 minutes into this video, where they explain the reasons why we don’t already have Thorium reactors. Unsurprisingly all the reasons
are totslly rotten.
Pioneered by the same guy who created The Light Water Reactor. He (just like Victor Frankenstein, who only too late realised how bad his own creation
was) got fired by US Gangster President (Richard Nixon) for contradicting the presents corrupt, corporate interest driven “science”.
It’s not even like this reactor would be bad for the economy, or too expensive to build. It would simply demand a change in direction, which in turn
would cause vested interests to loose investments they had already made.
Will we ever see it?
I don’t know. All I do know is I prefer (almost) any nuclear energy over fossil fuel energy, for the reasons laid out in
Even So: 3 Important Questions To Ask About That Nuclear Reactor They’re Building…
1. Does it have Passive Safety
? If not = very bad.
2. Is it cooled (directly) by water? We all saw the hydrogen explosion caused by water in Fukushima
3. Is it cooled by Liquid Sodium? If so = bad, mercury = ok but not by my house! If lead = perfect –not least as they’ve sacrificed at least some
profit, for increased safety.