Energy From Thorium Discussion Forum

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PostPosted: Feb 16, 2014 4:57 pm 
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Good to have you aboard, EP.

Regarding the thermal issues, one interesting phenomenon with MSRs is that heat producing fission products sort of go everywhere a bit. The ORNL MSBR for example had reactor cover gas circulation using the primary reactor coolant pumps. This would provide cooling for any fission products that stuck around in the reactor vessel and heat exchanger after a (rare) double drain accident (both fuel salt and coolant salt drained). If this was not done, very high temperatures, to the point of creep failing Hastelloy N, would be seen in the HX tubing. TA will face similar thermal problems.

One fact that is not encouraging is that TA does not even mention a cladding. They want to use "--". Never heard about that type of cladding before, must be fancy.

The Emperor has no cladding, I guess.


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PostPosted: Feb 16, 2014 8:22 pm 
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For getting rid of Xenon you need liquid fuel.
Hydrogen inside the core eats up neutrons.
Graphite changes volume. It caught fire at Sellafield and Chernobyl.
Deuterium is costly. Cant risk leaking at high temperature.
That leaves you with unmoderated fast spectrum MSR. Can anyone do it for purely civilian power? Even with the lollipop of waste burning thrown in?


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PostPosted: Feb 16, 2014 8:31 pm 
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Graphite did not catch fire in the Windscale pile.

What burned was aluminium fuel cladding and Magnesium in the 'isotope irradiation cartridges'.
If the Graphite had burned.... yeah, the pile would not have survived.


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PostPosted: Feb 17, 2014 4:00 pm 
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It was worse than that. From https://en.wikipedia.org/wiki/Windscale_Pile#Fuel, Unenriched uranium metal in aluminium cartridges with fins to improve cooling was used for the production of plutonium.

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PostPosted: Feb 18, 2014 3:00 am 
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Yes, uranium metal is pyrophoric, and burning/smoldering of the fuel itself releases most of the volatile FPs in it.

There are other misconceptions about the Windscale fire as well. For example, most people think that Wigner energy in the graphite is what caused the fire, but it actually appears to have been the high temperature annealing runs (attempt to anneal Wigner energy) that was the cause. The reactor was never designed for such high temperatures, yet the operators regularly ran the graphite at extreme temperatures. The kind of blatant stupidity and ignorance has helped to give nuclear power a bad rep.


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PostPosted: Feb 18, 2014 3:24 am 
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After the humiliation at Suez the nuclear weapons programme had drastically increased in tempo.
It was imperative that weapons production remain on track no matter what, at least until the Calder Hall and Chapelcross reactors could be brought online, which they were soon after.

And I am not sure what you would have proposed they do after they discovered Wigner energy and its problematic effects? Abandon the piles and put the nuclear programme back years?


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PostPosted: Feb 18, 2014 3:52 am 
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E Ireland wrote:

And I am not sure what you would have proposed they do after they discovered Wigner energy and its problematic effects? Abandon the piles and put the nuclear programme back years?


Make design changes so that high temperatures can be accomodated. If that is not possible (likely with this type of metal fuel and clad) then remove graphite to heat it out of pile. Do NOT heat up a system to several hundred degrees above its design point - EVER.

I have a home boiler. It is designed for low temperature space heating. What if I want to run at at 1000 degrees Celsius because I need to anneal the boiler metal? Just drain the boiler and run it at 1000C? Of course not. It is the same with every piece of equipment. You don't pressurize a car tire at 10 bars when it says max 4 bar. You don't put 3000 kg in a 1000 kg max elevator. You just don't. Its stupid. If you want this, make design changes. It is called management of change (MOC).

Stupid and igorant operators, regulators, and utilities have greatly contributed to nuclear power's bad rep. Look at Windscale, Chernobyl, TMI, Fukushima. Varying accidents but recurring tangents - stupid and ignorant design, followed by ignorant operators doing stupid things and being too stupid to realise what's going on or whats needed to stop the accident.


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PostPosted: Feb 21, 2014 3:08 am 
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People do make mistakes and things have to be made as foolproof as possible. Perhaps the reactors could be put on an autopilot a few minutes after any manual action is taken.


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PostPosted: Feb 21, 2014 3:58 am 
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Doing any of those things would pretty much require abandoning the reactor, since the graphite cannot be easily removed from the Windscale pile designs.
Which means putting the bomb programme back years.


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PostPosted: Feb 21, 2014 4:50 am 
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E Ireland wrote:
Doing any of those things would pretty much require abandoning the reactor, since the graphite cannot be easily removed from the Windscale pile designs.
Which means putting the bomb programme back years.


Nuclear reactor meltdowns are very good for your bomb production rate, you reckon?

It was stupidity and ignorance, plain and simple, and it has done nuclear power a great deal of harm. Without the stupidity and ignorance of Windscale, Chernobyl, TMI and Fukushima, we would be well underway in the final stages of powering the entire world with nuclear power.


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PostPosted: Feb 21, 2014 5:05 am 
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Cyril R wrote:
Nuclear reactor meltdowns are very good for your bomb production rate, you reckon?


The actual bomb programme was not significantly delayed as a result of the Windscale Fire.
Within a matter of a few months the piles were rendered obsolete by Calder Hall and Chapelcross so lost production was negligible. (Giving us 8 reactors with ~260MWt power compared to the two piles we had before).

Certainly less delay than would have been gained by abandoning the piles as soon as the problem with Wigner energy was discovered.

There was and is no significant outcry over the Windscale fire, as it was such a minor accident in an era before the 24 hour news cycle and modern tabloid journalism.

Cyril R wrote:
It was stupidity and ignorance, plain and simple, and it has done nuclear power a great deal of harm. Without the stupidity and ignorance of Windscale, Chernobyl, TMI and Fukushima, we would be well underway in the final stages of powering the entire world with nuclear power.


Very people in Britain even know about the Windscale fire, and most that do accept the report's conclusions that the health effects are negligible and that the staff of the reactor did everything possible to handle the accident with 'considerable dedication to duty' on the part of all concerned.
Nuclear power is not a good fit for our current society I am afraid, with its demands for rapid returns on investment and the like, it is not a coincidence that reactor production went off a cliff with the rise of the post 79 consensus, except in those countries that never really believed in it. (In the west that is basically France).
Only a state backed, and in many cases, state operated programme can produce reactors in the quantities required, otherwise capital discount charges wreck the business case.


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PostPosted: Feb 21, 2014 6:54 am 
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Nuclear reactors used to be cheaper than coal plants. That was because there had been little regulatory ratcheting and inhuman quality control requirements. Then there were nuclear accidents like TMI, Windscale, Chernobyl, and now Fukushima. These have increasingly ratcheted up the cost.

The anti-nuclear forces have certainly exaggerated the consequences of these accidents, yet at the same time, there is no doubt in my mind that the industry has also shot itself in the foot repeatedly with the high level accidents that have stupidity and ignorance, and sometimes corruption, at their core. If they had prevented these by good design practise and sensible management of change and operations of the plants, none of the extreme quality control burdens would be in place. Nuclear plants might be built today for $ 500/kWe rather than $5000/kWe.


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PostPosted: Feb 21, 2014 7:46 am 
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As regards to MOCs, the Windscale reactor could have simply used stainless steel cladding to take the higher intermittent temperatures of graphite annealing runs. It would have been a simple change at only a small penalty in fuel efficiency, not important for natural uranium fuel (bomb production involves low burnup anyway).


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PostPosted: Feb 22, 2014 11:45 am 
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Quote:
Nuclear power is not a good fit for our current society I am afraid, with its demands for rapid returns on investment and the like, it is not a coincidence that reactor production went off a cliff with the rise of the post 79 consensus, except in those countries that never really believed in it. (In the west that is basically France).
Only a state backed, and in many cases, state operated programme can produce reactors in the quantities required, otherwise capital discount charges wreck the business case.


Agree. But, China is 1/5 of the entire World. I'm sure you are not including them in 'our current society'. They really are the key to show the rest of the World what is possible. They are doing well, and might start building a lot faster in the near future. The startup of the first AP1000 at Sanmen, and the completion of the first CAP1400 (maybe in 4 years) are going to be key milestones.

Westinghouse is already talking about an order for 8 more reactors from China. It wouldn't surprise me if that happened the day after Sanmen 1 goes critical.


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PostPosted: Feb 22, 2014 7:18 pm 
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We're getting pretty afar field here. Stick to Transatomic's technical white paper.


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