Climate Change and Renewable Energy News and Discussion

FairAndUnbiased

Brigadier
Registered Member
Please, Log in or Register to view URLs content!

Bad news again. More storms and rain hit the already devastated Midwest in the wake of the deadly tornado on December 10.

More tragedy is possible, especially if workers are still being forced to be at work during peak storm hours.

Please, Log in or Register to view URLs content!
 

Anlsvrthng

Captain
Registered Member
There are really no cons besides the technical difficulty. It's very hard to keep ~600C molten salt contained for 40-80 years within a reactor, even more difficult to have a self-sustaining Thorium cycle (currently you need to add some Uranium to keep the cycle going).

The advantages are numerous, but safety is number one. HTGC reactors replaces the primary coolant (i.e. the fluid/gas that directly absorb the heat the reactor produces), which until now is primarily pressurized water, with pressurized gas. This means that if there's containment failure, the reactor can explode. In order to reduce the risk of it, very large and sturdy containment vessels are needed, and this is actually one of the major reasons why nuclear reactors are so expensive. MSRs operate at near atmospheric pressure. If containment fails, the liquid leaks out, cools, and solidifies instead of exploding catastrophically (e.g. Chernobyl, Fukushima). This also allows the containment vessel to be much smaller, and possibly a lot cheaper, since the issue is more with finding the right material rather than building gigantic steel and concrete containment vessels.

There's also a passive safety feature for MSRs, which is that if a reactor is out of control and excessive heat is released, the mixture of molten salt and fissile material expands and reactivity goes down, essentially a negative feedback loop. This is because in a MSR the fissile material is "dissolved" and mixed into the primary coolant, so the fissile material will be further apart and thus less likely to maintain a chain reaction when the coolant expands.

Since the fissile material is mixed into the primary coolant, i.e. it exists in fluid rather than solid or gas form, it's also very easy to separate the various fuels and fission products chemically, so the "spent fuel" can be easily reprocessed. Reprocessing a spent pebble would be much more difficult as it's an intricately designed multi-layer and multi-component solid pebble.

And of course, using Thorium as opposed to Uranium as a fuel carries its own advantages. Thorium is about 3x more plentiful, and specifically for China it not only has a large supply of it (not the largest in the world by far, but a lot more than Uranium), it's also a common and currently discarded byproduct of rare earth mining. More than that, only 0.3% of Uranium is actually fissile U235, the rest is non-fissile U238. The concentration needs to be increased via centrifugation to 5-20% for most commercial reactors (>90% for nuclear weapons and some nuclear sub reactors). A Thorium reactor, in its final form, can utilize 90% of the initial Thorium. We're pretty far from that though so it's just a theoretical advantage for the next few decades. The intermediary and byproducts are much harder to make into nuclear weapons, which reduces proliferation risk when exported as a commercial products. That's obviously a disadvantage if you actually want it to make nuclear weapons, one of the reasons this tech has been ignored for so long.

These are just some of the basics, we've got a loooong way to go to make it reality. The current Gen IV tech, particularly HTGC reactors and Fast Sodium Reactors are pretty good, long overdue upgrades over Gen I-III tech.
Safety 1 - temperature
the pressuriezed water reactor works in narrow temperature range, means the expansion of fuel is neglible , not enought to stop the reaction. The peble bes / molten salt reactor working with wider temperature range, means the expansion can stop the reaction.

Safety 2 - explosion
There two type of explosion danger with the pressurised water reactors, fist is the steam, as the pressure of the water drop the temperature collapse as well, and the energy generating extreme ammount of steam, like an explosion.
The other is above 700 celsius the Zirconium used as fuel cladding react with the oxygen of water, generating lot of hydrogen. That explode as it escape .

Safety 3 - enviromental contamination
The most problematic material from the fission product is the Cs-137 isotope, that contaminated Fukushima / Chernobil. The Caesium has similar chemical properties like the other first column of periodic table, reacting immedietly and fast with water , and nearly all of possible chemical compound mobile in water . Reason why nearly all of the Caesium of Fuku/Chern ended in the enviroment, and with 30 years half time it will stay there for long time.

Molten salt reactor could remove it, but problem with it is the salt is water soluble, so if the molten salt touch water then all fuel and fission product will enter the water base. The peble ped icontain the fuel and all material in hard carbon, so it won't enter the enviroment.

Thorium :
Two possible process there , the Pu-239 as fuel, U 238 as seeded material, or U-233 the fuel, and T-232 as seeded material.

PRoblem with the U238 cycle is the 238 has slighly worst cross section for thermal neutrons , and the pu 239 has slightly less neutrons.

Means in thermal reactor the U238 -Pu239 cycle can't reach the above 1 breading ratio, but the Th232 - U-233 cycle could.


The type of the reacotr is not so important, a standard pressuired water reactor could run with Thorium cycle as well.

PRoblem is to run it in Thorium cycle (or any other reactor) it needs contionus reprocessing, and aprox 10 years of U233 accumulation, and in meantime U238/Pu239 has to be the fuel.
 

Anlsvrthng

Captain
Registered Member
Very pathetic.

This happens when the sociohackers in the politics try to do job that needs math/engineering skills.


The pre-requisite for wind/solar and electric transport is the cheap and abandunant storage capacity, but the investent into that area laggin by 15-20 years behind the actual windmils.

Means up to this point they used for storage the writen off coal/natural gas power plants .

As soon as they stop to produce out the quadratic relationship between the randomly changing wind speed and power generation become obivous. And all cost structure up to this date gone down on the drain .


Still no visible sign about that the windmills and solar panels could cheat the "limits of growth "
 

FairAndUnbiased

Brigadier
Registered Member
Please, Log in or Register to view URLs content!

The NA east coast is one of the most vulnerable regions in the world to climate change thanks to being one of the few places in the world that has cyclone type storms (hurricanes) but no barrier islands to reduce them.
 
Top