Have you heard of a Pebble Bed Reactor (PBR)?.................
“Have you heard of a Pebble Bed Reactor (PBR)?.................”
Yes South Africa, Germany both had experimental ones, China has two in experimental status right now.
TRISO fuel is impressive it can get to crazy high burn ups....maximum burnup for TRISO fuel is around 20% FIMA (fissions per initial heavy metal atom)
Huge fan, can’t melt down, reaches 1000C temps with either helium or molten salt cooling so industrial heat and more importantly heat storage tech works with it.
Take the graphite out and use silicon carbide for the buffer and shells and chloride salts you can also do fast spectrum or epithermal spectrum. Breed ratio is not as good as a liquid metal fast reactor but it is above 1 so once you start it you only need depleted uranium supplies.
Problem is C14 all that graphite in the pebbles gets irradiated and a good amount of it ends up as C14 and 5000 year half life’s not ideal given how biologically active carbon is.
It’s also super difficult to reprocess pebbles they resist nitric acid you have to crush and burn the graphite out and the silicon carbide too. Then you have CO2 gas that’s loaded with C14 carrying CO2 that is a disaster waiting to happen you need to turn all that CO2 back to solid graphite and bury it in a medium level waste storage repository for at least 10 half lives so 50,000 years this is the valid argument against pebble bed reactors.
My preferred reactors are.
Molten sodium cooled fast reactor in both Aalo sized modular and BN1200 sized gigawatt scale.(reprocessing off site like Rosatom does)
Integral Fast Reactor (IFR) with dozens of 500MW modules all sharing a single reprocessing plant onsite
Molten salt cooled fast reactor with on-site metal fuel reprocessing for high temp applications 1000C+ with NaCl salts.
D-D catalyst fusion fission hybrid breeder with stainless clad metal uranium first wall fuel pins as the neutron multiplication and fission energy booster 50-200x energy gains vs fusion Q level. Surrounded by a water breeding blanket with light water for neutron capture to deuterium fuel and 7% uranium nitrite for Pu breeding of crazy amounts per year 8000kg for 1000mw of fission hybrid thermal in the inner part. You can also use stainless clad metallic actinides instead of uranium for the fission multiplier Np,Am,Cf all have higher multiplication rates vs U238 since they fast and thermal neutron fission plus you are burning up all the long lived trans uranium elements in one go. The support ratio for my next face reactor can reach 100+ to one.
CANDU in a slightly enriched MOX fueled at 1.2% Pu 239 for triple the fuel life vs natural uranium and one third rhe spent fuel mass to reprocess. You only need to remove fission products and add Pu239 back to 1.2% given CANDU conversion ratio of 0.8 you need 40 ish kg per year of Pu239 from the hybrid breeder.using this slightly enriched MOX fuel cycle a single 1gigawatt fusion fission hybrid supports 200 one gigawatt CANDU. <<<<this is the way.
CANDU are cheap to build the S.Koreans did them for $2800/kw on time and on budget. Do more everywhere and in bulk there is no shortage of deuterium it’s 46 trillion tonnes in the ocean.
Graphene makes for a much better way to get at deuterium not only in seawater but in that liquid breeder blanket too. Even without graphene tech existing methods more than efficient enough. The heavy water doesn’t get used up in a CANDU it’s recycled ,purified and reused only small amounts of make up are needed for the kg lost to neutron captures to tritium but that’s...fusion fuel for the hybrid feeding the CANDU it closes the cycle elegantly.