Molten salt is definitely the way to go. However, as you can tinker with the reactants as it is running it is an effective way to produce a number of nasty things with A level knowledge and tools. As such I have read that they have been discouraged by the major powers over the years who preferred the technical merit * or cost barriers of the old fashioned, now heavily regulated and flawed, designs. Which is bonkers, given the wider benefits of the proper use of molten salt which is completely walk away safe and tsunami or other catastrophe man or natural event proof.
* merit for making bomb grade material
Absolutely. Nobody is suggesting it would be safe to stand next to a live nuke reactor inside the environmental shields. Trying the same trick in a submarine or next to a fusion reactor (if it ever works) would be just as bad. You would be crispy toast just as quickly as you would standing in front of a coal fired burner outlet.
The issues for any power plant are build costs, running costs, fuel costs, used fuel disposal and end of life plant disposal costs.
With PWRs the plants are huge as they have to be able to contain a steam or hydrogen explosion in the reactor vessel. They also need many layers of safety systems simply to keep then safe. That huge dome is not the reactor its just a super strong containment building. Fukishima by the way had no safety containment so when it went pop the reactor contents went skywards. It really should not have been running at all. The back up power generators, along with the site power transformers were all on the seaward side protected by a (not high enough) sea wall. They could not keep the reactors cool, hydrogen and oxygen built up inside and soon enough went bang.
PWRs are massive machines that cost massive money to build and operate. Nobody wants them other than as political statements to massage a country's CO2 figures.
The Moltex molten salt reactor is really very clever. The reactor tank is a stainless steel box with a bolt on lid. It's tough but equally not a humungous pressure vessel because it operates at atmospheric pressure. It does of course need thick concrete radiation containment but does not need any fancy explosion containment dome and does not need fancy back up safety systems as its fundamentally fail safe.
The fuel salt is contained in small stainless steel tubes. They only have to last a two years in service before they are pulled out and replaced. These tubes are open at the top so the noble gasses (which cause so much hassle in a PWR) can escape. This no different to a typical PWR core so the regulators are happy.
The expired fuel salt is chemically - read low cost - reprocessed (reprocessing PWR fuel is massively costly). The usable fuel elements go back into the reactor for further burning down. The remaining stuff, with a life to safe of 200 to 300 years, is vitrified into glass pucks for long term storage. The stuff that comes out of PWRs has a dangerous life of 250,000 years.
The Moltex uses the same salt type (without the fuel) as a heat transfer medium to the steam generators. Steam is made at 560 degs C so can drive a standard power plant turbines (cheap). PWRs need bespoke one-off turbines - expensive to make and repair.
If the coolant (or rather heat extraction) pumps stop running, the reactor will get hotter, but stabilise at a higher temperature which effectively stops the reaction. It will just sit there hotter than normal (but still safe) while making no power. This makes it naturally load following - ideal for filling in where wind and solar generators are not doing anything useful.
The Moltex runs in the fast spectrum. This is generally considered difficult to do, so Alvin Weinburg kept to the thermal spectrum with a carbon moderator. Kirk Sorenesen explains really well why this is a good idea. However, Ian Scott of Moltex has managed to get create a fast spectrum reactor without the hazardous molten sodium that normally used to cool fast reactors. He intends to burn ordinary enriched uranium fuel but he could burn the waste fuel from PWRs or even the low grade plutonium left over by reprocessing plants like Windscale. The plant in New Brunswick, Canada will burn uranium but got the gig because they can reduce the stored waste fuel stockpiles the country is paying megabux to keep safe. Lithuania have also expressed an interest.
When a PWR goes bang, it releases radioactive, iodine, caesium and strontium. The latter is heavy so stays near the accident site but it is nasty stuff. The other two are gasses that go into the air are quickly absorbed by living things causing cancer and even death. But in nature, iodine and strontium are only found as salts and they stay that way in a molten salt reactor fuel. They cannot escape as gasses even if the lid fell off.
This all adds up to a plant which is fundamentally safe. It does not need an army of expensive specialists for safe operation and it's cheap to build. The fuel can be burnt to around 99% used as opposed to 1% used so waste storage is not an issue. Fuel processing is simple chemical job. Solid oxide fuels used in PWRs cost a fortune to manufacture with yet more high tech kit and operators.
At end of life, the reactor vessels can be removed and stored until their residual activity has decayed. Just as we do with any radiated materials. They are not massively "hot" but do need management. This would be just the same with nuke fusion reactors. You can't fuse hydrogen without making enormous amounts of gamma rays. But as Moltex do not have radioactive pressure vessels, the reactors could have a very long working life. That will be another regulatory issue.
Existing thermal solar power plants heat salt in a solar powered furnace and store the hot molten salt in high temperature heat stores. That stored heat raises steam when the sun isn't shining. Moltex are building a 1000 MW reactor to heat similar thermal stores. That can deliver peak loads of 3000MW so the power output can follow the daily load cycle while the reactor runs at full power 24/7. Planned on the grid by 2025.
They expect the "built on site" New Bruswick plant to undercut the most efficient natural gas plants on costs per MWH. When they go to factory production they expect to undercut coal on costs per MWH. That's before the revenue generated by cleaning up waste PWR fuel is taken account of.
That will put coal out of business. Nobody wants the stuff but its cheap so poor countries will use it until something better comes along. Eventually thorium will be allowed as a fuel. China and India are on the case, but Moltex are well placed to do that as well as all their other good stuff.
the muppet visits dropped dramatically.
