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Peripherally related: molten salt thermal energy storage is also something the nuclear industry has been considering using to help improve load-following econom
by acidburnNSA 7y ago
Peripherally related: molten salt thermal energy storage is also something the nuclear industry has been considering using to help improve load-following economics of nuclear in a heavily variable renewable world. The idea is the nuke would run 24/7 at constant power but the load of the plant would be swapped from the thermal storage tank (in the day while solar is providing all the electricity) to the grid. Meanwhile, the load of the solar thermal system would be turned off during the day and turn on at night. This effectively doubles the power capacity of the nuclear plant to help fill in the duck curve as the sun sets.
Doesn't help with seasonal renewable variability, but for day-to-day, it's pretty slick. The cool thing over TFA is that now it can work in many more geographic areas (e.g. where solar thermal doesn't make as much sense due to low intensity sunlight and there's more solar PV).
Conventional nukes aren't great at going to these temperatures so this is mostly a thing "advanced" reactor people talk about.
e.g.: https://inldigitallibrary.inl.gov/sites/sti/sti/6339782.pdf https://inldigitallibrary.inl.gov/sites/sti/sti/6339782.pdf
Of course then there are molten salt cooled/fueled reactors, which is different from energy storage, making this topic even more confusing.
- ambicapter 7y ago> Conventional nukes aren't great at going to these temperatures so this is mostly a thing "advanced" reactor people talk about. Are the temperatures too high or too low?
- Analemma_ 7y agoToo low - water-cooled reactors are designed to bring the water in the secondary cooling system to just above the boiling point, because anything beyond that is wasted energy (the temperature of the steam doesn't really matter as far as driving turbines). So retrofitting a molten-salt system onto these reactors isn't very efficient and you would ideally want a new reactor design intended for that from the beginning.
- jandrese 7y agoIt seems like a serious materials challenge problem to come up with a molten salt that has the right nuclear characteristics (neutron moderating, etc...) and is not horribly corrosive/flammable/etc... Especially if your usage model is to let the salts heat up to outrageously high temperatures during the day and then draw them down over night.
- SECProto 7y ago> (the temperature of the steam doesn't really matter as far as driving turbines) This goes against everything I seem to remember from thermodynamics - superheated steam is exactly what is used for driving turbines, with saturated steam as the cold side outlet of the turbine. It's what makes district heating useful - there is still heat energy left in the saturated steam, too low grade for driving turbines, but still useful for heating apartments etc
- stickfigure 7y agoIndeed, superheaters have been used since the early 1900s to dramatically increase the thermal efficiency of steam engines. https://en.wikipedia.org/wiki/Superheater https://en.wikipedia.org/wiki/Superheater Also, IIRC superheaters are especially important in turbine applications because water droplets damage the blades.
- mcguire 7y agoWhat's your turbine pressure? Steam at 700°F is apparently 3000psi, which is the highest temperature/pressure I can find. Edit: Best Q/A thread I've seen recently: https://www.researchgate.net/post/At_what_temperature_water_will_decompose_to_Oxygen_and_Hydrogen https://www.researchgate.net/post/At_what_temperature_water_... "We need this value to be more specific numerical form to utilize in design of high temperature and high pressure steam boilers and turbines working at 300 bars."
- deleted 7y ago[deleted]
- hairytrog 7y agoadvanced nuclear using a molten salt loop fro the buffer: https://usnc.com/MMR.html https://usnc.com/MMR.html
- AtlasBarfed 7y agoLFTRs would have faster startup shutdown, and should be able to be built in smaller sizes so "banks" of reactors could be made active.