# Could Project 705 Lira Liquid Metal Cooled Reactors be Used on Land for Power Generation? **URL:** \ **Category:** Factual Questions\ **Created:** [November 17, 2018, 7:18am UTC](https://boards.straightdope.com/t/could-project-705-lira-liquid-metal-cooled-reactors-be-used-on-land-for-power-generation/824671 "2018-11-17T07:18:17Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![cjackson](https://avatars.discourse-cdn.com/v4/letter/c/a3d4f5/32.png) [@cjackson](https://boards.straightdope.com/u/cjackson)\ **Post date:** [November 17, 2018, 7:18am UTC](https://boards.straightdope.com/t/could-project-705-lira-liquid-metal-cooled-reactors-be-used-on-land-for-power-generation/824671/1 "2018-11-17T07:18:17Z")
[Alfa-class submarine](https://en.wikipedia.org/wiki/Alfa-class_submarine) These vessels utilized lead-bismuth cooled fast reactors, as opposed to the usual pressurized water reactor. As far as power on land goes, are there any significant advantages over current nuclear reactors? I get that they were ahead of their time, but when will this reactors time come? ---
**Author:** ![griffin1977](https://avatars.discourse-cdn.com/v4/letter/g/977dab/32.png) [@griffin1977](https://boards.straightdope.com/u/griffin1977)\ **Post date:** [November 17, 2018, 7:32am UTC](https://boards.straightdope.com/t/could-project-705-lira-liquid-metal-cooled-reactors-be-used-on-land-for-power-generation/824671/2 "2018-11-17T07:32:39Z")
I’ve not heard it discussed. But I have heard a lot of talk of Molten Salt reactors being the future of nuclear power. One of the big advantages is they tend to “failsafe” (as unlike water salt does not boil off in the event of the reactor over heating) > **[Molten salt reactor](https://en.wikipedia.org/wiki/Molten_salt_reactor)** > > A molten salt reactor (MSR) is a class of nuclear fission reactor in which the primary nuclear reactor coolant and/or the fuel is a molten salt mixture. Only two MSRs have ever operated, both research reactors in the United States. The 1950's Aircraft Reactor Experiment was primarily motivated by the compact size that the technique offers, while the 1960's Molten-Salt Reactor Experiment aimed to prove the concept of a nuclear power plant which implements a thorium fuel cycle in a breeder reacto... ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [November 17, 2018, 3:21pm UTC](https://boards.straightdope.com/t/could-project-705-lira-liquid-metal-cooled-reactors-be-used-on-land-for-power-generation/824671/3 "2018-11-17T15:21:51Z")
Another advantage is they have greater operating temperature, which means greater thermal efficiency. (because the equation for the maximum free energy you can extract from heat is (1 - Tc/Th)). This means a smaller reactor could produce more energy, at the cost of less nuclear fuel. (in present reactors, it’s not really the fuel that is a significant cost, but the refueling is quite expensive) The disadvantage of any sort of really new nuclear reactor design - many have been proposed and money spent on - is it costs a fortune (10-20 billion, 10-20 years) to build nuclear reactors according to the _old_, well understood designs. This cost is so enormous that basically the only way a utility company can afford one requires heavy government support and generally the cost of the resulting electricity is more expensive than doing it other ways (right now, with no carbon tax, the cheapest way is a combined cycle natural gas plant). So yes, reactors similar to this, or using thorium and exotic setups, or a dozen other proposed ways all have significant potential to be better. But the economics don’t support them and national governments are reluctant to make the investments they would need because of the risks and negative public reactions. ---
**Author:** ![Frankenstein\_Monster](https://avatars.discourse-cdn.com/v4/letter/f/ccd318/32.png) [@Frankenstein\_Monster](https://boards.straightdope.com/u/Frankenstein_Monster)\ **Post date:** [November 17, 2018, 6:40pm UTC](https://boards.straightdope.com/t/could-project-705-lira-liquid-metal-cooled-reactors-be-used-on-land-for-power-generation/824671/4 "2018-11-17T18:40:51Z")
Assuming you are talking about Lead-cooled or Lead-Bismuth cooled fast reactors, commonly abbreviated LFR. LFRs are fast reactors but not breeder reactors (not meant to have a breeding blanket). Their advantages in today’s context are: much more efficient fuel usage, much more thermally efficient, much safer, and potentially can “close the fuel cycle” meaning eliminate almost all of the radioactive waste. E.g. [here](http://www.westinghousenuclear.com/New-Plants/Lead-cooled-Fast-Reactor) No large land-based LFRs have actually been built today, but they have really enthusiastic supporters. Russia is furthest along in actually planning to build large land-based LFRs, thanks to their experience with their submarine LFRs. [BREST-OD-300 news 1](http://www.world-nuclear-news.org/NN-Russian-notes-progress-with-fast-reactor-technology-23081601.html), [news 2](http://www.world-nuclear-news.org/NN-Russia-to-build-fast-reactor-fuel-plant-in-2018-29121701.html) “Europe” has finished an LFR design: [LEADER](https://cordis.europa.eu/result/rcn/147643_en.html) Westinghouse also has an LFR design: [Advanced Demonstration and Test Reactor Options Study](https://art.inl.gov/ART%20Document%20Library/Forms/AllItems.aspx?RootFolder=%2FART%20Document%20Library%2FAdvanced%20Demonstration%20and%20Test%20Reactor%20Options%20Study) (click the “Attachment\_4\_Westinghouse\_LFR\_DR” PDF link, lots of detailed info) Those latter two links have extensive detailed info on the advantages and challenges of LFRs. ---
**Author:** ![Frankenstein\_Monster](https://avatars.discourse-cdn.com/v4/letter/f/ccd318/32.png) [@Frankenstein\_Monster](https://boards.straightdope.com/u/Frankenstein_Monster)\ **Post date:** [November 17, 2018, 7:25pm UTC](https://boards.straightdope.com/t/could-project-705-lira-liquid-metal-cooled-reactors-be-used-on-land-for-power-generation/824671/5 "2018-11-17T19:25:53Z")
For completeness, should mention [China](https://www.sciencedirect.com/science/article/pii/S2095809916301576) and [Korea](https://aip.scitation.org/doi/pdf/10.1063/1.4916841) work on LFRs.