Lithium hydroxide from Li-7 as used in thermal reactors

In summary, Lithium hydroxide is used as an anti-corrosion additive in light water reactors purely for the "longevity" and "well being" of the vessel and structural auxiliary elements like steam pipes etc. Lithium separation is a rather chemically "nasty" task if using the COLEX process, but other processes are available. Russia and China are sources for lithium, but the US is currently undertaking a program to enrich Li.
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So I read that lithium hydroxide made from Li-7 is used as an anti-corrosion additive in light water reactors purely for the "longevity" and "well being" of the vessel and structural auxiliary elements like steam pipes etc.

Lithium separation is a rather chemically "nasty" task if using the COLEX process , I see there are others as well but much less effective. Given US no longer operates Li separation facilities where do US reactors get their Li-7 needed inventory?
I would assume Russia and China.
And why only Li-7 is used but not ordinary Lithium containing both the Li-6 and Li-7 stable isotopes?
Is it because Li-6 in a neutron rich environment (the core) would produce too much Tritium?, Because chemically I would suspect that using ordinary Lithium instead of Li-7 for the lithium hydroxide solution would make no difference in the chemical anti corrosion properties?

Comments are welcome, thanks.
 
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LiOH is used as a buffer for soluble H3BO3 in PWR primary coolant. The goal is to achieve a pH > 6.9, and preferably ~7.1 to 7.4 (at ~300°C), in order to prevent dissolution of Ni from steam generator tubing (and stainless steel cladding on carbon steel PV and other components) as well as crud deposition in the core. Zn is also injected into the coolant to suppress Ni dissolution.

Li in LiOH is enriched in 7Li for the reason one cited above, that 6Li experiences (n,α) reaction resulting in T production.

Russia is a source and China is a potential source. There is currently a program in the US to enrich Li, or rather produce separate streams of 6Li and 7Li.

Russian VVER systems have used KOH for the same purpose.

One can reduce the demand of LiOH by reducing the required concentration of H3BO3 through enrichment of 10B in the boric acid. However, one must weight that against hypothetical boron dilution events and the reactivity insertion accidents.

Some background
http://www.world-nuclear.org/information-library/current-and-future-generation/lithium.aspx
 
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1. What is lithium hydroxide and how is it used in thermal reactors?

Lithium hydroxide is a chemical compound composed of lithium and hydroxide ions. It is commonly used in thermal reactors as a coolant and moderator to slow down the neutrons produced during nuclear fission. It also helps to regulate the temperature and pressure within the reactor.

2. How is lithium hydroxide produced from Li-7?

Lithium hydroxide can be produced from Li-7 through a process called electrolysis, where an electric current is used to break down the lithium ions into lithium hydroxide and hydrogen gas. This method is commonly used in the nuclear industry to obtain high purity lithium hydroxide for use in thermal reactors.

3. What are the advantages of using lithium hydroxide from Li-7 in thermal reactors?

One of the main advantages of using lithium hydroxide from Li-7 in thermal reactors is its ability to efficiently slow down and absorb neutrons, making it an effective coolant and moderator. It also has a high melting point and can withstand high temperatures, making it suitable for use in nuclear reactors.

4. Are there any safety concerns associated with using lithium hydroxide from Li-7 in thermal reactors?

While lithium hydroxide is generally considered safe to use in thermal reactors, there are some safety concerns that need to be addressed. These include the potential for corrosion of reactor components, as well as the release of hydrogen gas during the electrolysis process. Proper safety measures and regulations are in place to ensure the safe handling and use of lithium hydroxide in nuclear reactors.

5. Can lithium hydroxide from Li-7 be used in other applications besides thermal reactors?

Yes, lithium hydroxide from Li-7 has various other applications, including in the production of lithium-ion batteries, ceramics, and pharmaceuticals. It is also used in the purification of air in spacecraft and submarines, as well as in the production of lubricants and greases. Its unique properties make it a versatile compound with many industrial and scientific uses.

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