Waste--In theory, LFTRs would produce far less waste along their entire process chain, from ore extraction to nuclear waste storage, than LWRs. A LFTR power plant would generate 4,000 times less mining waste (solids and liquids of similar character to those in uranium mining) and would generate 1,000 to 10,000 times less nuclear waste than an LWR. Additionally, because LFTR burns all of its nuclear fuel, the majority of the waste products (83%) are safe within 10 years, and the remaining waste products (17%) need to be stored in geological isolation for only about 300 years (compared to 10,000 years or more for LWR waste). Additionally, the LFTR can be used to "burn down" waste from an LWR (nearly the entirety of the United States' nuclear waste stockpile) into the standard waste products of an LFTR, so long-term storage of nuclear waste would no longer be needed.
Decommissioning remove the material unused salt for use at other plants. Some contamination may occur, so either reuse on site. Or worst case, crush building and store for 300 years of decontamination. This contamination would be much lower level compared to what is happening at current plants.
Runaway reactions are impossible with LFTR so no Meltdown/china syndrome. The reactor is underground, so it will be terrorist resistant. If a leak happens the molten mix will quickly solidify and not go anywhere (stay out of the groundwater).
Kiss your keyboard goodbye!