in thorium-based fuels. is a significant neutron absorber and, although it eventually breeds into fissile , this requires two more neutron absorptions, which degrades neutron economy and increases the likelihood of transuranic production. Alternatively, if solid thorium is used in a closed fuel cycle in which is recycled, remote handling is necessary for fuel fabrication because of the high radiation levels resulting from the decay products of . This is also true of recycled thorium because of the presence of , which is part of the decay sequence. Further, unlike proven uranium fuel recycling technology (e.g. PUREX), recycling technology for thorium (e.g. THOREX) is only under development. Although the presence of complicates matters, there are public documents showing that has been used once in a nuclear weapon test. The United States tested a composite -plutonium bomb core in the MET (Military Effects Test) blast during Operation Teapot in 1955, though with much lower yield than expected. Advocates for liquid core and molten salt reactors such as LFTRs claim that these technologies negate thorium's disadvantages present in solid fuelled reactors. As only two liquid-core fluoride salt reactors have been built (the ORNL ARE and MSRE) and neither have used thorium, it is hard to validate the exact benefits. Thorium-fueled reactors Thorium fuels have fueled several different reactor types, including light water reactors, heavy water reactors, high temperature gas reactors, sodium-cooled fast reactors, and molten salt reactors. List of thorium-fueled reactors From IAEA TECDOC-1450 "Thorium Fuel Cycle – Potential Benefits and Challenges", Table 1: Thorium utilization in different experimental and power reactors. Additionally from Energy Information Administration, "Spent Nuclear Fuel Discharges from U. S. Reactors", Table B4: Dresden 1 Assembly Class. See also Thorium Thorium-232 Occurrence of thorium Thorium-based nuclear power List of countries by thorium resources List of countries by uranium reserves Advanced heavy-water reactor Alvin Radkowsky CANDU reactor Fuji MSR Peak uranium Radioactive waste Thorium Energy Alliance Weinberg Foundation World energy resources and consumption References Further reading Kasten, P. R. (1998). "Review of the Radkowsky Thorium reactor concept" Science & Global Security, 7(3), 237–269. Duncan Clark (9 September 2011), "Thorium advocates launch pressure group. Huge optimism for thorium nuclear energy at the launch of the Weinberg Foundation", The Guardian B.D. Kuz'minov, V.N. Manokhin, (1998) "Status of nuclear data for the thorium fuel cycle", IAEA translation from the Russian journal Yadernye Konstanty (Nuclear Constants) Issue No. 3–4, 1997 Thorium and uranium