In the manufacture of fuel containing U-233, some handling issues arise that are beyond those associated with fabrication of fuels containing recycled plutonium, which is generally mixed with depleted uranium (MOX fuels). This is mainly due to the fact that U-233 is always associated with U-232, which, as mentioned in Section 8.1.2, has a high specific activity because of its radioactive daughters, especially Tl-208. Hence, U-233 handling and processing require additional biological shielding (compared with plutonium) so that fuel manufacture and all handling operations through to reactor charging must be done remotely. Thus U-233 fuel fabrication and handling is a major technical hurdle and constitutes one of the main drawbacks of the Th/U-233 closed fuel cycle, because it generates a significant cost penalty. It must be added that reprocessed thorium also contains Th-228 and Th-234, the first of which also has the hard gamma emitter, Tl-208, as a daughter, preventing direct handling for tens of years.

It may be possible to reduce the shielding requirements if fuel fabrication is started promptly after reprocessing before there has been significant ingrowth of the U-232 daughters. However, this strategy might be risky in the case of potential delays in the fabrication process as these might allow the gamma dose rate to reach unacceptable levels. This topic has to be studied in detail to assess the real impacts of various recycling strategies on handling issues.