Guanheng Zhang (alumnus), Gang Wang, Lucas David, Sai Vadlamudi, Massimiliano Fratoni, Ehud Greenspan
The Seed and Blanket (S&B) concept is able to support several new 2- and 3-tier advanced fuel cycle systems to improve nuclear fuel cycle sustainability. Instead of using the thorium blanket of the S&B reactor in a once-through mode, accumulating a large inventory of Trans-Th elements, this study assesses the feasibility of using the discharged Trans-Th to feed PWRs and molten salt reactors (MSRs) that operate on a closed fuel cycle (their fuel is recycled). This fuel cycle option provides a possible solution to the large amount of U-233 bred in the S&B core whose decay daughters are the major contributors to long-term radioactivity and radiotoxicity.
The specific fuel cycle considered here is a three-stage energy system PWR(LEU)-S&B-PWR(Trans-Th) illustrated below. Stage 1 contains once-through low enriched uranium fueled LWRs, Stage-2 uses S&B reactors having TRU-transmuting seed and thorium blankets, and Stage-3 has LWRs that operate on a closed U-233/Th fuel cycle. The recovered Trans-thorium from Stage 2 is mixed with some fresh thorium to serve as the makeup fuel of the Stage-3 PWR. All the discharged fuel is reprocessed and recycled except for the uranium recovered from Stage-1 discharged fuel and a fraction of the thorium discharged from Stage-2 blankets. The seed of Stage-2 S&B reactors is fed with TRU separated from Stage-1 PWRs. This system may offer the fastest and possibly most cost-effective way to get rid of the High Level Waste from the nuclear industry. It is found that one S&B core can support 3.3 PWRs in this 3-tier advanced fuel cycle system.