2018 | AFC ACCOMPLISHMENTS 133 zirconium, and rare earth elements was added to the U-TRU feedstock to produce the final fuels.Table 1 shows the final composition of the fuel. It should be noted that the original nominal fuel composition included 1% and 3% of the rare earth simulated fission products, however, after casting an average of 14.5% of the rare earth elements were lost.The nominal simulated rare earth ratio was 53Nd:25Ce:16Pr:6La, however, as seen in Table 1 the ratio changed to an average ratio of 41Nd:39Ce:15Pr:6La. Reported relative error on the rare earth elements was 5-10%, this may account for some of the ratio change. The change in ratio also indicates a preferential crucible interaction or oxidation of some of the rare earth elements. Once the fuel was cast and Nominal Comp Total U Total TRU Zr Total RE Nd Ce Pr La Other* U-24TRU-10Zr-1RE 65.76 23.31 9.6 0.86 0.34 0.34 0.13 0.05 0.98 U-24TRU-10Zr-3RE 64.66 24.00 9.25 2.54 1.07 0.97 0.37 0.12 Rodlet ID Nominal Comp Cladding Coating Capsule Fill Gas Cladding Temp IRT1-R1 U-24TRU-10Zr-1RE HT-9 NONE 64.5He:35.5Ar 550±25°C IRT1-R2 U-24TRU-10Zr-3RE FC92 NONE 66.2He:33.8Ar 525±25°C IRT1-R3 U-24TRU-10Zr-3RE HT-9 TiN 85.1He:14.9Ar 600±25°C IRT1-R4 U-24TRU-10Zr-3RE FC92 Cr 60.0He:40.0Ar 500±25°C IRT1-R5 U-24TRU-10Zr-1RE FC92 NONE 65.6He:34.4Ar 525±25°C cut to length it was encapsulated in either HT-9 or FC92 steel cladding. Of the five rodlets, one had a chromium fuel cladding chemical interaction barrier layer and another had a TiN barrier layer.Table 2 shows the test matrix, and Figure 1 shows the completed rodlets. After final inspec- tions the rodlets were encapsulated in containment capsules. Figure 2 shows a typical example of the final capsule, ready for shipment to the reactor. The containment capsule provides a safety barrier between the sodium and fuel and the reactor coolant in case of a cladding breach, but also provides thermal separation allowing the peak inner clad temperatures to reach prototypic liquid metal cooled fast reactor temperatures.The cladding temperature is dependent Table 1. Summary of final fuel compositions in wt%. Table 2. Summary of the test IRT-1 test matrix.