Current Status of R and D of Nuclear Fuel Elements for PWR in Indonesia

The Experimental Fuel Element Installation (EFEI) of PTBN - BATAN was designed for PHWR fuel element of CIRENE type. Currently the R and D in EFEI have trend to modify the installation for PHWR and PWR fuel fabrication in one place. It has been initiated with modification of equipment necessary for PWR prototype fuel PIN fabrication. Modification is includes in pelletizing area, PIN fabrication area, and criticality nuclear safety and health physics protection. Based on the existing CIRENE pelletization technology, development is carried out by modifying the replaceable punch and dies of the compaction machine and pellet blade of the grinding machine. R and D of PWR fuel pellets with improved characteristics for high burn-up application by adding dopant / additive (TiO2, Nb2O5, V2O5 ) and burnable poison ( Gd2O3, Er2O3) in pellets. Low enriched UO2 is simulated using natural UO2 via ADU and depleted UO2 via AUC. The powder is compacted in 11 mm dies using hydraulic press. The compacting process parameters are determined based on both the compressibility and compactibility as indicated consecutively by the density and mechanical strength of the green pellets. The compacting pressure is chosen based on the condition that gives the UO2 pellets a maximum green strength with a density within the specification requirement. The selected pressure is 4.0 ton/cm2 for standard pellet, and 3.5 ton/cm2 for UO2 + additive and UO2 + burnable poison. The sintering parameters for UO2 pellet: temperature sintering 1700 oC, heating rate of 250 oC/h and soaking time of 4 hours. The sintering parameters for UO2 with dopant / additive (TiO2, Nb2O5, V2O5 ): temperature 1200 oC, heating rate of 250 oC/h and soaking time of 3 hours. The sintering parameters for UO2 with burnable poison (Gd2O3, Er2O3): temperature of 1200 oC, heating rate of 250 oC/h and soaking time of 3 hours. In the manufacture of PIN, welding box should be modified so that it is compatible with TIG welding machine. Due to unfinished modification, PIN fabrication is done in BATAN BANDUNG. The result of this experiment indicates that 15 seconds of post purge time produce weld surface which is accepted on visual control quality process. The 7.5 rpm velocity of the weld and by using argon as shielding gas can reduce the cost of welding so that this condition is chosen on first end plug welding of the fuel pin. (author)