Study on Fast Reactor and Accelerator Target Using Lead and Lead-Bismuth Coolants

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(1) Burnup and safety analyzes were performed for a long life small safe reactor, and the events of UTOP, ULOF and ULOHS were simulated. The feasibility of CANDLE burnup concept was confirmed for a lead-bismuth cooled reactor with 2 m in radius and 0.5 m in radial reflector thickness.(2) The poisons produced by spallation in the lead-bismuth target of accelerator-driven system and the hazard of the long lived radiological products were evaluated.(3) The behaviors of polonium adsorption and the removal of polonium contamination on quartz glass by baking were investigated experimentally.(4) Lead-Bismuth Technology, Material Corrosion and Control of Oxygen Concentration(i) A lead-bismuth flow loop was designed and fabricated, and operated with the desired performance.(ii) The technique of oxygen concentration control in lead-bismuth by means of injecting argon, hydrogen and steam into lead-bismuth was established.(iii) A solid electrolyte oxygen sensor mounted in the lead-bismuth loop pro … More vided a reasonable electro-motive force corresponding to the oxygen potential given by the injection of argon, hydrogen and steam mixture into lead-bismuth.(iv) As a result of two steel corrosion tests at 550 ℃ and 2 m/s for 1,000 hours in a lead-bismuth flow, the weight losses of the high Cr steels : SUS430, SUS405 and STBA26 were lower than the other steels due to Cr oxide corrosion suppression layer. The weight loss and damage of SUS316 were the largest among the tested steels because of high solubility of Ni into lead-bismuth. In the corrosion test at the oxygen concentration of 3.6x10^<-7> wt. %, erosion damage appeared in the test pieces of low Cr steels : SCM420, F82H, STBA26, HCM12, and 2 l/4Cr-1Mo steel. The penetration of lead and bismuth into SCM420, STBA26, STBA28 and SUS316 and the dissolution of Fe and Cr into adherent lead-bismuth in ODS, F82H, NF616 and HCM12 appeared.(v) The dissolution of steel into lead-bismuth and the penetration of lead and bismuth into the steel were simulated by the molecular dynamics method.(5) Thermal-Hydraulics of Lead-Bismuth(i) The flow characteristics of a natural circulation using a gas lift pump was investigated experimentally.(ii) Natural circulation in lead-bismuth cooled reactor was analytically examined.(iii) An electro-magnetic flow meter with MI cable type electrodes plated with Rh was the best performance.(iv) Mass diffusion between lead-bismuth and different liquid metals were well simulated by the molecular dynamics method. Less