No abstract

210Po, a highly toxic element with strong volatility, is one of the main source terms of a Gen-IV lead-cooled fast reactor (LFR). Therefore, the radioactive safety caused by 210Po has become an important topic in LFR-related research. In order to simulate the behavior of 210Po in an LFR, this work developed a multi-physics model of an LFR from the perspective of radioactive transport. Considering the effects of nuclide decay, cover gas leakage, containment ventilation, and Po aerosol deposition, a comprehensive simulation was carried out to evaluate the sensitivity of those effects on the 210Po distribution in detail. Preliminary results indicate that during normal operation, most of the 210Po in the LBE exist in the form of PbPo, and around 10–9 of 210Po could evaporate from the LBE into the cover gas, and then further leak into the containment. In addition, even if the leakage rate of 210Po in the cover gas into the containment is maintained at 5‰ per day, due to the deposition of Po aerosol, the 210Po contamination on the inner surface of the containment is still below the radioactivity concentration limits.

No abstract

No abstract

Existing depletion and source term calculation codes lack flexible interfaces, which is difficult to meet the actual engineering design needs. Based on the Chebyshev rational approximation method, a new depletion, activation and source term calculation code TIST is developed and verified. Full-fidelity depletion library based on ENDF-VII.0 and EAF2010 contains 3837 isotopes is generated. Flexible interfaces are built-in to support cross sections from different sources for depletion and activation calculations. The EAF2010 library and the cross sections from the high-fidelity code NECP-X are adopted by TIST for the verification in this work. Based on the nuclide inventory of the depletion and activation calculation, the radiation source term calculation capability of TIST is developed, including the radioactivity, the decay heat, the neutron source and the photon source. The comparison results with NECP-X and FISPACT demonstrate good accuracy of TIST.