Fission product release under severe accidental conditions: general presentation of the program and synthesis of VERCORS 1–6 results

Feasibility study of passive gamma spectrometry of molten core material from Fukushima Daiichi Nuclear Power Station unit 1, 2, and 3 cores for special nuclear material accountancy – low-volatile FP and special nuclear material inventory analysis and fundamental characteristics of gamma-rays from fuel debris

“…TEPCO is planning to survey the inside of the containment vessel in its mid-to long-term road map for decontamination of 1F, which would reveal the characteristics of the fuel debris and the step-by-step accident sequence would be understood. Here, on the basis of the data from the TMI-2 fuel debris and follow-up experiments worldwide [21][22][23][24], the volatility is defined and categorized by the release fraction from fuel material, and the following FP release fractions are assumed in the present paper: up to ∼100% for volatile FPs such as cesium (Cs) and iodine (I); 10%∼50% for low-to medium-volatile FPs such as ruthenium (Ru) and antimony (Sb), which tend to be largely absent from the oxide melt phase but are found concentrated in metallic stringers; and 0% to several per cent for low-to non-volatile FPs such as lanthanides (Ln) and zirconium (Zr), which are generally stable in the oxide melt phase but could be influenced by high temperature and the atmospheric conditions. Even with a large release fraction of Cs, the ratio of 134 Cs/ 137 Cs has often been used as an index of the burnup in the cleanup of TMI-2 and the Chernobyl Drum Assay System [25] in Chernobyl-4 and other cleanup …”

Mechanistic modelling of urania fuel evolution and fission product migration during irradiation and heating

“…the behaviour of caesium in the VERCORS 4 test. This test from the French VERCORS program [3] was performed at high temperature and in pure hydrogen during the final part, after clad pre-oxidation in mixed atmosphere at an intermediate temperature plateau. Results of the MFPR code simulations are given in Figs.…”

“…As a first objective, the code is used for interpretation of complex large scale [2] or semi analytical experiments [3], but is also used for benchmarking of more simplified reactor code models and could be part of a fuel performance code in near future. It is extensively validated against separate-effect tests, semi-analytical out-of-pile tests and large scale in-pile tests.…”

Simulation of fission products behavior in severe accidents for advanced passive PWR

“…Experimental research on fission products release behavior was conducted by many investigators (Ducros et al, 2001;Lewis et al, 2008;Luis and Herranz, 2010), and many experiments played an important role to aerosol behavior (Mäkynen et al, 1994(Mäkynen et al, , 1997. Meanwhile many analytical tools are developed.…”