Summary of TMI-2 core sample examinations

The key role of sample analysis in Fukushima Dai-Ichi decommissioning, debris management, and accident progression investigation

“…More than 90% of the sample material was related to fragments with dimensions of 1-5 mm. Particles more than 1 mm in diameter were selected for optical metallographic imaging and SEM-EDS analysis, confirming that the upper layers of the solidified corium mostly consisted of molten uranium-zirconium oxide (Akers et al, 1986;McCardell et al, 1990). The typical analysis flow for grab samples is represented in Figure 1.…”

Reflooding with internal boiling of a heating model porous medium with mm-scale pores

“…Also, it is worth mentioning that the ratio of the capillary length of HFE-7000 to the diameter of the cylindrical heating elements is similar to the one obtained when considering the ratio between the capillary length of water at 100°C and a characteristic 5 mm particle size, typical of the one observed in debris bed. Indeed, observations of the damaged TMI-2 reactor [42] and different experimental studies (see, e.g., the TMI-2 core sample examinations by McCardell et al [43], the LOFT experiment analysis by Coryell et al [44], and the microscopic observations of fuel samples made by Manzel and Walker [45]) characterized the particles formed by the collapse of fuel rods: their size d p approximately lies between 1 and 10 mm. Thus, realistic boiling conditions are obtained in the present experimental setup, as far as bubble size and confinement effects are concerned.…”

Viscosity measurement of molten alumina and zirconia using aerodynamic levitation, laser heating and droplet oscillation techniques

“…In particular, the focus is placed on zirconia (ZrO 2 ), since it is an influential component of corium. For instance, the zirconia accounts for 13.75 % of the oxides in the corium of Three Mile Island accident [ 2 , 3 ]. Despite the high interest in the viscosity of molten zirconia, few experimental data have been reported due to its high melting temperature and high vapor pressure.…”