A preliminary investigation of the free-liquid surface sloshing motion on the ALFRED's model is presented. Fundamental base harmonic excitations have been post-processed for three forcing amplitudes at $a_y/D=$ 0.013, 0.039, 0.076, where D is the external diameter of the tank, and near/at and away $f_y=$ 0.89Hz, the estimated numerical first sloshing frequency. The complexity of the annular tank geometry and the internal structures makes the sloshing process hard to predict and to analyse. The wave-structure interaction adds complexity in evaluating the sloshing modes.\\
A first sloshing mode is basically experienced in each of the harmonic test series, with non-negligible nonlinear components since the smallest external base excitation. Some frequencies can be identified in the PSD for the smallest external amplitude cases. The maximum wave amplitude for the nominal water depth of $h_{model}=$ 8.84cm is reached in a frequency range that goes from 0.94Hz to 1.12 Hz. When $a_y/D=$ 0.076 ($a_y=$ 30mm), a plateau on the maximum amplitude is experienced. The wave steepness increases at higher forcing amplitudes, as well as the motion becomes more violent and critical if studied in similarity with ALFRED.\\ 
Shallow water condition has been tested because the geometric dimensions of the special tank don't allow filling enough of the pool to have a deeper water depth. The greater wave amplitude is reached at lower forcing frequency for the smaller water depths, while higher ones lead to more intense sloshing processes. If it's good to have smaller wave amplitudes, on the other hand, it is dangerous to experience resonance at lower frequencies.\\
A hazardous internal structure has also been tested for the harmonic base excitation, removing the 3D printed tubes representing the steam generators. The motion in the simulated damage configuration is less damped, so is more critical for the model and, in similarity, for the actual demonstrator. Violent motion is easier to be experienced for damaged internal arrangement and higher accelerations.\\
The seismic test series have been conducted in one direction and in the three directions, for the same water depths and internal configurations set-up for the harmonic base excitation ones. The harmonic ones revealed to be a powerful tool to analyse the experimental investigation of sloshing processes when the norm-base earthquake is simulated. In fact, basically the same previous considerations can be applied when the norm-base input signal is applied in one direction.\\
Ultimately, the norm-base earthquake in three directions emphasizes the importance of being aware of the fundamental free surface behaviour. Similarly, equipped test series exhibit higher wave amplitude when the signal is simply applied in all the direction and not only in one. The full scale effect assessments show that the seismic simulations and some of the harmonic test series are in agreement with the hypothesis made on the ground accelerations of the regions mentioned.\\
Finally, it is encountered that sloshing in the primary pool of ALFRED is a problem of concern for the hard-to-predict behaviour, which makes really tricky to provide a numerical model (objective for the sloshing framework of the PASCAL project), and the great amplitudes reached during the dynamic processes. Despite some of the tested conditions are ten times the estimated ones in Mioveni (Romania, the building site for ALFRED), the critical motion experienced also for the simpler and less intense external excitations exhibits the necessity of further investigation of the sloshing processes and, potentially, more accurate models of the demonstrator.\\
The experimental investigation of sloshing could be improved and could keep into account force measurements by means of the strain gauge sensors, alongside the information on the free surface displacement. A more complete and dedicated experimentation could be done for the vertical excitation, different in more ways from  the horizontal ones. Seismic simulation test series could be studied after the post-processing of harmonic external excitation in two and three degree of freedom. Finally, more realistic earthquake signals could be scaled for the shaking facilities for a more useful simulation of extreme events that very potentially lead to catastrophes.