Reportedly, this design has been advertised as having a core damage probability of only 3x10 core damage events per reactor-year.

In the first methodology, expected damage is related to ground shaking intensity in terms of MMI through damage probability matrices.

Earlier designs of the BWR, the BWR/4, had core damage probabilities as high as 1x10 core-damage events per reactor-year.

A damage probability matrix (DPM) was then developed for each building class which describes the probability of being in a certain damage level (i.e., light, moderate, heavy, etc.) given the ground shaking intensity.

A "significant precursor" is an event that leads to a conditional core damage probability (CCDP) or increase in core damage probability (CDP) that is greater than or equal to .

As accidents can have different magnitudes, for instance, a Tire damaging only a small part of a historical building or a conflagration gutting an entire building or even several buildings on a given site, it is necessary to have at least a good idea of the damage probability distribution correlating the LE with the magnitude of the accident.