It is important that blockages are highly available.Typically, the availability of primary defenses is a main design concern in system design. However, people tend to disregard high-order risks, such as failure of blockages.
In the TMI accident, the PORV was equipped with an indicator of its state, but the design did not consider the case of failure of the state indicator.
It is important that blockages are highly available.
The blockage of the November 2016 fire was based on airplanes arriving from neighboring countries. It took hours for these airplanes to arrive, but they were needed immediately.
This case study exemplifies the need to ensure that the blockages are highly available.
Updated on 25 Mar 2017.