Fault Assessment
The Fault Schedule (FS) should be structured to allow each node of operation to be viewed separately and should match the nodal approach to hazard and fault identification, Deterministic Safety Assessment (DSA) and Probabilistic Safety Assessment (PSA).
The Deterministic Safety Assessment (DSA) comprises a combination of Design Basis Accident Analysis (DBAA), Beyond Design Basis Accident Analysis (BDBAA) and Severe Accident Analysis (SAA) which provides a demonstration of the integrity of a plant, utility or facility through sufficient Defence in Depth (DiD).
Beyond Design Basis Accident Analysis (BDBAA) is necessary to establish that there are adequate margins to the Design Basis Accident Analysis (DBAA) such that a Structure, System or Component (SSC) does not fail due to a small increase in the severity of a design basis cause, leading to a potentially catastrophic failure i.e. exhibit a cliff-edge effect.
Design Basis Accident Analysis (DBAA) may not include the full range of identified faults because it may not be reasonably practicable to make design provision against the more unlikely faults.
Once the significant faults and hazards have been identified the key safety functions can be determined to ensure that the plant design will be adequate to support safe construction, commissioning, operation, maintenance and decommissioning.
A Probabilistic Safety Assessment (PSA) complements the Deterministic Safety Analysis (DSA) of credible accident scenarios and enables an assessment against numerical risk criteria.