Deactivation safety analysis

Initial stress and pore pressure in the foundation were firstly generated in the numerical model with the backfill elements being deactivated. Consolidation analysis then was performed on staged-construction of backfill. Safety analysis based on the SRM was carried out after the calculation of the final construction stage was finished. 

In the late 1980s, DOE initiated tasks to provide new DOE orders that addressed nuclear safety documents and nuclear criticality safety. These documents were necessary to establish DOE nuclear safety policy and requirements in anticipation of the change to a regulated process. In 1991-1992, the DOE issued four DOE orders that defined the requirements for preparing Unreviewed Safety Questions (USQs) (DOE Order 5480.21), TSRs (DOE Order 5480.22), Safety Analysis Reports (DOE Order 5480.23), and Nuclear Criticality Safety (DOE Order 5480.24). They were used for the specification of nuclear safety requirements and used in conjunction with 10 CFR, Part 830 (10 CFR 830), Subpart A—Quality Assurance (QA) Requirements—for enforcement action under the PAAA regulatory process. These orders were deactivated on the issuance of 10 CFR 830, Subpart B—Safety Basis Requirements—and replaced by DOE guides. 

AQS is a procedure that drives the analyst and allows him to identify all the missions that are fimction-ally to be performed in order to mitigate the accident that is described by the PSA sequence. In these missions some are mainly driven by human decisions and actions. We call them Human Factor missions (HF mission). If it is plausible, the failure of one HF mission is an HFE one HFE happens if a HF mission fails. Then headings in PSA events trees are HF missions. Since the HF missions are built from a safety function analysis, they cover all the cases described in the table 1 by providing the analyst with all the required functions (or sub fimctions) to consider. The failure is then define as the deactivation of a safety funtion or sub fimction, that contributes to degradate the situation. 

This analysis identifies safety concerns associated with facilities that are decommissioned/closed. The deactivation process involves placing a facility into a safe mode and stable condition that can be monitored if needed. 

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