The outcome of the process assessment either confirms that adequate arrangements are in place and/or suggests improvements to enhance the ability of individual plants and processes, and Sites as a whole, to withstand low probability/high consequence accident scenarios. Typical examples could include, a prolonged full Site Black Out (SBO), a significant seismic event, flood, or a malicious act.
The RESEP, was developed to be a structured, deterministic, and consistent approach to applying the stress tests at the Sellafield site. The RESEP is a staged assessment process, and includes the following:
- Progression of events from individual plants and processes to the whole site, including domino effects
- Searching for 'cliff edge' effects and development of timelines for critical mitigating response actions
- Assessment of infrastructure requirements both on and off-site
An essential part of the process is to identify the Critical Safety Function (CSF) for each plant using the principles of nuclear safety. This allows attention to be firmly focused on the actions essential to sustain the CSF. The existing emergency arrangements are assessed to identify the logistics i.e. time, resources, tools, access, plant conditions etc., required to implement and then sustain each of the backup systems. Two timelines are produced for each plant/process:
- A pessimistic timeline where any backup that depended upon external help to implement was disallowed
- An optimistic timeline where Site help was allowed, if required, to implement and maintain the backup systems.Structuring the RESEP process in this way ensures the essential services i.e. power, water, steam etc., the extent of Site help required, and the adequacy and duration provided by the declared backup systems to protect the CSFs are clearly identified.It has been deployed on a complex nuclear chemical site with multiple facilities, processes and working patterns. RESEP can be applied to new/future operations and or existing sites/ facilities to identify additional safeguards which may have arisen as a result of changes in the risk perception, changing legislation, regulation, etc.
DBD Defined Deliverables
- Although developed for the nuclear industry it is easily transferable to non-nuclear high hazard processes.
- Leading and managing the development of emergency preparedness including “hard engineering” and “command and control decision making” from design through inactive and active commissioning, to handover to operations
- Managing implementation of the Resilience Evaluation Process (RESEP) including defining plant/process CSF’s
- Production of bespoke facility/project response timelines
- Resilience Options Diagram (ROD), to clearly identify the optimum time for deployment of backup systems including options and any potential consequences of deploying the backup options for example hazard to operators.
- Production of Severe Accident Management Strategy Option Diagrams (SAMSOD) for use in Emergency Control Centres to support event response decision making
- A report prepared for each high consequence plant/process detailing the effectiveness of each of the backup systems with recommendations for improvements for any shortfall or gap found
- A report prepared on the overall effectiveness of emergency management processes
- A report on the reliability of the Sites infrastructure
The Results/Client Benefits
- Robust, auditable, documented review process supported by the UK Nuclear Regulator.
- Fit-for-purpose emergency arrangements Visual tool to aid informed decision making during a severe accident.
- An emergency plan with both operational and safety case requirements fully integrated.
- Provision of Emergency Preparedness Intelligent Customer capability.
- The ability to proactively manage a severe accident.