6. MITIGATION AND REMEDIATION OF FOREIGN MATERIAL INTRUSION
6.2. Mitigation of a current foreign material
6.2.4. Recovery and retrieval
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support future activities and the improvement of FMM and FMMP. This information and knowledge can be obtained, collected and preserved by various methods and tools including photographs, videos.
Retrieval methods and tools (including the compatibility and vulnerabilities of the equipment to be used), e.g. hand, grapple-, disk- or cone-equipped snakes, tapes/adhesives, magnets, reach rods, vacuum systems, flushing systems, temporary screens and strainers;
Recovery pathway, including systems to be opened, flow paths to be used, locations for system entry/intrusion (e.g. manholes, drains, vents), and their ranking based on, among others, safety, ALARA, schedule, resources, risks, hazards, retrievability of FM;
— Entry conditions and prerequisites for FORAR procedure/process/activity implementation;
— Hazards, risks and consequences associated with retrieval process for:
Industrial, radiological and nuclear safety;
Equipment reliability;
Creation of new and additional FM;
Existing equipment damage and creation of further damages;
— Measures to eliminate or minimise FM risks and hazards during the activity, e.g. for:
Further spread or transport of FM during recovery activities;
Prevent further FM risk and hazards, as well as new targets and paths, during recovery activities;
Prevent recovery and retrieval tools from becoming FM themselves (as there are several OPEX on broken or stuck tools);
— The necessary activities for locating and removing FM(s) including all the measures to be taken for other requirements, expectations and associated requirements and actions, such as:
Temporary SSC and equipment modifications (opening, disassembly etc.) for accessibility needs, including the FMM/FMC measures around those SSCs and equipment;
Operability, availability, functionality of SSCs that will be modified/worked on for the implementation of FORAR activities, including tagout;
Radiological protection and ALARA assessment;
Environmental and confined space conditions assessment and associated requirements and actions;
Normal and emergency ingress/egress paths for personnel and equipment;
Power and other sources needed and their configuration;
— The schedule and resources to be utilised for the recovery and retrieval, including:
Qualifications, knowledge, skills and competencies needed for the activity;
Training needs (including mock-ups) of personnel performing the retrieval;
— Methods for the monitoring of FM, retrieval equipment and their status during the retrieval efforts;
— Inspection and monitoring requirements, methods, tools and timings;
— Exit conditions from FOSAR and entry back to system close-out of the original activity that cause FMI, including hold points to wait for parallel assessments, for example:
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Analysis of recovered materials;
Commissioning test and operation results after the FORAR;
Close out to ensure that the SSCs are FM free from the FMI incident;
Operation (or construction) department’s clearance;
— Follow up surveillance requirements and methods;
— Possible ‘Plan B’ and readiness to act on it.
It should be noted that, in cases that are noted in Section 6.2.2, immediate actions for mitigation of and recovery from an FMI event may be needed owing to the potential for further decrease in nuclear, radiological or industrial safety. In such cases, where the preparation of a detailed FORAR Plan is proven to be detrimental, the FORAR Plan may be accommodated by a prompt FORAR decision and impromptu strategy/tactic that could be implemented immediately with appropriate review, approval, supervision and oversight. By doing so, it is ensured that appropriate FM is promptly recovered, and the SSC is restored in a safer and more timely manner to prevent further degradation of the SSCs and protect people, equipment or environment.
As a good practice, the FORAR Plan may include a ‘do nothing’ option to provide the decision makers with an input on the impact/value of not retrieving the FM, i.e. consequences, resources needed for evaluation (which is discussed in Section 7). A ‘do nothing’ option can be particularly considered in cases that removal/recovery/retrieval efforts of the material are proven to carry unacceptable or intolerable safety risks than justifying the FM as a part of the plant design and configuration. However, this preview of a possible evaluation process may require comprehensive investigations and assessment of all aspects in integrated design and overall operation of the SSCs, utilising the original/existing design basis information and knowledge with solid scientific and engineering justification that would override the original design.
6.2.4.2. Conduct of foreign object reach and recovery
Once the FORAR Plan is reviewed and approved by all relevant and concerned parties, a FORAR Working Procedure (i.e. FORAR Work Instructions) can be prepared to describe how the FORAR will be performed. Depending on the weighted scale of the graded approach, the details of these instructions could vary from task to task. Therefore, the requirements, expectations and criteria for the preparation of FORAR Working Procedure/Instruction as to its type, scope and content, as well as the review and approval requirements, need to be defined by the FMMP (and/or other plant/project programmes).
Whether it is performed in accordance with strategy that is thoroughly evaluated and determined (i.e. by a comprehensive FORAR Plan and a detailed FORAR Working Procedure) or an impromptu strategy/tactic that is implemented under abstract work instructions (providing that the supervision and oversight are similar to those for the formal FORAR plan and procedure), the conduct of the FORAR activities need to be aware of and uphold the following key aspects, as a minimum:
— Nuclear, radiological and industrial safety requirements, which are always the utmost importance, and ALARA principles;
— Risk of relocation or repositioning of FM during recovery to create risk to SSC at hand and other SSCs (for example, risk of recovery efforts/tools causing its migration further into the SSC or getting into more unsafe or complex position to retrieve);
— Introduction and intrusion of new/additional FM into the SSC at hand and other SSCs, causing additional FM problems, from/by:
Breakup or damage to the equipment or tools (or any parts of those) utilised for the recovery and retrieval;
New or additional structural damage to SSC caused by the movement of the equipment or tools.
Again, it is a good practice to collect as much information and knowledge about the FM and FORAR evolution during the conduct of the FORAR activities to be utilised in analysis or disposition and closure of the task. As for FOSAD, collected evidence and information will also support subsequent assessments/analysis, incident investigation, future FOSAR activities and the improvement of FMMP. Methods and tools to obtain, collect and preserve information and knowledge during a FOSAR is the same as those that are used for FOSAD.
It is also a good practice to collect as much information as possible before removing the FM which can help in the reconstruction of FMI, including the transport and stoppage of FM during its movement.
Similarly, the entire FORAR activity needs to be reviewed and examined after the activity is completed as there will be lessons learned for the FMI event and from the detection and recovery processes.