The goal of FME is prevention. It is to prevent the introduction of foreign materials such as residue, dirt, debris, tools and equipment into open systems or components to avoid equipment damage. Its about safety. Safety of the plant equipment, which also provides a safe working environment for people, and provides safety and stability to future jobs, projects, and careers.
Plants where FME practices have not been followed have resulted in significant damage and economic loss when materials end up in areas where they do not belong. Pickering B Unit 6 generator, Pickering A liquid zone control system (deteriorated elastomer from the diaphragm valve), Bruce boilers and Point Lepreau heat transport pumps are some examples.
Foreign material that enters systems can cause equipment degradation or inoperability, fuel cladding damage, and high radiation and contamination levels that are spread throughout the plant. Examples exist where a single small machining chip or even a single bristle of a wire brush has caused fuel cladding damage, resulting in high radiation levels and forced outages to replace the leaking fuel. Other cases have occurred where the dust and small stellated particles from valve seat lapping have become activated as they pass through the reactor core, resulting in high radiation, hot spots in piping, and high contamination levels. As a result, great care and many precautions must be taken to avoid the introduction of foreign material into plant systems.
FME is achieved with a “focus on prevention” attitude. This attitude requires that individuals think through activities before they are performed to prevent the introduction of foreign material.
In addition to these conscientious efforts, a number of other key principles and expectations underlie all work to be performed in the plant. Workers must recognize when they are about to perform an activity that can generate foreign material. Any drilling, cutting, grinding, machining, filing, lapping, and other such activities generate small particles of foreign material that require attention. All foreign material created must be captured or otherwise contained. Action must be taken to prevent the possibility of spreading the material. The traditional approach of cleaning up afterward is not sufficient to meet this objective.
Workers must be alert to the potential for discovery of foreign material at all times. An initial inspection should be performed prior to opening a sensitive system or component, and any unexpected conditions encountered should be reported immediately to supervisory personnel. Immediate reporting is also required when foreign material exclusion (FME) controls are deemed lost during work task performance. Unless absolutely necessary to establish a safe condition, foreign material that is not immediately retrievable should not be disturbed or recovered until a recovery plan is established.
The intentional introduction of foreign material, such as leak sealing compound, chemicals, or lubricants, requires additional controls to ensure compatibility with the system and to prevent inadvertent spreading of the foreign material.
Finally, the proper management of foreign material in a nuclear power plant is extremely important. It is based upon common sense methods to keep unwanted material out of the systems and to properly deal with it when detected or inadvertently introduced. Well-informed, proactive, and responsible workers are the first line of defense for avoiding a potentially expensive and damaging event that could seriously affect the safety and operability of the plant.
References:
Urjan, Daniel (2008) Foreign Material Exclusion Program at CNE CERNAVODA Nuclear Generating Station. http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/40/073/40073560.pdf?r