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Foreign objects (for example, welding rods, wires, screws, nuts, gasket material) which are introduced by the secondary system are flushed into the lower steam generator (SG) area, “filtered” by the tube bundle and deposited at the tube sheet. Metallic objects of a certain size can endanger the integrity of SG tubes. Foreign particle evaluation and determination of potential for endangering neighboring tubes (risk level) must be performed immediately to avoid further damages. Appropriate retrieval of detected foreign objects in a precise and reliable manner without causing any damage to SG tubes is therefore essential.


The integral FOSAR concept considers all relevant steps for reliable foreign object search and retrieval:

  • Remote-controlled visual inspection of all tube aisles in tube bundle area up to the tube support plate – mapping
  • Evaluation of indications of primary side non-destructive examination, loose part fretting, wear, pitting, etc.
  • Risk assessment, planning of retrieval sequence and route
  • Foreign object retrieval by use of specifi c tools.


The system contains visual inspection manipulators, FOSAR positioning unit / feeding manipulator for tape deflection combined with specific cameras, lighting and flexible modular retrieval tools. It allows high manoeuvrability as well as rapid assembly and disassembly with low set-up times.


A set of easily exchangeable grippers for different foreign objects search and retrieval requirements (for example, type, size, location of particles) covers a wide range of applications. Additional suction devices and magnetsare available on specific demand. Special, highly qualified personnel with up-to-date knowledge and long-term experience ensure optimum performance.

 

Your Benefits

  • Time savings thanks to rapid and highly reliable performance
  • Enhanced efficiency in foreign objects search and retrieval
  • Reduction of radiation exposure
  • Ensures SG integrity
  • Outage optimization and therefore cost savings
  • Support to component lifetime extension programs
  • Field service worldwide


References
FOSAR is applied regularly as an integral part of SG services to ensure it is ready to use for ad-hoc asks without delay. Furthermore, Framatome performs FOSAR activities in nuclear power plant (NPP) primary circuits within recurrent outage services.


Reactor types / designs:

  • KWU pressurized water reactor (PWR)
  • Framatome PWR
  • Westinghouse PWR


NPPs in:

  • Europe (Germany, Switzerland, France, Belgium, the Netherlands, Spain, Finland)
  • Brazil

Interested in SG Foreign Object Search and Retrieval on Top of Tube Sheet?

CANDU Reactors VVER Reactors CANDO VVER Westinghouse