EDF EL4 Reactor Internals Characterization

Brennilis, Brittany, France




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Electricité de France (EDF), planned a set of characterization works for the Eau Laude Quatre (EL4) reactor block, Brennilis in France.  The EL4 reactor is presently in the Storage with Surveillance (SWS) phase of decommissioning and EDF is planning for the final stage of decommissioning.  The EL4 Reactor is being decommissioned by EDF who identified and established an upfront set of characterization works to help define the best alternative for the final dismantling and decommissioning phase of the facility.

Development of the detailed decommissioning plans including the post closure safety case requires verification of the radiological inventory.   Most of the radiological inventory within the EL4 facility is associated with the various components of the reactor block.  EDF NMNTI to accomplish deep drilling and sampling of the EL4 reactor block and to perform the following:

  • Provided sampling data (i.e. sample collection, down hole photos from inside the reactor vessel, dose levels with depth) for correlation to the calculated estimates of the radiological inventory present in the activated reactor block components and,
  • Provided the sampling results in a final report.
TruPro® sampling:

  • Operated without the use of water, to retrieve dry representative samples,
  • Powered by a facility electric supply coupled to 100-meter electrical extension cables if necessary,
  • Removal of approximately 26 discrete concrete and metal samples,
  • Removed incremental depths of potentially contaminated materials from predetermined sampling points sequentially to depth,
  • Collection of all particulate from sampling operations into specialized filter units with no risk or spread of contamination,
  • Produced representative samples of each structural component material, Concrete, Lateral and axial screens, Vessel shell ring, Vessel bottom head, Pressure tubes, and by going completely through to the reactor internal void spaces with extraction of as many metal powder, chippings and filings samples as practically possible and permissible from the main metal and concrete layers across void spaces.
  • Breaching of the concrete biological shield was repaired following the sampling to allow the structure to accomplish its regular function prior to breaching (i.e. radiation shielding).
  • All sampling equipment was mobile and modular for the tightly confined working areas.
Sampling of the EL4 reactor block materials, by using the TruPro® technology and approach, allows EDF to adjust the radiological calculations for the material inventories of the activated reactor block and metal component structures for French regulatory approval. The analytical results acquired from the concretes and metals will be used to establish the relative correlation of characterization data to activation product inventory estimates.


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