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APPLIED | WINTER 2019 | SAVANNAH RIVER NATIONAL LABORATORY | 3







                                                                                           Multiple pinhole images reveal the
                                                                                           distribution of plutonium across the floor
                                                                                           as well as accumulated on equipment
                                                                                           and air filters on the walls of the largest
                                                                                           PuFF facility cell






        Remote Radiation Mapping                                Equipment and material to mitigate radiological hazards
        Using both the patented SRNL GrayQb™ Single Face remote gamma   during decontamination activities
        radiation mapping device as well as the Germanium Gamma-Ray   The DOE-EM Office of Technology Development and Office of
        Imager developed by PHDS Co., SRNL performed remote imaging   Infrastructure & Deactivation and Decommissioning sponsored
        of the PuFF cells to better estimate the quantity and visualize the   SRNL development and adaptation of equipment and material
        distribution of the residual Pu-238. Creating a composite radiological   to reduce the radiological risks—potential worker exposure and
        image of the facility enabled management to develop efficient   escape of contamination--of performing decontamination activities
        decontamination plans and workers to practice cleanup work safely in   within the cells.
        a realistic mock-up of 235-F.                           SRNL has demonstrated the use of the electrostatic particle
        Tools to overcome physical constraints                  collector Aerosol Contaminant Extractor (ACE) 2.0 developed
                                                                and patented by SRNL to collect airborne radioactive particles
        Working closely with the 235-F Risk Reduction team, SRNL also   to minimize fugitive contaminant release during decontamination
        identified, designed, and fabricated tools to facilitate the physical   operations. The modular design of the ACE 2.0 makes it adaptable
        performance of the decontamination activities. The PuFF cells offer   for small and large area operation.
        few penetrations for access and tight spaces in which to work,
        especially to perform decontamination activities for which they were   To further ensure worker safety
        not designed. To help overcome the physical constrictions of the work   during decontamination activities,
        spaces, SRNL has found or custom made safe, lightweight, highly   SRNL identified a fixative to stabilize
        functional tools to allow workers easier access to and dexterity of   residual contamination on surfaces in
        movement in the cells.                                  the PuFF gloveboxes and cells. The
                                                                3M FireDam  Spray 200 is a water-
                                                                         TM
        Removal and analysis of first MAR from PuFF cells       based, incombustible fixative that
        The Pu-238 that is removed, along with any contaminated tools, will   dries to form a tough, elastomeric
        be safely stored for eventual packaging and shipment to the Waste   coating. The spray adheres to most
        Isolation Pilot Plant (WIPP) in New Mexico for final disposition.   materials and can be applied by   Applying fixative in 235-F PuFF for
                                                                airless sprayer, brush, or roller.  radiological “hot” test
        Following years of planning and preparation work, the 235-F Risk
        Reduction team removed the first material-at-risk (MAR), equipment   The FireDam fixative will be used along with the ACE 2.0 particle
        contaminated with plutonium, from the PuFF cells in October 2018.   collector to mitigate the hazards from residual surface and airborne
                                                                contamination during decontamination activities. The ACE 2.0 will
        SRNL performed non-destructive assay (NDA) of the MAR to   be operated before and after fixative material application to capture
        determine the Pu-238 content. NDA measurements of the material   residual airborne contamination. The FireDam coating material will be
        removed are critical to ensure that the waste drums do not contain   applied using two methods, direct pour and sprayer.
        more Pu-238 than can be received by WIPP. The first waste cut was
        well below the allowed amount. SRNL is scheduled to assay all future   In June 2018, SRNL conducted a “cold” (non-radioactive)
        waste cuts as well.                                     demonstration in the 235-F PuFF mock-up process cell to train
                                                                235-F Operators on ACE 2.0 operation and FireDamTM application
                                                                techniques. The fixative “hot” test in 235-F PuFF Process Cell 7 and
                                                                Entry Hood started in September 2018 and will run for a six month
                                                                evaluation period.
                                                                After removal or stabilization of the Pu-238, the cells will be vacuumed
             SRNL Aerosol Contaminant                           using a HEPA filter customized for that purpose by SRNL and
             Extractor 2.0 electrostatic                        otherwise cleaned to remove any leftover plutonium.
            particle collector (front) and
          housing with electronics (back)
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