| Abstract |
The Savannah River National Laboratory (SRNL) has completed a series of tests (Phase 1 and Phase 2) to assess the potential use of a Mylar tear-off system as a primary or secondary protective barrier to minimize acid etching (frosting), accidental scratching, and/or radiation damage for shielded cells, glovebox, and/or chemical hood windows. Conceptually, thin, multi-layered sheets of Mylar (referred to throughout this report as the ProTec tear-off system) can be directly applied to the shielded cell, glovebox, or hood sash window to serve as a secondary (or primary) barrier. Upon degradation of visual clarity due to accidental scratching, spills/splatters, and/or radiation damage, the outer layer (or sheet) of Mylar could be removed refreshing or restoring the view. Due to the multilayer aspect, the remaining Mylar layers would provide continued protection for the window from potential reoccurrences (which could be immediate or after some extended time period). Although the concept of using a tear-off system as a protective barrier is conceptually enticing, potential technical issues were identified and addressed as part of this phased study to support implementation of this type of system in the Defense Waste Processing Facility (DWPF). Specific test conditions of interest to the DWPF included the performance of the tear-off system exposed to or under the following conditions: (1) acid(s) (concentrated (28.9 M) HF, concentrated (15.9M) HNO3, 6M HCl, and 0.6M H3BO3) (2) base (based on handling of radioactive sludges with pH of approx. 12 13) (3) gamma radiation (due to radioactive sources or materials being used in the analytical cells) (4) scratch resistance (simulating accidental scratching with the manipulators), and (5) in-situ testing (sample coupons exposed to actual field conditions in DWPF) The results of the Phase 1 study indicated that the ProTec tear-off concept (as a primary or secondary protective barrier) is a potential technical solution to prevent or retard excessive damage that would result from acid etching, base damage (as a result of a sludge spill or splatter), gamma radiation damage, and/or accidental scratching (due to manipulator/tool contact). |
