SDU6 Interior Liner Testing & Evaluation

Abstract

Two liner materials (Marseal ® M-3500 and REMA Chemoline ® 4CN) proposed for use as a liner inside the Saltstone Disposal Unit 6 (SDU6) were subjected to specific ASTM tests (tensile and lap-shear) after immersion in 50% and 100% simulant solutions for 1000 hours at the Savannah River Ecology Laboratory. Both liner materials exhibited good resistance to the simulant chemistry, at least based on the tests performed and the test duration/conditions imposed. In lap-shear tests, both materials failed in the base material rather than peeling apart, confirming good adhesion. The REMA 4CN bromobutyl elastomer showed superior bonding characteristics and absence of warping or delamination at the conditions tested. The Marseal M-3500 material (PVC/EVA blend with polyester reinforcement) exhibited deformation and debonding in some locations. The cause of the deformation and delamination observed in the Marseal M-3500 material is not fully known, but possibly attributed to thermomechanical stress at immersion temperatures, and the thermoplastic nature of the material. The immersion temperature (68 °C) is slightly greater than the maximum use temperature limit quoted for the Marseal M-3500 liner (65 °C), though the basis for the service limit is unknown. The testing performed was limited in scope and only for these two liner materials. These tests were primarily performed to screen for severe incompatibility or short-term degradation in Saltstone bleedwater simulants at bounding solution temperatures. Additional testing is recommended to assess long-term performance and the overall service life of the liner.

SDU7 Interior Liner Testing & Evaluation

“…Testing was performed by SREL and SRNL on two liners (REMA Chemoline 4CN bromobutyl elastomer, Marseal M-3500 thermoplastic/Elvaloy ® copolymer). Of the two, the REMA Chemoline 4CN system was selected based on superior test performance and material behavior [5][6][7].…”

“… 100% humidity  pH between 3.7 and 13.7  Temperature range: -11 °C to 60 °C  Radiation dose, estimated at 0.82 Mrad over a 25-year period [7] The 1000-hour immersion period was initially based on the time at peak temperature of 68 °C from a SDU6 one-dimensional thermal model and was used for previous testing of the SDU6 liner [6][7]17]. The time period exceeds the minimum one-month exposure period in ASTM D6943-15, Standard Practice for Immersion Testing of Industrial Protective Coatings and Linings (Method A) [11].…”