Corrosion of barrier materials in seawater environments

Abstract

Lgi DISCLAIMERPortions of this document may be illegible electronic image products. Images are produced from the best avaiiable original document. ABSTRACT A brief review has been carried out on the performance of barrier materials for low-level radioactive wastes in seawater environments. The environments include those for shallower coastal waters as well as the deep ocean (down to 3800 m). The review is mainly focused on metallic materials since they are the most common for seawater service and they have the largest data base. Information from the literature is usually pertinent to shallower coastal locations, but there is a valuable source of corrosion data obtained from several studies of metallic specimens exposed to ocean-bed conditions. In addition, the corrosion of carbon steel barriers has been evaluated for actual waste containers that were retrieved from previously-used disposal sites in the Atlantic and Pacific Oceans. Of the metallic materials studied, carbon steel showed the least corrosion resistance. Failure by non-uniform attack in a typical waste container could occur in as little as 25 y in some ocean environments. Penetration by local attack, such as pitting and crevice corrosion resistance was also observed for more expensive materials such as low-alloy steels, stainless steels, titanium alloys, zirconium alloys, copper alloys, nickel alloys, aluminum alloys, and lead alloys.iv

Deep-Sea Biofilms, Historic Shipwreck Preservation and the Deepwater Horizon Spill

“…In both areas, sediment not observed prior to 2013 covered sections where new holes were emerging, providing another line of evidence of a sedimentation pulse at this location after the spill. Although these data are only available for U-166, a wreck that has been on the seafloor for 76 years, the corrosion rate at this site, revealed through still images, appears orders of magnitude higher than rates reported in the literature, and has accelerated across the time series presented here (Heiser and Soo, 1995;Melchers, 2003). This is unexpected and suggests a connection between spill fallout and metal loss of historic shipwrecks on the seafloor.…”

“…Over a decade of progressive deterioration has been observed on the aft deck and conning tower of U-166 (Figure 7). Ordinarily, the corrosion rate of carbon steels and other low-alloy steels in seawater follow non-linear dependence upon exposure time with the highest corrosion rates at the earliest exposure times (Heiser and Soo, 1995;Melchers, 2003). This is contrary to observations at U-166 in 2013.…”

Radiological Conditions of the Western Kara Sea: assessment of the radiological impact of the dumping of radioactive waste in the Arctic Seas

“…Radionuclide release from the dumped steam generating installations was assumed to be driven by corrosion of the materials forming the reactor structure and nuclear fuel [80]. Applying the best available predictions for corrosion rates in an Arctic environment [81][82][83][84], models were then developed to predict the release rates of the fission product, actinide and activation product inventories in the reactors. Using the inventory and construction data, corrosion rates were applied to simple computer models of the protective barriers to produce radionuclide release rates for three scenarios labelled A, B and C:…”

“…(1) Structural materials. Extensive literature search has been undertaken for common structural materials such as stainless steels and mild steels, and the best estimate corrosion rates employed are believed to be on the conservative side of the range of values examined [81,82]. Soo [83] reviewed values determined by the IASAP and considered them reasonable for the bulk and pitting corrosion rates of stainless steel.…”

“…CORROSION RATES AND FILLER LIFETIMES USED FOR IASAP STEAM GENERATION INSTAL-LATION MODELS[81][82][83][84] …”