Sub-surface corrosion research on rock bolt system, perforated SS sheets and steel sets for Yucca Mountain Repository
Friction type steel rock bolts are one of the most commonly used for reinforcing tunnels, since the late 1970’s due to their ability to sustain large rock mass displacements. These ASTM A607 steel rock bolts are tubes slotted along the length with one end tapered for easy insertion into a drill hole and the other end with a welded ring flange to hold the bearing plate. It is more commonly used these days to reinforce tunnels, and also being studied for underground support for nuclear repositories. We studied corrosion behavior of this A607 steel rock bolts using electrolytes in three different concentrations; 1X,10X,100X, in aerated (oxygenated) and deaerated (nitrogenated) conditions from 298 to 363K for nuclear repository applications. The corrosion behavior for 1X and 10X concentrations for this rock bolt were similar in both aerated and deaerated conditions except the corrosion rates were a order of magnitude higher in the aerated condition; ranging from ~30 to 200mm/yr for deaerated and 150 to 1600 mm/yr for aerated. The corrosion behavior using 100X electrolyte was quite different in aerated condition showing initial increases in the corrosion rate between 298 to 338K ( ~210 to 2400 μm/yr) and an unusual steep decrease from 338 to 348K(~2400 to 750 μm/yr). General as well as pitting corrosion were observed for these steels. In this paper we report results from potentiodynamic polarization and potentiostatic tests in simulated electrolytes as a function of concentration, temperature and environment. We also compare corrosion behavior of the A607 rock bolt steel with 1040 and A36 steels using the same electrolyte and similar environment.
Waste Package Degradation process Model Report
A crucial element of the long-term postclosure safety strategy for the potential monitored geologic repository at Yucca Mountain is to contain high-level radioactive waste (HLW), and to keep that waste and its container as dry as possible. There are several degradation processes that could impact the performance of the engineered barrier system (EBS). The role of this PMR is to describe one of the process-level models (Waste Package Degradation) utilized to evaluate these degradation processes. To evaluate the postclosure performance of the monitored geologic repository proposed for construction at Yucca Mountain, a Total System Performance Assessment (TSPA) will be conducted. A set of nine Process Model Reports (PMRs), of which this document is one, is being developed to summarize the technical basis for process-level models supporting the TSPA model. These reports cover the following areas: Integrated Site Model; Unsaturated Zone Flow and Transport; Near-Field Environment (NFE); EBS Degradation, Flow, and Transport; Waste Package Degradation; Waste Form Degradation; Saturated Zone Flow and Transport; Biosphere; and Disruptive Events. These PMRs are supported by several Analysis and Model Reports (AMRs) that contain more detailed technical information. This technical information consists of data, analyses, models, software, and other documentation necessary to defend the applicabilitymore » of each model for its intended purpose. The PMR is intended to ensure the traceability of waste package degradation information from its various sources through the AMRs, PMRs, and eventually in TSPA.« less
SR topography of plastically deformed Fe-Si bicrystals - observation in situ and post mortem
SR reflection topography was applied to study the interaction of slip dislocations with the grain boundaries in Fe-4at%Si bicrystals deformed by compression. Three experimental settings with either a white or monochromatic beam were used and the corresponding orientation contrast analysed. Dislocation transmission through the grain boundary was observed in bicrystals with favourable geometry of the slip systems.