The corrosion rate of carbon steel in compacted bentonite was evaluated with regard to the test period length, temperature, chemicals of solution and bulk density of compacted bentonite.The average corrosion rate decreased gradually with increasing test period up to 180 days in immersion tests. The corrosion rate of carbon steel in compacted bentonite at a dry density of 1.32g/c was estimated to be about 0.01 mm/y which was one order of magnitude lower than that in bentonite slurry. No significant influence of temperature on corrosion rates was observed in compacted bentonite in the range of 50-180 *C . Variation of kinds and concentration of anion(chloride, floride, sulfate, and carbonate)in aqueous solution did not have much influence on the corrosion rate of carbon steel.Immersion tests of carbon steel in compacted bentonite at a dry density of 0.69 -1.32 g/cm 3 , which was mixed with an aqueous solution(synthetic sea water and distilled water), were carried out. The corrosion rate in compacted bentonite decreased from 0.04 to O.O05mm/y as the density of bentonite increased.This result suggests that the corrosion rate of carbon steel in compacted bentonite is governed by the diffusivity of corrosive materials. In general, oxygen is the dominate factor affecting corrosion rate, therefore prediction of the average corrosion rate of carbon steel was carried out on the basis of the diffusion behavior of dissolved oxygen in compacted bentonite.The prediction agreed with experimental results. INTRODUCTIONThe Japanese concept for high-level radioactive waste management is based on immobilization with borosilicate glass, folllowed by 30 to 50 years of storage for cooling, and ultimate disposal in underground formations deeper than several hundred meters (I ) . Candidate sites have not been selected yet, and site characteristics such as composition of groundwater have not been determined.According to the current engineered barrier system concept, waste glass packed in the waste container(overpack) is emplaced in a borehole. Buffer materials are emplaced between the overpack and host rock. These engineered barrier systems act as a primary barrier to the release of radionuclies from the radioactive waste to host rock.The primary role of the overpack is to confine the radionuclides for more than several hundred years. The life of the overpack will be mainly limited by corrosion Two types of materials were sellected as candidate overpack materials for achieving this long life. One is corrosion allowance type material and the other is high corrosion resistance type material. Carbon steel is the primary candidate of corrosion allowance type metal.Immersion tests in test solution have been conducted in order to estimate the influence of individual environmental factors on the corrosion behavior of carbon steel. Immersion tests in bentonite slurry have also been carried out to estimate
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.