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Title: Humid-air and aqueous corrosion models for corrosion-allowance barrier material

Abstract

Humid-air and aqueous general and pitting corrosion models (including their uncertainties) for the carbon steel outer containment barrier were developed using the corrosion data from literature for a suite of cast irons and carbon steels which have similar corrosion behaviors to the outer barrier material. The corrosion data include the potential effects of various chemical species present in the testing environments. The atmospheric corrosion data also embed any effects of cyclic wetting and drying and salts that may form on the corroding specimen surface. The humid-air and aqueous general corrosion models are consistent in that the predicted humid-air general corrosion rates at relative humidities between 85 and 100% RH are close to the predicted aqueous general corrosion rates. Using the expected values of the model parameters, the model predicts that aqueous pitting corrosion is the most likely failure mode for the carbon steel outer barrier, and an earliest failure (or initial pit penetration) of the 100-mm thick barrier may occur as early as about 500 years if it is exposed continuously to an aqueous condition at between 60 and 70{degrees}C.

Authors:
; ;  [1]
  1. INTERA, Inc./CRWMS M&O, Las Vegas, NV (United States)
Publication Date:
Research Org.:
TRW, Inc., Fairfax, VA (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
206639
Report Number(s):
CONF-951155-90
ON: DE96006376; TRN: 96:008801
DOE Contract Number:
AC01-91RW00134
Resource Type:
Conference
Resource Relation:
Conference: Fall meeting of the Materials Research Society (MRS), Boston, MA (United States), 27 Nov - 1 Dec 1995; Other Information: PBD: [1995]
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 05 NUCLEAR FUELS; 99 MATHEMATICS, COMPUTERS, INFORMATION SCIENCE, MANAGEMENT, LAW, MISCELLANEOUS; PITTING CORROSION; COMPUTERIZED SIMULATION; CONTAINERS; PERFORMANCE TESTING; HIGH-LEVEL RADIOACTIVE WASTES; UNDERGROUND DISPOSAL; CONTAINMENT; LEAKS; YUCCA MOUNTAIN; MOISTURE; ALLOYS; CARBON STEELS

Citation Formats

Lee, J.H., Atkins, J.E., and Andrews, R.W.. Humid-air and aqueous corrosion models for corrosion-allowance barrier material. United States: N. p., 1995. Web.
Lee, J.H., Atkins, J.E., & Andrews, R.W.. Humid-air and aqueous corrosion models for corrosion-allowance barrier material. United States.
Lee, J.H., Atkins, J.E., and Andrews, R.W.. 1995. "Humid-air and aqueous corrosion models for corrosion-allowance barrier material". United States. doi:. https://www.osti.gov/servlets/purl/206639.
@article{osti_206639,
title = {Humid-air and aqueous corrosion models for corrosion-allowance barrier material},
author = {Lee, J.H. and Atkins, J.E. and Andrews, R.W.},
abstractNote = {Humid-air and aqueous general and pitting corrosion models (including their uncertainties) for the carbon steel outer containment barrier were developed using the corrosion data from literature for a suite of cast irons and carbon steels which have similar corrosion behaviors to the outer barrier material. The corrosion data include the potential effects of various chemical species present in the testing environments. The atmospheric corrosion data also embed any effects of cyclic wetting and drying and salts that may form on the corroding specimen surface. The humid-air and aqueous general corrosion models are consistent in that the predicted humid-air general corrosion rates at relative humidities between 85 and 100% RH are close to the predicted aqueous general corrosion rates. Using the expected values of the model parameters, the model predicts that aqueous pitting corrosion is the most likely failure mode for the carbon steel outer barrier, and an earliest failure (or initial pit penetration) of the 100-mm thick barrier may occur as early as about 500 years if it is exposed continuously to an aqueous condition at between 60 and 70{degrees}C.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1995,
month =
}

Conference:
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  • The Yucca Mountain Site Characterization Project is evaluating candidate materials for high level nuclear waste containers (Waste Packages) for a potential deep geologic repository at Yucca Mountain, Nevada. The potential repository is located above the water table in the unsaturated zone. The rock contains nominally 10% by volume water and gas pressure in the emplacement drifts of the repository is expected to remain near the ambient atmospheric pressure. The heat generated by the radioactive decay of the waste will raise the temperature of the waste packages and the surrounding rock. Waste Package temperatures above the ambient boiling point of watermore » are anticipated for the waste emplacement scenarios. Because the repository emplacement drifts are expected to remain at the ambient atmospheric pressure, the maximum relative humidity obtainable decreases above the boiling point of water. Temperatures of the Waste Packages and the surrounding rock are expected to reach maximum temperature within 100`s of years and then gradually decrease with time. Episodic liquid water contact with the WPs is also expected; this will result in the deposition of salts and mineral scale.« less
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  • Current conceptual designs for radioactive waste disposal containers for repositories call for a thick outer barrier of corrosion-allowance material such as carbon steel and a thinner inner barrier of corrosion-resistant material. A model has been developed for calculating the contribution of the corrosion-allowance material to containment life. The model is based on the equation of Stahl for immersed aqueous corrosion of low-carbon steel. Corrosion depth was calculated as a function of time for both the expected environment (humid air) and enhanced corrosion. For the mass loadings considered, the calculated corrosion penetration after 10 (exp 5) years was never greater thanmore » 60 mm, whereas the proposed barrier thickness is 100 mm. Thus, the corrosion-allowance barrier in proposed conceptual designs will be long-lived under expected conditions. No evidence was found that high mass loadings will lead to early, catastrophic failures. Modelling of unexpected conditions produced earlier failures due to less protective oxides and larger rate constants. These effects can be mitigated by using a high mass loading to produce dry conditions.« less