Computer Modeling of Nuclear Waste Storage Canister Corrosion

Computer Modeling of Nuclear Waste Storage Canister Corrosion
Author:
Publisher:
Total Pages:
Release: 1979
Genre:
ISBN:
GET BOOK

Current plans for nuclear waste disposal include placing the waste in a canister to isolate it from the repository environment for 1000 years. Corrosion prediction techniques are currently inadequate to quarantee the canister performance over this length of time. We are attempting to better predict the corrosion process with the help of computer modeling. We developed a program to calculate anodic and cathodic polarization curves using Tafel slopes, equilibrium exchange current densities, and other electrochemical parameters obtained from the experimental corrosion literature. The model generates and displays polarization curves for different values of environmetal parameters such as temperature, pH, and concentrations of pertinent species in the vicinity of the canister material. For the case of uniform corrosion in acidic media, our model predicts corrosion rates in fair agreement with literature values.

Modeling the Corrosion of High-level Waste Containers

Modeling the Corrosion of High-level Waste Containers
Author:
Publisher:
Total Pages: 14
Release: 1998
Genre:
ISBN:
GET BOOK

A key component of the Engineered Barrier System (EBS) being designed for containment of spent-fuel and high-level waste at the proposed geological respository at Yucca Mountain, Nevada is a two-layer canister. In this particular design, the inner barrier is made of a corrosion resistant material (CRM) such as Alloy 825, 625 or C-22, while the outer barrier is made of a corrosion-allowance material (CAM) such as A516 or Monel 400. At the present time, Alloy C-22 and A516 are favored. This publication addresses the development of models to account for corrosion of Alloy C-22 surfaces exposed directly to the Near Field Environmental (NFE), as well as to the exacerbated conditions in the CAM-CRM crevice.

Nuclear Corrosion Modeling

Nuclear Corrosion Modeling
Author: Roy Castelli
Publisher: Butterworth-Heinemann
Total Pages: 195
Release: 2009
Genre: Science
ISBN: 9781856178020
GET BOOK

Corrosion in nuclear power plants cause reductions in efficiency and increases in deposit build-up on plant surfaces, making for expensive maintentance and potential radiological health hazards. This book guides studies to predict and minimize corrosion, thus making nuclear power safer and more cost effective. Too often, reliance on empirical models and on-site testing of existing plants makes study and prediction of corrosive effects in nuclear reactors into a pricey and lengthy process. Introducing the experimental procedures, set up, sample preparation and computer modeling suggested in this book will save precious time and resources in a field where the significant time and expense to get and keep plants on-line are two of the chief concerns preventing broader commerical viability. * The only book to focus exclusively on preventing nuclear corrosion * Uses computer modelling to tie together chemical engineering, civil engineering, corrosion science, and nuclear engineering into a cohesive solution to a vexing nucelar problem * Includes all fundamental equations, example data sets and experimental techniques

Electrochemical and modelling studies on simulated spent nuclear fuel corrosion under permanent waste disposal conditions

Electrochemical and modelling studies on simulated spent nuclear fuel corrosion under permanent waste disposal conditions
Author: Nazhen Liu
Publisher:
Total Pages:
Release: 2017
Genre: Radioactive waste canisters
ISBN:
GET BOOK

The safety assessment models for the deep geological disposal of spent nuclear fuel require a fundamental understanding of the corrosion of spent fuel in a failed waste container. The overall research goal of this project is to investigate the corrosion of simulated spent fuel under permanent disposal conditions, using both model simulations and experimental investigations. A model for fuel corrosion has been expanded to determine the relative importance of radiolytic hydrogen and hydrogen from corrosion of the steel vessel in suppressing fuel corrosion. It was shown that, for CANDU (CANada Deuterium Uranium) fuel with moderate in-reactor burnup, only micromolar concentrations of hydrogen from steel corrosion are required to completely suppress fuel corrosion. In a partially closed system (i.e., within cracks in the fuel) radiolytic hydrogen alone can suppress corrosion to a negligible level. The model was validated by comparing the calculated corrosion rates with published measurements. Agreement between calculated and measured rates indicated that corrosion is controlled by the rate of radiolytic production of oxidants, in particular hydrogen peroxide, irrespective of the reactivity of the fuel. Experimentally, the influence of rare earth doping on the reactivity of UO2 was investigated. For REIII-doped UO2, the onset of matrix dissolution was accompanied by the enhanced oxidation of the matrix to UIV1{u2212}2xUV2xO2+x. This can be attributed to the onset of tetragonal lattice distortions as oxidation proceeds which leads to the clustering of defects, enhanced diffusion of OI (interstitial oxygen)to deeper locations and destabilization of the fluorite lattice. A further investigation of the doping effect was performed on a series of (U1{u2212}yGdy)O2 materials (y = 0, 0.01, 0.03, 0.05, 0.07 and 0.10). Overall the increase in doping up to 10% does not exert a major influence on reactivity possibly due to the competition between an increase in the number of (Ov)s (oxygen vacancy) and a contraction in the lattice constant.