Date of Award

Spring 1-1-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Yunping Xi

Second Advisor

Franck Vernerey

Third Advisor

Jeong-Hoon Song

Fourth Advisor

Mija H. Hubler

Fifth Advisor

Ross B. Corotis

Abstract

To ensure safe operation of nuclear power plants (NPPs) during their service life and enhance the performance of spent nuclear fuel (SNF) storage systems, comprehensive investigation on the behavior of concrete and their components under the long-term nuclear radiation is needed. A theoretical model was developed first to predict the deterioration of concrete under neutron radiation, taking into account both of the effects of neutron radiation and the radiation-induced heating on the mechanical property and volume change of concrete. It was shown that the volume change of concrete is dominated by the expanding characteristic of aggregates. Since neutron radiation can deteriorate mechanical properties of the concrete materials, it’s critical to obtain the accurate neutron radiation levels in concrete structures during their service live. Neutron diffusion equations and heat conduction equation were used for prediction of neutron radiation and thermal field in concrete, respectively. The effects of potential variations of transport properties due to neutron radiation and elevated temperature on neutron diffusion in concrete were estimated. A simplified example of a typical concrete biological shielding wall was analyzed up to 80 years, and the results were discussed. The results show that neutron radiation and elevated temperature can result in considerable increases of neutron flux and fluence in the concrete. In order to understand the current state of knowledge about nuclear irradiated concrete, a collection of articles on neutron and gamma-ray radiation damage to concrete and/or its components was acquired. Information on testing conditions and concrete performance was extracted from the collected literature, and a database was developed. Data analysis of the effect of neutrons levels, water-cement ratio, aggregate fraction, and temperature on various properties of cementitious materials subjected to neutrons irradiation was conducted, and the results were presented. In order to monitor the long-term deterioration process of concrete used in NPPs, the self-sensing capability of carbon fiber reinforced cementitious composites under mechanical loading and elevated temperature was experimentally studied, and the results were described. It has potential to become a sensor and can be used to monitor the long-term variation of strain in concrete of NPPs structures or SNF storage systems.

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