Core Design of Pressurized Water Reactors with Fully Ceramic Microencapsulated Fuel
Open Access
- Author:
- Shapiro, Rachel Ann
- Graduate Program:
- Nuclear Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- None
- Committee Members:
- Massimiliano Fratoni, Thesis Advisor/Co-Advisor
Arthur Thompson Motta, Thesis Advisor/Co-Advisor
Maria Nikolova Avramova, Thesis Advisor/Co-Advisor - Keywords:
- PWR
TRISO
accident-tolerant fuel
fully ceramic microencapsulated fuel
neutronics - Abstract:
- Fully ceramic microencapsulated (FCM) fuel is an accident tolerant design that takes advantage of TRISO technology, embedding the particles in a ceramic matrix (SiC) to form fuel pellets and rods. Surrounded by a SiC clad, the FCM design offers improved fission product retention and eliminates zirconium altogether - providing enhanced performance over conventional UO2/zirconium-alloy fuel in terms of preventing a high temperature steam-zirconium reaction. To be implemented in current or future PWRs, FCM fuel must meet or exceed the neutronic performance of standard fuel. Limited by low heavy metal loading, an FCM fuel assembly requires high enrichment and large fuel rods to match the cycle length of a standard fuel assembly. This study investigated the core design, neutronics and thermal-hydraulics of a PWR loaded with FCM fuel and sought to optimize the assembly design to minimize the enrichment required to reach fuel performance similar to that of conventional fuel. It was found that the implementation of FCM fuel in a 17x17 assembly requires close to 20% enrichment and large fuel rods. This design performs comparably to standard fuel (4.5% enrichment) in terms of cycle length, reactivity coefficients, intra-assembly power peaking factor, burnable poison penalty, and control rods worth, but requires an increase of pumping power. A parametric analysis spanned a large design space varying fuel outer diameter and pitch-to-diameter ratio, and down selected two alternate assembly designs: 11x11---1.65 cm outer diameter and 1.18 P/D, and 9x9---2.12 cm outer diameter and 1.12 P/D. These designs meet the cycle length requirement with 18.6% and 16.2% enrichment, respectively, but feature smaller MDNBR compared to a reference assembly. It was estimated that a slight increase in rod outer diameter increases MDNBR to the desired level and implies a pressure increase of 10%.