Research Programs

Advanced Nuclear Power

-- Select program -- A Very Long Cycle Boiling Water Reactor Solid Hydride Fuel for Long-Lived LWR Core Design Investigation of Nanofluids for Nuclear Applications Supercritical Water Reactors Advanced Gas Cooled Modular Pebble Bed Reactors Fission Product Barrier Integrity Fuel Performance Modeling High Performance Alloy Development for Liquid Metal Service Supercritical CO2 Power Conversion System Methods for Risk-Informing Future Reactor Regulation Gas Cooled Fast Reactor Evaluation

Publications:

1. J. Wang, R.G. Ballinger, “The Effect of Design and Uncertainty on Coated Particle Fuel Reliability,” ANS Annual Summer Meeting, San Diego, CA June 1-5, 2003
2. J. Wang, R.G. Ballinger, J.T. Diecker, “Design Optimization and Analysis of Coated Particle Fuel Using Advanced Fuel Performance Modeling Techniques,” Second Topical Meeting on High Temperature Reactors 2004 (HTR-2004), Beijing, China, September 22-24, 2004.
3. J. Wang, R.G. Ballinger, “Fracture Mechanics Based Coated Particle Fuel Failure Models,” Second Topical Meeting on High Temperature Reactors 2004 (HTR-2004), Beijing, China, September 22-24, 2004.
4. J. Wang, R.G. Ballinger, H. J. MacLean, J.T. Diecker, “TIMCOAT: An Integrated Fuel Performance Model for Coated Particle Duel,” Second Topical Meeting on High Temperature Reactors 2004 (HTR-2004), Beijing, China, September 22-24, 2004.

Investigators

• Ronald Ballinger
• Jane Diecker
• Chaiyod Soontrapa

Fuel Performance Modeling

One of the critical elements of the pebble bed reactor is the performance of the microsphere fuel. Since traditional containments are not deemed necessary for the pebble bed reactor, the integrity and quality of the fuel becomes a key to the safety of the plant. Most modern high-temperature gas reactors use TRISO fuel, which is a multi-layered coated particle of fissile material. The primary containment function is provided by a silicon carbide layer which is applied by a chemical vapor deposition (CVD) process to each microsphere. The coated particle consists of a low density graphite buffer layer to accommodate fission gas release, and an inner and outer pyrocarbon layer (on either side of the SiC layer) to provide protection for the silicon carbide.

An analytical fuel performance model of the fuel microsphere has been developed and benchmarked to tests performed by the Department of Energy for the NPR reactor fuel. The code has been subsequently used to optimize fuel design for the modular pebble bed reactor which has identified some fuel design changes that would reduce the probability of fuel failure. The model is undergoing further improvements that will allow it to more accurately predict time to failure. Among these modifications are the inclusion of a fuel chemistry model and the expansion of capability to allow use of the model in transient and accident conditions.