Morteza Imani

IR-FRA: Thermomechanical Analysis of Fuel Rods (PWR)

IR-FRA is a numerical code I developed during my M.Sc. (2011–2014) at Shahid Beheshti University for steady-state, long-term thermo-mechanical analysis of light-water reactor fuel rods (PWR/WWER). The project was supported by the Management & Construction of Nuclear Power Plant Company of Iran and implemented by me at SBU. IR-FRA models pellet–cladding interaction (PCI), gap conductance, creep, swelling/densification, fission-gas release, and temperature/stress fields along the rod to inform performance and safety assessments.

Fuel performance PCI / PCMI Finite Element + Virtual Work

Purpose & capability

  • Predict temperature, stress/strain, displacement in fuel & cladding.
  • Model gap heat transfer (gas conduction, contact, radiation) and oxide growth.
  • Simulate PCI/PCMI over long burnups with creep down, swelling, densification.
  • Estimate fission gas release and plenum pressure evolution.

Outcomes

  • Benchmarked against reference codes (e.g., FROBA, BISON) and published/experimental data.
  • Computed contact timing and gap evolution consistent with WWER1000 data.
  • Modular structure for axial segmentation and burnup-dependent material models.

Technical scope (non-sensitive)

Thermal

Radial heat conduction in pellet/clad; coolant convection (Dittus–Boelter/Jens–Lottes), burnup-dependent UO2 conductivity, oxide layer growth, and composite gap conductance.

Mechanical

Equilibrium from the principle of virtual work with generalized plane-strain; finite-element solution for u–ε–σ; fuel swelling & densification; cladding creep-down.

Fission gas

Diffusion/release model for grain/grain-boundary transport; coupling to gap pressure and thermal conductance across burnup.

Publication

  • Annals of Nuclear Energy (2015) — Numerical study of fuel–clad mechanical interaction during long-term burnup of WWER1000. DOI