Grizzly 3D LWR reactor pressure vessel probabilistic fracture mechanics model

[bwspenc]

Model Description

This is a 3D probabilistic fracture mechanics model of a reactor pressure vessel (RPV) in a pressurized water reactor, run with the Grizzly code. This model has two stages. The first stage computes the thermomechanical response of the RPV in a postulated loss-of-coolant accident transient that results in pressurized thermal shock conditions. The second stage uses the results of the thermomechanical simulation as input, and uses a Monte Carlo method to compute the overall probability of fracture given occurrence of that transient, based on evaluations of samplings of the population of flaws in the RPV.

The thermomechanical model uses a 3D mesh. It can run on a workstation (on the order of 10 hours to run on 8 processors), but runs much faster on HPC. The probabilistic fracture model can also be run on a workstation with a small number of RPV samples (1000), but requires running on HPC spread out across multiple nodes to run with the 50,000 samples required for Monte Carlo convergence. The input files are set up to run the full cases, but the 'tests' file is set up to run abbreviated versions of both of these.

Project description

This model was developed by Ben Spencer and Will Hoffman at INL. Model development was funded by the DOE LWRS and NEAMS programs. Maintenance of this capability will continue under the NEAMS program.

Impact

Grizzly is uniquely able to model RPV fracture in 3D. This will be a useful case to use as a basis for studies that couple Grizzly with other 3D codes.