An Adaptive Model for Decay Heat Estimation Using Scram Curves

This study introduces an adaptive model for estimating decay heat in nuclear reactors, particularly
during transient scenarios with steadily reducing reactor power. Traditional approaches to decay
heat calculation often rely on extensive nuclide tracking or standardized procedures. The former
approach can be resource-intensive, requiring detailed tracking of a multitude of nuclides, while the
latter often has limited applicability. The adaptive model proposed in this paper offers an alternative
solution that circumvents these challenges by utilizing precalculated decay heat curves from scram
scenarios. This methodology allows for on-the-fly decay heat calculation during simulation, adapting
to varying power levels without the need for detailed nuclide tracking.
The paper provides a description of the adaptive model, including its mathematical framework
and operational procedure. The model’s test case is developed using the IAEA benchmark exercise
related to the loss of flow without scram test conducted at the Fast Flux Test Facility, a sodium-cooled
fast reactor. The model is verified through single assembly calculations, where it demonstrates high
accuracy in comparison to the depletion solver of the Monte Carlo code Serpent. This demonstrates
the model’s potential as a promising alternative for decay heat estimation in the analysis of accident
scenarios.