Solution of the Lambda modes problem of a nuclear power reactor using an h–p finite element method

•An hp finite element method is proposed for the Lambda modes problem of a nuclear reactor.•Different strategies can be implemented for increasing the accuracy of the solutions.•2D and 3D benchmarks have been studied obtaining accurate results.

Lambda modes of a nuclear power reactor have interest in reactor physics since they have been used to develop modal methods and to study BWR reactor instabilities. An h–p-Adaptation finite element method has been implemented to compute the dominant modes the fundamental mode and the next subcritical modes of a nuclear reactor. The performance of this method has been studied in three benchmark problems, a homogeneous 2D reactor, the 2D BIBLIS reactor and the 3D IAEA reactor.